Weather Discussion: KSTL Dec 11 2009

For Friday: Temperatures will remain in the 20's until late morning when the skies clear and the wind shifts south-west bringing the high into the upper 30's by mid-afternoon. Blustery winds reaching 13 knots during the day will slow to 7 knots and shift south in the evening. There is a slight chance for freezing drizzle on Friday night, precipitation amounts will be trace.

KSTL Forecast for Thursday

Nothing too exiting for thursday:
Expect clear skies and cold conditions. As ridge moves
into the area temperatures will settle but will remain cold...
gusty conditions will make windchill a major factor.

Forecast Discussion For Wednesday @ 6Z till Thursday @ 6Z

The period will begin with the storm moving out of the area by 12z on Wednesday and the area beginning to dry out being on the back side of the trough and surface low. These features will usher in the coldest air yet for season with temps not warming any above Tuesday's lows. Wednesday night's lows will be plunging into the teens. With the tight pressure gradient associate with the low to the north east winds will be above 20kts for most of the period. With the low temperatures and high winds it's going to feel a lot colder than what the thermometer reads.

Thursday's KSTL Discussion

With the first major out break of Canadian cold air, this period is featured with cold air advection and surface high pressure. Both the GFS and NAM show 850mb temperatures getting as low as -10C with the flow from the west turning south west 00z Saturday. This will signify the trough axis passing of over the area. That will be the beginning of temperatures moderating for weekend.

KSTL Dec 3 2009

The cold front moves out of the forecast area Thursday but the cold temperatures linger due to mixed layer CAA following the front. Lingering flurries are possibe before 11:00am, cloud cover should diminish in the afternoon. High temperature will be in the upper 30's, low in the low 20's daytime cold NE winds around 12 knots dropping to 8 knots and shifting NW in the evening. Cold temperatures will remain through Friday.

Wednesday Forecast for KSTL

Two low pressure systems approaching the area will result in some rain throughout the day, changing to snow in the early evening. From most of the models, it looks like the worst weather will just miss the area, as the low associated with the shortwave trough tracking from the NW and the Texas Low racking to the NE converge east of KSTL. Most of the local precip will result from the descending cold front, with some wrap around from the second low. Temperatures will remain low through wednesday, and I am expecting it to be lower than what the models forecast. Winds will be gusty and high throughout the period.

Errors in the model forecast track for either low could result in significantly different weather either way, with more precip if the lows converge closer to KSTL, and little to no precip if they converge further east of the area.