311
FXUS63 KFGF 191202
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
702 AM CDT Sun May 19 2024

.KEY MESSAGES...

- Isolated severe thunderstorms are possible this evening in far
  southeast North Dakota. Hail to 1 inch is the primary threat.

- 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 700 AM CDT Sun May 19 2024

Light returns associated with high based showers are spreading
into the southern Red River Valley matching up with earlier
trends in CAMs/guidance. There is some lightning activity in SD,
but confidence is low this more unstable air mass will make it
up this far north during the early morning hours wit hthis
current wave. Otherwise, forecast for the rest of the day is
still on track per earlier discussion.


&&

.DISCUSSION...
Issued at 351 AM CDT Sun May 19 2024

Southwest flow is beginning to build into the central/Northern
Plains in response to building mid/upper level troughing over the
Pacific Northwest. This trough is expected to continue to amplify
and deepen southwest flow over the plains and a series of waves
ejecting through this flow (along with increase moisture advection)
will keep periodic rain/thunderstorm chances in our forecast area,
with confidence reasonably high through mid week despite some
variations with timing/evolution of some of these waves. By late
next week this trough breaks down and a more zonal/progressive flow
featuring lowered heights aloft as the northern storm track shifts
south. There is lower confidence in evolution of any waves and low
confidence in any potential impacts). Temperature trends will be
seasonably mild in the mid 60s to lower 70s the next several days,
but below average temperatures (50s/lower 60s) become favored during
the later periods.

Severe risk today: Several impulses bring scattered showers/isolated
thunderstorms during the day, with a more organized mid level
shortwave passing south of our region late this afternoon and
evening. THe norther extent of this will feature a near by
baroclinic zone where southerly flow will help increase BL Tds. Mid
level lapse rates are shown to steepen enough to support an axis of
elevated instability near our forecast area by late
afternoon/evening. Consensus is favoring better instability farther
west and southwest based on the surface pattern and with increasing
low/mid clouds resolved by all current guidance there isn`t
currently a risk for surface based parcels (elevated parcels will
support hail/wind as primary threats if there is any threat). As
current guidance shows lowered instability towards our area (around
1000 J/KG max MUCAPE) confidence is lowered in any strong/severe
storms. There is still high shear (40-60kt effective shear) and some
CAMs try to hold some organized/embedded cells together as they
approach far southeast ND during the 6pm-10pm period. 0-3km shear is
in the 30-35 kt range, so while profiles are not that supportive of
a wind risk (DCAPE less than 800 J/KG) there is still a low threat
for downburst winds if a cell takes on brief/orthogonal linear
structures (as some CAMs show).

Midweek rainfall (Tuesday-Wednesday): There is increased consensus
on a stronger negatively tilted mid level trough passage through SW
flow over our eastern forecast area, with the potential for
organized/deformation and widespread moderate to localized heavy
rainfall. Excessive rainfall isn`t expected as any higher totals
(1-3") would fall over a longer duration. Impacts to possibly
delay any planting operations are possible though across
northwest MN/west central MN as 24hr probs for at least 0.5" is
near 80% and 1"+ is 50%.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 700 AM CDT Sun May 19 2024

VFR condtions should preavil throug the afternoon, with MVFR
ceilings and possible IFR ceilings arriving later in the
evening/overnight period. Otherwise, high based showers are
possible early in the TAF period, with more organized/better
rain chances arriving later this evening when there may also be
better thunderstorm chances (though TSRA coverage should still
be low enough to keep out of TAFs for now).

&&

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

&&

$$

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