Weather

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Area forecast discussion 
National Weather Service Grand Forks ND 
924 am CDT Monday Oct 6 2008 


Discussion... 
a moist and meridional flow has caused the Gulf to remain 
open...and plentiful moisture continues to advect into the 
northern plains. Precipitable waters are running over 200 percent 
of normal at 12z (1.34 at kabr)...and with another trough moving 
into the central Dakotas today...expect rain showers to continue. 
The area will also be in an area of enhanced upper level 
divergence near the right entrance region of an upper jet...so 
will be going near 100 probability of precipitation for the Red River valley region today. 
Drying will slowly move from west to east by afternoon...and this 
trend is handled well in the current grids. I will increase quantitative precipitation forecast 
amounts a bit...and go in the 0.50 to near 0.7 inch range in the 
South Valley today. Otherwise...we will check over the current 
grids...but little overall change is needed today. 


The fog may become an issue overnight near the inverted trough 
once clearing moves in from the west. We will add a mention to the 
grids and move it from west to east overnight. 


&& 


Aviation... 
MVFR ceilings to rule most of the day...with pockets of IFR ceilings at 
times through 17z. There have been a few holes in the lower cloud 
deck but they will be short lived. Southeast winds will remain 
gusty at times today and turn gradually west behind a surface 
trough which will pass through dvl near 18z and gfk-far near 00z and tvf 
near 03z and bji near 12z Tuesday. 


&& 


Previous discussion... /issued 346 am CDT Monday Oct 6 2008/ 


Short term... 
forecast challenge is ending time of precipitation. Two separate 500 mb waves 
this morning...one over northern Texas with a large area of 40kt 850 mb 
southerly winds from eastern Texas into eastern ND/western Minnesota sending moisture 
our way. One band of warm advection precipitation moving through area overnight 
producing up to 0.75 inch of rain...but continued development of 
lighter showers will continue feed northward in southerly moist 
flow. In addition...fast moving short wave over Montana and 
southern Alberta will shift east quickly and help shift northern 
section of precipitation eastward this aftn/tonight. Surface trough associated with 
this short wave near a Estevan to Bismarck to west of Huron South Dakota line. 
Heavier rains just east of this trough will shift east ahead of 
short wave. Result will be widespread rains in eastern ND through 18z 
then the focus this afternoon will shift more into the Red River valley 
and western Minnesota. After 00z...main focus will be east of the river over 
Minnesota. Montana short wave will move east and then northeast 
into Ontario tonight...and have less impact on helping to move 
front eastward tonight. This will mean a slower end to precipitation to 
much of Minnesota tonight into Tuesday morning. Current gridds 
have this pegged pretty well with only minor modifications made 
for coordination purposes. Total rain amts will be 1 to 1.50 inches 
in most areas. 


Brief clearing will occur Tuesday into Tuesday night from west to 
east before a fast moving 500 mb short wave moves along the North 
Dakota/Canada border on Wednesday. 00z GFS/NAM have trended faster 
with this system in having surface cold front through eastern ND Wednesday morning 
and into northwest Minnesota Wednesday midday-early afternoon. Did keep low probability of precipitation through 
daytime Wednesday for this system...but all indications are that Wednesday 
afternoon will see rapid clearing over eastern ND in cooler airmass behind 
front. 


Long term... 
GFS model still all over the place in regards to Friday-sun system so 
confidence level in overall pattern is lower than usual. 00z 
Canadian has low developing in Kansas and moving to eastern Minnesota/western WI 
Saturday with rain over Minnesota/eastern South Dakota/eastern ND and a cold rain at that. 
00z European model (ecmwf) has a much deeper upper low over The Rockies into northern 
plains and a slow moving and wet storm system for Fri-sun. Stay tuned. 


&& 


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


$$ 
Dk