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419
FXUS63 KFGF 301722
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1222 PM CDT Tue Apr 30 2024

.KEY MESSAGES...

- Rain chances continue through the week with near normal
  temperatures.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1217 PM CDT Tue Apr 30 2024

Rain is beginning to move into the CWA slowly but surely. The
good news is, lightning activity has remained fairly limited
thanks to limited instability. This should continue through the
early afternoon. Lightning remains a potential outcome this
afternoon south of I-94.

UPDATE
Issued at 944 AM CDT Tue Apr 30 2024

Fog will continue to diminish over the next several hours this
morning. Fog will be gone by noon at the latest. Showers and
thunderstorms are still expected later this afternoon and
evening.

UPDATE
Issued at 610 AM CDT Tue Apr 30 2024

Fog has persisted long enough to become a nuisance but any
pockets less than 1 mi have tended to be transient and last no
longer than 1 hours any given area thus the hesitation to go
dense fog advisory or even SPS. This should clear up as winds go
from calm to gentle this morning helping to mix things up a
bit. Anyways could see locally dense for in areas though 9am.
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&&

.DISCUSSION...
Issued at 239 AM CDT Tue Apr 30 2024

The upper low currently centered over Thunder Bay Ontario will
continue to drift east/northeast amid zonal flow. Shortwave
ridging over western North Dakota will quickly pass over us
today before the next trough ejects east out of western MT,
arriving later today. In the meantime pockets of low stratus
with drizzle may drop visibility as low as 1-3 miles with fog
development possible under any of these areas of lower clouds.
Only a 20-30% chance of fog development so leaving as just
patchy fog for now and any areas that do see fog are unlikely to
see dense fog (<1/4 mi) as the inversion is pretty weak. Might
see some brief bouts of sun this morning and early afternoon
though would bet on more clouds than not with the MT wave
quickly approaching and associated clouds nearing by midday.

Despite strong warm air advection from 850-700mb we will remain
north of the effective surface warm front which will set up
from the ND/SD/MN border east into north central WI keeping us
on the cooler side today with highs in the 50s to low 60s in the
far south. Rain begins by noon in eastern ND pivoting northeast
overspreading the remainder of the FA by the evening commute.
Could see a few thunderstorms in the far south epically in west
central MN this afternoon and evening where steep mid level
lapse rates >7.5 C/km and MUCAPE of 200-500 J/Kg could support
some small hail though this is likely conditional upon the
northward placement of the warm front and and afternoon heating
at the surface during breaks in clouds which as mentioned before
is expected to be limited. Overall looking for another
widespread quarter to half inch but isolated higher totals
remain possible in thunderstorms. This wave continues east
Tuesday night with another day in the low 60s Wednesday.

The parade of waves continues Wednesday night and beyond. Went ahead
and grouped the late Wednesday night through Friday period as the
next round, although it won`t continuously rain this entire time.
There should be at least two areas of precipitation late Wednesday
night into Thursday morning. During this period, a 700mb low remains
pretty stationary over northeast Montana, while a wave rotates
around its eastern side. The main area of precipitation should be
down around southeast South Dakota into southern Minnesota, closer
to the actual surface low. This convection should become elevated
Wednesday night into Thursday morning, with good 850mb warm
advection, a low level jet, and deeper moisture. Showers associated
with this area may reach as far north as our southeast FA. A
secondary area of precipitation also looks to develop over central
or eastern North Dakota, associated with the upper jet and some
700mb frontogenesis. At this point, the NBM shows the highest
probabilities for greater than 0.25 inches (50 percent) just
brushing our far southeast FA to around 40 percent over central and
eastern North Dakota. This system maintains pretty strong dynamics
for Thursday afternoon through Friday, as the 700mb low consolidates
over eastern North Dakota and lifts north-northeast.

There should be somewhat of a break Friday night, before another
little wave on Saturday skirts the far southern FA again. At this
point, the deeper moisture continues to stay south of this area
again, and the far southern FA would only be brushed with minimal
rainfall. Brief ridging follows through at least Sunday, maybe even
into early Monday, which would allow temperatures to get back to
normal or even above normal (low 70s in the southern Valley). After
this point, as the previous shift noted, one cluster shows a trough
at the same time another cluster shows a ridge over the Plains. So
although the forecast carries low chances for precipitation, the
confidence is very low.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
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Issued at 1217 PM CDT Tue Apr 30 2024

The main aviation challenge for the TAF period will be a brief
time of VFR conditions this afternoon before falling back to
MVFR/IFR. Expect at least MVFR ceilings through the entire TAF
period, with the potential to fall to IFR overnight tonight.
Rain will move from southwest to northeast through the day
today, but lightning is not expected for any TAF site. The only
TAF site where lightning may arise would be FAR, but the
probability is low (20% chance).
-- End Changed Discussion --

&&

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

&&

$$

UPDATE...Perroux
DISCUSSION...Godon/TT
AVIATION...Perroux