Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 182054

Area Forecast Discussion
National Weather Service Grand Forks ND
354 PM CDT Mon Sep 18 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 312 PM CDT Mon Sep 18 2017

Severe potential tomorrow afternoon will be the primary forecast
concern for the period.

A few lingering showers late this afternoon across northwestern MN
from a weak shortwave will pull out of the area. Winds will
continue from the south southeast as a surface trough continues to
strengthen over the northern Rockies. Dew points are in the 50s
across the southern counties with some low 60s not far away to the
south. With continued moisture advection overnight, there could be
a fair amount of stratus across the CWA. These clouds will help
keep lows a bit more mild than the past few nights in the 50s, but
will also impact convective development for tomorrow.

With a strong upper trough over the northern Rockies and a
significant lead shortwave approaching the MT/ND border by 00Z
Wednesday, there will be plenty of forcing for convective
development. The surface trough will be moving into the central
Dakotas during the day tomorrow, with a cold front right behind.
At this point, think there should be enough clearing across the
southwestern CWA tomorrow morning for some good destabilization,
with some CAPE values of 2000 J/kg possible, although if clouds
hang around longer than expected it will be less. Convection
firing along the trough axis/front will move into our western
counties during the afternoon and spread eastward during the
evening. The NAM lags behind the global models and seems a bit of
an outlier. There will be plenty of deep layer bulk shear of 50
kts plus. At this point a linear system with possible QLCS
development seems possible. The storms will continue to push
eastward through Tuesday night.

.LONG TERM...(Tuesday night through Monday)
Issued at 312 PM CDT Mon Sep 18 2017

A cold front is expected to pass through eastern North Dakota late
Tuesday afternoon/evening into northwestern Minnesota by Tuesday
night. Confidence is high that showers and thunderstorms will
develop along and ahead of the cold front late in the afternoon
through the evening hours. There is risk for strong to severe
thunderstorms to develop with main threats associated with the
strongest storms being wind gusts to 75 mph and hail to 1.5 inches
in diameter. A tornado or two cannot be ruled out as well. Most of
the precipitation will be out of the area by Wednesday morning,
leaving cooler temperatures and northerly winds.

Quieter weather is in store for Wednesday night into Thursday with
highs reaching into the warm mid 70s. Rain chances will return late
Thursday night through Saturday night as a slow moving cold front
moves through the area, with the best chances being Friday night
into Saturday for west central Minnesota. With the slow movement of
the system, rainfall amounts at least an inch are possible from
Fergus Falls to the Bemidji area. Rain should be tapering off Sunday
morning with clearing skies and cooler temperatures in the mid 50s
to low 60s expected for the end of the weekend and start of the work


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1229 PM CDT Mon Sep 18 2017

Conditions are VFR at all TAF sites this afternoon with some
showers around KTVF and KBJI. Those showers should dissipate later
this afternoon, and the evening hours will be fairly quiet and VFR
but stratus will begin moving in later tonight. Think that MVFR
and even IFR cigs will spread north and west as moisture moves
into the area. KFAR and KBJI will see lower conditions the
earliest with KDVL the latest. Some improvement towards the end of
the period is possible at the further south TAF sites. Southeast
winds will remain fairly steady in direction but speeds will ramp
up towards the end of the period with gusts in the 25 to 30 kt
range in many areas by mid day Tuesday.




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