323
FXUS63 KFGF 202110
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
410 PM CDT Sat Jul 20 2024

.KEY MESSAGES...

- There are daily chances for showers and thunderstorms today
  through Monday. While the chance for severe weather is less
  than 10%, a few strong storms capable of small hail and gusty
  winds to 50 mph may occur.

- Smoke from Canadian wildfires will linger across the region
  through at least Monday, potentially longer. This may impact
  air quality.

&&

.DISCUSSION...
Issued at 318 PM CDT Sat Jul 20 2024

...Synopsis...

Water vapor satellite imagery reveals an expansive, well defined
upper low over western QB into ON, with high amplitude upper
ridging through the western CONUS into western CAN. This is
placing the Northern Plains and portions of the Upper Midwest
under weak northerly flow aloft, with weak flow is greatly
limiting wind shear. At the surface, a backdoor cold front is
pushing through western ON into northern MN pushed by the
aforementioned QB/ON upper low. Sufficient instability and
moisture is present for convection.

Thick and widespread smoke is also noted on visible satellite
imagery over the majority of central and western CAN into the
northern tier of the CONUS.

Ensemble guidance indicates the upper synoptic pattern will be
rather stagnant over the next several days. Because of this, the
backdoor cold front stalls and washes out/retreats back east
tonight into tomorrow. Because of this stagnant pattern, the
buoyant air mass lingers around the area. Additionally, weak
northerly flow aloft will help funnel smoke from Canada into our
area through at least Tuesday.

...Daily chances for showers and storms...

The resident air mass over the region is composed of rich
boundary layer moisture, seen by sfc dew points in the upper 60s
to low 70s. There is likely some enhancement from
evapotransportation that typically peaks around this time of
year as most CAMs this morning did not show 70 dew points. This
is aiding moderate instability. While wind shear is weak, there
is enough instability to generate tall enough storms to deposit
small hail, as well as downdrafts resulting in gusty winds up to
50 mph.

With a lack of changing air masses, and stagnant synoptic
pattern, the potential for small hail and gusty winds to 50 mph
will be present in relatively stronger storms today through
Monday.

Due to wind shear less than 25kt and lack of better forcing for
lift, the chance for organized thunderstorms leading to severe
hazards is very low, less than 10%.

...Wildfire smoke...

Most smoke is from wildfire activity in northern BC, AB, and
into the Yukon and Northwest Territories of Canada. Persistent
flow from this source region into our area is forecast by
ensemble guidance through mid week, keeping smoke confidently
over the area through Monday, potentially lasting as long as
Thursday/Friday even. There will also be opportunity for smoke
to reside at the surface during this timeframe, which would
reduce air quality. Low confidence in how when and how thick
smoke will be at the surface, thus lowering confidence in
impacts from reduced in air quality. But ultimately there will
be potential for impacts from reduced air quality through much
of the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1220 PM CDT Sat Jul 20 2024

VFR conditions throughout the TAF period with the exception of
vicinity thunderstorms. Looking at satellite the thick smoke
aloft covers all the TAFS sites. According the latest PIREPs the
smoke layer stops at 5000 ft so that is represented in the TAFS
as the SCT layer. The smoke layer may also delay thunderstorm
development to create more uncertainty but still thinking after
21z scattered thunderstorms may pop up until 0300 to 06z.

&&

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

&&

$$

DISCUSSION...CJ
AVIATION...MM