681 
fxus63 kmpx 041723 
afdmpx 


Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota 
1122 am CST Thursday Dec 4 2008 


Aviation.../18z taf issuance/ 
band of -shsn moving through ec Minnesota at this time. Visibilities lower to 
around 1 mile in heavier band. This will likely affect krnh and 
lesser degree Keau during the afternoon. Otherwise...cold trough 
moving across region the remainder of the afternoon...should 
continue the threat of MVFR ceilings/-shsn through 23z-00z. Question 
remains if lower clouds will linger through the night. Appears NAM 
and to some degree the GFS holding onto lower level moisture... 
especially in the 2-4k feet range during the night. Will hold onto 
the clouds over the eastern forecast area until after 07z at kmsp/krnh and will 
hold overnight at Keau. Will hold them VFR for now. Later tonight 
and Friday...strong low level warm air advection develops ahead of next short 
wave. This will quickly spread middle/high level clouds east over the 
forecast area through midday Friday. Then expect lowering ceilings and perhaps S- 
affecting western taf sites before 00z Sat. 


&& 


Previous discussion... 
/issued 426 am CST Thursday Dec 4 2008/ 
an area of light snow continues to traipse across the forecast 
area early this morning...induced by faint shortwave energy in the 
base of the trough centered over Hudson Bay. The associated area 
of 850-500mb q vector convergence shifts east of the County Warning Area this 
morning...with measurable snowfall expected to end around 
daybreak. However...scattered flurries will be possible for a good portion 
of the day under the influence of the departing upper trough. Cold 
air advection and an 850mb temperature decline to around -20c will 
contribute to maximum temperatures around 10 to 15 degrees below 
climatological normals...as readings top out in the middle/upper 
teens and low 20s. 


After today...attention shifts to a clipper system prognosticated to dip 
across the north central Continental U.S. On Friday. There was good agreement 
between the latest runs of the GFS/NAM/ECMWF in bringing 
measurable snowfall to the County Warning Area between 00z and 12z Saturday. 
Snowfall amounts between one and two inches appear 
likely...especially across North/East central Minnesota and west 
central WI...where snow growth should be decent per forecasts of 4-5 
-ubar/S of Omega at the -15c temperature level. 


Chilly temperatures prevail over the weekend...with a low level 
high pressure ridge in control. The next shortwave trough in the 
parade is forecast to arrive late Sunday and Monday. Although 
there are still notable difference in the model solutions with 
respect to timing/placement aspects of this feature...agreement is 
decent enough to warrant high chance probability of precipitation between 00z Monday and 
00z Tuesday. High pressure will make a fleeting appearance late 
Monday into Tuesday...with yet another weak system expected by 
midweek. 


&& 


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


$$ 


Dwe/ls