2010 Annular Solar Eclipse PFS Bulletin No. 5

FOREWORD

This is 2010 Annular Solar Eclipse PFS Bulletin No. 5, the final forecast update before the eclipse, issued in both English and Chinese. No major changes were made on the forecast philosophy since last bulletin. The forecast diagrams mentioned below may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=2, http://www.fnmoc.navy.mil and http://www.ecmwf.int. Numeric forecast for various locations may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=1. RSS feed of this service is available at http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=46.

ANALYSIS

The three global models, NCEP GFS at JAN14/00Z, ECMWF at JAN 12/12Z, and FNMOC NOGAPS JAN 13/18Z now show an almost consistent forecast: a significant westerly trough over central Yangtze Valley and Western Sichuan Plateau with an associated wet area south of the annularity path to 116E over east. The 1030hPa contour reaches 30N, but the near-surface wind forecast suggests the winter monsoon has weaken at that time. NOGAPS suggested that the visibility of most part of Myanmar, Sichuan Basin, Central Yangtze Valley and nearby area would be poor. EFS suggested a minimum chance of rain along the annularity path.

OBSERVATION

Here is a list of the weather on Jan. 13 of some major cities along the annularity path:

• Mandalay, Myanmar: sunny, visibility around 8 km.
• Ruili, China: overcast to broken clouds, visibility around 20 km.
• Dali, China: sunny, visibility near 30 km.
• Chongqing, China: mist and fog, visibility around 3 km.
• Nanyang, China: mainly sunny, visibility over 20 km.
• Jinan, China: sunny, visibility around 23 km.
• Qingdao, China: sunny, visibility around 15 km.

FORECAST

The divergence between the models is minimum, therefore, the uncertainty of this forecast is reduced to minimum. This forecast also makes use of ground-based observation and satellite data.

Local forecasts are listed below.

• In Myanmar: mainly sunny with a few clouds, with some haze in valley.
• In Yunnan, China: mainly sunny with a few clouds and good visibility.
• Around Chongqing, China: mist and fog, with low visibility, but sunshine is possible on highlands.
• Around Shiyan and Nanyang, China: broken clouds, but likely to be cirrus, with low to fair visibility.
• In Shandong, China: cloudy, but likely to be cirrus, the visibility shall be fair.

REVIEW UPDATE

Before Feburary 28.

2010 Annular Solar Eclipse PFS Bulletin No. 4

FOREWORD

This is 2010 Annular Solar Eclipse PFS Bulletin No. 4, issued in both English and Chinese. No major changes were made on the forecast philosophy since last bulletin. The forecast diagrams mentioned below may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=2, http://www.fnmoc.navy.mil and http://www.ecmwf.int. Numeric forecast for various locations may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=1. RSS feed of this service is available at http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=46.

ANALYSIS

NCEP GFS JAN12/06Z's forecast shows a significant westerly trough around 103E 28N, the associated wet area reaches 116E over the annularity path. Over the east, the 1030hPa contour reaches 30N, but the near-surface wind forecast suggests the winter monsoon has weaken at that time.

ECMWF JAN12/00Z's forecast shows the same westerly trough over western China, but is about 3-5 degrees west of GFS's forecast. Meanwhile, ECMWF gives a slightly stronger winter monsoon persisting over East China.

FNMOC NOGAPS JAN12/06Z's forecast gives a westward westerly trough located between the ECMWF's prediction and GFS's prediction, centred at 100E, 28N. NOGAPS also expect a strong but weakening winter monsoon persisted over east, with 1030hPa contour reaches as south as 25N. NOGAPS also notes low visibility (<10km) may be applied at Sichuan Basin and at the annularity path over Yangtze Valley. FNMOC EFS JAN12/06Z's forecast suggests minimum chance for significant rainfall along the annularity path.

For analyses of the models above, we can depict: a westerly trough lies at somewhere over the northern Indo-China Peninsula, and a winter monsoon is weakening over mainland China; however there is still considerable divergence over the location of the westerly trough between the models.

FORECAST

Since the divergence between the models is still quite significant, the uncertainty of this forecast remains moderate. The situation varies over the models. If GFS gets it right (on an eastward trough and a weak winter monsoon), then we can expect a fair weather over the west of Yunnan, but generally poor sky around Sichuan Basin and some parts of Central and South China. However, statistically ECMWF has a better performance, and what is more, NOGAPS also suggests a slow moving trough, so in this forecast the author consider the situation of a slow moving trough and a slow weaken monsoon. It should point out that many weather websites employ GFS, which is somehow against the philosophy of this forecast, as their numeric model, so there can be significant difference between this forecast and the weather information from the internet.

Local forecasts are listed below.

• In Myanmar: mainly clear with a few clouds, with some haze in valley. More clouds to the northeast.
• In Yunnan, China: mainly cloudy along the annularity path; however, if the westerly trough moves faster than expected (or close to GFS's forecast), then there will be a good chance for a less cloudy or even sunny weather.
• Around Chongqing, China: foggy.
• Around Shiyan and Nanyang, China: sunny weather possible with fair visibility for solar observation at low elevation.
• In Shandong, China: sunny or less cloudy weather possible, but the visibility may be low for solar observation at low elevation.

NEXT UPDATE

Brief final update around January 14 0400 UTC.

2010 Annular Solar Eclipse PFS Bulletin No. 3

FOREWORD

This is 2010 Annular Solar Eclipse PFS Bulletin No. 3, issued in both English and Chinese. There are some changes on the forecast philosophy. The forecast diagrams mentioned below may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=2, http://www.fnmoc.navy.mil and http://www.ecmwf.int. Numeric forecast for various locations may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=1. RSS feed of this service is available at http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=46.

ANALYSIS

NCEP GFS JAN10/06Z's forecast shows a significant westerly trough over 105-107E at 25N-35N, the associated wet area reaches 116E over the annularity path. Over the east, the 1030hPa contour reaches 30N, but the near-surface wind forecast suggests the winter monsoon has weaken at that time.

ECMWF JAN10/00Z's forecast shows the same westerly trough over western China, but is about 5 degrees west of GFS's forecast. Meanwhile, ECMWF gives a slightly stronger winter monsoon persisting over East China.

FNMOC NOGAPS JAN10/06Z's forecast gives an even more westward westerly trough, centred at 95E, 25N and extend to West Sichuan Plateau. NOGAPS also expect a strong but weakening winter monsoon persisted over east, with 1030hPa contour reaches as south as 25N. NOGAPS also notes low visibility (<10km) may be applied at Sichuan Basin and Zhengzhou nearby area. FNMOC EFS JAN10/06Z's forecast suggests a chance for significant rainfall at 0-20% is expected along the annularity path over Yunnan, Sichuan and Chongqing.

For analyses of the models above, we can depict: a westerly trough lies at somewhere over the northern Indo-China Peninsula, and a winter monsoon is weakening over mainland China; however there is significant divergence over the location and strength of the westerly trough between the models.

FORECAST

Since the divergence between the models is significant, the uncertainty of this forecast increases to moderate to large. The situation varies over the models. If GFS gets it right (on an eastward trough and a weak winter monsoon), then we can expect a fair weather over the west of Yunnan, but generally poor sky around Sichuan Basin and along the annularity path over east. However, statistically ECMWF has a better performance, and what is more, NOGAPS also suggests a slow moving trough, so in this forecast the author consider the situation of a slow moving trough versus a slow weaken monsoon. It should point out that many weather websites employ GFS, which is somehow against the philosophy of this forecast, as their numeric model, so there can be significant difference between this forecast and the weather information from the internet.

Local forecasts are listed below.

• In Myanmar: partly cloudy, with some haze in valley. More clouds to the northeast.
• In Yunnan, China: mainly cloudy or overcast along the annularity path, may be a few rain patches. Rains more likely over east of 102E.
• Around Chongqing, China: foggy with drizzles.
• Around Shiyan and Nanyang, China: sunny or less cloudy weather possible with fair visibility for solar observation at low elevation.
• In Shandong, China: sunny weather possible, but the visibility may be low for solar observation at low elevation.

NEXT UPDATE

January 12 at 1600 UTC or when changes apply on forecast philosophy.

2010 Annular Solar Eclipse PFS Bulletin No. 2

OVERVIEW

This is 2010 Annular Solar Eclipse PFS Bulletin No. 2, issued in both English and Chinese. There is 7 days away from the event, uncertainty for this forecast is small. The forecast diagrams mentioned below may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=2, http://www.fnmoc.navy.mil and http://www.ecmwf.int. Numeric forecast for various locations may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=1. RSS feed of this service is available at http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=46.

ANALYSIS

NCEP GFS JAN08/06Z's forecast shows a significant dry area over Yunnan and Central China on the height of 850mb humidity shows there is a large dry area over Central China and western Indo-China Peninsula. The Mean Sea Level Pressure shows the 1020hPa contour reaches 25N, indicating a mild winter monsoon persisting over mainland China. However, there is no notable feature on 500hPa geopotential height forecast.

ECMWF JAN08/00Z's forecast shows a mild to strong winter monsoon is persisting over Central China as the 1020hPa reaches near 20N, the southern limit of 1030hPa contour is about 2-3 degrees south of the GFS's prediction. Again, no notable feature is shown on 500hPa geopotential height forecast.

FNMOC EFS JAN08/00Z's forecast suggests a weakening winter monsoon with 1020hPa reaches 20N but 1030hPa near 35N. It also suggests a chance of significant rainfall (generally less than 10%) along the path from Ruili to Nanyang at the day time of January 15.

For analyses of the models above, we can depict a persisting but probably mild and/or weakening winter monsoon over mainland.

FORECAST

Since the models have came to a rough agreement on the strength of winter monsoon, the uncertainty of this forecast is reduce to small. Local forecasts are listed below. Please be aware that the forecast philosophy may trim as there is still 7 days to go for the event.

• In Myanmar: sunny, with some haze in valley.
• In Yunnan, China: generally sunny, a few or some clouds to the east, but the cloud amount may still allow an enjoyable observation along the annularity path.
• Around Chongqing, China: foggy, but sunshine is likely over highlands.
• Around Nanyang, China: mainly sunny, the visibility is estimated to be 15 km or better, allowing a reasonably good sky for low elevation observation.
• In Shandong, China: mainly sunny, the visibility is estimated to be about 10-15 km or better, it is possible for observers to get the "fire ring" at horizon.

NEXT UPDATE

January 10 at 1500 UTC or earlier.

2010 Annular Solar Eclipse PFS Bulletin No. 1

OVERVIEW

This is 2010 Annular Solar Eclipse PFS Bulletin No. 1, issued in both English and Chinese. There is 10 days away from the event, uncertainty for this forecast is moderate. The forecast diagrams mentioned below may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=2, http://www.fnmoc.navy.mil and http://www.ecmwf.int. Numeric forecast for various locations may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=1. RSS feed of this service is available at http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=46.

ANALYSIS

NCEP GFS JAN05/06Z's forecast on 500hPa geopotential heights of JAN15/06Z revealed two moderate westerly troughs over western Yunnan-Guizhou Plateau and Huai Valley. However, the forecast on 850mb humidity shows there is a large dry area over Central China and western Indo-China Peninsula. The Mean Sea Level Pressure shows the 1030hPa contour well-controls most of China, indicating a strong winter monsoon persisted.

ECMWF JAN05/00Z's forecast on 500hPa geopotential heights of JAN15/00Z shows a mild to strong winter monsoon is persisting over Central China. A significant westerly trough stays at Yunnan-Guizhou Plateau, but about 5 degrees east of GFS's. The 1030hPa reaches Liaodong Peninsula and Yangtze Valley.

For analyses of the models above, we can depict the existence of a significant winter monsoon over mainland with a rapids zone over the Yellow Sea, and a significant westerly trough over somewhere in the Yunnan-Guizhou Plateau.

FORECAST

Since there are notable divergences over the strength of winter monsoon and the exact position of westerly trough, the uncertainty for this forecast is moderate. Local forecasts are listed below. Please be aware that the forecast philosophy may change as there is still 10 days to go for the event.

• In Myanmar: clear, with some haze in valley.
• In Yunnan, China: more cloud to east, the cloud can be heavy for observation to the east of, probably, 102E.
• Around Chongqing, China: fog with drizzles, but can be cloudy over northeast.
• Around Nanyang, China: mainly clear, according to near ground forecast and observation over past five years, the visibility may be 15 km or better, allowing a reasonably good sky for sun at low elevation.
• In Shandong, China: mainly clear, according to near ground forecast and observation over past five years, the visibility may be about 10 km. If GFS is right on a strong winter monsoon, then the visibility over Central and East China can be much better.

NEXT UPDATE

January 8 at 1500 UTC or earlier.

July 22 Great Solar Eclipse PFS Bulletin No. 14 [FINAL]

OVERVIEW

This is July 22 Great Solar Eclipse PFS Bulletin No. 14 [FINAL], issued in both English and Chinese. Observations and analysis of the actual weather on July 22 as well as review and conclusion of this compaign are presented.

OBSERVATIONS

Satellite observations

Images from geostationary meteorological satellite Fengyun 2-D of totality zone over mainland China on July 22 0045Z, 0115Z and 0115Z are shown as Figure 1, 2 and 3, with the totality eclipse path manually marked in red line.

Figure 1: Fengyun 2-D image of totality zone over mainland China on July 22 at 0045Z (raw size)

Figure 2: Fengyun 2-D image of totality zone over mainland China on July 22 at 0115Z (raw size)

Figure 3: Fengyun 2-D image of totality zone over mainland China on July 22 at 0145Z (raw size)

Images from geostationary meteorological satellite Fengyun 2-C of totality zone over East Asia and western Pacific Ocean on July 22 from 0000Z to 0330Z with 30min interval are shown as Figure 4-11 (listed at the buttom). An animation of these images is also shown below (click for raw size file).

Animation 1: Fengyun 2-C animation from July 22 0000Z to 0330Z of East Asia and western Pacific Ocean (raw size - 18.2M)

Surface observations

• Surat, India: SYNOP (42840) data depicts an overcast weather with 10/10 cloud cover and moderate rain at 0000Z. Sky condition was about the same at 0300Z.
• Bhopal, India: SYNOP (42667) data depicts an overcast weather with 10/10 cloud cover and light rain at 0000Z. Sky condition was about the same at 0300Z. The data also depicts a temperture drop of 0.4C from 21/1800Z to 22/0000Z and a difference of 1.8C between 21/0000Z and 22/0000Z under similar weather situations.
• Patna, India: SYNOP (42492) data depicts a partly cloudy weather with 9/10 cloud cover at 0000Z and 8/10 cloud cover at 0300Z. The clouds were mainly stratocumulus cumulogenitus at 00Z (5/10), becoming cumulostratus and alto cumulus translucidus at 03Z (each 4/10).
• Litang, China: SYNOP (56257) data depicts a mostly clear weather with 4/10 cloud cover at 0000Z, the clouds were stratocumulus cumulogenitus and cirrus densus (each 2/10), with the buttom at a height of 600-1,000 meters. The weather had become more cloudiness at 0300Z, with 9/10 cloud cover, but most of the clouds were cirrus densus (8/10). Observers around this area (Haizikou Pass, Dinggong Grassland, Derong) reported successful observing and similar weather situation. No significant drop of temperature was observed at 0000Z according to the data.
• Kangding, China: SYNOP (56374) data depicts an overcast weather with 10/10 cloud cover (all were stratocumulus cumulogenitus) at 0000Z, becoming 9/10 with mainly cumulus (7/10) at 0300Z. Observers in this area reported observing failures. However, observers at Zimei Pass (approximately 70 kilometers southwest) reported a "mostly clear" weather during the totality. No significant drop of temperature was observed at 0000Z according to the data.
• Chengdu, China: METAR (ZUUU) data depicts a mainly cloudy weather with a few showers around the time of eclipse.
• Chongqing, China: SYNOP (57516) data depicts a fine weather with 7-8/10 cloud cover (all were cirrus densus) at 0000Z and 0300Z. Eclipse observations around this area were successful. No significant drop of temperature was observed around the totality according to the SYNOP data and METAR data from ZUCK.
• Yichang, China: SYNOP (57461) data depicts a mostly clear weather with 5/10 cloud cover at 0000Z, mostly alto cumulus translucidus and cirrus densus; at 0300Z the sky was even better, with 2-3/10 cloud cover. Eclipse observations around this area (such as Yichang, Jingzhou, Jingmen) were highly successful. The data also depicts a temperture difference of 0.8C between 21/0000Z and 22/0000Z and 2.3C between 21/0300Z and 22/0300Z under similar weather situation of the two days.
• Wuhan, China: SYNOP (57494) data depicts a mostly cloudy weather with 9/10 cloud cover at 0000Z and 0300Z with cirrus densus and growing alto cumulus translucidus. Cloud blocked the totality in some areas; in other areas the totality were not satisfying due to cirrus. The temperture at 0200Z was approximately 1C lower than 0100Z according to METAR data from ZHHH.
• Anqing, China: SYNOP (58424) data depicts a mostly cloudy weather with 9/10 cloud cover (all were alto cumulus opacus) at 0000Z and 0300Z. Generally speaking, observations around this area (including Tongcheng, Tongling, Xuancheng) were unsatisfying, with several sites (generally close to the Yangtze River) failed to see the totality. But observers about a hundred kilometers to the south (Huangshan, Jiujiang) enjoyed a much better view of the totality.
• Hangzhou, China: SYNOP (58457) data depicts a mostly cloudy weather with 9/10 cloud cover at 0000Z and 0300Z with mostly stratocumulus cumulogenitus and alto cumulus translucidus. Observers over the north (such as Shanghai, Suzhou, Wuxi) experienced rain during the eclipse. However, observers around Hangzhou and Ningbo reported that the sky had clear up at the time of eclipse.
• Yaku-shima, Japan: METAR data from RJFG depicts the weather to be cloudy around the time of eclipse with showers at first.
• Iwo Jima, Japan: METAR data from RJAW depicts the weather to be cloudy around the time of eclipse with showers at first. However, reports from Iwo Jima indicating that the totality was visible thru clouds.

ANALYSIS

Surface analysis chart by Hong Kong Observatory at July 22 00Z is shown as Fig. 12. Combining with a 500hPa geopotential height from NOAA/ESRL PSD reanalysis data (Fig. 13), we can see the remain of western Pacific subtropical high over Southeast China and a shearline at around 30N over East China.

Figure 13: July 22 00Z East Asia surface analysis chart by HKO

Figure 14: July 22 00Z 55hPa geopotential height chart by NOAA/ESRL PSD

Combining with products from KMA, JMA, and analysis products of NOGAPS and GFS (graphs not presented), the following features at July 22 00Z can be depicted:

• A deep low pressure was lifting over India Peninsula, bringing cloudy and rainy weather to totality area over India.
• A weak ridge was persisted over 95E on the backside of a low level trough at 105E (over the western Sichuan Basin), the totality area had generally less cloud despite the complex terrain.
• A moderate ridge, possibly the remain of subtropical high, persisted over 110E (eastern Sichuan Basin and western Hubei Province), enabled observers around this area to get an expectional view of the eclipse.
• A large stationary front associated with a mid-latitude cyclone over Hokkaido from eastern Yangtze Valley and East China Sea to Japan was persisted, with a possible weak low pressure area at the buttom (around Wuhan). The front had prevented many sites from the totality; however, a number of observers stayed away from the front were lucky enough to get the eclipse -- although not exceptional -- thru clouds.
• A splitted subtropical high was centred near Taiwan.

REVIEW

PFS for the event was started on July 6. However, it was not until July 9 (bulletin No. 4) did the forecast manage to made a "decent" guess of the weather on July 22. The following paragraph was copied from bulletin No. 4:

...we can expect large areas over Eastern China -- generally east of 115E 30N (i.e. east of the trough) -- are being covered by heavy cloud. Rains are likely, since a clear shear line is presented on the 850hPa wind chart. On the other hand, the weak ridge over central China are possible to bring an acceptable weather to the totality area between Chongqing and Wuhan.

The totality area over India are possible to be under clouds produced by a 500hPa low pressure over northern Gulf of Bengal. Areas over east of Ryukyu Islands are possible to share a cloudless weather granted by the western Pacific subtropical high.

The remark of good weather between Chongqing and Wuhan is exceptional. The remark of unsatisfied weather over east of Wuhan is also consistent with the actual situation. Unfortunately, although "right guess" did occasionary appeared in the following bulletins, the guesses remained unstable until July 17 (bulletin No. 11), i.e. before the employed models depicted a similar situation.

On July 18, 4 days prior to the event, the author published his "final prediction" of the weather on July 22 (bulletin No. 12) before flying to Shangri-La for the eclipse. Combining with the revision (on July 21, bulletin No. 13) and the actual weather conditions listed above, we may sumarize as below:

• Forecast for India goes "mainly cloudy over western and eastern totality area, may be mostly clear around Patna". The forecast generally matches the actual situation despite being somewhat too opmistic, as the satellite data shows the weather was better over east while western India was covered by heavy clouds.
• Forecast for western Sichuan goes "mostly cloudy over west, including big Shangri-La (Deqin, Derong, Daocheng), may be suitable for eclipse for some lucky area. More clouds over eastern part (Gongga Shan/Minya Konka, Ya'an, Emei Shan)" The forecast generally matches the actual situation but had been somewhat too pessimistic. Satellite data and observing reports showed the weather to be partly to mostly clear over the western part. It was indeed cloudy over most area of eastern part, although observers to the west of Gongga Shan/Minya Konka were blessed by a clear region.
• Forecast for Chengdu-Chongqing Plain goes "mainly cloudy with a few showers. There is a weak chance that the weather to be better over east", the chance was upgraded to moderate in the revision bulletin. Generally matches despite its conservativeness.
• Forecast for Hubei Province goes "weak chance for western area (like Enshi) to be better; mainly overcast over the entire province, but clouds may be slightly thinner (may permits a partial eclipse observation) over the south since it locates further from the shearline". The chance was upgraded to moderate in the revision bulletin. Actual weather condition highly matched the trend of this forecast, however it was somewhat too pessimistic even after the revision. The area over west and south was excellent, even some areas in Wuhan did witness the totality.
• Forecast for South Anhui goes "...the southern area of South Anhui might be slightly more promising since it will keep a distance from the shearline...", this matched the case. But according to the satellite data, the area well away from Yangtze Valley also enjoyed a cloudless sky, at least in the morning.
• Forecast for pan-Yangtze River Delta goes "generally overcast with rain". Although a number of cities (such as Shanghai) around this area were indeed overcast with rain, lucky observers around Hangzhou did witness the totality thru a large cloudless region. The author failed to note the possibility of the appearance of such a significant cloudless region.
• Forecast for Ryukyu Islands goes "mainly cloudy, with a few or some sunshines". It seems there were not much observers at this region, but satellite images depicted this forecast was about right.

CONCLUSION

The author notices that in this compaign, the forecast for "possible opmistic" situation (such as the situation for Chongqing and western Hubei Province) were somewhat too conservated. What is more, comparision between actual weather and forecast by automatic numeric model shows the accuracy of the later was not as satisfying as human forecast (such as Fig. 14). Although now being applied into using by 7Timer! and providing a good assistment on assessing the weather situation during this compaign, the 35km NCEP/GFS still needs to incorporate closely with human experiences for a most reliable forecast on great event. The 12km MM5/GFS was even more unsatisfying than 35km NCEP/GFS  and further adjustment is required on the model. After all, from the discussion above we can depict that, the compaign was generally successful, accuracy of the forecast was agreeable for most areas.

Figure 14: GFS JUL21/18Z's cloud cover forecast of July 21 21Z

ACKNOWLEDGEMENTS

• The author is happy to learn that a number of observers had made the right decisions according to his forecast. Total solar eclipses are rare, but not as rare as meteor storms. No matter whether you had witness this eclipse, sooner or later you will have an excellent eclipse somewhere else.
• Original Fengyun 2-C and Fengyun 2-D images are kindly provided by the National Satellite Meteorological Center (NSMC). The original Fengyun 2-D images are kept by Cao Zhiqiang of NSMC.
• The author would like to thank colleague Zhou Linjiong for his valuable discussions and helps of this work. The author would also like to thank Johnson Lau, Dickson Fu, Zhang Linna, Robert Yen, Chen Sisi, Shi Liaoshan and Cheng-Su Diandian for their valuable discussions, contributions and helps.
• The author would like to thank Dr. Cui Chenzhou for providing web service for 7Timer!.
• The author would like to thank all of you for the supports of his work.

July 22 Great Solar Eclipse PFS Bulletin No. 13

I'm about to leave now so I write it short. Generally speaking no big changes on the models. The hope for totality area between Chengdu and Wuhan is now moderate, as on 500hPa and 700hPa there are ridges on the diagram. But after all you are highly advise to check high resolution satellite image started from now. Over Sichuan Basin there are likely to have some low and mid clouds as caused by terrain, meanwhile the hope for area over eastern Yangtze Valley remains weak, but I heard that Tongling City will fire rockets to get the clouds away. On the other hand, one of my friend rang Shanghai Meteorological Bureau and confirmed that Shanghai won't send rockets for clear.

This bulletin shall be the last one before the event, I hope everyone will have the best luck over the a few minutes.

Quanzhi @ Shangri-La

July 22 Great Solar Eclipse PFS Bulletin No. 12

EDITIONAL NOTICE

The server at NAOC (National Astronomical Observatory of China) was scheduled to be offline for maintenance on July 17 at 0400 UTC to 0800 UTC. However, the server was still offline until 1520 UTC due to some technical problems, led to the cancellation of July 17's update. Meanwhile, my departure delayed from July 18 to 19 for some reasons. Thus, bulletin No. 12 would be my final bulletin in detail for the eclipse. So I include all the information available to manage to make my best guess in this bulletin. During these days, I have experienced a work with hard pressure. I would like to have my most grateful thankness to all of you for your supports. Many people (including me) have work hard for many days for the event, and I wish best of luck on July 22 for every of them.

I have made decision to a 4,100m highland in northern Shangri-La (at the edge of Tibet Plateau) for the eclipse. I will fly to Kunming later tomorrow. Internet connections should be available until July 21, so I may be able to write a few lines when possible and necessary.

OVERVIEW

This is July 22 Great Solar Eclipse PFS Bulletin No. 12, issued in both English and Chinese. The forecast reasoning has not changed since previous bulletin. There is only 4 days away from the event. The uncertainty for this forecast remains very small. The forecast diagrams mentioned below may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=2 and http://www.fnmoc.navy.mil. Precision numeric forecast for exact locations may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=1. RSS feed of this service is available at http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=46.

ANALYSIS

NCEP GFS JUL18/00Z's run depicts the following:

1. Western Pacific subtropical high is rapidly weakening from tau 72 thru tau 96 (JUL21/00Z to JUL22/00Z), with its 500hPa 5880gpm contour drifting eastward from mainland China to around 140E. However, 500hPa streamlines forecast still depicts a weak anticyclone (a splitted high) over South China at JUL22/00Z, with a northward ridge locates at about 110E.
2. A Northeast China vortex locates around 130E 46N as indicated by 500hPa geopotential heights and streamlines forecast for JUL22/00Z, with a shallow trough developing and moving from 124E at tau 72 to 133E at tau 96. At tau 96 the trough is expected to extend to northern Ryukyu Islands.
3. A westerly flow is located along 30N as indicated by 700hPa isotachs forecast around tau 96, an associated 700hPa trough is located around 120E 34N to 126E 40N with a 850hPa shearline. An associated area of positive vorticity will move across East China until tau 108.
4. The main body of Arabian Sea subtropical high remains west of 70E around tau 96, a low pressure is located in eastern India Peninsula.

ECMWF JUL18/00Z's run depicts the following:

1. 500hPa geopotential heights of JUL22/00Z also revealed a rapidly weakening subtropical high over East Asia, the situation has no significant difference with the forecast of GFS. The situations of a low pressure over India Peninsula and the westerly flow over East Asia (revealed by 850hPa wind speed) are also close to the GFS's.
2. 850hPa shearlines at 120E 32N to 127E 34N and 105E 30N to 118E 33N are expected, with a strain of low pressures along the Yangtze River.

FNMOC NOGAPS JUL18/00Z's run depicts the following:

1. Western Pacific subtropical high is rapidly weakening from tau 48 to tau 96, with no area higher than 5880gpm over mainland China at tau 84 (JUL21/12Z; for a comparasion, GFS suggests a splitted high with intensity over 5880gpm is still visible over mainland China). At tau 96, the 5880gpm contour locates around 150E, which is also more eastward comparing with the forecasts by GFS and ECMWF. In all, NOGAPS presents a faster-weaken subtropical high compare to GFS and ECMWF. However, a ridge can be identified from the 500hPa streamlines forecast for JUL22/00Z, extending from 120E 25N to 105E 31N.
2. A Northeast China vortex locates around 128E 52N as indicated by 500hPa geopotential heights and streamlines forecast for JUL22/00Z, with an insignificant trough over northern Korea Peninsula. The intensity of this trough is apparently weaker than the expectation of GFS.
3. A westerly flow is located along 30N as indicated by 700hPa isotachs forecast around tau 96, an associated 700hPa trough is located around 110E 30N to 118E 34N with 700hPa and 850hPa shearlines. An associated area of positive vorticity will lingering around Central China around tau 96.
4. The main body of Arabian Sea subtropical high remains west of 75E around tau 96, a low pressure is located in Gulf of Bengal.

For analyses of three numeric models above, we can now depict:

1. Western Pacific subtropical high will be weakening dramatically around July 21-22, this conclusion is supported by the consistency of all three models as well as the southward behaviour of Qinghai-Xizang anticyclone ridge, the occurence of an El Niño event and the declination of Southern Oscillation Index (SOI). However, the models have also suggested that a weak ridge is possible to remain around the northern part of South China.
2. A significant shearline will be located somewhere along the Yangtze Valley at July 22, with its exact position and intensity being determined; the Southwest China vortex shall be weak.
3. India Peninsula will mostly be controlled by a low pressure instead of a strong Arabian Sea subtropical high at JUL22/00Z.

The uncertainty for this forecast remains very small as the results from all three models are consistent. We shall note that many statistic studies have showed that the ECMWF model is superior than all other models for forecast within 120 hours.

By July 18 at 09Z, Typhoon Molave (07W) is located near Hong Kong and shall be dissipated overland within days. It is unlikely that Molave will affect the weather of July 22.

HUMAN FORECAST

The forecast is remains pessimistic. According to the results of the models and past studies, there seems to be only the luck few who can get the totality. The uncertainty has further reduced since the consistency of three models remains good. Local forecasts as well as advisories of usage are listed below.

Totality area over India:

• Prognostic Reasoning: the Arabian Sea subtropical high remains moderate and is unlikely to bring fine weather for India, a low pressure around the east coast may bring unstable weather.
• Forecast: mainly cloudy over western and eastern totality area, may be mostly clear around Patna.
• Advisory: to weather of India the author is not as familiar as China's. However, due to the lack of an in-control subtropical high and an occurence of a low pressure around the east coast, a clear weather over the entire zone is unlikely. GFS indicates a generally cloudless weather around Patna, while FNMOC EFS predicts a precipitation chance of 20-90% over the totality zone during the day.

Totality area over western Sichuan, China:

• Prognostic Reasoning: the Southwest China vortex is expected to be weak, however the Arabian Sea subtropical high is also moderate, thus, extreme weather over large area is not expected.
• Forecast: mostly cloudy over west, including big Shangri-La (Deqin, Derong, Daocheng), may be suitable for eclipse for some lucky area. More clouds over eastern part (Gongga Shan/Minya Konka, Ya'an, Emei Shan) with moderate precipitation chance at the morning according to FNMOC EFS.
• Advisory: weather forecast for highland is always very challenging, the author has investigated a number of weather archives for Derong and Minya Konka, the relationship between basic meteorological elements and actual weather appeared to be very complex. remarks from experienced local people or guides shall be employed seriously if any. Long term statistic data showed that northern Shangri-La area has a good possibility of being clear even in July. It is reported that the total sunshine time for Derong is 2,700-3,000 hours. For eastern area, July is the rainy season, and the forecast we have does not support a significant chance for an exception.

Totality area over Chengdu-Chongqing Plain, China

• Prognositic Reasoning: the lack of a significant Southwest China vortex suggests the weather shall not be too bad. However, as this area is at the buttom of a trough, plus a weak anti-clockwise stream in-controlled, the weather will not be too opmistic. The weather can be slightly better over east as all three models suggest something like a weak ridge or a weak high.
• Forecast: mainly cloudy with a few showers. There is a weak chance that the weather to be better over east.
• Advisory: there appears to be no significant system in-controlled. It can say with some confidence that rains or clear over large area is unlikely; however, a chance of less clouds and a few more sunshines can not be ruled out, as three models had indicated. The author should point out that minor systems like the weak ridge mentioned above is difficult to predict, so please follow the most recent weather information before you make decision.

Totality area over Hubei Province, China

• Prognositic Reasoning: all three models proposed something like a weak ridge or a weak high over west, but the most area is expected to suffer from affection of a shearline locates over the north.
• Forecast: weak chance for western area (like Enshi) to be better; mainly overcast over the entire province, but clouds may be slightly thinner (may permits a partial eclipse observation) over the south since it locates further from the shearline. Light rain is possible for some area throughout the day.
• Advisory: it can be say with some confidence that decent weather for most area is unlikely. Base on experience, a region of cloudless will locate somewhere around the shearline, however, its size is depending on the intensity of the shearline, which is hard to predict. In all, get prepared to move around and follow the most recent weather information. If possible, check the high resolution satellite image on the early morning of July 22 and make final decision.

Totality area over South Anhui Province, China

• Prognostic Reasoning: the low level shearline is expected to locate over the northern part of Anhui Province, whether or not that its associated clouds would affect sites among South Anhui depends primary on the intensity and exact location of the shearline, which the three models have not yet agree with each other.
• Forecast: since we have noted that ECMWF is more reliable than other two models, we may take ECMWF as consideration. The weather will be generally overcast with rain patches according to the forecast of ECMWF, but may be slightly cloudless over south -- like Huangshan. If NOGAPS or GFS gets it right, it will be cloudy, with much higher chances for the appearance of cloudless regions.
• Advisory: as noted above, the intensity and exact location of the low level shearline play an important role on judging the possibility for South Anhui to get a decent view. However, the southern area of South Anhui might be slightly more promising since it will keep a distance from the shearline no matter which model gets it right. In all, check the high resolution satellite image on the early morning of July 22 to make final decision if you can.

Totality area over pan-Yangtze River Delta, China

• Prognostic Reasoning: the low level shearline is expected to locate around Shanghai. Since the shearline here is close to the front lingering from East China Sea across Japan, the possibility for this shearline to be a weak one is not high.
• Forecast: generally overcast with rain.
• Advisory: weather over this area is less promising than those above. However, weather is varying from day to day, any kinds of situation cannot be ruled out.

Totality area over Ryukyu Islands, Japan

• Prognositic Reasoning: a westerly flow is lifting over this area, however the trough is well clear to the north.
• Forecast: mainly cloudy, with a few or some sunshines.
• Advisory: weather over ocean is quite dynamic. Although this area is not expected to be controlled by subtropical high as usual, cloudless regions are probable.

Conclusion and Remark

• Generally speaking, there is no place to be better from cloud than any other places, except for places around Shanghai seems to be less opmistic according to the forecast we have.
• Weak ridges noted above may bring slightly better weather, however they are hard to be precisely predicted.
• You may better stay at the site you picked and accept whatever happened to you. If you can fly off or can drive around, keep monitoring the weather, preferably weather diagrams prior to July 21 and satellite images in the final hours, and make final decision accordingly. A fine collections of the resources by meteorolgist J. Anderson is available at http://home.cc.umanitoba.ca/%7Ejander/tot2009/fcsts.htm.

12KM MM5/GFS FORECAST

The 12km MM5/GFS model is online and is now under test. Eclipse map produced by Occult 4 has been combined with the cloud cover graph. Please download the KML file and open it with Google Earth (http://earth.google.com/). The forecast time is July 22 from 0000 UTC to 0400 UTC with 1-hour interval, the forecast region includes most of totality area over China. This model shall be updated automatically everyday at about 0200 UTC.

Warning: by using this product you have acknowledge that the product is under very first test and is only posted as an alpha version, 7Timer! is not responsible for any damages or expenses you may incur as a result of any inaccuracy. To help you better assess the products we have, you are highly advised to read the tips below before using.

• Tip 1: 7Timer! has two models now, the original GFS model of 35km and 3-hour interval, which the forecast may be found at APanel section (local forecast for 72 hours) and Weachart section (charts of global for 384 hours) which you can find at the 7Timer! website (http://7timer.y234.cn/V3/product.php?language=en); and the MM5/GFS dynamic numeric model of 12km and 1-hour interval, which uses GFS data for initialization and is under very first test and is only posted here for the eclipse. My experience is that GFS is usually more reliable, despite its resolution is far from as good as MM5/GFS. So, check GFS chart when using MM5/GFS, and assess the reliability of the situation accordingly.
• Tip 2: When there are less than 72 hours from the event, APanel can be used to assess the weather condition for an exact location. However, since APanel also uses the low resolution 35km/3h GFS data, the trick given in Tip 1 still plays -- when the forecast by MM5/GFS (the product you are using) is similar to what GFS given, you may use MM5/GFS for a more precise estimate of the weather as it has a much better resolution. Otherwise, please do not take the result MM5/GFS gives too seriously.

12km MM5/GFS Forecast KML File

NEXT UPDATE

When possible. Might be July 20 at 1600 UTC or earlier.

ACKNOWLEDGEMENT

I would like to thank Dr. Cui Chenzhou from National Astronomical Observatory of China for working with the server problem overnight. I would also like to thank Zhang Linna from Beijing Meteorolical Bureau and President Dickson Fu from Sky Observers' Association (Hong Kong) for their valuable discussion and help. I would also like to thank Cheng-Su Diandian for her support of this work.

July 22 Great Solar Eclipse PFS Bulletin No. 11

EDITIONAL NOTICE

This bulletin is revised at July 16 1730 UTC, missed tropical cyclone information is added, and the precision forecast map comes online.

OVERVIEW

This is July 22 Great Solar Eclipse PFS Bulletin No. 11, issued in both English and Chinese. The forecast reasoning has slightly changed since previous bulletin. There is only 6 days away from the event. The uncertainty for this forecast is upgraded to very small. The forecast diagrams mentioned below may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=2 and http://www.fnmoc.navy.mil. Precision numeric forecast for various locations may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=1. RSS feed of this service is available at http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=46.

ANALYSIS

NCEP GFS JUL16/00Z's forecast on 500hPa geopotential heights of JUL22/00Z revealed a weak subtropical high over western Pacific with an oblique ridge. An animation with nearby taus shows the subtropical high is weakening, with 5880gpm contour stays east of 140E at JUL22/00Z, but a weak splitted  high can still be spotted by 500hPa streamlines of JUL22/00Z although no contour is shown on the geopotential heights. On the other hand, a westerly trough is locating over Central China, and a 850hPa shearline is lifting over the Yellow Sea and Jiangsu Province (around 120E 34N). The position and the intensity of the Arabian Sea subtropical high did not suffer a major change since last run. Meanwhile, forecast for 300hPa geopotential heights revealed that the ridge of Qinghai-Xizang anticyclone locates south of 30N.

ECMWF JUL16/00Z's forecast on 500hPa geopotential heights of JUL22/00Z has retracted the claim of a strong western Pacific subtropical high to be persisted around July 22. Its situation is similar to NCEP GFS's now although the intensity of the subtropical high is still higher than the later's, with the 5880gpm contour reach west of 140E and a splitted subtropical high locates over Taiwan (as noted above, this splitted high does also appeared on GFS's forecast for JUL21/12Z for an intensity of over 5880gpm but not for JUL22/00Z). Weak 850hPa shearline is still suggested over southern Jiangsu Province with no 500hPa westerly trough visible, while the monsoon over India persisted.

FNMOC NOGAPS JUL16/00Z's forecast on 500hPa geopotential heights of JUL22/00Z also depicts a weak western Pacific subtropical high, the intensity is weaker than GFS or ECMWF suggest, with 5880gpm contour east of 150E. 500hPa streamlines analyses show a weak ridge over Ryukyu Islands extending to Central China. On the other hand, an area of 850hPa positive relative vorticity can be spotted over Jiangsu Province, an associated shearline is visible on 850hPa and 700hPa streamlines analyses. The main body of Arabian Sea subtropical high locates in Saudi Arabia, with a weaker intensity comparing with GFS's forecast. Monsoon over southern India is persisted. Forecast for 300hPa geopotential heights revealed a ridge of Qinghai-Xizang anticyclone locates south of 30N, which is consistent with GFS's.

For analyses of three well-known numeric models above, we can now depict:

1. Western Pacific subtropical high is likely to be weaker than long term mean (for a long term mean graph, please refer to bulletin No. 6), all three models have depicted a highly similar result on this conclusion. A southward Qinghai-Xizang anticyclone ridge and a development of El Niño event also suggest a similar trend. However, the models have also suggested a splitted high or a weak ridge is possible to turn up around East China Sea.
2. A low level shearline can be located around 115E 33N (i.e. in Jiangsu Province), this is also suggested by all three models. The intensity of this shearline remains in question but shall not be strong. There is also a chance for a drifted southwest vortex located over Central China (suggested by GFS).
3. India Peninsula is unlikely to be controlled by the Arabian Sea subtropical high, but a monsoon will run in at that time.

The uncertainty for this forecast is upgraded to very small as the results from all three models are consistent.

By July 16 at 18Z, tropical storm Molave (07W) locates over east of Luzon and is expected to move into South China Sea in the coming days. It is likely that Molave will affect the weather of July 22.

FORECAST

The forecast is much more pessimistic than the previous bulletin since ECMWF and NOGAPS have both retract their expectation of normal-to-strong western Pacific subtropical high. The uncertainty has reduced since there is no significant divergence between the models. Local forecasts are listed below. Please be aware that these forecasts may change as there is still 6 days to go for the event.

• In India: mainly cloudy over most totality area but may have more sunshine over east (suggested by GFS). Showers are likely during the day. 
• In Sichuan and Chongqing, China: cloudy to overcast, may have a few sunshines. FNMOC EFS suggests a precipitation probability of >90% on the mountainous area west of Chengdu, but for Chengdu-Chongqing plain the probability is less than 10%. However, GFS proposes a possibility of heavy rain at Sichuan Basin produced by the developed southwest vortex.
• Around Wuhan, China: cloudy to overcast with precipitation probability of >40% according to EFS.
• Around Tongling, China: cloudy to overcast with precipitation probability of >50% according to EFS.
• Pan-Yangtze River Delta, China: cloudy to overcast. 
• Ryukyu Islands, Japan: cloudy as the subtropical high is weak.

The 12km MM5/GFS model is coming online and it is now under test, initialization for this run is at JUL14/18Z. Eclipse map produced by Occult 4 has been combined with the cloud cover graph. Please download the KML file and open it with Google Earth (http://earth.google.com/). The forecast time is July 22 from 0100 UTC to 0400 UTC with 1-hour interval, the forecast region includes most of totality area over China. Warning: by reading this message you have acknowledged that this is a service that still under test! My experience is that sometimes it is not better than the original GFS, although resolution of the later is much lower than this service. For GFS forecast maps, please refer to http://7timer.y234.cn/V3/product.php?language=en&product_id=2.

Download the KML file

NEXT UPDATE

July 17 at 1500 UTC or earlier.

July 22 Great Solar Eclipse PFS Bulletin No. 10

OVERVIEW

This is July 22 Great Solar Eclipse PFS Bulletin No. 10, issued in both English and Chinese. The forecast reasoning has slightly changed since previous bulletin. Although there is only 7 days away from the event, the divergent results given by difference models make the uncertainty for this forecast remains moderate. The GFS forecast diagrams mentioned below may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=2. Precision numeric forecast for various locations may be found at http://7timer.y234.cn/V3/product.php?language=en&product_id=1.

ANALYSIS

GFS JUL14/18Z's forecast on 500hPa geopotential height of JUL22/00Z revealed a weak subtropical high in western Pacific. On the other hand, there is an northeast vortex over Northeast China, with a 850hPa shearline over northern Bohai Sea, but there is no significant westerly trough over North China. The position and the intensity of the Arabian Sea subtropical high did not suffer a major change since last run. In all, the positions of the major systems had not been revised significantly but instead of their intensities. Meanwhile, the ridge of Qinghai-Xizang high is near 30N as spotted from 100hPa geopotential height diagram, which is nearly the same as that of last run.

ECMWF JUL14/12Z's forecast on 500hPa geopotential height of JUL22/00Z still suggested a strong western Pacific subtropical high with its 5880gpm contour reach 110E. A weak 850hPa shearline is purposed around Bohai Sea with no 500hPa westerly trough visible, while the monsoon over India persisted.

FNMOC NOGAPS JUL14/12Z's forecast on 500hPa streamlines suggested a situation similar to ECMWF's, with a splitted subtropical high centred around Wuhan. Again, no significant westerly trough can be seen around North China; but FNMOC EFS JUL14/12Z's forecast on 5640gpm contour probability of JUL21/12Z suggested a deeper-than-usual East Asia Major Trough with 90% probability that the 5640gpm to be located near 45N, and this is consistent with what GFS suggested.

By July 15 at 00Z, good disturbance 91W is activing over west of Palau while poor disturbance 94W is centred over northern South China Sea, but the probability for them to affect the weather of July 22 is low. However, we shall note that NOGAPS did suggest two weak tropical cyclones activing over western Pacific Ocean around July 22.

FORECAST

The divergent results available make it difficult to figure a confident prediction. It is encouraging to see both ECMWF and NOGAPS have suggest something promising. Local forecasts are listed below. Please be aware that they are rough due to the moderate uncertainty of enviromental forecast and may suffer major changes.

• In India: cloudy and rainy over most totality area as a monsoon run in. May be have some sunshine over Patna and further east. 
• In Sichuan and Chongqing, China: overcast and rainy as a southwest vortex is centred over Sichuan Basin according to GFS; but can be partly clear if ECMWF and NOGAPS get it right. 
• Around Wuhan, China: shall be cloudy with showers according to GFS, but can be mostly clear according to ECMWF and NOGAPS.
• Pan-Yangtze River Delta, China: situation close to Wuhan. 
• Ryukyu Islands, Japan: shall be cloudy with a few heavy showers according to GFS, but can be mostly to partly clear according to ECMWF and NOGAPS.

NEXT UPDATE

July 16 at 1500 UTC or earlier. Precision forecast for mainland China with a resolution up to 12km might be available for test by that time.

ACKNOWLEDGEMENT

I would like to thank President Dickson Fu from Sky Observers' Association (Hong Kong) for his valuable contribution to this work.