972 
fxus63 ksgf 211057 
afdsgf 


Area forecast discussion 
National Weather Service Springfield MO 
457 am CST Sat Nov 21 2009 


..update to aviation... 


Discussion... 


Forecast challenges deal primarily with temperatures through the 
weekend...followed by timing of next frontal passage the early part of next week. 


Currently...surface high centered over Illinois this morning 
giving US an easterly to southeasterly wind flow. 11-3.9u satellite 
imagery showing stratus deck still hanging across southern 
Missouri into northern Arkansas. Temperatures remain quite warm 
with low 50s across southern Missouri and middle 40s across central 
Missouri at this time. Our next storm system moving into The 
Rockies this morning with ridging from New Mexico north into North 
Dakota out ahead of this system. Upper circulation continues over 
northern Texas on water vapor imagery with dry slotting over most 
of the County Warning Area. 


For this weekend...generally followed met guidance on temperatures 
as it has been doing very well the past couple days. Should see 
temperatures once again in the low 60s as the stratus deck breaks 
up...despite 850/925mb temperatures being a little cooler today 
over yesterday. This cooling should be offset by sunshine this 
afternoon. Upper low over Texas forecast to track across northern 
Louisiana through the day...effectively cutting off any Gulf 
moisture return. Looks dry and warm through the weekend before our 
next system approaches early next week. Continued following 
met/WRF guidance on temperatures. GFS does show a weak shortwave 
pushing through the area Sunday afternoon...but with no Gulf 
moisture return...kept the forecast dry. 


The 00z GFS starting to come more in line with the European model (ecmwf) on 
positioning of upper low and associated cold front Monday 
afternoon into Tuesday. Still a little further north with the low 
center tracking across Iowa..while European model (ecmwf) track it more across 
north central Missouri Monday night. Both show a fairly strong 
cold front pushing through Monday night into Tuesday and have 
continued chance probability of precipitation for this time frame. Pretty good shot of cold 
air behind the front as well with 850mb temperatures falling to 
-4c Tuesday afternoon. A secondary shortwave with another shot of 
cold air looks to be on tap for Wednesday with 850mb temperatures 
falling to -6c...so looks like Tuesday through Thursday will 
probably see temperatures below normal based on better agreement 
between the two models. Will most likely see our first real freeze 
of the season Thursday morning with lows in the upper 20s area wide. 


Claycomb 




&& 


Aviation... 


For the 12z tafs...jln/bbg on the edge of VFR/MVFR category and 
believe MVFR may be possible by 13-14z through the morning hours. 
Otherwise expecting VFR ceilings through the period. 


Lindenberg 


&& 


Sgf watches/warnings/advisories... 
MO...none. 
Kansas...none. 
&& 


$$