Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 260641
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1241 AM CST Sun Feb 26 2017

.UPDATE...
Issued at 1233 AM CST Sun Feb 26 2017

Snow is exiting the region so have ended the chances for snow
east central faster than earlier forecast. Also getting some fog
along the edge of the cold air in clearing skies northwest. Put
patchy fog there. Lowered min temperatures to around 5 below north
central.

UPDATE Issued at 928 PM CST Sat Feb 25 2017

Very little change with this forecast update other than to blend
to observed trends through 03 UTC as the band of moderate to heavy
snow across north central North Dakota will continue to propagate
into the upper James River Valley as the upper level shortwave
propagates southeast.

UPDATE Issued at 537 PM CST Sat Feb 25 2017

The 15-18 UTC global suites match well with observed trends
through 2330 UTC with a band of moderate to at times heavy snow
along the US Highway 2 corridor of northwest and north central
North Dakota. Accumulations of 2 to 4 inches are still favored
with this band. Across the southwest, convective snow showers at
times significantly reducing visibility have been a bit better
handled by the CAMs through their 22 UTC iterations. Based on
their trends, expanded higher PoPs into south central North
Dakota through this evening with steep mid level lapse rates ahead
of the shortwave.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 246 PM CST Sat Feb 25 2017

Highlights in the short term period are: first, a period of
moderate to heavy snowfall northwest, north central, and into the
northern James River Valley this afternoon into tonight. A Special
Weather Statement has been issued informing the public of between
2 and 4 inches of snowfall expected. Secondly, ice jam impacts
remain possible along the Yellowstone River and the Missouri River
upstream of Williston. Continued to advertise this in a Hydrologic
outlook. Please see the Hydro discussion below for further details.

High resolution models as well as the NAM/GFS/ECMWF indicative in
a period of moderate to heavy band of snow developing northwest
this afternoon, then progressing southeast into the northern James
River Valley tonight. Latest water vapor imagery shows a shortwave
trough into southeast Saskatchewan and northwest North Dakota.
Radar and surface observations show light snow northwest into portions
of north central, with 3hr pressure falls maximized in northeastern
Montana. Baroclinic zone/frontal boundary extends from northeast
Montana into southern North Dakota. Expect snowfall to increase in
intensity as a surface low pressure develops and deepens in response
to increased frontogenetical forcing aligning with synoptic scale
ascent across northwest into north central. With mid level lapse
rates around 6.5C/Km and the approach of a 70kt jet streak/left
exit region riding atop, expect a deeper/stronger circulation to
evolve, leading to period of moderate to heavy banded snow. Thus,
have strongly followed the higher resolution models on POPS and
QPF this afternoon into tonight resulting in a snowfall swath of
between 2 and 4 inches from northwest, north central, and into the
northern James River Valley. In addition, followed the previous
shifts idea of increased winds resulting in patchy blowing snow. A
3hr pressure bubble rise continues per GFS which comes in behind
the surface low this evening and overnight. Expect the snow/wind
to taper off tonight from northwest to southeast.

Another shortwave/weak clipper system swings through Sunday afternoon
and evening with a chance of snow northwest and north central. Snowfall
accumulations are light, a couple tenths of an inch.

.LONG TERM...(Sunday night through Saturday)
Issued at 246 PM CST Sat Feb 25 2017

Northwest flow aloft dominates through Thursday resulting in below
normal high temperatures and near daily chances for light snow as
several weak clipper systems slide through. At this time, nothing
significant in terms of precipitation is expected. The upper flow
becomes zonal but remains progressive Friday into next weekend.
This results in moderating temperatures with normal to above
normal highs Friday and Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1233 AM CST Sun Feb 26 2017

Surface high pressure across Manitoba will move southeast today.
Surface low pressure across southwest Saskatchewan will also
track southeast. MVFR conditions due to clouds will be prevalent
from KISN-KDIK-KBIS-KJMS with VFR expected at KMOT.

&&

.HYDROLOGY...
Issued at 246 PM CST Sat Feb 25 2017

Occasional ice jams due to ice breaking up continue along the
Yellowstone River in eastern Montana. River rises will be
possible on the Yellowstone in North Dakota from Fairview,
downstream to the Missouri River near Buford when ice jams
release. Ice affected rises may also be possible along the
Missouri River from the Yellowstone downstream to Trenton and
Williston. Those with interests along the Yellowstone and Missouri
Rivers near the Montana border should be prepared for the
possibility of rising river levels.

&&

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

$$

UPDATE...WAA
SHORT TERM...KS
LONG TERM...KS
AVIATION...WAA
HYDROLOGY...JJS


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