Weather

428 
fxus63 kfgf 211853 
afdfgf 


Area forecast discussion 
National Weather Service Grand Forks ND 
153 PM CDT Thursday Aug 21 2008 


Short term... 
the main challenge will be wind speeds over the next 24-30 
hours...and severe potential late this afternoon and overnight. A 
vigorous trough is digging into the Idaho area...with several 
shortwaves moving towards the northern plains. Models have a good 
handle on the overall scenario...and like the GFS quantitative precipitation forecast fields with 
the NAM a bit better with surface moisture and overall instability fields. 


For late this afternoon/overnight...expect winds to remain near 
advisory levels through 02z...and will continue the Wind Advisory 
here. Otherwise...severe potential should develop in the dvl basin 
after 21z...with middle 60s dewpoints trying to probability of precipitation there this 
afternoon. The cap is pretty strong...but should be overcome as 
large scale ascent overspread region towards 00z. The timing of 
severe convection will be tricky...and may be delayed a bit and 
wait for larger wave that will approach the area towards 06z. The 
best chance for convection through the night should be confined to 
the dvl basin...but there is the threat for storms anywhere after 
06z so will mention. I am a bit concerned with the strength of the 
dynamics with this system...moving 


For Friday/Friday night...a strong cold front and potent upper level 
wave will rotate the northern plains and southern Canada. Winds 
will shift to the west by Friday afternoon in all areas. The best 
threat for convection will be across the north closer to upper 
low. Temperatures will cool from recent days...and expect a windy day 
with another Wind Advisory possible with about 30-35kt to mix as 
layer becomes adiabatic by afternoon in the north. 


For Sat/sun...expect temperatures well below normal with high pressure in 
control. Temperatures will likely remain in the 60s for the north on 
Sat...and a cold morning is likely Sunday morning. A slow warming 
trend will develop on Sunday with more sunshine expected and 
slowly warming thermal fields. 


Long term [mon-thu]... 
model preference today is with the European model (ecmwf) for Mon/Tue...then more 
toward the GFS ensemble for the last two days of the long term 
forecast. The Monday/Tuesday time frame looks pretty quiet...with surface high 
pressure pretty close to the forecast area. Did inherit low precipitation chances for 
Tuesday afternoon...but did trim them back to just the kdvl region. 
Better chances for precipitation look to be Wednesday into Thursday as a trough over the 
western part of the country shifts east. This will bring a slow 
moving surface front into the western Dakotas. For the most part temperatures 
look to continue from normal to just a bit above normal. 


&& 


Aviation... 
wind speeds...wind directions (associated with a cold frontal 
passage) and thunderstorm chances will be the big aviation challenges. The 
gusty winds should slacken off a bit by middle evening when the Wind 
Advisory is also set to expire. Convective chances will be greater 
by kdvl...where there could be some evening thunderstorms plus more thunderstorms 
when the actual front passes. This front looks to be near kdvl 
around 12z...to the valley around 14/15z...and to kbji toward noon. 
Gusty winds will return behind the cold front...but this time from 
the west. 


&& 


Fgf watches/warnings/advisories... 
ND...Wind Advisory until 9 PM CDT this evening for ndz006>008-014>016- 
024-026>030-038-039-049-052>054. 


Minnesota...Wind Advisory until 9 PM CDT this evening for mnz001>009-013>017- 
022>024-027>032-040. 


&& 


$$ 
Dk/godon