Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 171232
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
632 AM CST Sat Feb 17 2018

.UPDATE...
Issued at 632 AM CST Sat Feb 17 2018

Only minor modifications made to current forecast with this
update. Update included tweaks to sky cover, temps, and wind.

&&

.SHORT TERM...(Today through Sunday night
Issued at 349 AM CST Sat Feb 17 2018

An upper level trough is currently moving through the region...
with a surface cold front about to enter the area from the
northwest. This front will sweep through the area today...keeping
temps from rising much during the day. A ridge of high pressure at
the surface will pass through the area quickly this evening
before pressure falls again in advance of Sunday`s low pressure
system.

Late Saturday night snow will spread from west to east across the
area as a potent upper wave moves east out of the Northern
Rockies. The low will pass through SD...with ND on the northern
side. Strong frontogenesis is expected over the forecast area with
the potential for significant banding of snow. Models are in good
agreement that an event is coming...but the placement of this
east-west band varies from as far south as Lisbon to Wadena to as
far north as Grand Forks to Upper Red Lake. The peak of this band
will likely see 3-6" with the potential for over 6" in a small
band. Have generally followed a middle of the road approach with a
slight lean toward the northern solutions (NAM/ECMWF models). The
thermal profiles are rather isothermal from the surface to 625
mb. But what it lacks in instability it makes up by being in the
middle of the dendritic growth zone (-10C to -20C). Snow ratios
will likely be 20:1 or higher in areas. Freezing drizzle still
looks to be possible on the southern side of the snow band as
thermal profiles show we lose the ice crystals aloft and are left
with supercooled-liquid water.

The winds pick up on the back side of the low as the snow ends.
Have increased winds a bit, but may need to increase more if
models trend more like the NAM. Blowing snow could be a problem on
Sunday afternoon and early evening in the Red River Valley after
the snow has tapered off.

Have issued an SPS for the late Saturday night/Sunday event.
Messaging included the uncertainty and the potential for banding.

.LONG TERM...(Monday through Friday)
Issued at 349 AM CST Sat Feb 17 2018

Much of next week will feature a long wave trough anchored from the
Northern Rockies through the Great Basin while a Bermuda high sets
up off the southeast coast. Split flow will still predominate with
the northern plains in zonal to southwest flow most of the time. On
Mon and Tue, the primary surface low will track through the Central
Plains toward the Great Lakes leaving pcpn chances largely over the
southern half of the forecast region. The GFS remains drier over a
greater area than the ECMWF which has waves for Mon and Tue, again
focusing on the south. Surface high pressure will begin to dominate
Tue night through Wed, with colder overnight temps and highs
remaining below average for Wed.

Later in the week (Thu/Fri) with the high farther east, return flow
will boost afternoon temperatures into and through the 20s. Some low
impact warm air advection pcpn is possible on Fri. &&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1131 PM CST Fri Feb 16 2018

VFR conditions expected with steady west to northwest winds on
Saturday. CIGs expected to be primarily mid to high level for much
of the period and will start to lower late Saturday evening.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1131 PM CST Fri Feb 16 2018

VFR conditions expected with steady west to northwest winds on
Saturday. CIGs expected to be primarily mid to high level for much
of the period and will start to lower late Saturday evening.


&&

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

$$

UPDATE...Knutsvig
SHORT TERM...Knutsvig
LONG TERM...WJB
AVIATION...Knutsvig


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