Scientific Forecaster Discussion
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Area forecast discussion...updated
National Weather Service Grand Forks ND
947 PM CST Thu Nov 21 2019
issued at 947 PM CST Thu Nov 21 2019
As surface high pressure continues to build southward, temperatures
have bottomed out for much of the northern valley with locations
in northeast ND dropping briefly into the single digits below
zero. Further east in portions of Minnesota lakes country, cloud cover is
keeping temperatures in the teens with flurries.
Update issued at 655 PM CST Thu Nov 21 2019
Surface high pressure over fresh snow cover across parts of the
Devils Lake basin and portions of northeast ND has caused
temperatures to drop into the single digits under cloud free skies.
Adjusted low temperatures down a few degrees in the coldest
areas, but additional adjustments are possible. Nocturnal
radiational cooling conditions and dew points in the single digits
above and below zero early this evening bring potential for much
of the newly snow covered areas to see temperatures near to below
Short term...(this evening through friday)
issued at 258 PM CST Thu Nov 21 2019
Clearing overnight and how cold we will get will be the main
forecast issues for the period.
The main shortwave trough has shifted off the the east, and high
pressure has been building into central portions of the Dakotas.
There has been some clearing already in the Devils Lake basin and
portions of the far northern Red River valley, but the question is
how much clearing we will get. Most of the high resolution runs
shift the low level moisture further east as the upper system
continues to pull away this evening. The center of the surface
high will be sinking southward overnight, with winds shifting to
the southwest and some pretty good warm air advection kicking in
later tonight. There was a pocket of below zero temps last night
in north central ND with clear skies and new snow, and may have to
watch our northern areas for something similar tonight. We will
not be as calm overnight so did not go that low, but did lower the
blended solution a bit down to the 0 to 5 f range in the northern
Red River valley where there is the best chance for clearing and
before warm air advection starts. Think that temps will bottom out
quickly this evening where it clears out then start rising.
Tomorrow, warm air advection continues with 850mb temps rising
back above zero. There should be a fair amount of sunshine along
with southwest winds favorable for warming, so continued to keep
highs rising into the 30s.
Long term...(friday night through thursday)
issued at 258 PM CST Thu Nov 21 2019
Friday night...a fairly vigorous clipper system will be moving
into the Red River valley. However, it is progressive and there is
good consensus on keeping all the quantitative precipitation forecast up in Canada. The shortwave
will shift winds to the west, and with good mixing for much of the
night lows will stay in the 20s.
The long term period will consist of multiple chances for wintry
weather with a general cooling trend in temperatures.
Saturday through Monday
For the day on Saturday, surface high pressure in the central
rockies will keep westerly flow and milder temperatures in the 30s
to low 40s. However, precipitation chances return for Sunday as a
Canadian low tracks towards the Hudson Bay. With the current track,
the best chances for precipitation will be in the northern half of
eastern North Dakota and northwestern Minnesota. With similar
surface temperatures as on Saturday, warmer air could allow for mix
of rain and snow during the day before becoming all snow that night.
Overall, model guidance suggests light amounts with some ensemble
solutions suggesting amounts of more than 0.10 inches. Continued
shortwave troughing will keep chances for precipitation into Monday
and Monday night.
Tuesday through Thursday
Light precipitation chances continue for Tuesday associated with
500mb shortwaves. With 500mb heights suggested to run 10 to 20 dam
below normal, temperatures look to be colder with precipitation
likely remaining as snow with current model suggestions.
For the end of the long term period, focus will shift towards a
potentially large winter system that could impact Holiday travel in
portions of the Midwest. While confidence is increasing, there is
still a large degree of uncertainty for the location and timing of
this system. However, the current consensus for placement brings an
area of low pressure from The Rockies towards the northern plains to
Great Lakes region during the middle to latter portion of the week.
Uncertainty is still very high with this system, but potential
timing near the Thanksgiving Holiday means that travel impacts could
be of concern.
Aviation...(for the 00z tafs through 00z Friday evening)
issued at 655 PM CST Thu Nov 21 2019
MVFR 1-2kft ceilings and flurries will prevail this evening east of
the Red River valley, mainly affecting bji and areas south and east.
After ceilings advect eastward out of the Red River valley, clear
skies and mostly light and variable winds will prevail through
early Friday morning. Winds will decrease overnight, becoming
light and variable as sfc high pressure moves through. VFR
conditions are expected on Friday with sustained southwest winds
at 10-20 kts and gusts up to 25 kts.