768 
fxus63 kfgf 022033 cca 
afdfgf 


Area forecast discussion 
National Weather Service Grand Forks ND 
230 PM CST Tuesday Dec 2 2008 


Discussion... 


Forecast challenge concerns temperatures and minor snow chances. 
Models fairly close with main features however prefer GFS relative humidity and 
thermal fields which have initialized a little better so will use 
for details. 


Cold front will exit southeast forecast area this afternoon with cold advection 
continuing overnight. Forecast area looks to be between two favored 
areas for light snow tonight. The first area will be along 
baroclinic ribbon and frontogenetical forcing currently as far north 
as S central ND. This band to gradually shift south affecting areas 
to our south however parts of the region may see a little light 
snow. Another yet weaker area of snow potential will be over far NE 
forecast area located in deeper layered relative humidity closer to upper support. Overall 
confidence low on measurable potential so will mainly go slight 
chance probability of precipitation. Spotty cloud cover...mixing and lack of snow cover will 
offset cold advection. Exception will be far northwest with snow cover and 
will have lowest mins this area. Otherwise will go with slightly 
warmer mav guidance. Concerning current wind headlines winds 
gradually diminishing and further reduction expected shortly after 
sunset as cold advection and pressure rise maxima shift east. If 
current trends continue will cancel. 


A couple of weak waves will rotate through deepening middle level 
trough through Wednesday. Deeper layered relative humidity also increases along 
with convective temperatures in the teens. With cold air in place 
and relative humidity and wave will continue to keep slight chances going. Cold 
advection bottoms out but with clouds should be minimal temperature 
recovery. Only aid in thermal recovery will be lack of snow cover 
again exception being over forecast area northwest forecast area. 


Region remains in cyclonic flow through period with deepening 
trough. Secondary shot of cold advection with passing wave will 
further cool column. Surface high center remains to our west which 
will keep some light mixing going and models also hint at potential 
cloud cover. For this will tailor temperatures towards slightly 
warmer maximum again except over snow cover. 


Thursday looks rather similar to Wednesday overall. Column does 
begin to dry slightly from west-east so measurable potential looks pretty 
none and will maintain flurries dropping any mention west of valley 
during afternoon. Temperature recovery again looks minimal. 


Could see some clearing Thursday night however this likely to be 
offset by warm advection and westerly surface flow as surface high 
shifts to our south. Also lack of snowcover will also have an 
effect. 


West surface flow/warm advection continues into Friday ahead of 
next clipper so temperatures should moderate closer to seasonal 
averages. At this point see no reason to increase probability of precipitation in warm 
advection zone as moisture looks limited. 


Long term... 
fairly messy long term with pop chances throughout most of the 
period. A lot of uncertainty remains between long term models. 
However...decided to go with the slightly slower and weaker GFS as 
compared to the European model (ecmwf) and Canadian. The region will remain in 
northwest flow with several waves moving through. Sat night/early 
sun and Tuesday appear to be the best bet for no snow shower chances. 
Much lower than average temperatures will also impact the region for 
the weekend with the possibility of low temperatures dropping below 
zero. A slight warming trend at the beginning of next week will 
bring temperatures back up to near normal values. 


Aviation... 
VFR conditions will give way to MVFR ceilings overnight. -Sn possible at 
gfk...far...and bji with only some -shsn at dvl and far. Northwest 
winds will continue at all sites with gusts near 30 kts. Winds will 
diminish after sunset and should be around 10 kts by 00z. 


&& 


Fgf watches/warnings/advisories... 
ND...none. 
Minnesota...none. 
&& 


$$ 


Voelker/homann