910 
fxus63 kmpx 212318 
afdmpx 


Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota 
618 PM CDT Thursday Aug 21 2008 


Discussion... 


Slug of moisture associated with upper trough lift north out of east Iowa has 
spread showers across southeast Minnesota into SW WI. There has been sufficient 
heating early this afternoon in ec Minnesota to probability of precipitation a few showers and 
thunderstorms as convective temperature in lower 80s has been 
reached. Expect these convective showers to become a bit more 
widespread the remainder of the afternoon before rapidly diminishing 
during the evening. Showers associated with middle level trough lifting 
out of Iowa will continue at least until 06z in southeast County Warning Area. Overnight 
temperatures will be mild with warm, moist southerly flow and mostly 
cloudy skies. Convection currently firing NE nodak in strong low 
level jet where airmass has destabalized...but should lift north of County Warning Area 
overnight. 


Attention then turns toward precipitation chances for tomorrow with 
approach of cold front and vigorous upper trough. Instability not 
overly impressive...but strong 0-6km bulk shear in 50 knot plus 
range vicinity of cold front could pop a few strong storms. Expect 
a scattered line of thunderstorms to develop in SW into central Minnesota 
in the early/middle afternoon moving across eastern areas mainly in the 
evening. 


Dry and cool Canadian pressure pushes in for the weekend with 
surface dewpoints likely dropping at least into the upper 40s across 
much of the area. Will also have some fairly gusty west winds on 
Saturday with nam80 prognosticated soundings showing 20 to 25 knot winds 
available for mixing. 


Another quite vigorous upper trough expected to move out of the 
northern rockies middle week driving another cold front across the area 
on Wednesday. Started probability of precipitation Tuesday night in west and spread across 
area on Wednesday. 


&& 


Aviation.../00z taf issuance/ 


Middle level low pressure lifting NE across miss valley region toward 
southern WI with a shield of rain showers mainly affecting Keau 
area. The shower chance will linger until about 04z. A large area 
of MVFR to IFR ceilings is in place to the west and north of the 
middle level low. South-southeast low level winds will carry this areas of low 
ceilings into much of the area overnight. The greater chance of 
IFR ceilings will be along and east of a line from kstc to krwf. 
Expect the low ceilings to fill in and expand after about 03z. 
There will also be areas of visibilities below 3 sm in fog 
overnight...mainly over eastern areas. The next weather feature 
during the forecast period will be a cold front moving into 
western Minnesota by late morning or early afternoon on Friday. Low 
clouds and ceilings will lift during the morning leaving scattered 
040-060 during the afternoon. The chances for thunder affecting 
the area during the forecast period are slim at this point. The 
atmosphere will be capped into early afternoon but scattered convection 
could develop after about 20z. The best chance for thunder will be 
from kstc to kmsp and krnh. 


&& 


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


$$ 


Bap/jpr