Walhalla, North Dakota Weather Forecast Discussion

016
FXUS63 KFGF 151733
AFDFGF
Area Forecast Discussion
National Weather Service Grand Forks ND
1233 PM CDT Mon Sep 15 2025
.KEY MESSAGES...
- Isolated severe thunderstorms possible this afternoon in parts
  of northwest Minnesota (SPC level 1 out of 5).
&&
.UPDATE...
Issued at 1233 PM CDT Mon Sep 15 2025
The negatively titled trough axis is now over the southern RRV
with scattered shower activity spreading est-northeast. The main
theta-e axis and region of higher mid level lapse rates remains
east and there is more consistent clearing within that region.
Environmentally, we are still looking at a window for MLCAPE
greater than 1500 J/KG overlapping effective shear of 35-40kt in
our northeast right as the main trough axis swings north. If
initiation occurs in that window (2pm-5pm) we may see a brief/fast
moving severe thunderstorm or two (main threats hail/wind).
Consensus of CAMs and the last 8hr of HRRR runs favor this
mainly in Canada, but there were a few CAMs at 12Z still showing
initiation in our northeast (right by Lake of the Woods County),
so we will continue to monitor the potential for severe storm.
UPDATE
Issued at 1016 AM CDT Mon Sep 15 2025
Pockets of low stratus are still lingering over parts of our CWA
(more regions of clearing in NW MN). Showers ares starting to
develop into southeast ND as the mid level trough rounds the
upper low into our CWA. Guidance still shows the window for
surface based destabilization in our northwest MN counties
where deep layer shear will remain high (30-40kt). Recent trends
in HRRR do favor initiation in Canada instead of our CWA.
Still, some 12Z guidance does support a window for severe
initiation in our northeast, and we will continue to monitor.
UPDATE
Issued at 653 AM CDT Mon Sep 15 2025
500 mb low and sfc low in between Bismarck and Dickinson ND at
11z. Clouds to the east of the upper low over the RRV and NW are
racing north, but overall remain scattered in coverage. Rain
has been regulated to ares near and just west of the upper low.
06z model data and HRRR a short wave on the southeast edge of
the 500 mb trough near Sioux Falls. This races north today to
near Grand Forks at 18z and then into Manitoba by 00z. With this
feature an area of showers will develop or move north out
eastern SD/southwest MN this morning, reaching mid RRV 18z and
then translate north. If enough surface heating is there with
temps around 80 in NW MN where dew pts will be highest then a
fast moving line of scattered storms will likely form with
primarily strong wind gusts threat.
&&
.DISCUSSION...
Issued at 345 AM CDT Mon Sep 15 2025
...Synopsis...
Sfc low and 500 mb low in northwestern South Dakota at 08z. This
will move north and be near the Manitoba/Saskatchewan/North
Dakota border region by late afternoon. A short wave axis will
rotate northeastward as the upper low moves north thru the area
today.
...Isolated severe storms possible in NW MN this afternoon...
As temps warm potential for MU CAPES near 1800 j/kg in a
band from Roseau to Bemidji and HREF indicates some t-storm
development in that Roseau and N Beltrami county area 20-21z and
then quickly moving north. Mid level jet of 45 kts at 500 mb in
the area and max winds at 850 mb 35-40 kts in area of the
northern RRV and northwest MN. So potential exists for brief
wind gusts to exceed 60 mph in any storm that forms as bufkit
soundings near Roseau and Baudette show a mixed layer up 850 mb
and sfc temps around 80/low 80s and sfc dew pts 65-68.
As this short wave trough moves thru the other areas showers and
a thunderstorm or two are possible mid morning into early aftn
over E ND into west central MN, but timing of short wave with
best heating and instability favor far northeast fcst area.
Windy today with surface low moving north and pressure gradient
sufficient for south winds 20-35 mph today...highest in the
central and north RRV and far NW MN where 925/850 mb winds are
strongest. 925 mb winds 35 kts 18z-21z and 850 mb winds 35-40
kts in these areas. Close to wind advisory, but overall suspect
close to not quite. Thus needing t-storms developing to bring
down a bit higher wind gusts.
For tonight, the upper level system and surface low lift farther
north more into central Manitoba and will see shower chances
diminish with dry conditions fcst after 03z and skies clearing.
Tuesday mostly sunny though some patchy clouds. 850 mb temps a
bit cooler into NE ND but 850 mb temps 20+C remain from E SD
into west central MN where 80s are likely.
Tues night into Wednesday will see a separate 500 mb wave drop
south and give a chance for a few showers or t-storm in SE ND
into MN closer to residual warmth and 1000+ j/kg instability.
As this short wave digs south into South Dakota or Nebraska and
merges with another wave a larger upper low may develop
Thursday into the weekend giving chances for showers and
t-storms. ECMWF in particular is showing potential for heavy
rain period for southeast ND into west central MN Thursday and
Friday.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1233 PM CDT Mon Sep 15 2025
There is a lingering area of stratocumulus moving across
northeast ND with MVFR ceilings (localized IFR near KDVL) which
may spread into far northeast MN (KTVF) before lifting back to
VFR. This is along the leading edge of low pressure to the west
and is followed by scattered showers which should impact parts
of eastern ND and northwest MN through the afternoon. The best
chance for lightning activity (less than 30%) is over north
central MN later this afternoon and early evening. The
probability for lightning activity at TAF sites is too low for
inclusion.
Gusty south winds continue through the afternoon gradually
decreasing during the evening as daytime mixing ends and
surface gradient decreases. The shift in surface low pressure
eventually results in west-southest winds developing Tuesday
morning in northeast ND (less than 12kt).
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Riddle/DJR
DISCUSSION...Riddle
AVIATION...DJR

NWS FGF Office Area Forecast Discussion