Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 131851
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1251 PM CST Tue Feb 13 2018

.UPDATE...
Issued at 1236 PM CST Tue Feb 13 2018

Latest obs showing visibilities across the north from Langdon to
Cavalier to Hallock varying down in the 1 to 3 mile range. Winds
sustained 20 to 25kts with gusts 30 to 35kt, a bit higher at
Langdon with its higher elevation, but no blowable snow available.
No other changes needed for the rest of the afternoon and into the
overnight. Temps in the upper teens and on track for 20s this
afternoon.

UPDATE Issued at 943 AM CST Tue Feb 13 2018

Impacts for today advertised well with how much blowing snow will
occur causing reduced visibilities primarily across the northern
half of the forecast area. Guidance suggests strongest winds will
be at or near criteria for a couple hours in the early afternoon.
Will continue to monitor webcams and sfc obs for visibility
reductions. SPS will be issued to highlight the potential for
blowing snow impacts.

&&

.SHORT TERM...(Today and tonight)
Issued at 326 AM CST Tue Feb 13 2018

Snow this morning and the possibility of blowing snow this
afternoon will be the main issues for the period.

Northern branch shortwave trough along with some mid level warm
advection has brought a fairly broad area of light snow across the
central CWA early this morning. Web cams confirm that light
amounts are reaching the ground. Short range models have struggled
with the snow, bringing it further southeast than it is actually
occurring, although the recent RAP run has been trending a bit
better. The shortwave will move quickly off to the northeast, and
think that our light snow will be done by mid morning. Not too
much banding potential is apparent and amounts will generally be
a half an inch or less.

There will be a decent pressure gradient today as the surface
trough over Canada moves further east. South to southwesterly
winds will pick up throughout the day, and although high
temperatures will rise into the 20s the breezy winds will keep
things from feeling very warm. The question is how high winds will
get and how much blowing snow will be possible. The pressure
gradient is good and there will be a good mixed layer. However,
there will also be a cross valley component to the wind and
surface winds are not unidirectional with the upper levels. Think
the northern Red River Valley could flirt with wind advisory
criteria. The blowing snow model gives a few hours of 20-30
percent probability of less than a half a mile up in the northern
counties, although coverage is pretty patchy. Not confident enough
to go with an advisory for blowing snow in the north but will hit
in the HWO and social media the potential for reduced visibilities
in the northern Valley today.

Southwesterly surface winds continue into tonight with warm air
advection. The mixing should keep readings in the teens even with
decreasing clouds.

.LONG TERM...(Wednesday through Monday)
Issued at 326 AM CST Tue Feb 13 2018

Upper air pattern transitions to more zonal flow by 12Z Wed and
Pacific moisture becomes a concern w/ a wave moving across northern
tier Wed night into Thu...as a sfc cold front sinks into the region
during the overnight period.  Thickness gradient increases and
soundings support all snow as the front moves through and temps
rapidly fall...with Thu highs setting up a tight gradient from
around zero in NW to the upper teens in the SE.  Made adjustments to
top down grids to support snow and remove mention of FZRA...per
coordination with BIS/ABR offices.  The tail end of the work wee
will see a rebound in temperatures into the teens Fri aftn.  Models
become out of phase w/ H500 pattern during the weekend but general
zonal to SW flow supports a bit more active wknd with chances of
snow mainly from Sat through Mon night.  Latest model blends
indicating best chance Sat night and Sun with main impacts
continuing to be north of Highway 2.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1236 PM CST Tue Feb 13 2018

Winds the primary concern for the TAF period with VFR CIGs and
VSBYs. South to southwest winds gusting to aournd 30 kts in the
valley today will diminish with sunset with inversion developing.
Wind shear above the inversion this evening is possible as
westerly winds at 2000ft are expected to be in the 30 to 40kt
range.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&

$$

UPDATE...JK
SHORT TERM...JR
LONG TERM...Speicher
AVIATION...JK



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