Weather

174 
fxus63 kfgf 070826 
afdfgf 


Area forecast discussion 
National Weather Service Grand Forks ND 
326 am CDT sun Sep 7 2008 


Discussion... 
deep cyclonic flow continues for the northern plains...and a 
shortwave is rotating through the forecast area this morning. A 
band of showers continues to move into southeastern areas...with 
lightning dissipating over the past few hours. The models captured 
this feature well...with the GFS initializing the surface cold front 
slightly better. Therefore...prefer the GFS although all models 
are in good agreement...leading to a fair amount of confidence in 
the overall forecast. 


For today...very low convective temperatures in the low 50s north/middle 50s 
south should mean all areas seeing cumuliform clouds by afternoon 
along with temperatures below normal. There is lingering cyclonic flow and 
some weak lift...although there is no instability to speak of. 
Therefore...expect a few showers...with the best threat in the 
north and east where lifted indices are near zero. Subsidence 
moves into the area quickly from the northwest by 00z...and it may become 
breezy with about 20kt to mix efficiently during the afternoon. 
There may also be some patchy fog through 14z in the far east near 
the surface boundary as clearing moves in during the pre dawn hours. 


For tonight...surface high pressure builds in and temperatures will fall 
below normal. There is a shortwave that will approach late 
tonight...and enough clouds could move in before temperatures fall too 
much. It will be cold enough though for at least some areas to see 
localized patchy frost mainly in the north and west...and will mention 
where forecasted lows are 37 degrees and a bit colder. We/ll have 
to watch for possible frost headlines Monday morning...although 
current thinking is that some clouds and recent rain will will 
keep the boundary layer just moist en ought to preclude a widespread 
frost threat. 


North Monday...cold air aloft per 500mb temperatures around -23c should and 
a weak shortwave will mean another chance for showers mainly in 
the north. There is some weak lift as well...but overall moisture 
is limited in the 800-600mb layer...so not expecting much more 
than a few hundredths where rain reaches the ground. There is no 
instability to speak of...so will only mention showers. Temperatures will 
once again be cool and very similar to Sunday...with convective 
temperatures in the middle 50s. 


For Tue/Wed...return flow develops and a transient southwest flow 
aloft is expected on Wednesday. Moisture will increase on Wednesday with some 
elevated instability and an increasing low level jet...coupled 
with the right entrance region of an upper jet. Therefore...expect 
some showers and a few thunderstorms Wednesday/Wednesday night. 


By Thu/Fri...drier air quickly builds into the northern plains and 
precipitation threat should end from west to east by afternoon. Temperatures 
should warm to near normal with some afternoon sunshine and fairly 
warm thermal fields. 


Looking ahead to next weekend...it appears a cold front may move 
through the region. This could bring the threat for some showers 
and thunderstorms into the region. 


&& 


Aviation... 
some morning MVFR conditions possible in the east...with VFR to 
perhaps MVFR ceilings in all areas by late morning. Ceilings will 
rise and scatter out by late afternoon from west to east. Northwest winds 
may gust to near 20 knots in the valley this afternoon behind the 
cold front. 


&& 


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


$$ 
Dk