518
FXUS63 KFGF 142337
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
637 PM CDT Tue May 14 2024

.KEY MESSAGES...

- On and off showers through at least the next week.

- Thunderstorm chances increasing over the next few days. A low
  probability scenario exists which would include a few strong
  thunderstorms on Friday.

&&

.UPDATE...
Issued at 637 PM CDT Tue May 14 2024

Activity on radar continue to be mainly associated with
sprinkles (non measurable rain) or virga, due to a dry 8-10 KFT
dry layer below this mid level CU deck. HRRR still shows a
signal for scattered showers/iso-T developing to the west this
evening near the surface trough axis/instabilty gradient and
spreading east towards the Devils Lake Basin before
weakening/falling apart. There are a few showers within a CU
field along that axis but no lightning activity. If it did occur
impacts would be limited to just lightning activity as much
more stable air is in place this evening.

&&

.DISCUSSION...
Issued at 230 PM CDT Tue May 14 2024

...Synopsis...

Water vapor imagery indicates zonal flow aloft with several upstream
shortwaves meandering toward the region. Ensemble guidance in good
agreement with the general zonal flow pattern, but differ with
timing, strength, and location of individual shortwaves. All in
all anticipate on and off showers through at least the next
week with possibly a stronger thunderstorm. Through the next
week, the 25-75 percentile range for rainfall amounts across the
majority of the forecast area is 0.50-1.50 inches.

...On and Off Showers...

Water vapor indicates immediate subsidence through the late
afternoon behind the departing wave, but many more waves
approaching. HRRR indicates a few storms initiating across
north central ND this afternoon moving into the Devils Lake
basin this evening. This scenario seems plausible given the
current plume of instabilty ahead of the surface
convergence/low pressure. Any storms that do develop would
quickly dissipate this evening as they depart from the
instability.

Next wave of concern is currently across Idaho, with another
lead wave across southwest South Dakota. Ensemble guidance in
good agreement indicating these features will slowly propagate
through the region on Wednesday, with rain chance increasing
especially Wednesday afternoon and into the evening.

Beyond Wednesday, timing and location of waves uncertain.

...Severe Storm Potential...

There is a stronger wave that will be approaching from the
northwest by Friday, and ensemble guidance shows many different
scenarios with how this system will develop across southern
Canada. Location of this feature by Friday into Saturday will be
important, as stronger and further west would lead to increased
moisture return along with warmer temperatures and greater
instability, with the potential for strong to severe storms. In
fact, the CU machine learning indicates a low chance for severe
storms Friday and Saturday. Of course, a weaker and further east
system would not allow for moisture return or warmer
temperatures thus limiting instabilty. At this point each
scenario has an equal chance of happening.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 637 PM CDT Tue May 14 2024

VFR conditions should prevail through the evening and early
morning hours across eastern ND and northwest MN, with virga and
a few sprinkles (minimum coverage/impacts). There is a signal
for actual showers or maybe a thunderstorm late this evening in
the vicinity of KDVL (thunder chances much lower than shower
chances). Better rain chances overspread most TAF sites in
eastern ND and northwest MN Wednesday southwest to northeast,
along with decreasing ceilings to MVFR (some IFR near KDVL).
Winds will tend to remain east or southeast until low pressure
pushes into northeast ND late Wednesday afternoon (north-
northwest winds arrive at DVL on back side of surface low).

&&

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

&&

$$

UPDATE...DJR
DISCUSSION...TG
AVIATION...DJR