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Area forecast discussion...updated 
National Weather Service Grand Forks ND 
1107 am CST Thursday Mar 11 2010 


Update... 
issued a pns for 3 day rain totals. 


Forecast about as expected. Next wave of rain entering our far 
southeastern forecast area at this time with rain entering Alexandria and 
Elbow Lake at 17z. Worrisome is some thunderstorms at St cloud and 
msp and areas of heavy rain on observation as radar shows band of precipitation is 
convective. Right now forecast is for 0.50 inch of addl rain in southern 
Red River basin but will need to watch for higher amts. Band of rain 
will overspread southern Red River and wctnr Minnesota this afternoon and reach northern 
valley in less intense Mode this evening. The light snow in the 
dvl basin has ended. Kept low probability of precipitation for rain/snow this afternoon but dont 
expect much. 


Did up probability of precipitation this evening over the Red River valley. Latest models 
continue with idea of another area of rain spreading in Friday so 
may well have to up probability of precipitation. Latest GFS hangs grunge and at least chance 
of drizzle through the weekend. 


&& 


Previous discussion... /issued 400 am CST Thursday Mar 11 2010/ 


Short term... 
the main forecast challenge is precipitation. When looking at the latest 
surface analysis...an area of low pressure is centered in MO...with 
an inverted trough extending through Iowa into west Minnesota. When comparing the 
models...the models remain generally in pretty good agreement 
through the rest of the work week. Therefore...ended up leaning 
toward the NAM solution for probability of precipitation and used a model blend for temperatures. 


The inverted trough remains pretty stationary through the area today 
as the initial surface low fills and the second upper level low gets 
absorbed into the current 500mb low that is stationary in the 
Central Plains. The result is continued periodic precipitation...with the 
bands of precipitation wrapping around the basically stationary low pressure 
system into Friday. 


Current radar imagery has one band moving east to west from east ND into 
central ND and another band lifting into S Minnesota. Timing the 
development and location of these bands continues to be a challenge. 
The potential for fog and drizzle remains between the precipitation 
bands...due to the high amounts of low level moisture. Dense fog has 
developed in parts of southeast ND and wc Minnesota...in vicinity of the lightest 
winds. Thus...will issue a dense fog advisory until noon and let the 
day shift monitor the fog dissipation. 


The model sounding profiles and surface temperatures continue to 
show temperatures primarily at or above freezing for today...just 
like the past couple of days...so kept the precipitation for today basically 
liquid. However...some colder air is still expected to try to work 
into the system from Canada...which could provide enough cooling to 
change the rain to snow...especially during the overnight hours on 
the west side of the inverted trough. However...with low level moisture 
remaining high...if precipitation can change over to snow...it will be 
difficult for any significant accumulation to occur. 


The low drifts east enough by Sat and a surface high pressure ridge 
builds in to finally cut off the precipitation potential. 


Long term [sun - mon]... 
the main challenges in the long term forecast are temperatures due 
to the potential for some sunshine early next week. The GFS and Gem 
model runs are in decent agreement...but the European model (ecmwf) is the outlier 
for precipitation and cloud cover. Leaned on the GFS and Gem. 


High pressure should influence the North Plains sun and Monday...keeping 
the region mostly dry. The European model (ecmwf) is the outlier...developing a 
small upper level low over the region...and indicating considerable 
precipitation along and east of the valley. Think this is a poor model run of 
the European model (ecmwf)...so leaned on the much drier GFS and Gem. The GFS and 
Gem imply at least partial cloud cover sun and Monday...so ignored 
the clearing on Monday that is implied by the European model (ecmwf). Temperatures 
look near to above normal. There should be some cooling west of the 
valley on Monday. 


Aviation... 
basically...IFR/MVFR ceilings and visibilities if fog and rain expected to 
continue today. Winds will remain from the north-NE around 10 kts as 
well. 


Hydrology... 
the rains have been light and steady...which has helped to 
compact the snow pack...but so far has not been heavy enough to do 
much more. Additional precipitation amounts for today into Sat are less 
than one quarter inch along and north of a Valley City to Ada to bji 
line. S of this line...additional amounts up to three-quarters of 
an inch are possible. 


&& 


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


$$ 
Riddle/ng