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691
FXUS63 KFGF 191744
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1244 PM CDT Wed Jun 19 2024

.KEY MESSAGES...

- Additional chances for thunderstorms and heavy rain are
  possible late Thursday through Saturday.

- Active weather continues early next week, with another chance
  for showers and possibly strong thunderstorms Monday and
  Tuesday.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1244 PM CDT Wed Jun 19 2024

The development of our cumulus has expanded from the Red River
and east into our Minnesota counties. Closer to the surface high
the cloud formation is still being supressed so our forecasted
temperatures may slightly be too low for the Devils Lake Basin
and the Northern portion of southeastern North Dakota.

UPDATE
Issued at 1001 AM CDT Wed Jun 19 2024

A low level cumulus field is slowly dissipating or moving east
as the low level moisture is trapped under our high pressure.
Most of the models have the lower levels drying out by 18z but
we shall see if those clouds fully dissipate or not.
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&&

.DISCUSSION...
Issued at 402 AM CDT Wed Jun 19 2024

...Synopsis...

Upper flow remains out of the southwest today into Thursday before
favoring more of a zonal tendency. The H5 trough bringing rain over
the past several days is pushing off to the northeast, which will
serve to end our rain chances as we approach mid morning. A period
of quiet weather prevails this afternoon through late Thursday ahead
of our next system that is set to move through the area Thursday
night through Saturday. Zonal flow then looks to remain in place
through next week, with several transient shortwaves showing up in
ensemble guidance at various times. Some of these shortwaves have
enough pattern support to mention the possibility of strong to
severe thunderstorms.

Skies are expected to gradually clear from west to east today as
this mornings showers move out of the area by mid morning. High
temperatures should be able to reach the low 70s where we see the
best clearing, with perhaps middle to upper 60s where cloud cover is
more persistent. Rain is not expected after midday across the entire
forecast area.

For Thursday, 850 mb flow gradually shifts, starting northwesterly
during the morning hours, then becoming southerly by late afternoon.
This will allow some degree of moisture return into the low to mid
levels, although some uncertainty remains regarding PW values. This
will ultimately be determined by the H5 ridge over the eastern
CONUS, and how much it weakens and elongates by late Thursday. Most
guidance weakens the ridge, but there is still some disagreement to
what extent it weakens. A stronger ridge allows better moisture
return into the Northern Plains, which will set the stage for our
next system heading into Thursday night and Friday.

...Heavy Rain and Thunderstorms Possible Thur through Sat...

Rain chances increase on Thursday from south to north as a theta-e
gradient lifts northward into the Northern Plains and Upper Midwest.
While there is still uncertainty regarding moisture availability,
there is support (60 percent chance) for at least 0.50 inch of
precipitation across portions of the region south of I-94. The axis
of development for this precipitation will be somewhat stationary
Thursday night through late Friday, when a shortwave is expected to
move across the area. MUCAPE ahead of the shortwave could be upwards
of 2000 J/Kg according to model soundings, which could support a
mention of isolated strong to severe thunderstorms, which would
likely be elevated due to the overall lack of surface based
instability. Shear in both the 0-3Km and 0-6Km layers are supportive
of large hail and damaging wind gusts. Tornado risk will be heavily
dependent upon whether or not convection becomes surface based,
which would support tornadic storms should this be the case. At this
time, this looks like a less likely scenario. The highest
probability for severe storms will be Friday afternoon and evening,
with perhaps another chance Saturday afternoon.

...Active Weather Continues into Next Week...

A progressive and very active shortwave pattern is expected to
persist into next week. Exact timing of these shortwaves is likely
to change due to the progressive nature of the H5 pattern; however,
there is good agreement that there will be several shortwave
passages next week. The first wave could move through the area
Monday into Tuesday, with good agreement between ensembles regarding
the potential for strong to severe storms. At this time, GEFS
probability for surface CAPE greater than 2000 J/Kg is over 70
percent Monday afternoon and evening. Model soundings also show a
shear profile supportive of discrete cells. This will depend heavily
on timing, which could change in the coming updates; however,
pattern support remains strong for potentially impactful weather
through a good part of next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
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Issued at 1244 PM CDT Wed Jun 19 2024

A low level cumulus field is the main reason for the VFR/MVFR
conditions at all TAFs site except KDVL which is expected to
remain relatively clear because its closest to the surface high.
Around 06z to 09z some brief showers will move from the south
ahead of the warm front however, there is some uncertainty on
how far north these showers will move and may reach KFAR. By
12z these showers will move East and may move over KBJI. VCSH
was placed in the TAFS to account for this uncertainty.
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&&

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

&&

$$

UPDATE...MM
DISCUSSION...Lynch
AVIATION...MM