394
FXUS63 KFGF 200916
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
416 AM CDT Wed Aug 20 2025

.KEY MESSAGES...

- There is a 1 of 5 risk for severe thunderstorms Thursday
  across much of eastern North Dakota, northwest Minnesota, and
  west central Minnesota. Hazards could include golf ball sized
  hail and damaging wind gusts to 70 mph.



&&

.DISCUSSION...
Issued at 402 AM CDT Wed Aug 20 2025

...Synopsis...

Third day of ground fog, with focus early this morning in NW MN.
Webcams and obs show though the 1/4 mile stuff remains
transitory...and not long lasting and widespread. But may do SPS
as coverage of lower vsby in ground fog a bit more than prev
nights. Otherwise we finally got rid of all that low clouds, so
outside of what low clouds form near sunrise, today should
finally be mostly sunny. South winds increasing this aftn into
the 15-25 mph range in E ND, less farther east. Warm advection
at 850 mb shows about a rise of +2C today, but with south-
southeast wind never a warm wind, kept NBM highs today which
were in general low 80s. This aligns with HRRR sfc temps.

Better mixing with some wind tonight should prevent fog
formation. Will need to watch t-storms that form this evening
and overnight in parts of SE Saskatchewan into western Manitoba.
CAMs and global models suggest a complex of storms will
eventually organize on nose of 850 mb 40-50 kt in parts of SW
Manitoba (Dauphin region) and move east overnight with southern
edge possibly edging into DVL basin after 06z. SPC for day 1
marginal has it mostly to out west along the Intl border. That
makes sense as main 850 jet is western ND into western MB
tonight and main 500 mb jet remains anchored from southern Sask
into central Manitoba.


...Risk of severe storms Thursday...

From going over various machine learning tools and ensembles,
models, overall feeling is that severe chances are a bit lower
than what it looked like 24 hours ago and also may be a bit
south. This all due to potential cloud cover and elevated
convection that may move into and persist over parts of NE ND
and NW MN Thursday morning. This convection would be non-severe.
Cold front itself will be near a Roseau-Fargo line at 00z Fri.
Surface temps look lower than prev fcsts with highs low 80s
north to low-mid 80s south. Sfc CAPE values prog to be 1500 j/kg
north and 2500 j/kg south with more heating. Bulk shear is
sufficient 30-40 kts, but main mid level jet remains more so in
southern Saskatchewan into Manitoba closer to the parent upper
low in northern Saskatchewan. Thus forcing to generate severe
storms may be limited. If convection can form risk of large hail
and damaging winds are the main threats. I feel some supercells
will form and then become emedded in a broken line 21z-00z
perios from NW MN into east central and southeast ND. Tornado
threat is quite low. Never zero anytime you have potential
supercell development. But main warm front and surface low
remains well north of the border.


Beyond Thursday....500 mb low deepens and forms a Hudsbon Bay
low over the weekend thru first half of next week. Cooler
airmass in place. Some showers around Lake of the Woods region
Saturday, otherwise cooler and drier.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1132 PM CDT Tue Aug 19 2025

Radiational fog can`t be ruled out again tonight, however drier
BL conditions due to northerly flow does decrease the potential
at many location in eastern ND. The best chance is over
northwest and north central MN, with a period of IFR at KBJI
during the 10-14Z period Wednesday morning. Increasing
southerly gradient results in increasing south-soutehast winds
Wednesday. Strongest winds (gusts to 25kt) would be expected in
northeast ND in the afternoon period.

&&

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

&&

$$

DISCUSSION...Riddle
AVIATION...DJR