557
FXUS63 KFGF 181726
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1226 PM CDT Sat May 18 2024

.KEY MESSAGES...

- Winds gusting to 40 mph are expected across much of eastern
  North Dakota 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 1226 PM CDT Sat May 18 2024

Widespread gusts in the low to mid 30s currently in eastern
North Dakota with showers diminishing in northwest Minnesota. A
few gusts to 40 mph still remain possible with the showers
before they cross the Canadian border in the next hour or two.
Wind advisory remains in effect until 7pm.

UPDATE
Issued at 954 AM CDT Sat May 18 2024

Continuing to track showers east with no lightning activity yet
but briefly gusty winds to 40 mph. Starting to see a better
signal for some stronger storms with lightning activity by the
time the line currently near Grand Forks makes it northeast to
Lake of the Woods.

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 /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1226 PM CDT Sat May 18 2024

Strong westerly winds will continue this afternoon across ND
taf sites (DVL, GFK, FAR) with 25mph gusty 35mph (occasionally
40+ mph) through 4pm. Showers have exited the area but
developing cumulus south of low north of the intl border with
keep MVFR ceilings for most this afternoon with SCT to BKN at
030 to 050. VFR by 01z as clouds dissipate while winds dying off
by 10-11pm.

&&

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

&&

$$

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