日环食精密预测公报第三号

前言

　　这是2010年日环食精密预测公报第三号，以中文和英文编制。本报的预测方法较上报有一定变化。公报中提及的预报资料可在http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=2, https://www.fnmoc.navy.mil和http://www.ecmwf.int查阅。对于任意地点的数值预报可查阅http: //7timer.y234.cn/V3/product.php?language=zh_cn&product_id=1。本服务的RSS种子为http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=47。

分析

　　NCEP GFS在1月10日06Z初始化的预报显示南支槽正在东经105-107度上活动，与其关联的湿区在环食带上延伸至东经116度。1030百帕等值线触及北纬30度，但近地面风场显示届时冬季风已减弱。

　　ECMWF在1月10日00Z初始化的预报则认为南支槽在100-102度左右，较GFS偏西约5度；从地面图上观察，ECMWF给出了一个稍微偏强的冬季风。

　　FNMOC NOGAPS在1月10日06Z初始化的预报给出了更偏西的南支槽，中心大致位于东经95度，北纬25度左右，延伸至川西高原；1030百帕等值线触及北纬25度。NOGAPS同时指出四川盆地和郑州一带的能见度将会低于10公里。同一时刻的EFS认为云南大部、四川及重庆在15日白天出现显著降水的概率介于0-20%之间。

　　可以看出：中南半岛北部将有一西风槽，大陆上的冬季风正在减弱，但对于这一对系统的位置/强弱，三个模式分歧较大。

预报

　　由于各模式分歧显著，因此本报的不确定性升至偏高。如果GFS正确（即南支槽较偏东、冬季风很弱），则云南西部天气较好，但从云南东部开始的环食带天气皆不佳。但从历史统计上来看，ECMWF的准确率较GFS高一点，而且相对而言ECMWF和NOGAPS的预报比较接近，因此本报偏重于这两者的预报，采取了较偏西的南支槽以及偏强一些的冬季风。请注意：由于目前网络上绝大多数的天气网站都采用的是GFS，鉴于上述理由，它们的预报和本报的分歧可能较大。

• 云南地区、四川南部：大致多云或阴天，可能有几阵雨，靠东的地区降雨概率更大些；
• 重庆地区：有雾和毛毛雨；
• 十堰、南阳一带：可望天晴或少云，能见度一般，适宜观测；
• 山东地区：可望天晴，但灰霾可能会对观测造成一定影响。

下次更新

　　1月12日北京时间24时，或当预报方法有显著变化时。

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, https://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.

日环食精密预测公报第二号

纵览

　　这是2010年日环食精密预测公报第二号，以中文和英文编制。距离日环食尚有7天，本预测的可信度为较高。公报中提及的预报资料可在http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=2, https://www.fnmoc.navy.mil和http://www.ecmwf.int查阅。对于任意地点的数值预报可查阅http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=1。本服务的RSS种子为http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=47。

分析

　　NCEP GFS在1月8日06Z初始化的预报指出：在1月15日，850百帕湿度场上华中、云南大部分地区较干燥。1020线至北纬25度左右，1030线控制华北及辽东半岛。ECMWF在1月8日00Z初始化的预报则认为1020线可南达北纬20度，1030线较GFS的预报要偏南一些2-3个纬度，对冬季风的估计较GFS稍强一些。FNMOC EFS集合预报则给出了一个稍微缓和的冬季风，1020线达北纬20度，但1030线则仅控制华北地区，同时认为从瑞丽到南阳的环食带在15日白天有显著降水的概率为接近10%。可以看出：届时将有显著但趋弱的冬季风控制我国大部分地区。

预报

　　各模型在冬季风强度的预报上已经接近，因此本预报的不确定性降为较小。地域预报给出如下，请随时留意随着时间的推移和观测数据的更新带来的预报修正。

• 云南地区（含环食带掠过的临近地区，如攀枝花等）：大致天晴，向东的云量可能会有所增加，但影响日食观测的概率不大；
• 重庆地区：预计为大雾天气，但高地上可能会有阳光；
• 南阳一带：大致天晴，根据现在的情况来看，城区一带的能见度在15公里以上，对低仰角的观测较为有利；
• 山东地区：大致天晴，预计城市地区的能见度在10-15公里左右，可能对日食观测较为有利。

下次更新

　　1月10日北京时间23时或更早。

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, https://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.

日环食精密预测公报第一号

纵览

　　这是2010年日环食精密预测公报第一号，以中文和英文编制。距离日环食尚有10天，本预测的可信度为中等。公报中提及的预报资料可在http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=2, https://www.fnmoc.navy.mil和http://www.ecmwf.int查阅。对于任意地点的数值预报可查阅http://7timer.y234.cn/V3/product.php?language=zh_cn&product_id=1。本服务的RSS种子为http://7timer.y234.cn/V3/wordpress/?feed=rss2&cat=47。

分析

　　NCEP GFS在1月5日06Z初始化的预报指出1月15日，在淮河流域和云贵高原西部各有一条高空槽，但850百帕湿度场则认为华中大部分地区较干燥。1030线控制全国大部分地区，表明一股强烈的冬季风正在影响我国。

　　ECMWF在1月5日00Z初始化的预报指出1月15日，华中由一股中等至偏强的冬季风控制，云贵高原上空有一条南支槽，但较GFS预报的要偏东约5个经度。1030线控制了辽东半岛及长江流域以北的地区。

　　我们可以看出，届时将有一股显著的冬季风影响我国，在黄海上空有急流，在云贵高原附近有明显的南支槽。

预报

　　由于GFS和ECMWF在冬季风的强度以及南支槽的具体位置上存在分歧，本预报的不确定性为中等。地域预报给出如下，请随时留意随着时间的推移和观测数据的更新带来的预报修正。

• 云南地区：向东云量逐渐增多，在大约东经102度开始可能会对观测造成显著影响；根据近地面气象要素预测和过去几年的情形来看，大理一带可能为晴间多云至多云的天气；
• 重庆地区：雾，有微量降水，向东北方向云量可能有减少的趋势；
• 南阳一带：大致天晴，根据近地面气象要素预测和过去几年的情形来看，城区一带的能见度可能在15公里或更好些，利于观测日食；
• 山东地区：大致天晴，根据近地面气象要素预测和过去几年的情形来看，城区附近能见度大约为10公里左右。如果GFS的预测较准确，则东部地区环食带内的能见度可以大幅提高。

下次更新

　　1月8日北京时间23时或更早。

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, https://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.

APanel and Weachart unavailability at 0306Z/0312Z

Because of the forthcoming test for Weachart upgrade, services for APanel and Weachart are unavailable for 0306Z and 0312Z (Jan. 3, 06Z/12Z). Normal APanel forecast should resume at 0318Z run.

重要更新

　　衷心感谢来自香港的Johnson Lau先生为晴天钟编写了新的初始化模块，今后更新速度可望稳定地大幅提高，预计数据初始化4个半小时内就可以公布预报（如下午2时初始化的数据，在18时30分前可公布）。

　　Lau先生的工作使得天气图拓展成为可能，本人正在进行相关的研发工作，预计升级后的天气图可达到1日运行4次的标准。

　　2010年日环食的精密预报将在1月5日开始，对于历史天气情况的分析正在进行之中。

New DIP module reduces process time

Thanks to warm-hearted contributor Mr. Johnson Lau, 7Timer is now enjoying a DIP module with minimum data transfering time. The new DIP module has been put into operation since 0206Z, we expect that the AP forecast will be released no more than 4h30m after the initiallization.

Lau's effort also makes the Weachart extension possible. I'm now working on a major upgrade of Weachart, aiming at a forecasting for more "region" (but possibly with reduced elements) , updates for four times per day, and a revised user interface.

The PFS for 2010 Annular Solar Eclipse will starts on January 5.

2906Z regular update cancelled

A brief note here: since the distributed downloading feature is now under test, the 2906Z (06Z of December 29) update is cancelled, but the 2912Z will resumed. We are now switching to a "distributed downloading mode", which is still under test, and recent updates might be unstable. Stay tuned.