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Area forecast discussion 
National Weather Service Grand Forks ND 
948 PM CDT Sat Mar 20 2010 


Update... 
new hydrology discussion below. 


&& 


Discussion... 
positive tilted upper level ridge over the northern rockies will 
move into the northern plains by tonight and Sunday. Exit region of 
northwest-southeast orientated jet will shift into southern man and southern 
Ontario by morning. Water vapor loop suggested upper jet had nosed 
into southern Canada. A clear sky was across the area with some thin 
cirrus spilling into western ND. 


Cold front was located over central Manitoba and is forecast to move 
southeast tonight. May brush northeast zones late Sunday morning. 
Forecast area will be under the warm sector for tonight. Models 
forecasting low level moisture and temperatures to increase off the surface 
for tonight. Current dewpoints were in the middle to upper 20s across 
southern Canada and ND. Dewpoints were lower in southest zones and 
into South Dakota. Will go a bit cooler southeast zones and warmer elsewhere. 


&& 


Previous discussion.../issued 313 PM CDT Sat Mar 20 2010/ 
the main forecast challenges are temperatures and precipitation. When looking 
at the latest surface analysis...surface high pressure is centered 
in southeast South Dakota...with a ridge axis extending through central Minnesota into Lake 
Superior. When comparing the models...the models remain in pretty 
good agreement...so ended up leaning toward the a blend of the NAM 
and GFS for probability of precipitation and toward the cool side of the adjmav guidance for 
temperatures. 


The surface ridge continues shifting S and east tonight...with SW flow 
remaining over the North Plains through the night. Thus...looking for 
lows tonight a little warmer than last night...in the lower to 
middle 20s. 


For sun into Monday...a clipper starts moving toward the North Plains from 
Canada...keeping a S-SW flow into the area and good warm air advection into Monday. 
Thus...still expecting temperatures to moderate into the 40s by Monday...with 
even some lower 50s in west Minnesota possible. The next chance of precipitation will 
be on Monday afternoon as the low drops into central ND...with some 
light showers mainly in the north areas. 


For Monday night into Tuesday...the low passes and colder air returns to 
the North Plains...switching any precipitation to a rain/snow mix and even to 
snow...especially in the overnight hours. Precipitation totals will be 
light...with less than one tenth of an inch expected...as well as 
any snowfall accumulation to be less than one half inch. 


Long term [wed-sat]... 
pretty stagnant pattern holds through the long term period with 
northwest flow generally remaining in place. Not very much consistency 
between model solutions on the overall thermal setup...but a 
tight thermal gradient does look likely. However...just a little 
shuffling north or S of this gradient would make a marked temperature 
difference. Overall...trended temperatures toward normal for this time 
of year. Precipitation chances looking even more meager for Thursday night/Friday 
so removed these. Temperatures beyond the seven day period may take a bit 
of an upswing...with new 8 to 14 day forecasts showing above normal 
temperatures with near normal precipitation. 


&& 


Aviation...00z taf issuance 
some scattered low VFR SC will quickly dissipate after sunset tonight. 
Otherwise...scattered cirrus will prevail with SW winds overnight. 
Winds will veer S late Sun morning or early afternoon and be in the 
6-10 knots range. 


&& 


Hydrology... 
moderate to major flooding continues on the Red River from Wahpeton 
to Oslo. The tributaries on the Minnesota side of the river have crested 
and are falling...save for the Sand Hill river at Climax and the 
Wild Rice river at Hendrum. Those two locations will experience a 
protracted crest due to backwater effects from the Red River. The 
same effects will be felt on the Sheyenne river at Harwood and on 
the West Fargo diversion. 


No significant changes were made to any forecasts tonight. The Red 
River at Fargo and Moorhead is near crest...but does continue to 
rise ever so slowly and is thus still on track to have a peak stage 
near 37.0 feet Sunday. The broad crest wave will continue making its 
way north...also passing Halstad Sunday...and reaching Grand Forks 
Monday...Oslo by Tuesday and Wednesday...Drayton Thursday into 
Friday...and Pembina by the end of March. Ice in the Main Channel 
will continue restricting flow from Oslo north to the Canadian 
border. 


Temperatures are expected to rise into the 40s Sunday through 
Tuesday. This will cause some renewed snowmelt runoff in the upper 
reaches of the Sheyenne river...especially around Lisbon...where 
river model simulations suggest river rises by midweek. 


Also of note is that model simulations suggest peak runoff flow on 
The Turtle river in northeastern ND should occur tonight...so levels 
will then hold steady or begin a slow decrease Sunday. 


Finally...the river gage at Hallock was repaired and is now reading 
accurately. On the other hand...the Pembina gage has not reported 
since Saturday afternoon...so current readings are missing there. 




&& 


Fgf watches/warnings/advisories... 
ND...areal Flood Warning for Richland...Ransom...Sargent...Cass... 
Barnes...trail...Steele...Griggs...Grand Forks...eastern Walsh... 
and Pembina counties. 


Minnesota...areal Flood Warning for Kittson...western Marshall...western 
Polk...Norman...Clay and Wilkin counties. 


&& 


$$ 
Jh/Dr/dlh/cs