785
FXUS63 KFGF 181204
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
704 AM CDT Sat May 18 2024

.KEY MESSAGES...

- Winds gusting to 45 mph are expected across much of eastern
  North Dakota late this morning through early evening.

- An active pattern will keep occasional thunderstorm chances in
  the forecast through the middle of next week. Isolated strong
  to severe thunderstorms may be possible Sunday afternoon near
  far southeast North Dakota.

&&

.UPDATE...
Issued at 704 AM CDT Sat May 18 2024

Line of showers (maybe an isolated thunderstorm) is approaching
our western CWA along the leading edge of the main mid level
circulation (still near the SK/ND border region). I made some
adjustments to better reflecting the current timing (and lull)
between periods of rain, otherwise forecast is on track.


&&

.DISCUSSION...
Issued at 347 AM CDT Sat May 18 2024

The large scale pattern will be influence by a mid/upper trough
developing over the Intermountain West Sunday into early next week
that eventually breaks down allowing zonal flow to reestablish
itself over the Northern Plains by late next week. Actual flow/jet
streams may behave more like "split-flow" around this trough and
there is a higher variation in the position of southwest flow and
evolution of waves ejecting through southwest flow or eventually
the northerly flow as the trough moves east. This creates
particularly large variations in how forcing/insatiability and
ultimate QPF/thunderstorm chances evolve (including any related
impacts). High temperatures will tend to vary from the 60s to lower
70s, though there is reasonably high spread related to the
progressive nature of the surface pattern and any frontal
zones/precipitation/clouds that may develop.

Regarding winds: The current mid level wave exits to the east
through the day with morning rain/embedded thunderstorm ending.
Another period of showers may develop across our north with the cold
pool/mid level vorticity across our north through the afternoon.
This may be enough to result in more cloud cover that could
limit mixing and higher end gust potential. Still, as
unidirectional westerly flow increases even a shallower mixed
layer should support gusts occasionally to 45 mph across much
of eastern ND. This aligns with NBM probs for greater than 40
mph gusts (90% chance). Confidence at this point was high
enough to issue a Wind Advisory for most of our ND counties
(excluding far southeast ND).

Regarding severe thunderstorm chances: Instability has greatly
decreased this morning and cloud cover could limit daytime
heating/low level lapse rates today. While there may be higher
vorticity environments in our north closer to the mid level
circulation, I wouldn`t anticipate funnel development unless we
see more breaks in advertised mid level clouds during peak
heating. On Sunday afternoon/evening there is some guidance
that shows a window for isolated strong or severe thunderstorms
(large hail a primary threat) in our far southwest as the next
mid level shortwave rotates northeast within SW flow (variation
in how that pattern evolves). BL Td`s increasing and steepening
mid lapse rates are shown to contribute to elevated instability
in the 1000-1500 J/KG range while effective shear could be
anywhere from 30-50kt. Due to the high variation in surface
pattern (frontal zone may not set up this far northeast) and
stronger capping could limit the severe risk into our area.
Worth monitoring though.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 704 AM CDT Sat May 18 2024

THere is a small pocket of MVFR ceilings progressing into
northwest MN (resulting in brief impacts where it tracks)
otherwise VFR should prevail (4-8 KFT AGL CU). Scattered showers
(isolated thunderstorms) will progress over eastern ND and into
northwest MN through midday before exiting to the northeast into
Canada this afternoon. westerly winds should increase through
midday with occasional gusts as high as 40kt in eastern ND,
decreasing this evening with sunset/loss of daytime mixing.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Wind Advisory from 10 AM this morning to 7 PM CDT this evening
     for NDZ006>008-014>016-024-026>030-038-039-054.
MN...None.

&&

$$

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