223
FXUS63 KFGF 121535
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
935 AM CST Wed Feb 12 2025

.KEY MESSAGES...

- Extended period of very cold conditions. Hazardous wind
  chills this morning to 45 below zero in southern Red River
  Valley. Additional opportunities for hazardous wind chills
  tonight, Thursday morning, and this weekend into early next
  week.

&&

.UPDATE...
Issued at 935 AM CST Wed Feb 12 2025

Wide varieties in temperatures, and thus wind chill readings,
continue across the FA this morning. Currently, Grand Forks is
the mild spot, at -8F (air temperature), while Wahpeton is on
the other end at -22F. There is an area of clouds from Devils
Lake to Valley City, moving slowly to the south/southeast. This
will keep some cloud cover along and south of highway 200 today,
while other areas further north see more sun. Wind speeds are
going to stay on the lower end again, generally 5 to 15 mph. So
the current cold weather headlines should be able to expire
later this morning, with the need for another round tonight.

UPDATE
Issued at 714 AM CST Wed Feb 12 2025

Watching the slow east/southeast movement of clouds thru western
and central ND into northeast ND at 12z. Scattered clouds as
well upstream in SE Saskatchewan and SW Manitoba. This
associated with 500 mb trough which will slowly move thru the
area today. Therefore sky cover today will be varied with clouds
and sun. Light winds over fresh snowcover in southern RRV
allowed temps to drop to near 25 to 30 below early this morning.
Temps will recover thru the morning and still think by aftn all
areas out of cold weather advisory criteria.

&&

.DISCUSSION...
Issued at 317 AM CST Wed Feb 12 2025

...Synopsis...

Large arctic air mass gripping much of the northern tier of
CONUS and Canada is evident on satellite imagery via water vapor
and moisture imagery. This is a result of an expansive polar
upper low near Hudson Bay, with deep troughing through the
central CONUS into Mexico. This synoptic feature will dominate
much of the forecast period through at least next Sunday,
keeping majority northwest flow aloft over the Northern Plains.
This will continue the feed of arctic air and cold to very cold
conditions over our area into next week. More on the cold
conditions can be found below.

There is a brief reprieve from this flow as energy from a dying
upper low in the Pacific Northwest traverses the Northern
Rockies and Northern Plains into the Upper Midwest around
Friday. This energy mingles with the polar low bringing a quick
moving low pressure system into the Upper Midwest. Most
ensemble guidance quickly progresses synoptic forcing through
the Dakotas into Minnesota Friday, supporting snow production
within the eastern Dakotas into Minnesota. However, synoptic
forcing is likely to be on the weaker side given the expectation
of a rather diffuse wave nor strongly deepening mid level
trough. Additionally, moisture transport into this is
anticipated to be on the meager side. Lastly, there is not much
of a signal for mesoscale forcing to contribute for potential in
`over performing` in precip amounts. Ultimately this should
result in snow amounts/rates on the lighter side, with
interquartile snow totals in the 1-3 inch range, highest within
Minnesota.

As the system develops into Upper Midwest, increasing pressure
gradient should help increase northerly winds late Friday into
Saturday. While winds increase, they are not forecast to be
strong given the lack of strength of the system aloft as well as
weaker cold air advection due to such cold temperatures ahead of
the system. The interquartile of winds is in the 15-25 mph
gusting 25-35 mph, strongest within the Red River Valley. With
temperatures forecast in the single digits above and below zero,
and a fresher snowpack in place (outside of the central Valley),
patchy blowing snow and drifting snow appear most likely
scenario.

Ultimately this system is forecast to bring sub-advisory-type
impacts to portions of the Red River Valley and Minnesota from
light snowfall and blowing/drifting snow Friday into early
Saturday. The chance for advisory-type impacts is rather low,
around 10% chance within Minnesota.

...Hazardous cold...

There is high confidence in very cold conditions tonight
through Thursday, then again this weekend into next week. This
includes the potential for hazardous wind chills colder than 40
below zero.

Cold air aloft and ideal radiational cooling over a relatively
fresh and sufficiently deep snow pack is contributing to
temperatures into the twenties to around 30 below zero in
southeast North Dakota into west-central Minnesota. This
location will be a common theme for relatively cold/coldest
condition in our area due to the presence of fresher snowpack
compared to older/thinner snowpack further north.

These temperatures are combining with a light breeze between
5-10 mph between the western periphery of surface high centered
in central MN and an incoming weak surface trough in central
ND. This is resulting in growing coverage of wind chills between
40 and 50 below zero in observational datasets like AWOS/ASOS
and NDAWN.

While similar temperatures are occurring in west-central MN, a
lack of wind will limit the chance of wind chills colder than 40
below zero here.

Nearby into the I-94 corridor, incidences of wind chills near 40
below zero are being noted. However, these are perhaps a bit
more sporadic/isolated in time and space. Thus, will continue
to hold off on upgrading her.

Guidance supports warming temperatures shortly after sunrise
(around 9 am) will bring wind chills warmer than 40 below zero,
ending threat of these very hazardous conditions in this area.

Another period of hazardous cold comes tonight into Thursday
morning, mainly driven by air temperatures well into the
twenties below zero, with a medium chance of temperatures into
the thirties below zero, again in the aforementioned areas of
southeast ND into west- central MN, as well as in typical cold
spots of northwest MN.

After a brief reprieve Friday into the weekend, the polar low
and more unmodified arctic air moves very near our area from ON.
This includes potential for coldest air mass yet to move over
our area. Most ensembles depicting around a 40% chance of 850 mb
-30C or colder to brush into our area. This brings the high
 likelihood for another period of very cold conditions,
 including the potential for 30 below zero air temperatures and
 wind chills colder than 40 below zero. Timeframe for this air
 mass to impact our area is around Sunday night through Tuesday
 morning.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 551 AM CST Wed Feb 12 2025

Area of clouds in central and north central ND slowly moving
east...moving into Devils Lake area and will make it into the
much of the valley for a time mid to late morning/early
afternoon. Extent of cloud cover area wide into the afternoon
remains uncertain. Cloud bases look to remain in the VFR range
(5000-7000 ft agl). Chance for a few flurries but haven`t
noticed much on obs or radar. Winds turning becoming NW 10 kts.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Cold Weather Advisory until noon CST today for NDZ006>008-
     014>016-024-026>030-038-039-054.
MN...Cold Weather Advisory until noon CST today for MNZ001>009-
     013>017-022>024-027-028-030>032-040.

&&

$$

UPDATE...Godon
DISCUSSION...CJ
AVIATION...Riddle