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348
FXUS63 KFGF 101755
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1255 PM CDT Mon Jun 10 2024

.KEY MESSAGES...

- Showers and scattered thunderstorms are expected Monday night.
  The main threat will be lightning.

- Isolated severe thunderstorms possible Wednesday afternoon
  and evening, mainly northwest and west central Minnesota and
  extreme southeast North Dakota.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1255 PM CDT Mon Jun 10 2024

The forecast remains on track this afternoon, with shower
activity remaining just west of the Devils Lake area. Showers
and thunderstorms are expected to increase in coverage heading
through the afternoon and evening ahead of a shortwave trough.
Temperatures this afternoon are in the upper 60s to near 70
degrees.
-- End Changed Discussion --


&&

.DISCUSSION...
Issued at 330 AM CDT Mon Jun 10 2024

...Synopsis...

Sfc high pressure was located over eastern ND. Clear sky and
light winds over the area allowing for temperatures to drop into
the 40s in most areas, with a few 30s in the normally colder
spots in northwest and north central MN. Patchy fog seen at
Fosston AWOS at at the airport and webcam in Fosston shows some
patchy low lying fog around as well. Isolated coverage and will
burn off quickly.

Incoming system seems a good 3 hours slower than it was looking
24-48 hours ago. Will use primarily NBM 4.2 pops but as often
the case the leading edge of low chances may be too fast. But
overall look for chances for showers and a few t-storms to reach
DVL basin after 4 pm and then into the RRV mainly 10 pm to 1 am
and then spreading east thru the pre-dawn hours into MN. The
main 500 mb wave is moving northeast from south central Montana
into southern Saskatchewan thru 18z and then east-northeast
from there into the Lake Winnipeg region in Manitoba by 12z Tues.
Trailing cold front will move east and be the focus for showers
and a few t-storms but instability tonight with the front is
quite minimal with little to no CAPE by 06z. Thus mention of any
t-storms are more targeted for E ND vs MN. Dew pts remain in
the upper 40s ahead of this system and with main forcing from
upper low well northwest of us, QPF has trended down the past 24
hours with WPC QPF in the 0.05 to 0.30 inch now.

Frontal system moves east Tuesday morning but 500 mb wave
remains to our north near Lake Winnipeg and some moisture and
weak instability around the south side of the upper low will
bring a chance for a few showers or isold t-storm Tuesday
daytime in NW MN.


...Threat for severe storms Wed aftn/eve for parts of the
area...

Wednesday will see upper level ridging into the area and
advection of low level warm and moist air northward. 00z GFS
values for dew pts in the low 70s into RRV and NW MN are likely
too high and do not match the consensus of other models such as
the ECMWF, NAM, and even GFS ensembles. They would indicate mid
60s dew pts into the RRV 18z Wed. High temps do look
considerably warmer than was shown 24 hours ago, with highs low
to mid 80s. Going with mid 60 dew pts and temps in the mid 80s
give upwards of 2000-2500 j/kg for Wed mid aftn, esp SE ND/WC
MN with 1000 j/kg up to the Intl border. Mid level jet in place
and sfc-6km bulk shear is 50 kts more than enough for supercell
formation. But forcing, that is rather weak it appears. There is
a short wave trough behind the warm/unstable airmass moving in
along the border, and a weak low in south central Manitoba and a
sfc boundary moving into E ND midday Wed. This boundary looks to
get pushed east fairly quick and extend nr a Roseau-Fargo line
21z Wed period. This is when the better chance for thunderstorms
will occur, and with enough shear organized supercell discrete
cells evolving into clusters and eventually a line, but that
part may not be til it moves to our east and southeast. Thus
with enough uncertainty yet SPC has marginal risk roughly
Roseau-Fargo and east.

Best instability does seem to peg areas from DLH to FSD at
00z-03z and this area is where SPC starts to indicate better
organized severe activity with activity spreading east
overnight.

The weekend will see an upper trough intensify to our west with
more ridging over the eastern Plains and Midwest. This should
set the stage for increased t-storm chances Saturday and Sunday.
Will need to monitor this period for any risk of severe storm
potential.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1234 PM CDT Mon Jun 10 2024

VFR conditions prevail this afternoon, with increasing cloud
cover and rain chances this evening and overnight. MVFR ceilings
are expected at all sites during the overnight hours following
shower activity as a weak shortwave traverses the region. Winds
this afternoon and evening remain out of the south to southwest
at 15 to 20 knots. Winds will shift following the passage of the
shortwave, becoming west to northwest Tuesday morning.

&&

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

&&

$$

UPDATE...Lynch
DISCUSSION...Riddle
AVIATION...Lynch