289
FXUS63 KFGF 251935
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
235 PM CDT Wed Sep 25 2024

.KEY MESSAGES...

- Near critical fire weather is expected Thursday across
  southeastern North Dakota. There is a 20% that critical fire
  weather conditions develop.

&&

.DISCUSSION...
Issued at 223 PM CDT Wed Sep 25 2024

...Synopsis...

Quiet weather will continue through the evening and overnight
hours due to upper level ridging. While ridging remains the
main story through the weekend, there is a shortwave that will
pass through on Thursday. As the ridge breaks down early next
week, a trough propagates eastward, bringing with it cooler
temperatures and very low chances for a few showers.

...Wind and Fire Weather Thursday...

As the shortwave progresses eastward, its associated tightening
pressure gradient in conjunction with a 40 knot 850 mb jet will
promote gusty southerly winds. The area of highest wind looks
to be confined to the Devils Lake Basin and far northern Red
River Valley. In these areas, there is a 70% chance of seeing
wind gusts of 40 mph or higher. Further south, winds are
expected to be lighter, as winds aloft will not be as strong due
to the more northern placement of the jet.

While winds will be lower across the south, they are still
anticipated to be breezy, with gusts up to 30 mph. RH values as low
as 25% raise concerns for near critical fire weather. The largest
limiting factor for critical fire weather is that the driest fuels
and lowest RH values are across southeastern ND, while the highest
forecasted winds are displaced to the north. Therefore, while
critical fire with is not anticipated, there is a 20% chance that
they do develop. This is most favored where the driest fuels
and RH values can overlap with the higher winds, as the HREF
shows when using dual probabilities for RH and sustained winds.

...Weekend and Beyond...

Behind the passing shortwave, ridging will continue through
Sunday with well above average temperatures. A trough coming
off of the Pacific Sunday night into Monday will bring high
temperatures down to their seasonal averages, which are in the
50s and 60s. Another period of breezy winds, this time out of
the northwest, is anticipated behind the cold front. While the
trough will bring enough forcing to provide some showers Monday
and Tuesday, the placement and coverage of these are unknown.
Therefore, POPs remain under 20% early next week, painting the
idea of scattered showers. One other thing to note, breezy winds
overnight should at least limit the frost risk. No clear signal
exists for widespread frost early next week behind the cold
front, but widespread low temperatures on either side of 40
degrees seems likely Tuesday and Wednesday mornings.


&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1257 PM CDT Wed Sep 25 2024

VFR conditions are confidently in the forecast throughout the
TAF period. Upper ridging and surface high pressure will keep
skies mostly clear today through tomorrow. Despite calm winds
and clear skies in Minnesota, the chance for fog is very low due
to such dry air mass in place.

Increasing pressure gradient from the west will increase winds
out of the south Thursday as early as sunrise Thursday, peaking
during the afternoon with gusts 25-35kt in the forecast
Thursday afternoon.

Prior to increasing surface winds Thursday will be high
confidence in LLWS over eastern North Dakota tonight starting
between 00-03Z. Maximum winds will be around 40 kt at around
1kft above ground level. Included this in the DVL TAF, which may
linger as late as 15Z as the boundary layer just starts to mix
in the morning. Confidence decreases how far east LLWS gets,
which brings a low chance LLWS impacts KGFK and KFAR tonight.

&&

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

&&

$$

DISCUSSION...Rafferty
AVIATION...CJ