Area Forecast Discussion Issued by NWS Grand Forks, ND
000
FXUS63 KFGF 130858
AFDFGF
Area Forecast Discussion
National Weather Service Grand Forks ND
358 AM CDT Wed Mar 13 2024
.KEY MESSAGES...
- There is a 20 percent chance for a light freezing rain leading
to a light glaze of ice in the Devils Lake Basin and northern
Red River Valley near the US/Canada border late tonight into
Wednesday morning. This may impact the morning commute before
10 AM.
- There is a 10 percent chance for winter travel impacts between
Friday night and Sunday morning due to light accumulating
snow and blowing snow.
&&
.DISCUSSION...
Issued at 358 AM CDT Wed Mar 13 2024
Today: A mid level shortwave is moving over southern Canada
(circulation in WV imagery near southeast Saskatchewan/US border),
with more diffuse forcing ahead of this across eastern ND and
northwest MN where steep mid level lapse rates are in place.
Regional radars show a lot of showery returns, however a substantial
sub-cloud dry layer (shown on RAP soundings) has been limiting light
precipitation reaching the surface (mainly virga with only isolated
reports of sprinkles). There are some showers with slightly higher
returns that might be capable of brief light accumulations, but
where this activity has been tracking air/surface temperatures have
remained above freezing (34-41F). There is still a window through 10
am where a light shower could occur where surface temperatures are
near or below freezing creating slick travel near the US/Canada
border, but confidence in impacts is low based on current trends.
Ahead of the mid level clouds there has been a shallow saturated
layer and few pockets of dense ground fog, but webcams show limited
impacts in the northern Red River Valley and improvement should occur
as the clouds fill in over those areas.
Friday-Sunday: We are still tracking the evolution of a clipper type
system with all ensemble solutions at this point keeping the
strongest portion of the mid-upper low well east of our region.
There is a subset of ensembles that show a secondary shortwave
possibly dropping south farther west, but this is farther removed
from better moisture advection and isn`t resolved to produce more
than light QPF (0.01-0.05") if it were to occur. There remains
within the ensemble data sets probabilities for 0.25" QPF towards
northwest/north central MN which would be closer to the main upper
low (25%) and if this were snow could correlate to 2-3" snow
amounts considering the wetter/lower snow ratios expected.
Temperature profiles are a complication though as near surface
temperatures are favored to remain above freezing until the stronger
front arrives Saturday (and forcing/moisture aloft is decreasing at
that time). These temperature trends also lower confidence in blowing
snow impacts despite the strong wind signal highlighted by ensembles
behind the front (would need to occur with falling snow).
There is a signal for strong frontogenesis parallel to the frontal
zone and very steep low level lapse rates as the front passes with
upright instability (positive 0-3 KM ML CAPE) in the prefrontal
environment. As would be expected, the snow squall parameter is
positive along/behind this frontal zone raising the potential
for these types of features.
The most likely scenario for this pattern is a light rain/snow mix
and lighter snow accumulations of a dusting to 1" (90% chance).
However, there are reasonable scenarios where either intense snow
showers develop with locally higher rates leading to localized 1-3"
totals (reflected in 24hr ensemble probs in north central MN), or
even snow squall type features bringing brief whiteout conditions as
the front passes Friday night-Saturday morning.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1050 PM CDT Tue Mar 12 2024
VFR conditions prevail through much of the period, with only a
brief window for MVFR CIGs early Wednesday morning. A weak
shortwave will bring a chance for a light wintry mix or light
freezing rain, primarily for KDVL. Radar returns this evening
around the region are mainly virga, with precip not reaching the
ground thus far. This is expected to increase gradually through
the overnight hours before ending by mid morning Wednesday.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
DISCUSSION...DJR
AVIATION...Lynch