January 5th, 2010

2010 Annular Solar Eclipse PFS Bulletin No. 1

Published at 23:09. Filed under Precision Forecast Service; no comment so far.

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.