917 
fxus63 kmpx 140736 
afdmpx 


Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota 
136 am CST sun Mar 14 2010 


Discussion... 


Main forecast concerns deal with weak lift across western Minnesota today 
which was associated with a pv /potential vorticity/ anomaly in 
the weak flow across the northern plains. This anomaly is also 
evident on the latest WV imagery. Another concern is much drier 
air advecting into the eastern forecast area which will play havoc on 
temperatures in the forested areas of west central Wisconsin. 
These areas may approach 60 degrees due to abundant sunshine later 
today. 


Short/medium range models are fairly consistent with this weak 
wave moving very slowly eastward across the northern plains/upper 
Midwest in the next 2-3 days. Basically this wave will aid in 
enough lift to cause some light shower activity across western Minnesota 
today/tonight...then across central and southern Minnesota by 
Monday/Tuesday morning. Due to the strength of this system and not 
a lot of moisture...precipitation amounts will be light. Not until 
Monday night/Tuesday will another short wave allow for this weak 
system to move south and decrease the overall cloud cover and 
precipitation chances. 


Confidence level remains high for the upcoming pattern change by 
the end of the week. Although some subtle differences are noted in 
the amount of moisture as a strong cold front moves through on 
Thu/Fri...thickness values drop significantly. 


The latest ec does show the mean Arctic vortex further south and 
west across central Canada by late in the forecast period. Which 
means that cooler conditions should prevail at least for the Great 
Lakes region after the 18th. The latest naefs does show an overall 
decrease in the above normal temperatures across western Canada 
and into the northern plains for the 22nd to the 29th of March 
time frame. This trend has been show from previous runs since the 
7th. The biggest change in the ensembles is the sharp decrease in 
thickness values after the 18th of March. ..jlt.. 


&& 


Aviation.../06z taf issuance/ 


Greatest threat for visibilities at or below 1/2sm will be at kaxn/krwf where surface 
winds bit weaker and snow cover remains with very moist airmass 
still in place. Ceilings have been trending dwnward at kmsp/kstc last 
few hours and should become at or below ovc005 shortly and then remain through 
night. Bit stronger winds than last night...so expct vsbsy to 
remain at or above 1sm. Affects of drier air advecting in can be see in northwest 
WI where breaks developing in overcast. Expect Keau to remain MVFR and then Keau 
and krnh to become VFR by 18z. Imprvg trnd to work into east Minnesota drng afternoon. 


Kmsp...lowering ceilings developing across metropolitan arpts and expect them to remain in 
ovc005 range into Sun morning. Northeasterly winds bit stronger than last night so 
expect vsbysto remain at or above 1sm. Should see imprvg trend by lt Sun morning 
and espcly drng afternoon as drier air advects in from WI. 






&& 


Mpx watches/warnings/advisories... 
Minnesota...dense fog advisory until 11 am CDT this morning for Brown-Lac 
Qui Parle-Martin-Redwood-Watonwan-Yellow Medicine. 


WI...none. 
&& 


$$ 


Jlt/bap