Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 140831
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
331 AM CDT Thu Mar 14 2024

.KEY MESSAGES...

- There is a 50 percent chance for winds to gust as high as 50
  mph Friday afternoon through Saturday afternoon.

- There is a 10 percent chance for minor winter travel impacts
  between Friday night through Sunday morning due to brief heavy
  snow showers reducing visibility with light accumulations.

&&

.DISCUSSION...
Issued at 331 AM CDT Thu Mar 14 2024

Large scale pattern shows heights and temperatures aloft falling as
troughing deepens over the Hudson Bay region of Canada placing our
region in north-northwest flow aloft. Eventually flow flattens
into more of a westerly split-zonal type pattern by the middle of
next week. There is a period of impactful weather as the initial
deeper trough moves into the region Friday into the weekend,
otherwise the probability for impactful weather is low. Temperatures
will tend to return closer to "seasonal" ranges this weekend behind
the front, but the progressive nature of weaker waves and evolution
of the pattern next week creates larger spread in potential
temperatures (tendency for above average temperatures most periods
with lack of snow pack in place).

Today: Westerly flow remains in place aloft ahead of a shortwave
trough (currently centered over southeast Saskatchewan). Disorganized
forcing and mid level saturation has helped maintain shower type
precipitation. Due to a sub-cloud dry layer immediately very shallow
BL most of the returns on radar have been virga and where
precipitation has occurred it has not measured (just sprinkles or
flurries). The main shortwave trough drops south through central ND
this morning and HREF is showing a signal for lighter snow
eventually developing which could result in a dusting mainly in the
Devils Lake Basin and west of the Red River Valley through midday.
The track may keep the better forcing/deep saturation west and right
now there is a 20-30% chance for these limited impacts.

Friday-Sunday: There continues to be a good signal in ensembles for
windy conditions and potential advisory winds (gusts 45-50 mph),
especially as the cold front drops south Friday night into Saturday
morning. Deep mixing in westerly flow as gradient increases ahead of
this front could still result in near advisory winds Friday
afternoon, and ensembles show a higher probability along and west of
the valley initially before the front arrives. However, the pressure
rise couplet and CAA with the front could still support good
momentum transfer even into forested areas in MN. Ensembles show
these winds being possible (20-50% chance) across much of our CWA
even outside of the traditional valley as the front drops south
Saturday morning.

Regarding snowfall accumulation and visibility impacts: Over the last
24hr the signal for broad snow accumulations of 1" or greater have
greatly diminished with limited probs for 1"+ of 5% now confined to
the Northwest Angle. However, there is a broader signal for light
accumulation of a dusting (0.1"+) across northeast ND and highest
chances towards northwest MN. This signal aligns well with periods
of instability (steep 0-3km level lapse rates) and the potential for
convective showers to develop. Initially I still can`t rule out
squall type features where progressive parallel frontogenesis could
briefly organized precipitation ahead of the front, but the
evolution of the pattern isn`t ideal and temperatures profiles
questionable early on. Most activity looks like it will quickly
become showery with deep vertical wind shear behind the front within
the saturated adiabatic layer supporting possible HCR type
convective bands/rolls. However the showers evolve, they could
support intense, brief, localized, high rates which could drive
visibilities to near whiteout where they occur.

Those reduced visibilities would be the primary hazard, though a
north to south orientated HCR lingering in one spot could bring
light accumulations 1"+ (duration would matter and probabilities in
ensembles are in the single digits). There remains questions on
coverage (could remain isolated considering the lack of deeper
moisture advection). The precipitation type Friday into Saturday are
also in question due to the initially above freeing lower levels,
and the coldest BL temperatures not arriving until Saturday night
when all locations should finally drop below freezing. The spotty
signal for light shower activity doesn`t end Sunday (though ensemble
measurable snow chances are lower than on Saturday). It is possible
we could continue to see localized impacts continue most of the
weekend (though coverage/location of these impacts remains highly
uncertain). This type of pattern and impacts will carry a low
predictability horizon, so we will have to monitor.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1142 PM CDT Wed Mar 13 2024

Stratus continues to spread southward this evening, with KDVL
expected to see IFR CIGs during the overnight period. Patchy
fog is possible for many areas west of the Red River; however,
confidence is low regarding fog for areas in the Valley to
include KGFK and KFAR. For KGFK, MVFR conditions are expected
during the late overnight period and into Thursday morning, with
a low chance for IFR ceilings due to patchy fog, mainly to the
west. Further east, KTVF will see a chance for MVFR ceilings
early Thursday morning. For KFAR and KBJI, patchy fog chances
are lower; however, MVFR ceilings remain possible at KFAR, with
IFR CIGs at KBJI approaching sunrise.

&&

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

&&

$$

DISCUSSION...DJR
AVIATION...Lynch


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