Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 272046
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
346 PM CDT SAT AUG 27 2016

.SHORT TERM...(This evening through Tuesday night)
Issued at 239 PM CDT Sat Aug 27 2016

A quasi-zonal upper level flow will bring a couple chances of
thunderstorms to the forecast area through the short term period.

A shortwave trough has moved through the forecast area. This
resulted int thunderstorms over eastern ND this afternoon. But the
thunderstorm threat has ended for the day over western and central
ND. Therefore it should be a dry and quiet night. Shortwave
ridging is already taking place over western ND behind the exiting
shortwave and in advance of another mid-upper level circulation
that is currently dropping southeast over British Columbia.

The aforementioned trough/circulation and its associated surface
reflection will track east across central Alberta/Saskatchewan
through Sunday with a cold front extending south through north
central into southwest North Dakota by 00 UTC Monday. Ahead of the
cold front a warm front will move through the forecast area with
very warm temperatures expected Sunday. Afternoon highs will be
well into the 80s most areas with some lower 90s southwest and
central.

One concern behind the cold front Sunday afternoon will be
possible fire weather hazards. Minimum Humidities in the teens to
lower 20s across all of western ND. Does look like a wind shift to
westerly behind the front with 10 to 20 mph winds. We do mix out
well into the mid levels Sunday afternoon, but even here winds
over the southwest are in the 10 to 15 mph range. They are a
little higher over the west central into northwest ND, but
humidities are not as low as over the southwest. Will pass this
along to the evening shift to monitor as we move into Sunday.

Very unstable conditions are expected across central and eastern
ND Sunday afternoon within the thermal ridge ahead of the cold
front. There are some model differences, especially with regard to
the amount of low level moisture will be advected into the area
ahead of the front. The model consensus at this time is that the
best moisture advection will be east of the forecast area. thus
the best thunderstorm chances remain over the far north central
and into eastern North Dakota. One caveat would be if we could
exceed our current temperature forecast and/or keep a little more
moisture over central ND ahead of the front. This would help to
reduce the cap resulting in a better chance of thunderstorms over
central ND, and the risk of severe storms would also increase
given the increasing instability. Although the bulk shear is
meager at best Sunday afternoon ahead of the cold front. Will
stick close to the previous forecast and current consensus trend
with only slight chance pops over the far north central into the
northern James River Valley.

High pressure builds over the area Sunday night into Monday with
dry and seasonable conditions expected. Upper level ridging builds
on Tuesday ahead of a digging trough over the Pacific Northwest
bringing warming temperatures and another chance of thunderstorms
by Tuesday night.

.LONG TERM...(Wednesday through Saturday)
Issued at 239 PM CDT Sat Aug 27 2016

Warm weather with above seasonal normal temperatures will continue
through the longer term of the forecast, through the middle of the
Labor Day Holiday Weekend. There will be chances for thunderstorms
to start the longer term and then chances, albeit low, again into
that holiday weekend.

Zonal mid level flow at first is interrupted by a deepening trough
off the west coast. This trough acts to allow a ridge to build
downstream, over the Northern Plains. The result is a period near
the middle of the week with very low pops. As the ridge weakens, as
the trough advances, North Dakota comes under increasing southwest
mid level flow. A lee side surface trough brings moist southerly
flow back in with increasing instability and the chances for
scattered storms increasing to end the week and begin the long
weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 239 PM CDT Sat Aug 27 2016

VFR weather with light and variable winds, generally 10 knots or
less, is forecast through the TAF valid period.

&&

.BIS Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...TWH
LONG TERM...JPM
AVIATION...JPM



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