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Area forecast discussion...amended 
National Weather Service Grand Forks ND 
1121 PM CDT Wednesday Mar 17 2010 


Amended to update the hydrology section 


Discussion... 
positive tilted upper level ridge extended from the Great Lakes into 
South Dakota. Ridge will shift southeast tonight. Upstream the water vapor 
loop shows an upper level low located over southwest Saskatchewan with jet 
on the south side. 


Water vapor loop indicates a good band of drying over northwest ND 
and eastern Montana. Upper low forecast to move east across Saskatchewan. Also 
drying/darkening to move across the forecast area overnight as exit 
region of jet moves into northern zones. GFS cross section indicated 
good drying occurs aloft by 12z Thursday. Low level Theta-E ridge over ND 
will shift into Minnesota by morning. Dewpoints this evening were mostly in 
the low to middle 30s. Expect higher dewpoints to shift into Minnesota. 


Southwest flow off the surface turns to the west northwest by 
morning. Will lower temperatures a couple degrees for tonight over western 
zones. 


&& 


Previous discussion.../issued 341 PM CDT Wednesday Mar 17 2010/ 
the main forecast challenge is temperatures. When looking at the 
latest surface analysis...a ridge of high pressure extends through east 
South Dakota into east Minnesota...with a trough extending through central ND. When 
comparing the models...the models are in pretty good agreement into 
the weekend....so ended up leaning toward the NAM for probability of precipitation and the 
adjmav for temperatures. 


The surface ridge continues shifting east tonight and the trough passes 
by Thursday morning as well...turning the winds to a more west direction... 
which will assist in keeping temperatures up overnight. With cold air 
holding back a bit...expect to see another warm day on Thursday...with 
highs in the 40s. 


Colder air starts to push down into the North Plains for Thursday night and 
Friday...as the winds turn northwest. Could see some flurries or light snow 
as the cold air moves back in. However...expecting only a dusting at 
best at this time. The cold air advection continues through Friday night into Sat... 
with low temperatures dropping into the 10 to 20 degree range by Sat 
morning. 


Long term /Sat night through Fri/... 
long range models in general agreement with a Canadian wave moving 
across the County warning forecast area Sat night into sun. Primary difference with the 
models is the associated fronts impact on temperatures...with the European model (ecmwf) 
colder than the GFS...and HPC is leaning toward the cooler 
solution. 


In general...we will see a shift toward cooler temperatures as a couple of 
cold fronts move through from Sat evening through Wednesday. Probability of precipitation have 
been added to the forecast in the NE for Sat evening. However...the 
air mass looks rather dry...more likely a flurry scenario. Monday looks 
dry...then another wave moves through Tuesday into Wednesday. Current HPC 
solution looks a little fast when compared to the European model (ecmwf)...but do have 
probability of precipitation in during the day on Tuesday...with Tuesday night being the best chance 
for any precipitation. Looking more like snow versus rain with the cooler 
temperatures the European model (ecmwf) is showing...and have adjusted grids accordingly. 
Have kept mention of rain for afternoon hours as temperatures rise into the 
upper 30s. 


&& 


Aviation.../00z taf issuance/ 
currently VFR conditions for all area terminals with 
wind gusts diminishing and gradually shifting to the west overnight 
with skies remaining VFR for the ND taf sites. At the Minnesota taf 
locations...a shallow layer of moisture will be advected in from 
the north and bring the potential for broken-overcast IFR ceilings before 
sunrise through the early morning period of Thursday. Skies are 
expected to clear rapidly Thursday morning...with VFR conditions by 
16z. 


&& 


Hydrology... 
there is small erosion of a small dam on the Swan Creek northwest 
of Absaraka in Cass County. Please see the flsfgf for further 
details. 


Temperatures will remain fairly mild for this time of year through 
tomorrow (thursday). High temperatures on Thursday will reach the 
40s to low 50s...so expect more melting and local runoff. A cold 
front will pass through the northern plains Thursday night...so 
colder temperatures are expected Friday through early next week. 
Overnight lows should also be well below freezing over the weekend. 
Therefore...the colder weather will slow melting and local runoff. 
No significant precipitation is anticipated through at least the 
weekend. 


Many of the Minnesota tributaries to the Red River are nearing their 
crests or are already on their way down. Minor to major flooding is 
still expected for most of the North Dakota tributaries. The 
exceptions are at Walhalla and Neche along the Pembina river near 
the Canadian border...which have not responded significantly enough 
yet to the recent melting to warrant forecasts at this time. West 
Fargo and Harwood are experiencing backwater effects due to the 
Red River flowing into the lower end of the Sheyenne river. Moderate 
and major flooding is expected at all forecast locations along the 
main Stem Red River. Wahpeton will slowly fall for the coming 
days...but the rest of the main Stem Red River locations are still 
rising. 


As for gage equipment issues...Kindred is regularly coming in with 
bad data. The observed data for Kindred gage is estimated. Estimate 
a day or two for the gage to be fixed. Minto is having some ice jam 
issues...which account for its rising above the forecast. Minto will 
also be monitored. The Sheyenne river at Valley City fell due to 
smaller releases at Bald Hill dam. Stay tuned for future forecast 
updates as ice affects can result in rapid fluctuations in river 
levels. 


&& 


Fgf watches/warnings/advisories... 
ND...Flood Watch through Friday afternoon for ndz006>008-014>016-024- 
026>030-038-049-052-054. 


Areal Flood Warning for Richland and Cass counties. 


Minnesota...areal Flood Warning for Wilkin...Clay and Norman counties. 


&& 


$$ 


Jh/Dr/g2/dlh