046 
FXUS63 KFGF 040532
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1132 PM CST Thu Feb 3 2022

.UPDATE...
Issued at 1126 PM CST Thu Feb 3 2022

Current radar shows weak echoes over portions of northeastern ND 
and the central Red River Valley, although there is limited ground
truth, likely due to the struggle to saturate the column given 
dew points in the double digits below zero. There are flurries 
here at the office, and question is really one of the potential 
for measurable snowfall. No plans to change forecast, but will 
keep a high probability, low QPF forecast in tact...with little to
no impacts expected. Actually coor'd with neighbors to the south 
to stretch POPs into the southern valley, which will be the only 
change to grids with this update.

UPDATE Issued at 621 PM CST Thu Feb 3 2022

Sfc low over central ND now entering western zones with associated
inverted trough moving across Devils Lake basin. Associated WAA
light snow is pretty spotty attm, however do expect it to become a
bit more widespread across the north as it overcomes the dry air.
Still expecting less than one inch new accumulation. Current grids
well represent current observations and no sig changes planned.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 200 PM CST Thu Feb 3 2022

BOTTOM LINE UP FRONT:

The clippers start coming and they don't stop coming! Once again,
the main story of the period is two clippers, the stronger of 
which will come through Saturday. The first system sweeps through
the area tonight, bringing a swath of light snow with new
accumulations ranging from a dusting to an inch.

A much more potent system swings through on Saturday morning,
lasting through the day. The primary concerns from this system
will be accumulating snow and blowing snow impacts, including the
possibility of whiteout conditions. There is high certainty in at
least accumulating snow across the area, with higher totals likely
along and north of US Highway 2. The severity of blowing snow
impacts is a lot more hard to figure out. Given strong winds,
especially ahead of the system and combined with falling snow, it
appears likely that some blowing snow impacts will arise. Two ends
of the scenario for Saturday are:

Low Impact Scenario: Accumulating snow across the area with some 
gusty winds. Blowing snow impacts are possible at times, 
especially out in open country.

High Impact Scenario: Accumulating snow combines with falling 
snow to create whiteout conditions, primarily in open country. 
Blowing snow impacts are felt where new snow has fallen after 
falling snow ends.

Any scenario in between is also possible. This is a system with a
lot of moving parts to it, so stay updated for future forecasts.

TONIGHT THROUGH FRIDAY NIGHT...

Increasing cloud cover tonight in advance of a shortwave trough is
anticipated. Southerly "warm" (and I mean that in the most
sarcastic way possible) air advection should allow temperatures
to not be nearly as frozen as last night, with lows in the steamy
10 below to 20 below. Unfortunately, this means that wind chills
will persist above advisory criteria through at least tomorrow.
Some signals are there for a brief reprieve, but didn't want to
get too specific with the advisory, so ran it through noon
tomorrow. This will likely need reevaluation for possible
extension, so further updates are anticipated.

Regarding snow chances tonight...weak synoptic forcing over the
area will allow for widespread isentropic ascent. Moisture content
isn't too terribly high, although there is a solid signal for a
dusting to an inch in accumulations across most of the area. At
most, minor impacts to travel are possible.

SATURDAY...

Guidance continues to suggest a stronger clipper sweeping through
the area. Primary impacts for this system will be falling,
accumulating, and blowing snow. The severity of blowing snow
impacts is very uncertain at this time, although the potential for
whiteout is possible, especially Saturday morning.

Regarding Accumulating Snow Potential...Strong synoptic
forcing/warm air advection should facilitate some very solid
widespread snowfall around the low. Accumulating snow does appear
rather likely. NBM probabilities for >0.1" of snow are well above
80% across the central and north parts of the CWA. Probabilities
for >2" are 50% along and north of US Highway 2, approaching near
100% in the Lake of the Woods region. The primary timing for
falling snow will be late Friday evening into Saturday morning as
the clipper sweeps across the area. Deviations in track could
reasonably cause snow totals to change, but for the most part it
appears QPF certainty is rather high.

Regarding Blowing Snow and Blizzard Potential...The Age Old
Question of WFO Grand Forks, our mortal enemy: how much will the
snow blow? There are two facets to winds in association with the
clipper. Leading up to the event, southerly flow will dominate
most of the CWA. 925mb southerly winds look to exceed 30-40 knots,
indicating some potential for gusty southerly winds with the
falling snow. However, ascent will be occurring as this is in the
region of strongest warm air advection, across a baroclinic zone
that will have a tight temperature gradient. This is creating for
a very complicated forecast for blowing snow and blizzard
potential. Three primary uncertainties exist regarding blowing
snow and blizzard potential:

1.) Snow age is rather old, especially further south where
previous clippers struggled to drop snow. On top of that, freezing
rain issues along the western CWA covered a lot of the snowpack
(shown quite well on RGB Satellites). This makes it much more
difficult for snow to blow, leading to low confidence in blowing
snow from the ground. This would mean that the greatest chance for
whiteout conditions would come from falling snow.

2.) The baroclinic zone will have a rather tight temperature
gradient. North and east of the front, temperatures will still be
in the single digits, giving higher potential for blowing snow
impacts. Anywhere south and west of this front will struggle
mightily to get blowing snow and blizzard conditions. This is a
smaller scale issue to pin down, but would have significant
implications in locations of visibility problems.

3.) Winds are a tad marginal in mixing to the surface. Mixing
potential is rather low because of isentropic ascent, so there
really isn't anything to "punch" the heavier winds down to the
surface. Still, 20-25 knots does get us close to high-end advisory
to warning criteria, so something worth watching.

As the clipper moves through, winds will shift to northwest and
temperatures will fall rather rapidly. Unfortunately, to
complicate matters even more, winds are much weaker after the
initial surge of cold air advection. While temperatures will be
rather cold, winds don't look to push a signal for significant
problems, although some blowing snow impacts would be expected,
especially where new snow falls.

.LONG TERM...(Saturday Night through Thursday)
Issued at 200 PM CST Thu Feb 3 2022

Saturday night through Sunday...Reinforcing shortwave will be 
digging through the Northern Plains behind the main upper trough, 
with the surface low pulling off towards the Great Lakes. Surface 
winds will be slowly coming down throughout Saturday night and 
blowing snow impacts will be decreasing. Uncertain how much clearing 
we will get as the system moves off to the east, but think there 
will be enough cold air advection and breaks in the clouds to get 
back below zero Sunday morning. Surface high pressure over the 
region will keep temps cool into the day on Sunday, with readings 
back below average for that day. 

Monday through Thursday...The roller coaster temperatures continue 
into the first part of next week, with upper heights rising Monday 
ahead of the next approaching shortwave on Tuesday. Southerly and 
southwesterly winds will be picking up and there will be good warm 
air advection. After a below zero start Monday morning there should 
be enough mixing and warm air advection to bring temps back above 
seasonal averages. This will continue into Tuesday, and there is 
pretty good confidence in highs getting back into the 30s for that 
afternoon before the cold front comes back into the region. The 
overall ensemble mean seems to indicate that the cold air behind 
Tuesday's shortwave will be less bitter than our previous outbreaks, 
with highs still above seasonal averages for Wednesday and Thursday. 
However, cluster analysis has some signal of a colder pattern and 
box and whisker plots for temps are quite large indicating a lot of 
spread. Temps could remain fairly mild for February or be a bit 
colder than we have going, depending on how exactly the 
northwesterly flow sets up. Uncertainty is high with temperatures as 
well as light precip chances with some weak shortwaves moving 
through. 

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1126 PM CST Thu Feb 3 2022

Surface trough/wind shift has moved into the DVL area and will
continue across the region tonight, entering GFK/FAR around sunset
as winds shift to the northwest. Intermittent MVFR cigs will
continue all sites E of DVL tonight as the light snow continues.
Becoming less confident of IFR cigs as obs upstream seem to be
more ice crystals in the colder airmass across SE Sask/SW
Manitoba, that should work its way into NW MN by mid-morning.
However, currently GAF does show IFR however this appears to be
fairly isolated. So current thinking is predominant MVFR/VFR from
2K to 4K feet with some intermittent IFR in isolated areas. NW
winds tomorrow with improved cigs and vsbys, however some drifting
snow possible with increasing NW winds.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Wind Chill Advisory until noon CST Friday for NDZ006>008-014>016-
     024-026>030-038-039-049-052>054.

MN...Wind Chill Advisory until noon CST Friday for MNZ001>005-007-008-
     013>015-022-027-029-030-040.

$$

UPDATE...Speicher
SHORT TERM...Perroux
LONG TERM...JR
AVIATION...Speicher