964
FXUS63 KFGF 071432
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
932 AM CDT Tue May 7 2024

.KEY MESSAGES...

- Isolated thunderstorms mainly this afternoon over northeast
  North Dakota and northwestern Minnesota.

&&

.UPDATE...
Issued at 932 AM CDT Tue May 7 2024

Forecast remains on track with rain through the early afternoon
in the north before the dry slot moves in from the south. A few
shallow top thunderstorms will likely form along a differential
heating boundary propagating north through the dry slot along
the backside of the cloud cover. Would expect main hazards to be
lightning and gusty to winds to 40mph. Timing of these
thunderstorms would be roughly 2pm to 8pm Along and north of
I-94.

UPDATE
Issued at 714 AM CDT Tue May 7 2024

Rain band filled in the past 2 hours with light rain now from NE
ND southeast into central MN, moving NW. This aligns pretty good
with pops and will see the higher precip chances gradually lift
north this morning...with high pops remaining NE ND and parts of
NW MN thru the day. Showers will come to an end in SE ND and WC
MN as the band shifts north.

&&

.DISCUSSION...
Issued at 317 AM CDT Tue May 7 2024

500 mb low at 08z as over northwest South Dakota. Moisture feed
around this system is from northern Arkansas to central
Minnesota then back west-northwest across parts of North Dakota
and into southern Saskatchewan and Alberta. What has been
noticed is that moisture from the south as been weakening the
past 6 hours, perhaps due to convection from Iowa to northern
Arkansas. The trends in radar with showers moving NNW from
central MN is for diminishing returns as they move toward the
RRV. Thunderstorm chances have dropped greatly since 06z and
likely to remain thru 16z based off of SPC HREF Calibrated
Thunder fcst and HREF lightning prog via DESI. So through 16z
shower activity looks to be on the light side moving NNW thru MN
into eastern ND.

This afternoon will see upper low move a tad east to west of
Bismarck with sfc low drifting a bit NNE into southwest ND near
Hettinger. A trough rotating around this upper low/sfc low will
move into NE SD midday and then into SE ND mid to late aftn
with a subtle wind shift from southeast to south. Also drier
airmass moves in. Clearing chances appear limited and in this
area of SE ND/far WC MN (Valley city-Fargo-Fergus Falls-Wadena)
chances for afternoon showers or t-storms is quite low.

Farther north, north of the boundary 0-6 km shear is quite
strong near 40 kts due to stronger 850 mb winds but by 20z 850
mb winds are in the 35-40 kt range vs 50-55 kt currently. So
some shear exists but instability looks very weak...barely
100-250 j/kg and no sfc heating is anticipated with aftn temps
in the low 60s. With upper low sufficiently far enough west and
colder 500 mb temps wrapping around the system and more into
Nebraska thinking is that some t-storms will form in a narrow
axis from near DVL-GFK-BJI area mid aftn and move north, but
lack of instability, lack of cold air aloft, will prevent much
development. Bufkit soundings for GFK show a nearly vertical
temperature column from sfc to 500 mb with very limited CAPE
(50-100 j/kg). This is from both NAM and GFS models. So net
result is thinking any chance of a stronger storm is very low
(5 pct).


Chance for showers Wednesday as upper system drops south but
drier air also moves back in from the north. Instability is
focused in southern MN, so covearge of showers look scattered.
Clearing Wed night into Thursday.

GFS/ECMWF ensembles show 500 mb ridging into Alberta and
Saskatchewan Thu-Fri period and enough to height falls over the
Great Lakes for an upper level wave to drop south-southeast into
Minnesota Friday. This will give chances for showers, and with
some colder air aloft with wave several hundred CAPE and a
chance for a few t-storms mainly in northern or central MN.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 714 AM CDT Tue May 7 2024

East or east-southeast winds today gusty at times in the 20-27kt
range. Rain showers most widespread thru the morning and into
the aftn NE ND and into NW MN. Ceilings within rain area may
lower into MVFR range. Tonight faces uncertainty as lower
clouds may linger in the north vs in the south higher chance of
VFR conditions.

&&

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

&&

$$

UPDATE...TT
DISCUSSION...Riddle
AVIATION...Riddle