Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 180624

Area Forecast Discussion
National Weather Service Bismarck ND
1224 AM CST Wed Jan 18 2017

Issued at 1223 AM CST Wed Jan 18 2017

Surface winds across western and central ND were ranging from
southwest/west 5 to 20 mph. Only a few hundred feet above the
surface, stronger west winds of 35-45 mph were present. At times,
some of the higher elevation areas...mainly in southwestern ND or
along the Coteau ridge...were reporting west winds gusting to 30 mph
or more. This was creating some areas of drifting snow, and, in
turn, slippery conditions on roadways. The varying nature of the
wind speeds were also affecting surface temperatures...thus some
areas may dip down into the teens this morning, while other areas
may remain in the upper 20s to even lower 30s for much of the
overnight hours. Needless to say, trying to predict hourly
temperatures and overnight lows this morning is problematic.

UPDATE Issued at 950 PM CST Tue Jan 17 2017

Minor update to temperatures overnight. Temperatures are not
falling as earlier expected. Southwest winds and some mid/high
clouds are aiding in keeping temperatures mild this evening.

UPDATE Issued at 626 PM CST Tue Jan 17 2017

No major changes required for this update.


.SHORT TERM...(This evening through Wednesday)
Issued at 203 PM CST Tue Jan 17 2017

Temperatures continue to be the main problem in the short term

Currently, temperatures have risen into the mid 20s to lower 30s
across most of western and central ND. Winds were generally west
southwest 10 to 20 mph.

Tonight and Wednesday...We again leaned toward the cooler side of
guidance for lows tonight and highs on Wednesday. Did not go
quite as cold as some of the guidance tonight with our warm
temperatures aloft and enough of a gradient to keep winds in the 5
to 10 mph range. However, some of the guidance keeps overnight
lows just a bit cooler than we are right now. Some areas that keep
a little wind overnight may not see temperatures drop much, while
we think it`s wise to allow for at least a little bit of drop
over our consistently cooler areas over the far south central and
usual low spots.

To illustrate how much of a role our snowpack is playing for our
forecast highs, temperatures aloft from 85h to 50h are some of the
warmest we`ve seen for this time of the year, based on a 30 year
climatology from 1979 to 2009. NAM numerical guidance for
Dickinson, Bismarck and Minot are all within 5 degrees of record
highs. However, we are forecasting mid to upper 30s across most of
the forecast area. Since our snowpack is still fairly uniformly
deep across the forecast area, we feel pretty confident in
undercutting model guidance across the forecast area. A recent
study also indicates that at Bismarck, it`s awfully hard to get
much higher than 40 degrees with such a deep snowpack.

One possible fly in the ointment will be possible fog/stratus
issues once we start to melt some of this snow. Think melting
today will be minimal most areas and there will be a strong enough
gradient tonight as well to help keep fog from developing.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 203 PM CST Tue Jan 17 2017

Mild conditions continue Wednesday night and Thursday. Generally
accepted forecast highs Thursday, a bit cooler than tomorrow, but
depending on how warm we get tomorrow, we may need to drop these.
We did undercut lows a bit Wednesday night as surface gradient
over the area begins to relax. With light flow over the area
Wednesday night, may see some increased potential for fog as we
begin to melt some of our snowpack. Will hold off for now but
something later shifts may want to look at fog potential.

Expect increasing low level moisture from the south beginning
Wednesday night, with more widespread fog/stratus spreading west
and north across the forecast area late Thursday night and Friday.
This is when we also start to see mid level forcing lift
northward into the forecast area, as a blocking high remains to
our east. The first impulses are pretty weak and we are quite dry
above our nearly saturated lowest levels. Any precipitation is
expected to be very light but will need to monitor precipitation
type. Looking at temperatures aloft we would expect
drizzle/freezing drizzle or light rain/freezing rain. However, an
examination of wetbulb temperatures aloft would be much more
likely to yield rain or snow, depending upon the surface
temperature. At this time will keep a mention of just rain/snow as
wetbulb temperatures aloft typically work better than
temperatures with such a dry area aloft.

As we move into Saturday and Sunday our overall temperature
profile cools and we turn to just a chance of light snow. We
continue to remain on the cool side of the westerlies into early
next week. However any Arctic air remains well north of the area.
A couple of stronger upper level systems track across the
continental U.S. but at this time they track more across the
central and southern plains.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1223 AM CST Wed Jan 18 2017

VFR at all TAF sites through the TAF period. Surface winds mainly
southwesterly at 5 to 15 knots...however there is a strong westerly
wind field beginning only a few hundred feet off the surface -
around 35-40knots. Therefore added low level wind shear at TAF sites
until later this morning or by around 18z when forecast winds aloft
at that time suggest winds aloft not as strong. At times the strong
winds aloft may break through to the surface, creating strong gusty
surface winds. Some areas of southwestern ND experiencing drifting
snow with the stronger gusts and may affect runways.




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