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Area forecast discussion
National Weather Service Grand Forks ND
653 am CST Wed Dec 11 2019

Update...
issued at 645 am CST Wed Dec 11 2019

Temperatures remain firmly into the teens and twenties below zero
with wind chills continuing into the twenties and thirties below
zero. There continues to be a breeze out of the west near the
western Red River valley contributing to the frigid wind chills.
This will be the case through mid morning before getting into the
single digits below zero by midday. The sun will great US this
morning with clear skies above the Arctic high passing through.
Gradual warming continues through the afternoon and evening as
cloud cover increases and warm air advection starts ahead of tonight's clipper
system.

&&

Short term...(today through thursday)
issued at 312 am CST Wed Dec 11 2019

Main highlights today through Thursday include cold conditions
followed by a chance for light snow.

Surface high pressure housing an Arctic air mass slides southeast
through the northern plains today. Air temperatures will largely
stay in the teens to twenties below zero through the morning.
Coldest observed temperature as of 3:30 am is -31 f at kbdr in
southeast Hubbard County, Minnesota, and is collocated within a
clear air local minima of sensed infrared temperatures by GOES-16. A
westerly breeze of 5-15 mph still remains mainly north of I-94,
highest along the western Red River valley. While "warmer" here,
elevated winds are contributing to wind chills well into the
negative 30s. Elsewhere where it is not as breezy, very cold
air temperatures are still contributing to wind chills into the
negative 20s. These conditions will continue through the morning
before air temperatures begin to rise as the surface high moves
southeast of the area and low level warm air advection begins. Letting the Wind
Chill Advisory expire at noon still looks appropriate, and should
mark the end of wind chill concerns until perhaps this weekend.

Clear skies this morning will give way to increasing clouds from
the southwest. This comes ahead of the next clipper to move
through from the northwest tonight. This clipper is expected to
bring light snow to the area tonight into early Thursday. Dry air
associated with the Arctic air mass ahead of the clipper will have
to be overcome and is noted by top down column saturation in
forecast soundings. This leads the belief that radar returns will
start to show this afternoon into eastern ND, however likely will
initially be virga. The column eventually does saturate given the
persistent synoptic forcing and gradual moisture advection. There
continues to be a signature for fgen in the h9-7 layer, however
this looks to outpace the clipper and saturation. There could be
some banding show up on radar, but snow will not make it to the
ground until perhaps the backside of the band just when it should
move away.

Synoptic forcing will drive the majority of snowfall production,
and indeed the column is largely within the dgz. However forcing
will be on the weak side along with meager moisture availability.
Therefore light amounts of snow between 1-3 inches are expected.
Currently the majority of snow will fall along and south of the
US Hwy 2 corridor. Best chances for seeing higher end amounts
resides near the I-94 corridor. Given the lack of fgen, don't
think any "surprise" higher amounts are likely. Snow enters
western forecast area around 6 PM today, and exits the eastern forecast area around 6
am Thursday. Winds look to be relatively light with this system.

The rest of Thursday will be briefly quiet with light winds and
highs generally (and finally) above zero. This comes ahead of the
next clipper expected to move into the area Thursday night.
Details on that system are in the long term discussion.

Long term...(thursday night through tuesday)
issued at 312 am CST Wed Dec 11 2019

Main impacts for the period will be with snow Thursday night into
Friday.

Thursday night and Friday...there is good agreement on a fairly
vigorous shortwave clipper moving through for the end of the work
week. The 700mb low tracks just to the north of the international
border and there is only some weak mid-level frontogenesis with the
system. On the other hand, the shortwave is pretty potent and some
negative epv is available for mesoscale enhancement. Will continue
the trend of bumping up precip amounts a bit from the blended
solution. Will not pinpoint the location of any banding potential at
this time but hopefully get a general idea of several inches of snow
possible. Cold air advection coming in behind the surface low on
Friday will also kick winds up. Blowing snow model has the potential
for some patchy blowing snow west of the rrv, and it seems
reasonable to include at this point.

Saturday through Tuesday...another cold snap comes down behind the
clipper for the weekend, with temps again close to or below the zero
mark for highs. There is some indication of a weak shortwave moving
through on Monday, but pretty quick moving so will keep things dry
for now. Northwesterly flow for Tuesday, but differences in the
position of the Hudson Bay low and therefore heights over the
northern plains abound. There is not any strong signal in the
ensemble percentile plots for either temperature or precip, so will
keep dry and cold forecast that the blend gives US. Temps will be a
bit higher than the weekend with highs getting above zero, but still
well below seasonal averages.

&&

Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 645 am CST Wed Dec 11 2019

VFR and region-wide sky clear with light winds will dominate the taf
through 18-21 UTC. It is quite cold however with temperatures in
the teens to twenties below zero. Light snow is expected to move
through the region around 00 UTC this evening dropping cigs to IFR
and reducing visibility to around 1-3 sm. Snow moves out of the
area 06-09 UTC Thursday morning with lingering lowered cigs.

&&

Fgf watches/warnings/advisories...
ND...Wind Chill Advisory until noon CST today for ndz006>008-014>016-
024-026>030-038-039-049-052>054.

Minnesota...Wind Chill Advisory until noon CST today for mnz001>009-013>017-
022>024-027>032-040.

&&

$$

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