810 
fxus63 kmpx 220014 
afdmpx 


Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota 
714 PM CDT sun Mar 21 2010 


Discussion...updated for 00z aviation discussion below... 


Vapor loop clearly showing high latitude zonal flow across central 
and southern Canadian provinces. Second galvanizing feature concerns 
cut off low pressure tracking across the deep south. In 
between...most of upper Midwest enjoying another day of above 
average temperatures and abundant sunshine. Stacked low pressure system 
over Dixie will migrate into Middle Atlantic States by Tuesday 
morning. This will enable a weak Alberta clipper to trek into central 
Dakotas by Monday afternoon. Look for a pick up in southerly flow 
across much of County Warning Area tomorrow as gradient tightens slightly ahead of 
filling cyclone. Throw in an increase of 2 to 3 degrees on the 850mb 
winds...with 50 to 60% sunshine and we will easily break out into the 
middle 50s across much of the forecast area. Both gfs40...napster...and European all 
indicating continued filling of system as it proceeds into western Minnesota 
and Iowa on Monday night. Any appreciable moisture dispensed will be 
associated with 500 mb trough slightly to its Lee. Gfs40 isentropic anal per 
295k most aggressive with painting area of possible precipitation. Even so 
..only appreciable forcing indicated over extreme northern third to 
half of forecast area. Quantitative precipitation forecast very weak...with jet support also lacking during much 
of Monday night into Tuesday afternoon. As previous thinking 
indicated...would not be surprised to see very light showers or a 
drizzle scenario unfold with this system. 


Look for copious amounts of polar air to funnel into upper Midwest 
Tuesday afternoon into Wednesday...with brunt of cold air expected across NE Minnesota and 
northern WI. Should be a fairly clear cut thermal line set up across 
County Warning Area on Wednesday...as cold air across west central WI and east central 
Minnesota...slowly abates. Reinforcing shot of polar air in wake of more intense 
surface low pressure moving ito Great Lakes region on Thursday. This extra 
intrusion of cold air will put US back to near normal conditions in 
temperature dept right into Saturday. 


Looks like another stacked surface and 500 mb system unfolding across the central 
Great Plains for the weekend. Inverted trough from system will infiltrate 
our neck of the Woods late Friday night into early Sunday. 
1000-500mb thickness values and 850 temperatures...indicating a decent 
chance of light freezing rain across western third of County Warning Area Friday 
night...with changeover to all snow anticipated on Saturday. 
Moisture values up to a few tenths of an inch also expected. Keeping fingers 
crossed for measurable snow. If not...could be Last Chance for snow 
across much of forecast area in March...and first time no snow has fallen in March 
at msp. 


&& 






Aviation.../00z taf issuance/ 


VFR conditions to rule through 06z Tuesday. Main focus is Wind. 
Ridge is shifting eastward with SW surface winds gradually turning 
southerly. Strongest winds in western Minnesota at this time about 10 knots...and 
with increasing gradient... those should remain around 7-9 knots 
tonight. Eastern Minnesota and wisc will not see much of a gradient until 
Monday...and thus should have S or southeast winds tonight less than 5 
knots. Winds increase Monday morning...with 8-10 knots in wisc 
and 10-20 knots in Minnesota. A low pressure area in Alberta moves toward 
central Minnesota on Tuesday with an associated cold front. A few 
high clouds...cirrus are moving into to the western areas of the 
state. By 07z clouds could be bkn250. East of this area we can 
expect few-sct250 through the period. 


Kmsp...south southeast surface winds around 4kts overnight 
becoming south at 9kts increasing to 13kts after 19z with gusts to 
18kts. May see ovc250 after 00z. 






&& 


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


$$ 


Ajz/drl