7月22日日全食精密预测公报第十四号[总结报]

纵览

　　这是7月22日日全食精密预测公报第十四号[总结报]，以中文和英文发布。实际天气的观测数据、分析及结论会在本报中公布。

观测数据

卫星观测数据

　　静止气象卫星风云2号D星在7月22日北京时间8:45、9:15及9:45拍摄的图像如图1-3所示，全食带以红线手工标出。（点击可查看原图。注意：原图较大）

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

　　风云2号C星从22日北京时间8时至11时30分间隔半小时一张的可见光图像如图4-11所示（图像参见本报告英文版，http://7timer.y234.cn/V3/wordpress/?p=224），动画如下所示（单击查看原图，注意：非常大）。

地面观测数据

• 四川理塘[56257]：08时（北京时间，下同）资料显示大致晴天，总云量为4/10，积云性层积云及密卷云各占2/10，云底高600-1000米；11时云量增多，总云量达9/10，但密卷云占8/10。这一地区的观测者（海子山垭口、顶贡草原、得荣县）均报告成功观测日全食，且天气状况也相近。08时温度没有显著下降。
• 四川康定[56374]：08时总云量为10/10，均为积云性层积云；11时转为9/10，积云占7/10。这一地区的观测者未能观测到日食，但西南70公里子梅垭口的观测者则报告全食期间基本天晴。08时温度没有显著下降。
• 四川成都[METAR/ZUUU]：日食期间大致多云且有几阵雨。
• 重庆地区[57516]：在08时和11时大致天晴，总云量7-8/10但均为密卷云。这一地区的观测者均报告成功。气象数据没有显示这一地区的温度在日食期间有明显下降。
• 湖北宜昌[57461]：08时大致天晴，总云量5/10，大多为透光高积云及密卷云；11时天气更好，总云量2-3/10。这一带的观测者（宜昌、荆州、荆门一带）均非常成功。气象数据显示21日08时和22日08时之间有0.8度的气温差，21日11时和22日11时之间的气温差则达到2.3度，这两天天气情况相近。
• 湖北武汉[57494]：08时到11时期间总云量均为9/10，为密卷云及发展的透光高积云。天河机场的观测数据表明10时气温比09时要偏低大约1度。
• 安徽安庆[58424]：08时和11时大致多云，总云量9/10（均为蔽光高积云）。总得说来，这一带地区（桐城、铜陵、宣城等）的观测结果都不让人满意，有几个地方（均为靠近长江之地）未能观测到全食。但靠南100公里的观测者（如黄山、九江）的观测效果则好得多。
• 浙江杭州[58457]：08时和11时均多云，总云量9/10（积云性层积云和透光高积云）。靠北的观测地点（上海、苏州、无锡等地）在日食期间普遍有雨，但杭州和宁波一带的观测者报告日食期间天气放晴。

分析

　　香港天文台给出的22日08时地面分析如图12所示。结合NOAA/ESRL PSD的500百帕等压面再分析资料，我们可以看到中国东南部上空有减弱后副高的残余，华东北纬30度线附近有显著的切变线。

　　结合韩国气象厅、日本气象厅的资料以及NOGAPS和GFS的分析，可以看出22日08时的以下天气特征：

• 东经95度附近有一个弱脊，且位于东经105度（四川盆地西侧）的一个低空槽后，使得这一带地方的云量偏少；
• 长江下游一带有一道大型静止锋，槽底（武汉附近）有一个可能的弱低压，使得许多地方被云遮蔽，但远离该静止锋的观测者则大多幸运地看到日食；
• 台湾一带有一个断裂副高。

回顾

　　日全食精密预报服务从7月6日就开始运作，但直到7月9日（第四报）之前都没有能给出略为沾边际的预报。以下段落节选自公报第四号：

……高空槽前的地区——主要是武汉以东的地区，将会为浓密云层所覆盖，而且可能有雨，因为850百帕风场上呈现一个明显的切变线。……另一方面，为与华中的弱脊则可能为这一地区——主要是重庆和武汉之间的地区——带来可以接受的天气。

　　可以看出，这一预报是相当精确的。遗憾的是，尽管这一个“正确的猜测”在之后的几次预报中时有出现，其仍然是不稳定的，直到17日（第十一报）三个模式的预报比较一致之后才较为稳定。

　　7月18日，即是日全食之前4日，由于即将出发观测日食，本人发布了7月22日的“最终预报”（第12报）。结合21日发布的修正报（第13报），以及前文所述的实际天气情况，我们可以给出如下总结：

• 四川西部的预报为“大香格里拉地区北部大致多云，部分地区适宜观测；成渝平原西部山区云量更多……”。预报趋势与实际情况相符，但过于悲观了些。卫星资料和观测数据显示这一地区西部（稻城/得荣）一带为晴间多云的天气。川西东部（康定、峨眉山等地）云量倒的确偏多，尽管贡嘎山的观测者在全食期间幸运地等到一块巨大云洞。
• 成渝平原的预报为“大致多云有阵雨。靠东的地方有微弱可能天气略好”，修正报中认为“靠东地区天晴概率为中等”。总得来说预报算准确，尽管对于天晴概率的估计偏保守。
• 湖北地区的预报为“西部地区有轻微概率天气略好；全省大部阴天，但南部地区由于距离切变线较远，云可能略少，可以观测偏食……”，修正报中认为西部天晴概率为“中等”。实际天气情况与这一预报相当一致（西部、南部天气好），但即使修正以后的预报也过于悲观。西部和南部的天气是相当好，即便是较差的武汉也有部分地区可见全食。
• 皖南地区的预报为“皖南大致阴天有阵雨，但南部地区的云或许会略少一点。……皖南南部的概率总是偏大一些，因为它距离切变线较远”，这与实际情况相符。不过根据卫星数据，距离长江较远的地方（三四十公里以外）也基本没什么云。另外，所谓“皖南南部”定义不明确，应该说“全食带南部”之类，以免造成误解。
• 泛长三角地区的预报为“大致阴天有雨”。尽管全食带北侧的地区的确阴天有雨，但全食带南侧大多数地方天气很好。这一好天地区范围相当大（近百公里），因此未能预见到这一好天区出现的可能性，是预报的失败。

结论

　　本人注意到在这一次预报过程中，面对“可能乐观”的情形时，给出的预报偏保守（尤其是对于湖北西部和重庆地区的预测）。另外，自动数值模式在这一次预报过程中的表现强差人意（如图14），尽管它们在人工预报中是一个强有力的辅助，但尚无法独立给出十分具有信服力的重要事件的天气预报。12公里精度的MM5/GFS表现比原始GFS模式更差一些，这一模式仍需要进一步调整。总得说来，这一次预报还是很成功的，对于大多数地区的预报算是很准确的。

致谢

• 本人欣慰地了解到相当一部分观测者根据本预测作出了正确的选址决定。日全食是一种很罕见的天象，但相比流星暴雨来说还算比较常见的。不管这一次你是否看到了全食，拥有下一次极棒的全食体验只是时间问题，重要的是保留一个追求自然之美的梦想。
• 风云2号气象卫星的原始数据由国家卫星气象中心提供。风云2号D星原始数据的作者为国家卫星气象中心曹治强。
• 感谢周林炯同事的重要讨论和帮助。感谢Johnson Lau、Dickson Fu、张琳娜研究员、Robert Yen、陈思思小姐、石辽珊小姐和成苏点点小姐的重要讨论、贡献和帮助。
• 感谢崔辰州博士为晴天钟提供网络支持。
• 感谢各位对本工作的支持。

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.

7月22日日全食精密预测公报第十三号

　　我现在马上就要出发了，所以我会写得很短。简而言之模式的结果没有太大变化。500和700百帕脊仍然持续报出并比前报要强，成都和武汉之间希望中等。建议从现在开始可以跟踪高分辨率卫星影像。四川盆地一带可能有一些地形造成的中低云，长江下游希望仍微，但有可靠消息表明铜陵将发射驱云火箭。另一方面，有朋友致电上海气象局，得到的答复是上海不会为日全食发射火箭驱云。这应该是日食前最后一次更新了，我祝愿各位能在那几分钟有最好的运气。

叶泉志·小龙 @ 香格里拉

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

7月22日日全食精密预测公报第十二号

编者按

　　国家天文台服务器原定17日12-16时间进行维护，但因技术原因导致23:20前后服务才完全恢复正常，使得当日公报取消发布。同时，我的出发时间也从18日推迟到19日。因此，公报第十二号将成为日食公报中最后一期相近的公报，因此我尽我所能地根据所有情况猜测22日的天气。这半个月来我一直在巨大压力之下工作，在此感谢你们每一位的支持。所有人都为了日全食努力了很长时间，我在此祝愿大家当天都能有好天气。

　　我已决定到香格里拉北部海拔4100米的地区进行日全食观测，预计明天晚些时候飞昆明，但在7月21日前应该都能上网，因此当可能的时候我会尽量在此写些东西。

纵览

　　这是7月22日大日食精密预报公报第十二号，预报原理较上一报没有变化。现在距离日全食仅有4天时间，本报的不确定性为很低。以下提及的预测图可在http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=2及http://www.fnmoc.navy.mil查询，对任意地点的精细预测可到found at http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=1。RSS源为http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=47。

分析

　　NCEP GFS在今晨8时的预报结果反映：

1. 西太副高将在21日08时至22日08时之间快速减弱，其588线将从中国大陆东退至东经140度。然而，500百帕流线预报仍然显示出华南上空在22日08时有一个弱的断裂高压，向北有一条位于东经110度的脊。
2. 届时东北低涡位于东经130度北纬46度附近，有一浅槽发展东移，22日08时大致位于东经133度，向南延伸到琉球群岛北部。
3. 700百帕流线显示北纬30度上空有急流，在22日08时一道槽位于东经120度北纬34度到东经126度北纬40度，低层有切变线。关联的正涡度区将在华东地区东移。

　　欧洲模式在今晨8时的预报结果反映：

1. 西太副高将在21日08时至22日08时迅速减弱，东亚有西风急流，基本与GFS一致。
2. 东经120度北纬32度至东经127度北纬34度以及东经105度北纬30度至东经118度北纬33度有低空切变线，长江流域有几个近地面低压。

　　FNMOC NOGAPS在今晨8时的预报结果反映：

1. 西太副高将在20-22日迅速减弱，且幅度比以上两个模型认为的更大，但在22日08时，自东经120度北纬25度至东经105度北纬31度可能有一弱脊。
2. 届时东北低涡位于东经128度北纬52度附近，关联的弱槽位于朝鲜半岛北部。
3. 700百帕风场显示北纬30度附近有急流，且在东经110度北纬30度到东经118度北纬34度有关联的槽和切变线。正涡度区将在华中附近逗留。

　　根据以上结果，可以看到：

1. 3个模型非常一致地认为西太副高将在21-22日显著减弱；青藏高压脊线偏南、SOI指数的下降，以及厄尔尼诺的确立都支持这一点。不过，模型也都指出华南北部上空可能会残留一道弱脊。
2. 长江中下游地区的某处将有一条明显的切变线，但具体位置和强度尚不明朗；西南低涡不活跃。

　　由于三个模型给出的结论一致，本报的不确定性很小。应该指出的是，经验表明欧洲中心的模式在120小时以内最有可信度。

　　18日17时，台风莫拉菲正集结在香港附近海域，预料将在几日内消散，不太可能影响22日的天气。

人力预测

　　预报仍然悲观。根据模式预报以及过去经验，这次能看到日全食的人恐怕不多。鉴于模式的结果保持一致，预报的不确定性进一步下降。地方性预报以及参考意见如下所示。

四川西部

• 预报理由：西南低涡偏弱，阿拉伯海高压不强，因此大晴或者大片阴雨的情况都不太可能出现。
• 预报：大香格里拉地区北部大致多云，部分地区适宜观测；成渝平原西部山区云量更多，FNMOC集合预报显示降雨概率为中等。
• 参考意见：山区的预报从来都极具挑战性。我在这些天查阅了大量有关大香格里拉和贡嘎山的气象资料，得出的结论是基本气象要素与实际天气关联不明显。如果可能的话，应该重视当地人以及有经验的向导的意见。气候资料显示大香格里拉地区甚至在7月也有较高的晴天概率，有资料显示得荣地区年日照为2700-3000小时。但对于接近成渝平原的地区，7月是雨季，而且我们现在手头的预报资料并不预示着一个乐观的意外。

成渝平原

• 预报理由：西南低涡偏弱，但该地位于槽底且有气旋性环流影响，天气不乐观。鉴于三个模式都认为靠东的地方有一个弱脊，那一带天气有轻微可能较好。
• 预报：大致多云有阵雨。靠东的地方有微弱可能天气略好。
• 参考意见：这一带地区没有明显系统控制，可以有一定把握地说，不太可能出现大晴或者阴雨天气，云量略少的概率也不能排除。应该指出的是，诸如以上提到的弱脊等小系统很难预报，在作决定前请随时关注最新的天气情况。

湖北省

• 预报理由：三个模型都认为恩施一带可能有个弱脊之类的小系统，但大部分区域预计将受到位于湖北北部的切变线的影响。
• 预报：西部地区有轻微概率天气略好；全省大部阴天，但南部地区由于距离切变线较远，云可能略少，可以观测偏食。部分地区在日间可能有小雨。
• 参考意见：目前有一定把握的结论是大部分地方好天是不太可能的。根据经验，切变线周围会有一些少云的地方，但这些少云区的大小和难以预报的切变线的强度有关。总之，准备机动计划，同时密切关注最新的天气情况。如果可能的话，在7月22日早晨观察高分辨率的卫星图像，寻找可观测区。

皖南地区

• 预报理由：低空切变线预计将位于安徽北部，它对皖南的具体影响则要根据其强度和具体位置而定，但目前三个模型没有给出十分一致的预报。
• 预报：鉴于欧洲中心的预报可信度最高，我们根据欧洲中心的预报来进行预测。预计皖南大致阴天有阵雨，但南部地区的云或许会略少一点。如果NOGAPS或GFS预报正确，皖南将为多云，少云区出现的概率也要高很多。
• 参考意见：如同上面所说的那样，切变线的强度和具体位置将非常关键。但无论是哪种情况，皖南南部的概率总是偏大一些，因为它距离切变线较远。总之，如果可能的话，在7月22日早晨观察高分辨率的卫星图像，寻找可观测区。

泛长三角地区

• 预报理由：低空切变线预计将在上海一带。由于这一段切变线距离东海-日本的大型锋面系统比较近，它的强度不太可能偏弱。
• 预报：大致阴天有雨。
• 参考意见：这一带的天气比其他地方偏悲观。然而，天气每天都在变，任何可能性都无法排除。

结论及注脚

• 总之，所有地方差不多一样糟，除了上海一带看起来应该更加糟一些。
• 上面提到的弱脊也许会为邻近地区带来略好的天气，但它们很难准确预报。
• 最好还是呆在原来选定的地点，一切交给运气。如果你能到处飞或者开车到处走，时刻关注天气，在21日前可继续关注形势预报，在日食之前最后几个小时可以根据高分辨率图像进行邻近预报。气象学家J. Anderson的网站给出了不少很好的资源地址：http://home.cc.umanitoba.ca/%7Ejander/tot2009/fcsts.htm。

12公里MM5/GFS动力模型预报

　　12公里MM5/GFS模型正式测试，其中整合的日食图由Occult 4生成。请下载下面提供的KML文件并用Google地球打开(http://earth.google.com/)，预测时间段为22日北京时间8-12时，间隔为1小时。警告：使用本产品代表您已知悉，本产品仍处于初级测试阶段，仅为本次日食参考之用。鉴于天气预报服务之特殊性，晴天钟不为因任何旗下产品预测失败而导致的损失负责。为了协助您更好的评定天气情况，我强烈建议您在使用本产品前阅读以下使用技巧。（注：本产品所用为世界协调时，使用时要加上8小时才为北京时）

• 提示1：晴天钟目前使用两个模型：35公里/3小时间隔的GFS原始模型，为APanel（72小时地方预测）以及Weachart（384小时天气图）所使用，您可以在网站上找到；以及您现在所用的、利用GFS数据进行初始化的12公里/1小时间隔的MM5/GFS模型，它仍处于初级测试阶段，仅为日食参考而发布。我的经验是GFS模型一般更准确，但它的分辨率比MM5/GFS低很多。因此，在使用MM5/GFS之前，请先评定GFS的预报，看看MM5/GFS给出的预报是否与GFS的预报接近，然后根据不同情况来做不同的处理。
• 提示2：当距离日食只有不到72小时时，APanel可以用于对某一地点进行精细的预报。但是，由于APanel使用的是分辨率相对较低的GFS模型，以上技巧仍然惯用——当MM5/GFS给出的预报与GFS一致的时候，您可以使用前者的预报来对日食期间的天气进行更精细的评估；如果不是这样的话，请不要将MM5/GFS的预报看得太重。

12km MM5/GFS Forecast KML File

下次更新

　　条件许可时。可能是20日24时或更早。

致谢

　　感谢国家天文台崔辰州博士加班加点修复服务器故障，以及北京气象台张琳娜研究员以及香港坐井会会长Dickson Fu先生的宝贵讨论和帮助。感谢成苏点点同学对本工作的支持。

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.

7月22日日全食精密预测公报第十一号

编者按

　　本公报于17日1:30修正，遗漏的热带气旋信息被补上，精密预报图也上线测试。

纵览

　　这是7月22日日全食精密预测公报第十一号，预测理论较上一个公报有轻微变化，预测不确定性降低至很小。公报中提及的数值预测资料可参考http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=2及http://www.fnmoc.navy.mil，对任意地点的72小时精密预报可参考http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=1。本公报RSS服务种子为http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=47。

分析

　　NCEP GFS在今晨8时初始化的7月22日500百帕高度场预报显示出一个有倾斜脊线的弱副高。连续时次的显示表明副高正在减弱，588线停留在东经140度以东，但从500百帕流线分析来看，台湾上空有一个弱的断裂副高。另一方面，华中上空有一道西风槽，从黄海到江苏上空有一道850百帕切变线。300百帕高度场上，青藏高压的脊线位于北纬30度以南。

　　欧洲中心今晨8时初始化的7月22日500百帕高度场预报不再给出一个强盛的副热带高压，目前已经较接近GFS的预测（尽管对副高的强度预期仍然较高），588线略越过东经140度，台湾上空有一个闭合的断裂高压。江苏南部有一个弱的850百帕切变线，但500百帕上见不到西风槽。

　　FNMOC NOGAPS在今晨8时初始化的7月22日500百帕高度场预报同样显示出一个弱副高，但强度比前二者的预报更弱，588线停留在东经150度以东。500百帕流线分析显示从琉球群岛到华中地区有一道弱脊。另一方面，江苏上空有一个850百帕正涡度区，相关的切变线在850百帕和700百帕流场中可见。300百帕高度场预报显示青藏高压的脊线位于北纬30度以南，这与GFS的预报一致。

　　根据以上三大模型的预报，我们可以归纳出以下几点：

1. 西太副高的强度弱于多年平均值（多年平均值的图像可参考第六报），青藏高压脊线偏南及厄尔尼诺的出现也与这一结论一致，但三个模型也认为东海附近可能会有一个断裂高压或者弱脊。
2. 江苏附近上空有一个低空切变线，但强度不确定，可能不会太强。GFS还认为可能会有一个西南低涡移到华中一带。

　　因为三个模型给出的预报基本一致，本预报的不确定性降低为很小。

预报

　　由于欧洲中心和NOGAPS的预报都放弃了对强盛副高的估计，偏向GFS的预测，本报较前报悲观很多。而且，由于不同模型之间的分歧很小，本报的可靠性较前报高。地方性预测如下，请注意：在剩余的6天内，预报还是可能有变化的。

• 成渝地区：多云或阴天，也许会有两三阵阳光。FNMOC集合预报认为西部山区的降水概率高于90%，成渝平原的降水概率低于10%，然而GFS认为四川盆地可能会受移出的西南低涡影响而降大雨。
• 武汉地区：多云或阴天，集合预报给出的降水概率为高于40%。
• 铜陵地区：多云或阴天，集合预报给出的降水概率为高于50%。
• 长江口：多云或阴天。

　　12公里MM5/GFS模型正式上线测试，其中整合的日食图由Occult 4生成。请下载下面提供的KML文件并用Google地球打开(http://earth.google.com/)，预测时间段为22日北京时间8-12时，间隔为1小时。警告：使用本产品代表您已经知悉其尚处于测试阶段！作者的经验表明有时这一产品的准确性甚至不如原始的GFS数据，尽管后者的分辨率较低。若要使用GFS预测图，请移步至http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=2.

下载KML文件

下次更新

　　17日23时或更早。

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.

7月22日日全食精密预测公报第十号

纵览

　　这是7月22日日全食精密预测公报第十号，预测理论较上一个公报有轻微变化，预测不确定性维持中等。GFS预报图可参考http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=2，对任意地点的72小时精密预报可参考http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=1。

分析

　　GFS在今晨2时初始化的7月22日500百帕高度场预报显示出一个弱的西太副高。另一方面，东北低涡维持，在渤海上空有一条850百帕切变线，但华北并没有明显的西风槽存在。100百帕青藏高压的脊线位于北纬30度附近，与前一报相同。

　　欧洲中心昨晚20时初始化的7月22日500百帕高度场预报显示了一个强的西太副高，其588线最西越过东经110度，渤海附近有一条弱的850百帕切变线，但500百帕上没有见到有西风槽。

　　FNMOC NOGAPS昨晚20时初始化的500百帕流场给出的预报与欧洲中心的预报接近，武汉地区有一个断裂的副高，华北同样没有显著西风槽，但FNMOC EFS给出的5640位势米预报认为东亚大槽的强度将较多年平均值高，5640位势米抵达北纬45度的概率为90%，这一预报与GFS相符。

　　今晨8时，热带扰动91W和94W分别在帕劳西部海域和南海北部活动，预计它们影响7月22日天气的概率较低。不过，NOGAPS认为7月22日前后西太平洋将有两个弱的热带气旋活动。

预报

　　由于目前各个数值模型给出的预报分歧较大，做出一个确定性较高的预报颇有难度，但欧洲中心与NOGAPS的预报均趋于乐观。地方性预测如下，仅供参考：

下次更新

　　北京时间7月16日23时或更早。届时可能将有高精度数值产品放出。

致谢

　　感谢香港坐井会会长Dickson Fu先生的讨论。

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.