Clearbrook, Minnesota Weather Forecast Discussion

362
FXUS63 KFGF 161738
AFDFGF
Area Forecast Discussion
National Weather Service Grand Forks ND
1238 PM CDT Tue Sep 16 2025
.KEY MESSAGES...
- Isolated strong thunderstorms may develop early this evening
  over parts of west central Minnesota. If strong thunderstorms
  develop, small hail and lighting would be the main threats.
&&
.UPDATE...
Issued at 1238 PM CDT Tue Sep 16 2025
There are still some lingering sprinkles/virga with the earlier
mid level wave in our north and adjustments were made to reflect
that. The main baroclinic zone that could be a focus for late
afternoon/evening thunderstorm development is already farther
southeast and this has shifted the main theta-e axis away from
our CWA. CAPE profiles are much narrower in our area and very
elevated, due to drier air above the surface that has advected
into our CWA. Shear was already weaker in that region of
concern, so these trends lower confidence in severe thunderstorm
potential. 06Z/12Z CAMs no longer shows initiation in our
southeast CWA this evening either, matching these trends.
There are still some less organized impulses that are rotating
through the weak SW flow to the south, and could support a few
showers or thunderstorms. The lingering axis of elevated
instability (1000-2000 J/KG MUCAPE) is still in place with
steep mid level lapse rates, so an isolated strong thunderstorm
couldn`t be ruled out (if initiation were event to occur).
UPDATE
Issued at 642 AM CDT Tue Sep 16 2025
That shower and t-storm cluster that was near Bismarck indeed
moved northeast and just recently dissipated in the New
Rockford/Carrington area. High clouds is over south central into
eastern ND with a clear to partly cloudy in NW/WC MN. Balance
of the day to be partly to mostly sunny.
&&
.DISCUSSION...
Issued at 333 AM CDT Tue Sep 16 2025
...Synopsis...
As one upper low sits over central Manitoba early this morning,
there is one upstream moving south-southeast thru northwest
Saskatchewan and another upper low over northwest Wyoming.
The upper low in Wyoming is bringing southwest flow aloft into
southern ND early this morning along with a not well forecasted
short wave that is south of Bismarck. An area of showers and
t-storms continues to move slowly northeast and CAMs and global
models not handling it well at all. 07z HRRR is finally
catching the area of rain and moves it into the area between
Valley City and Devils Lake and then weakens it. But also
earlier model runs did the same thing after 1-2 hours. Coord
with BIS to spread some pops into that area btwn Valley City and
DVL early this morning.
...Potential isolated severe storms this evening...
With upper low and surface low in central Manitoba at the
surface south winds will turn a bit more westerly today, with
south-southweste winds holding from eastern SD into northeast
MN. This weak boundary will be in place with consensus from near
Ely MN back toward Elbow Lake MN and into northeast SD. MUCAPE
near and south of the boundary will reach 1500-2000 j/kg range
in a band from Duluth to Brainerd to Elbow Lake. Thus idea of a
narrow axis of isolated thunderstorms forming in that zone seems
reasonable. NAMnest is more aggressive than most though. So
pops in this area are not high yet as confidence in storm
formation remains more in the 30 percent range. SPC has this
zone mentioned from NE MN into SD in marginal risk, and this
covers far southeast fcst area. Timing wise if storms form it
would be after 6 pm. 0-6 km bulk shear isnt that great but
enough for a few supercells with shear around 25 kts. Hazard
would be potential for 1 inch hail and 60 mph winds.
There is some support from NSSL machine learning for a high
enough risk of severe storms in that zone to at least mention.
For the rest of the week, precipitation chances will depend on
position, development of upper low as models move the Wyoming
low into South Dakota. Very slow moving so a prolonged period
of shower and t-storm chances start Wednesday and persist into
the weekend, though how far north rain gets is uncertain. Model
blends and WPC both have rainfall amounts for the 12z Wed to 12z
Sun period of around 2 inches or more in far SE ND, parts of
west central MN. But this rain will fall in waves, but these
high amounts will be over a long period. But something to
monitor for any flooding potential if one period seems to be
more robust.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1238 PM CDT Tue Sep 16 2025
VFR conditions should prevail through the TAF period across
eastern ND and northwest MN. There are a few pockets of very
light showers/virga moving across northeast ND and far
northwest MN, which should progress east through the afternoon.
Additional showers or an isolated thunderstorms may develop in
far southeast ND and west central MN, but the probability for
impacts at TAF sites is low (less than 30%). Winds remain
lighter (less than 12kt) through the TAF period due to weak
surface gradient remaining in place. The trend should be for
winds to be out of the west-northwest during the daytime period
this afternoon/early evening and prevail from the northeast
after sunrise Wednesday.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Riddle/DJR
DISCUSSION...Riddle
AVIATION...DJR

NWS FGF Office Area Forecast Discussion