Weather

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Area forecast discussion 
National Weather Service Springfield MO 
1124 PM CST Monday Jan 5 2009 


..update to aviation... 


Short term (tonight through Wednesday night)... 


The main forecast focus over the next 36 hours will be the 
prospects for frozen precipitation. The best chances still appear 
to be across south central Missouri...but the rest of the Missouri 
Ozarks and southeast Kansas are not out of the Woods quite yet. 


In the upper levels...several ripples will pass through the area 
over the next 18 hours ahead of a main upper level trough. 
Periodic vorticity advection and increasing jet dynamics will 
enhance lift from time to time. The main lift looks to come 
tonight across south central Missouri in the form of low level 
pressure advection. 


The main factor going against precipitation...especially along and 
north of the Interstate 44 corridor...is the extremely dry air 
in the lower levels. Single digit surface dew points still extend 
south into extreme northern Arkansas as of 3 PM. Think moisture 
advection will increase enough across south central Missouri later 
tonight to better support precipitation making it to the surface. 
This will coincide with the better lift and wet bulbing. Have 
therefore placed likely probability of precipitation across this area. Measurable 
precipitation will be a lot tougher to come by further north and 
west given the low level dry air and lack of middle level saturation. 


As for precipitation type...think we could and will just about see 
everything across the forecast area. If anything falls at 
all...freezing drizzle or perhaps some very light snow look like 
the best bet across southeast Kansas and west central Missouri 
given the lack of cloud ice but cooler middle levels. That will 
transition to a better chance of light sleet and/or freezing rain 
across south central Missouri. Most areas will likely see very 
little if anything...except for south central Missouri where light 
accumulations of ice and sleet are anticipated. Therefore went 
with a Winter Weather Advisory over this area starting this 
evening and continuing into early Tuesday morning. 


Temperatures by Tuesday afternoon should warm above freezing over 
all areas...so any left over precipitation should be liquid in 
nature. We will need to watch that main trough axis coming in from 
the west later Tuesday afternoon into Tuesday evening. There is a 
chance that we could see enough lift and middle level saturation for 
an additional shot of precipitation. Tough call on precipitation 
type once again...but think we may see enough cooling of the 
atmospheric column for some light snow...if precipitation even 
materializes. 


Mainly dry weather is then expected into Wednesday and Wednesday 
night as a strong northwest flow commences. Do expect a cold front 
to pass through the area during the period...but the main lift 
with the associated upper level energy should remain north of the 
area. 


Schaumann 


&& 
long term (thursday through monday)... 


Northwest flow with embedded troughiness will rule the long term 
period. Temperatures will remain fairly seasonal through much of 
the period with a brief warmup on Thursday and Friday in advance 
of a cold front. Blended the long term model outputs with local 
climatology in temperature forecasting. Mex was predominantly too 
warm and most adjustments were made toward the cool side of 
guidance. 


The lone chance for precipitation will come along with a strong cold 
frontal passage on Friday night. Current indications are that the 
precipitation will be a light wintry mix with a transition from 
rain to freezing drizzle and sleet...to perhaps a few snow flurries. 
Once again...accumulations should be quite light as deep moisture 
will be lacking...and the duration of precipitation will be short 
lived as the system rushes through. Gusty northwest winds are 
also expected behind this cold front as the pressure gradient will 
be very tight with Canadian high pressure diving south across the 
plains. A second clipper will speed through the Great Lakes region 
by the end of the period but forcing will be weak across the 
Ozarks and only a wind shift and reinforcing shot of cold air are 
expected. 


Barjenbruch 




&& 


Aviation... 


For the 06z tafs...radar was showing scattered light showery 
precipitation in response to middle level shortwave lifting northeast 
into the area. 00z sgf sounding still shows a very dry layer from 
the surface to near 2000 feet so have only been getting scattered 
reports of sprinkles. Temperatures near the freezing mark or 
slightly below so have introduced a tempo group of -fzra in the 
06z tafs. Ceilings will likely remain 1500 feet or below through 
the overnight and have added some IFR ceilings at the sgf site. 
Ceilings should begin to lift by late morning to early afternoon. 


Lindenberg 


&& 


Sgf watches/warnings/advisories... 
MO...Winter Weather Advisory until 9 am CST Tuesday for moz097-098- 
105-106. 


Kansas...none. 
&& 


$$