Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 181440

Area Forecast Discussion
National Weather Service Grand Forks ND
940 AM CDT Sun Mar 18 2018

Issued at 936 AM CDT Sun Mar 18 2018

Expanded the drizzle or light snow mention south to cover the
Thief River Falls and Bemidji areas as morning observations
indicate some mist and flurries moving through with visibilities
down to 2 to 5 miles. Also lower highs some with stratus deck
covering the entire area will not see solar today.


.SHORT TERM...(Today and tonight)
Issued at 401 AM CDT Sun Mar 18 2018

Precip chances and type will be the main issue for the period.

The upper ridge axis over the Eastern Plains will start a slow
shift eastward today as the split flow trough enters the Western
Plains today. Moisture has been on the increase ahead of the
system with stratus overspreading the forecast area currently.
Some very weak radar returns just west of GFK have shown up but
uncertain at this point if anything is reaching the ground. Models
do indicate some weak isentropic lift with good condensation
pressure deficits moving from the central CWA into our MN counties
this morning. At least a few of the high resolution models,
including the RAP and ARW, have light QPF blossoming over the Lake
of the Woods region this morning, although other solutions are
dry. Model soundings at BDE have lower levels saturating just
before sunrise with some indications of drizzle although some
feeder/seeder is not out of the question. Have a mix of freezing
drizzle/snow turning to drizzle as temps rise this afternoon.
Temps are near the freezing mark overnight with the clouds, and
even with limited insolation think we will still make the mid to
upper 30s.

Tonight, the main low pressure system will be to our south, but
there will be enough broad lift as the northern branch shortwave
trough approaches to get precip developing over the area. The
models have been a bit slower to bring things into the CWA, mostly
after midnight tonight. Slowed the POPs just a tad. The GFS, NAM
and RAP all have high RH values in the good dendritic growth layer
of -12 to -18 C moving in tonight. Thus think the freezing drizzle
threat will be limited. Adjusted to only include a brief period of
FZDZ on the leading edge of the precip as it moves into the area
and then all snow. Clouds and precip will keep temps in the 20s

.LONG TERM...(Monday through Saturday)
Issued at 401 AM CDT Sun Mar 18 2018

12Z Mon - 12Z Wed

Water vapor loop indicated an upper trough over southern
ALTA/western MT with short waves over the ALTA/SASK border and the
other over western MT. Short wave will rotate around trough with MT
short wave moving into the Northern Plains on Mon. Another short
wave over northern ALTA will also follow in tow. Precip is expected
for the Red River Valley for Mon into Tue. Column looks saturated
so looks to be mostly snow.

Wed - Sat

Long wave pattern remains split with northern stream over northern
Canada and southern stream over the southern and eastern states.
Long wave trough over the eastern Pacific moves to the western US.
Long wave ridge over the western US shifts to the eastern US by the
end of the period. Long wave pattern relaxes through the period.
Pattern becomes more progressive.

Upper level ridge builds a bit over the Rockies then shifts into the
Plains by Thu. Moisture moves north Thu and Fri with rain or snow
occurring late in the work week.

Little change to high temperatures for Wed - Fri. Highs were
decreased one degree for Sat from yesterdays run.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 704 AM CDT Sun Mar 18 2018

Most TAF sites are MVFR although a few have scattered out to VFR
briefly and KTVF just went down to 1000 ft ceilings. MVFR
conditions will continue for much of the day today, with more
widespread IFR ceilings coming in later on tonight. Some of the
guidance brings down visibility late in the period but not
confident enough to include at this point. However, did put in
some snow at KDVL as there is good agreement on some flakes
starting to move in after 06Z. Have vis 2SM for now and will
adjust as the time gets closer. Winds will be light and variable
become north to northeast.




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