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Area forecast discussion 
National Weather Service Grand Forks ND 
433 am CST Wednesday Mar 10 2010 


Short term... 
the main forecast challenge is precipitation. When looking at the latest 
surface analysis...an area of low pressure is centered along the S 
Iowa/north MO border...with an inverted trough extending through central Minnesota. 
When comparing the models...the models remain in pretty good 
agreement through the next couple of days and then diverge slightly 
on the low placement by 12z Friday. Thus...ended up leaning toward the 
NAM solution for probability of precipitation and used either the shefbc or the mavbc 
guidance for temperatures. 


The inverted trough remains pretty stationary as the surface low 
drifts slowly north as a second upper level low gets absorbed into the 
current 500mb low that is stationary in the Central Plains. The 
result is a prolonged period of precipitation potential...with bands of precipitation 
wrapping around the basically stationary low pressure system the 
next several days. 


Current radar imagery has one band moving east to west S of a bji to gfk 
line at this time...with another band getting organized in southeast WI and 
S Minnesota. Timing these bands will be a challenge with the potential for 
fog and drizzle in between...due to the high amounts of moisture at 
low levels. 


The model sounding profiles and surface temperatures have remained 
at or above freezing the past couple of days...keeping the precipitation from 
this system so far liquid. However...some colder air is starting to 
work into the system from Canada...with the precipitation already having 
changed over to snow in the west parts of ND. With the atmosphere 
expected to cool aloft as well...especially on the west side of the 
inverted trough...do expect more mixing and change over of rain to snow 
the next couple of days. In conjunction...surface temperatures will 
become critical to determine if will end up with freezing rain. At this 
time...there are too many uncertainties to Pin Point a time frame 
or area that could see any significant icing...so will not issue any 
headlines. It does appear that the dvl area has the best potential 
for seeing snowfall accumulation in the 1 to 3 inch range by Friday... 
but this still remains below advisory criteria as well. 
Consequently...later shifts will need to continue to monitor this 
system for the possibility of headlines. 


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


Long term [sat - sun]... 
the main challenges in the long term forecast are temperatures 
due to the likely return of some sunshine this weekend. The models 
are in decent agreement Saturday...but diverge thereafter...notably 
with precipitation output. The GFS and dgex are indicating precipitation across the 
North Plains Sat night into sun...but the Gem and European model (ecmwf) are mostly 
dry. Leaned on the a blend of the Gem and European model (ecmwf) for this forecast. 


High pressure should influence the North Plains this weekend...providing 
some dry weather and some sunshine. The North Valley and dvl Lake Basin 
look the clearest...but the S valley and wooded region of Minnesota could 
continue to see mostly cloudy skies. Despite the GFS and dgex 
indicating precipitation across the region Sat night and sun...this seems 
much different than previous runs which were mostly dry. 
Therefore...leaned on the mostly dry European model (ecmwf) and Gem. Temperatures 
should be near to slightly above normal. 


&& 


Aviation... 
LIFR to IFR ceilings and visibilities to continue today in rain...dz and fog. 
Winds to remain less than 10 kts from the N-NE. 


&& 


Hydrology...the Army corp of engineers continues to draw-Down 
Lake traverse and Orwell dam in preparation for the Spring thaw 
and subsequent melt runoff. This has caused the Bois Delaware Sioux and 
Otter Tail rivers to rise to high water levels in the Breckenridge 
and Wahpeton areas. Water levels along the Bois Delaware Sioux and Otter 
Tail rivers will remain high for the next week to 10 days. Since 
the rivers are still ice covered...the river levels are expected 
to fluctuate. Ice jamming and associated flooding may occur during 
these releases. 


The best potential for rainfall today and tonight will start in 
southeast ND and wc Minnesota and then spread over all of east ND...northwest and wc Minnesota for 
tonight. A second round of rainfall remains likely for southeast ND and 
wc Minnesota on Thursday into Thursday night...before diminishing on Friday. Rainfall totals 
from today into Friday morning of around three-quarters of inch are 
possible in the S Red River valley...with around one quarter of an 
inch in the north. Temperatures into Friday are expected to continue above 
freezing during the day and fall to near or below freezing at 
night...which will continue to ripen the snow pack and keep a slow 
melt going. 


&& 


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


$$ 
Ng/grochocinski