Area Forecast Discussion
Issued by NWS Bismarck, ND

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893
FXUS63 KBIS 180026
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
626 PM CST Tue Jan 17 2017

.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
period.

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 00Z TAFS through 00Z Wednesday evening)
Issued at 626 PM CST Tue Jan 17 2017

VFR at all TAF sites through the TAF period.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...AJ
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...AJ



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