373 
fxus63 kfgf 072051 
afdfgf 


Area forecast discussion 
National Weather Service Grand Forks ND 
251 PM CST Wednesday Jan 7 2009 


Short term (wed-sat)... 
the forecast over the next few days was a bit challenging 
considering the potential winter storm Thursday night into Friday. 
The main challenges were headlines...snow potential...and wind 
potential. 


Today and tonight...the models are in fair agreement. Surface high 
pressure will push into the eastern Dakotas tonight...making for 
light winds and some clearing overnight. Cold temperatures are therefore 
likely tonight. 


Thursday into Friday...the high pressure should be centered near 
the Minnesota/Iowa border by Thursday afternoon. Clouds are expected to 
push into the eastern Dakotas by Thursday afternoon as a decent low 
pressure system builds out of the Montana rockies and enters the 
northern plains. This system is still expected to produce several 
inches of snow Thursday night into Friday. However...the latest 
European model (ecmwf)/GFS/NAM/Gem all indicate a more southern solution...with the 
heaviest snow falling further south than the previous runs. It 
seems likely that the heaviest snowfall of 5 to 8 inches will fall 
from a Valley City to Wahpeton line...which lines up well with the 
850 mb to 700 mb moderate frontogenesis band. Much of eastern 
ND...except for the far northeast...should see at least 3 to 5 
inches...including Devils Lake...Grand Forks...and Fargo. Much of 
west central Minnesota can also expect 3 to 5 inches...while the 
Bemidji...Hallock...and Baudette areas could see 1 to 3 inches. A 
general snow ratio of 14 to 1 was used for the snow forecast. Of 
further note...precipitable water will be up to 0.5 
inch...indicating the potential for significant snowfall. This 
more southern solution also rules out the threat for any mixed 
precipitation across southeastern ND since the warmer 850 mb and 925 mb 
temperatures will be in South Dakota. Winds are not expected to pose much 
of a problem for most of the snowfall period...but will pick up by 
late Friday morning just as the light snow is subsiding. 
Therefore...the brisk northerly winds could cause some blowing and 
drifting snow...mostly in open County along and west of the Red 
River valley. Did weaken the northerly winds a bit since the 
previous forecast appeared a bit too strong. A diurnal temperature trend 
was used Thursday night and Friday. Temperatures should be warming 
through Thursday night with the southerly winds...and temperatures should 
be falling after noon on Friday with the influx of Canadian air. 


Friday night into Saturday...the NAM is the outlier and continues 
to linger snow and clouds longer. But...went more towards the GFS 
and European model (ecmwf) with high pressure building into the Dakotas Friday 
night. The northwesterly winds weaken Friday evening...ending any 
drifting or blowing snow. Saturday looks like a fairly 
quiet day with westerly winds and partly sunny skies. 


Long term (sun-wed)... 
models initialized well and went with blended GFS/European model (ecmwf) solution for 
this package. Upper pattern shows a continued northwest flow and little 
change with respect to clipper systems transversing the area. 
However...the upper ridge is expected to amplify over the Canadian 
rockies early next week with a corresponding deepening of the trough 
over the Great Lakes. With thickness values dropping sharply behind 
an Arctic cold front expected to cross the region on Monday...there 
is a possibility the area can see some of the coldest temperatures 
of the season thus far. Otherwise...expect typical clipper weather 
with a chance for measurable -sn with some blsn behind the low. 


&& 


Aviation... 
ceilings/visibility expected to become VFR across the forecast area through the period as 
surface ridge moves east toward the Great Lakes. 


&& 


Fgf watches/warnings/advisories... 
ND...Winter Storm Watch from Thursday evening through Friday 
afternoon for ndz006>008-014>016-024-026>030-038-039-049- 
052>054. 


Minnesota...Winter Storm Watch from Thursday evening through Friday 
afternoon for mnz001>004-007-027>032-040. 


&& 


$$ 
Dk/grochocinski/Hopkins