Weather

919 
fxus63 kmpx 060457 
afdmpx 


Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota 
1057 PM CST Monday Jan 5 2009 


Update... 


Added 06z aviation discussion below. 


&& 


Discussion... 


After a cold start this morning...temperatures have rebounded a 
good 30 to 35 degrees today as southerly winds increased ahead of 
low pressure over the western High Plains. The southerly flow will 
prevail tonight with much warmer lows...mainly in the teens. 


Concerns during the forecast period are mainly centered around a 
low pressure system prognosticated to move through Thursday night and 
Friday and very cold Arctic air that will follow in its wake for 
the weekend. 


But until then...the low to our west will move across the forecast area on 
Tuesday and Tuesday night. Layer moisture is limited in the 
beginning but then increases as northern and southern stream 
energy combine southeast of here as a secondary low pressure deepens 
while moving through the Tennessee and Ohio valleys. Maintained low probability of precipitation 
for light snow across central and west central WI on Tuesday with 
chance probability of precipitation over the eastern County Warning Area Tuesday night and Wednesday. 


High pressure to spread southeast across the forecast area Wednesday night and 
Thursday with lows/highs a little below seasonal values. A short 
wave and low pressure system will approach Thursday night from the 
northern High Plains and then move across the forecast area on Thursday. 
Strong warm air advection/layer moisture develop ahead of this system along with 
plenty of adiabatic Omega. Maintained high chance probability of precipitation Thursday 
night and Friday. Problem developing with this system is the 
threat for freezing rain/freezing drizzle as an elevated warm layer 
moves into west central Minnesota during the night and passes across 
south central Minnesota early on Friday. Added the mention of light 
freezing rain to the aforementioned areas. Sref probabilities 
for freezing rain already on the rise across west central Minnesota 
Thursday evening. 12z European model (ecmwf) also showing the elevated warm layer 
moving through. 


In the wake of the this system...a rather strong Arctic high is 
forecast to build across the region Friday night and Saturday with 
low/high temperatures well below normal. In fact...trend today was 
to go with highs only in the single digits above zero for both 
Saturday and Sunday. If thats not enough...another clipper and 
even colder Arctic air are expected for next week. 


&& 


Aviation.../06z taf issuance/ 


VFR conditions expected all sites until early afternoon. Low 
pressure developing into the eastern Dakotas and western Minnesota 
by morning with frontal boundary extending through central Minnesota. 
Generally dry column moisture except for middle and high levels as 
short wave trough enters the area. Little chance of precipitation 
until cold front moved into western Minnesota behind the low 
pressure area. MVFR ceilings will likely develop in the cold advection 
pattern over northwest part of forecast area in the afternoon and then 
spreasding southeast during the evening. Sharpening upper trough may help 
to generate snow showers or flurries toward the end of the 
period...mainly over north and east taf sites. Visibility restrictions are 
not anticipated at this time. 




&& 


Mpx watches/warnings/advisories... 
Minnesota...none. 
WI...none. 
&& 


$$ 


Rah/jpr