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000
FXUS63 KFGF 181746
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1246 PM CDT Thu Apr 18 2024

.KEY MESSAGES...

- West to northwest winds occasionally gusting over 45 mph will
  result in difficult travel conditions for high profile
  vehicles and blow around unsecured objects today. Locations
  impacted include parts of eastern North Dakota and the
  northern Red River Valley in northwest Minnesota.

- Scattered snow showers are forecast across the region today
  through Friday, with the highest chances during the afternoon
  periods north of Highway 2. There is a 20% chance in impacts
  from brief visibility reductions under half a mile this
  afternoon through Friday.

&&

.UPDATE...
Issued at 1240 PM CDT Thu Apr 18 2024

Rain and snow showers continue, although impacts are super
limited. For this reason, the bulk of the impacts today will
continue to be the winds. Gusts will continue through the
remainder of the day.

UPDATE
Issued at 928 AM CDT Thu Apr 18 2024

Wind speeds continue to be between 20 and 30 knots right now
with occasional gusts to 35 knots. This will continue for the
remainder of the day today. Rain/snow showers are on the
precipice of crossing the international border, and should begin
to impact far northwest Minnesota within the next 2 hours.
Visibility observations have been difficult to come by, but
webcams indicate visibility has been fine for the most part.

UPDATE
Issued at 641 AM CDT Thu Apr 18 2024

Earlier this morning (between 4-5am) wind gusts in the 40-47
mph range started in the Devils Lake basin, earlier than
originally anticipated. I would have though low levels would
have been just stable enough/decoupled to limit the higher
gusts, but that inversion was either not as steep as advertised
or momentum transfer was able to overcome it. I went ahead and
bumped up the start time to the advisory earlier to account for
that trend. Otherwise, the forecast remains on track.

&&

.DISCUSSION...
Issued at 358 AM CDT Thu Apr 18 2024

A strong vertically stacked mid/upper low is in place over southern
Manitoba and will tend to slowly move east over the next several
days, resulting sin strong surface gradient and strong
unidirectional winds within a 3-5 kft dry adiabatic mixed layer.
Besides nighttime periods where there will be "some" decoupling
windy conditions should persist and there is a signal for sustained
within advisory criteria along/west of the Red River Valley. The
strongest signal in NBM4.2 probs (supported by sounding analysis) is
west of the escarpment in favored terrain regions and with more of
a westerly (than northwesterly) component to the flow this makes
sense (based on past events). Mixed layer winds aren`t "quite" as
strong during the day Friday, so confidence in advisory impacts is
lower (but should be monitored).

Regarding snow showers/visibility impacts: Within cyclonic flow/cold
pool, steep lapse rates should support pockets of snow
showers/flurries. Due to weak instability (up to 250 J/KG MUCAPE)
and unidirectional flow there may be a tendency for showers to
organize into HCR type bands, and CAM`s reflect both cellular and
elongated HCR type signals. The best chance for impacts in these
convective showers may be Friday as a shortwave drops south around
the back side of the mid/upper low. As this happens there may be
enough forcing/organization to cause more "horizontal" organization
of banding and squall type convective features (brief and not
resolved at this time by CAMs). Wet bulb profiles should support the
mix or change over in areas where air temps are above freezing at
the surface (will be variable in how p-type evolves). Due to warm
ground temperatures any accumulations (dusting to 1" based on HREF
PMM/NBM 25/75 probs)may struggle to actually accumulate/cause
impacts. Visibility reductions will be the primary concern. Due to
air temperatures in the mid 30s to low 40s at time of most organized
showers, it will take higher rates to achieve reductions to 1/2 mile
or less (based on Canadian blowing snow model). Where these types of
impacts actually occur will be hard to anticipate, though there is a
stronger consensus within HREF towards our northeast Lake of the
Woods region Friday.

Beyond Friday: The mid/upper low transitions east while the pattern
becomes a bit more complicated (more quasi-zonal) with the possibility
for another mid-upper low to move into the region from the Pacific
NW (interacting with stronger Hudson Bay low to the northeast)
through early next week before a more consistent signal for westerly
flow and rising heights. The evolution of the pattern should support
a general warming trend and a period of possible rain (lighter
signal) Monday followed by dry weather.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1244 PM CDT Thu Apr 18 2024

MVFR conditions should improve to VFR for all TAF sites. MVFR
cigs will impact the Lake of the Woods region, but should not
get as far south as BJI. Rain/snow showers may arise at all TAF
sites, but impacts to visibility are not expected to change
flight category. Winds will remain sustained between 20 and 30
knots through the day today, with occasional gusts up to 45
knots. Gusts should drop out after sunset, but winds will remain
sustained at least above 15 knots. Winds will increase once
again tomorrow, peaking after the TAF period.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Wind Advisory until 9 PM CDT this evening for NDZ006>008-
     014>016-024-026>029-038-049-052-054.
MN...Wind Advisory until 9 PM CDT this evening for MNZ004-007.

&&

$$

UPDATE...Perroux
DISCUSSION...DJR
AVIATION...Perroux