Garrison, North Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

221
FXUS63 KBIS 051930
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
230 PM CDT Mon May 5 2025

.KEY MESSAGES...

- Near-critical fire weather conditions are expected today
  across much of central North Dakota, including the James River
  Valley.

- Wind Advisory in the northwest for gusts up to 50 mph and
  blowing dust.

- Increasing chances for showers and thunderstorms in western
  and central ND this evening. Isolated severe thunderstorms
  southwest into central, mainly for 60 mph winds.

- Mostly dry with above average temperatures and breezy
  conditions at times through the end of the week.

&&

.DISCUSSION...
Issued at 230 PM CDT Mon May 5 2025

Currently a cold front is across the state southwest to
northeast. Showers in the far northwest have been mixing down 50
to 60 mph winds. The lower levels are also dry so this aids in
the downward momentum. Blowing dust plumes from the burn scars
in Ray and Tioga have made their way to Slope County! We have an
SPS out for that and a Wind Advisory out for winds in the
northwest.

Cumulus have started to pop along the eastern edge of
the front in western Morton through Hettinger County. There is
currently around 500 J/kg across the south central but capped.
So it should be at least an hour or two for attempts to break
it. The RAP forecast has the cap breaking at 3pm CT. Mixed layer
CAPE is almost nothing. Lapse rates are convectively okay at
7.5 and forecast to stay the same. Wind shear is 30kts along the
front where the cumulus are located. DCAPE is concerningly high
at 1200 J/kg currently, and forecast to be 1400 J/kg later.
Again all this is based off the RAP. SPC has a marginal risk
(isolated) from the southwest to the central part of the state,
including Bis/Man. The main threats are winds around 60 mph
based on the dry lower levels of the atmosphere and storm mode.
Model soundings have an inverted V hinting at dry air down low
that will accelerate the downdrafts of the storms. Storm mode
will be linear as the wind shear vector is near parallel with
the front. Quarter size hail is possible as storms develop but
then it will mainly be a wind threat. The CAMs have slowed the
timing down to around 23z, but will keep a very close eye on the
cumulus that already started. The severe threat should end
around 10pm CT, but showers and thunderstorms will continue in
the south and east through 5am CT with wrap around moisture with
the surface low. All this is in southwest flow, which will
change to a ridge until Friday. Tuesday will be slightly cooler
behind the front in the 60s and 70s. Then the warmer air with
the ridge moves in. Friday the flow changes to zonal, allowing
some shortwaves off the Montana mountains to give a slight
chance of showers and thunderstorms again. This weekend another
ridge moves over, allowing temperatures to possible climb into
the upper 80s! Sunday night into Monday where the active
southwest flow sets back up. Temperatures could also be in the
upper 80s, allowing thunderstorms to form.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 230 PM CDT Mon May 5 2025

VFR CIGs and VIS, except in blowing dust in the far west
currently. CIGs will increase west to east through the period
with MVFR in the west and south central. Thunderstorms are
likely in the south central and central this evening and
overnight, winds could gust up to 50kts in the storms. Winds
will continue to gust around 35kts through this evening,
especially west.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM CDT /6 PM MDT/ this evening for
NDZ001-002-009-010-017.

&&

$$

DISCUSSION...Smith
AVIATION...Smith