453
FXUS63 KFGF 172352
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
652 PM CDT Sat Aug 17 2024

.KEY MESSAGES...

- Wildfire smoke may impact sensitive groups within northwest
Minnesota and eastern North Dakota this weekend.

&&

.UPDATE...
Issued at 652 PM CDT Sat Aug 17 2024

Isolated showers in northwest MN are lingering but showing
weakening trends as we approach sunset this evening. Surface
layer smoke is in place mainly in ND but with decoupling we
could see smoke impacts increase. There is also a signal for
patchy fog/ground fog development Sunday morning in some CAMs
and with surface high centered over our CWA this seems
reasonable. I went ahead and adjusted PoPs weather to reflect
the showers through sunset and patchy fog Sunday morning,
otherwise the forecast appears to be on track.

&&

.DISCUSSION...
Issued at 232 PM CDT Sat Aug 17 2024

...Synopsis...

Current satellite imagery shows cumulus blooming across eastern
North Dakota and northwestern Minnesota this afternoon. Some pop-up
showers are appearing in northwestern Minnesota, but not expecting
any severe or impactful QPF from these showers. As a low pressure
system pushes into the northeastern United States, a 500mb ridge of
high pressure will move east as well. This ridge will build into the
northern High Plains into mid week, before flattening ever so
slightly. This will allow shortwaves to pass through the area,
giving us precipitation chances. Precipitation chances with these
shortwaves looks to be on the lighter side in guidance, with 30 -
40% chance of QPF exceeding a quarter of an inch Tuesday morning
into Wednesday morning. Once you look at probabilities for an inch
or more, the chances go down to <20% for any of the precipitation
chances next week. Uncertainty with these shortwaves still exists in
terms of forcing and moisture availability as we get into the work
week.

...Wildfire Smoke...

According to the RAP-13, Smoke from Canadian wildfires will remain
near the surface in at least small amounts through the night into
Sunday. This could aggravate those who are more sensitive to smoke
in the air, so if you are part of that group, use caution going
outside this weekend. This should lessen into the beginning of the
work week, and hopefully get cut off completely by the ridge
changing our flow to more southerly/southeasterly.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 652 PM CDT Sat Aug 17 2024

Smoke aloft and at the surface will continue to impact TAF sites
in eastern ND and northwest MN at times. Confidence is low
however in how long and how widespread sub-VFR visibilities
will be due to smoke though they could more commonly linger in
the 3-6sm during the nighttime period as low levels stabilize.
Patchy fog may also develop over parts of the region in the
09-14Z period also complicating visibility forecasts (and not
being well resolved by models). Ultimately we will need to
monitor short term trends tonight/Sunday morning. Surface high
pressure will result in light and variable winds overnight for
the region, with southeast winds 5-10kt eventually developing at
KDVL Sunday afternoon. CU should also redevelop with peak
mixing Sunday (generally in the 7000-10000 FT AGL range).

&&

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

&&

$$

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