722
FXUS63 KFGF 232331
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
631 PM CDT Thu May 23 2024

.KEY MESSAGES...

- Isolated to scattered severe thunderstorms are expected today
  between 4 pm and 10 pm south of Highway 2. Potential hazards
  include hail up to two inches and 70 mph winds, with a tornado
  possible.

- Heavy rain tonight into Friday over portions of the Red River
  basin may bring additional rises on area rivers.

- Patchy frost could form Saturday early morning in the Devils
  Lake basin, although will depend on cloud cover and wind.

&&

.MESOSCALE...
Issued at 358 PM CDT Thu May 23 2024

Thunderstorms are rapidly initiating along a surface warm front
stretching from central South Dakota into southeast North
Dakota. Strong veering near the warm front has allowed for
surface-based supercells to develop within the line. With the
bulk of our instability in the hail growth zone and strong
veering in the vicinity of the warm front, large hail is likely
to develop with any supercells. There is the low potential for
tornadoes with these supercells thanks to favorable kinematics
(especially if supercells can take a hard right turn), but
thermodynamics are heavily limiting. As we continue to rapidly
develop, upscale growth is likely and may see a transition to a
more wind based threat. At least in the near term, hail and
tornado risk continues to increase.

&&

.DISCUSSION...
Issued at 337 PM CDT Thu May 23 2024

Main upper low is still coming out from the northern Rockies
into the western Dakotas. Some convection firing in northeastern
SD on the leading edge of the 850mb jet and in uncapped 2000
J/kg SB CAPE has mostly been unorganized and not severe.
However, the CAMs still break out some more impressive
convective cells later on this afternoon and evening.
While the main wind shift with the warm front is still mostly down
in SD, there is some 55 dew points pooling further north near
the I-94 corridor where winds are from the east. That could make
some cells moving in that area interesting and could bring some
rotation in addition to the main hazards of hail up to two
inches and winds to 70 mph. Will continue to monitor how the
mesoscale features develop in the next few hours, but it still
seems that we will see some good chances for isolated to
scattered severe storms during the 21 to 03Z time frame.

As the instability decreases tonight, the main upper low will
still be coming out into the Northern Plains and the surface low
lifting into the Red River Valley. This time the main
deformation band sets up more over our northern counties, with
the Devils Lake Basin and northern Red River Valley seeing the
best probabilities of over an inch of rain. There is even some
50 to 60 percent probability of over 2 inches of rain by Friday
evening. The precipitation will continue to wrap around the low
pressure system as it lifts off into Canada Friday night. Some
colder temperatures start to come down the backside of the
system, with some of the models showing a few flakes mixing in
the far northwestern counties as early as Friday morning. No
accumulations or impacts expected. More cold air coming down as
the system pulls east Friday night, although there is some signs
of a reinforcing shortwave bringing some clouds that could
prevent frost formation.

The active pattern continues into the holiday weekend as flow
becomes southwesterly, although the bulk of the energy on Sunday
seems like it will be to our south. Northern branch shortwave
coming through Monday will dig into the Great Lakes Tuesday,
allowing ridging to build in and a warming trend for
Wednesday/Thursday.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 630 PM CDT Thu May 23 2024

Clusters of thunderstorms have developed across southeastern
North Dakota, with KFAR likely seeing the greatest chances of
VCTS for the next several hours. For KGFK and KTVF, scattered
shower activity could produce lightning briefly; however, the
more persistent rain is not likely to arrive until closer to
06Z. VFR conditions are generally being reported outside of
shower/thunderstorm activity, with MVFR to intermittent IFR
ceilings/visibility within heavier showers and storms. The
probability of IFR ceilings, however, will increase through the
late evening and overnight period across much of the area. Winds
are still expected to increase, with gusts up to 25 knots. Wind
direction prevails out of the east; however, there are many
outflow boundaries associated with thunderstorms that will cause
sporadic wind shifts through much of the afternoon and evening.

&&

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

&&

$$

MESOSCALE...Perroux
DISCUSSION...JR
AVIATION...Lynch