Area Forecast Discussion
Issued by NWS Grand Forks, ND

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410
FXUS63 KFGF 230452
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1152 PM CDT Tue May 22 2018

.UPDATE...
Issued at 1150 PM CDT Tue May 22 2018

Still monitoring the activity in south central ND and it remains
very slow moving and mesoanalysis shows no reason for them to
develop east. So kept them west of the fcst area. Did maintain
from continuity a low pop toward 12z for a chance of a
shower/t-storm clipping the far SE fcst area as warm advection
pcpn develops to our south and moves NNE. Risk is quite low though
but kept it in for collab purposes.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 326 PM CDT Tue May 22 2018

Thunderstorm chances tomorrow afternoon and night as well as
intensity will be the main issue for the period.

The main upper low continues to spin over the western CONUS with
some shortwave ridging over the Northern Plains. A lead shortwave
moving through southeast MT/northeast WY/western Dakotas will set
off some activity to our southwest tonight. Another weak shortwave
will be moving through Nebraska into SD/MN, which will bring some
convection to our southeast. Think that most of the showers and
storms will stick close to the warm front and be well to our
south, although Grant county getting clipped late tonight/tomorrow
morning is not out of the question. The southeasterly surface
winds will continue to bring dew points in the 50s, and there
will be some decent mixing. Think that better fog chances will be
to our east tonight so will keep things pretty quiet with lows
mainly in the upper 50s.

The upper ridge will amplify over MN tomorrow, with the main upper
low over MT. The surface low over the western Plains will be
deepening, and a warm front will be slowly moving into ND. That
front will continue to lift northward through the CWA Wednesday
night. Temperatures will climb into the mid to upper 80s across
the southern counties and lower 80s further north. Models have
some fairly stout CAPE values over 3000 J/kg. On the downside,
deep layer bulk shear is around 25 kts at best. Still, some
isolated severe activity with one inch hail and 60 mph will be
possible as the system lifts northeastward through the area.

.LONG TERM...(Thursday through Tuesday)
Issued at 326 PM CDT Tue May 22 2018

Thunderstorms will be possible again on Thursday afternoon and
evening across eastern North Dakota and northwest Minnesota.

A moist boundary layer airmass is expected to remain in place across
the northern Plains on Thursday. Depending on morning showers/cloud
cover, daytime insolation is expected to destabilize a boundary
layer airmass characterized by dewpoints in the upper 50s and low
60s. Forecast soundings suggest that this environment will support
MLCAPE in the 2-3k J/kg range with little convective inhibition
across much of the forecast area by the late afternoon hours.
Convection will likely be focused initially along a weak surface
trough draped north-south across eastern North Dakota as an upper
level shortwave ejects out over the northern Plains. Forecast wind
profiles show modest 0-6 km bulk shear values around 30 knots
oriented normal to the surface boundary. Storms initially forming
across eastern North Dakota will propagate eastward into northwest
Minnesota through the evening hours. Main threats for Thursday
afternoon/evening will be hail and strong winds.

Friday could see additional thunderstorm chances as remnant
boundary layer moisture will support some instability during the
afternoon hours. Storms may initiate as a shortwave propagates
through the region in weak zonal flow aloft. Weak shear and
relatively low CAPE value will limit the overall severe potential
for Friday, though a few strong wind gusts may occur as storms
develop over a deep, well-mixed boundary layer. Isolated afternoon
showers/storms will be possible through much of the weekend and into
early next week as afternoon heating and weak upper level impulses
allow for some convection to initiate.

Temperatures during the late week period are forecast to be the
warmest so far this year. Afternoon highs in the low 90s will be
possible across the southern River Valley with upper 80s expected
elsewhere across the forecast area.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1150 PM CDT Tue May 22 2018

VFR thru the pd...but question for 00z-06z Thu will be t-storm
coverage. Near t-storms brief MVFR cigs/vsbys can be expected.

&&

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

$$

UPDATE...Riddle
SHORT TERM...JR
LONG TERM...AM
AVIATION...Riddle



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