085
FXUS63 KFGF 200350
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1050 PM CDT Sun May 19 2024

.KEY MESSAGES...

- Band of showers and isolated non-severe thunderstorms
  overnight.

- The probability for greater than 1 inch of rainfall is 50%
  Tuesday into Wednesday across parts of northwest and west
  central Minnesota.

&&

.UPDATE...
Issued at 1047 PM CDT Sun May 19 2024

Things are working out as scheduled. Area of showers and
embedded thunderstorms working east-northeast thru eastern ND
into west central MN at 03z and they will push thru the rest of
the fcst area overnight with chances lingering around Lake of
the Woods or Bemidji areas after 12z. Airmass is stable, but
some small 50 dbz cores may yet produce small hail but even
those chances are diminishing.





UPDATE
Issued at 714 PM CDT Sun May 19 2024

As expected severe storms have initiated on north edge of
instability gradient into far south central ND south of
Bismarck with other storms south along the Missouri River in SD.
Instability parameters and forecasts via SPC meso page indicates
a sharp drop off in instability surface and aloft as it gets
closer to our far SW fcst area (Ransom/Sargenty ND). Not out of
the question a strong/severe storm will sneak into that area but
chance for severe is at this time 10 percent or less. New severe
t-storm watch is to our southwest. Otherwise will see the area
of thunderstorms weaken as they move into E ND and form an wide
band of showers and t-storms as they move into the central and
south RRV after 10 pm...more so toward midnight.

&&

.DISCUSSION...
Issued at 249 PM CDT Sun May 19 2024

Synopsis:

Southwest flow aloft will allow a notable upstream upper wave
to move through the Dakotas out of MT/WY this afternoon and
evening. This upper wave will bring showers and thunderstorms
through our area, including the chance for strong to severe
storms late afternoon into early evening within southeast North
Dakota.

Overall, upper troughing lingers over south-central Canada
through the rest of the week allowing several upper and mid
level waves across the Dakotas and Minnesota. One strong,
notable shortwave moves out of the Central Plains into Upper
Midwest around Tuesday. The current track progged by most
guidance of this wave brings center of low pressure through
NE/IA/southern MN area, keeping more unstable, robust convection
displaced from our area. Rather this places our area under the
deformation zone- type rain shield of the wave, bringing high
confidence in wetting rainfall to the region. There remains a
50% chance of widespread 1 inches of rainfall Tuesday to
Wednesday, with up to 3 inches locally not out of the question
should multiple and/or extended period of thunderstorms reside
within the deformation zone/TROWAL.

Additional waves thereafter move through the region. Although
spread within ensemble guidance increases in synoptic details,
lowering confidence timing, placement, and magnitude of
convection and rainfall amounts. Overall this pattern would
support near average temperatures.

Isolated Severe Storm Potential Southeast ND:

This evening`s approaching upper wave is helping pull higher
low level moisture this afternoon northward into lee
troughing/sfc low in western and Dakotas. Lee troughing and
upper support from the wave aloft will help spark convection
near the Missouri River from south-central ND through central
SD by mid afternoon. All guidance brings this convection east
in the form of clusters toward eastern Dakotas.

By the time this convection makes its way toward our area near
and just after sunset, instability will be waning. This thought
is reinforced by the lack of any instability over 500 J/kg in
eastern ND as of 3 PM this afternoon. Some additional WAA ahead
of the sfc low will help pull some weak instability to 1000 J/kg
into southeast ND, but likely be elevated in height as a
surface warm front is stalled near the SD/ND border. Regardless
of the marginal instability, sufficiently strengthed shear in
the cloud bearing layer will allow for organization of
convection. Additionally, elevated instability over a stable
surface layer will help push updraft depth deeper into the HGZ.
Thus there will remain the potential for hail up to the size of
ping pong balls (1.5 inches) in convection that moves into
southeast ND from the west. The window for strong to severe
thunderstorms in this area is quite small, between 8-10 PM.

Additional thunderstorms will be possible elsewhere within the
area this evening, however after 10 PM and away from southeast
ND, the chance diminishes markedly based on the expectation of
waning available instability.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 714 PM CDT Sun May 19 2024

VFR this evening and then potential IFR or low end MVFR cigs
forming late tonight into Monday AM as low pressure moves thru
SE ND into MN and low levels saturate. Showers and a few
t-storms anticipated so put in approx timing in TAFs for all but
DVL region where chance is a tad lower.

&&

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

&&

$$

UPDATE...Riddle
DISCUSSION...CJ
AVIATION...Riddle