Area Forecast Discussion
Issued by NWS Bismarck, ND

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702
FXUS63 KBIS 230014
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
714 PM CDT Tue Oct 22 2019

.UPDATE...
Issued at 714 PM CDT Tue Oct 22 2019

This evening, a potent midlevel circulation was evident on water
vapor imagery centered over central Montana. Modest warm air
advection within the warm conveyor belt region was responsible for
light rain in our far southwest counties this evening. Further
west, a line of showers and scattered thunderstorms stretched over
eastern Montana along the cold front associated with the
aforementioned low. Steep low level lapse rates in southern
Montana were responsible for efficient momentum transfer and 40-60
mph wind gusts. While RAP guidance keeps the steeper low level
lapse rates (and thus a more favorable strong wind gust
environment) in South Dakota and Wyoming, there is still a
possibility for strong wind gusts accompanying
showers/thunderstorms in the southwest counties in the next couple
hours with current storm motions at around 50 mph.

In the overnight hours, the midlevel low is forecast to move over
a tightening baroclinic zone stretching from around McKenzie
county through Sioux county. A quick burst of snow along this line
of frontogenesis overnight should be enough to produce around 1
to 2 inches of accumulation overnight. Recent RAP runs have been a
little more aggressive with QPF along a very narrow portion of
this band, which may signal locally higher amounts may be possible
where the greatest forcing of this band sets up. While no major
changes were made to the forecast now, this will need to be
watched as high-resolution guidance continues to flow in.

&&

.SHORT TERM...

Clear skies prevail across much of western North Dakota this
afternoon with clouds gradually building in from the southwest late
this afternoon. A rather fast moving H5 shortwave will traverse the
western portions of the CWA tonight, with showers, mixed rain/snow
and even a chance of an isolated thunderstorm. The best chances for
measurable precipitation will occur mainly along and southwest of a
line from Grenora to Linton. Upper limits of precipitation
accumulation will generally be in the 0.25 to 0.50 inch range. Where
we see a transition to snow, accumulations of up to 2 inches are
possible, with the highest accumulations forecast generally along a
corridor that runs from Watford City to Elgin. Although not
widespread, areas where we see stronger convective activity could
see higher snowfall totals up to 3 inches. The Bismarck area is
expected to remain on the eastern side of the system, with lighter
snowfall totals of less than one inch.

Heading into Wednesday morning, light snow will change back over to
rain and persist into the early afternoon. Look for high
temperatures in the 30s to lower 40s. Low temperatures will fall
into the middle to upper 20s Wednesday night into Thursday morning.

.LONG TERM...

We will see a bit of a reprieve in precipitation On Thursday and
Friday before our next system moves into the region. Westerly flow
will allow high temperatures to climb into the 40s for Thursday and
into the 50s to near 60 degrees on Friday. A strong H5 low will move
across southern Alberta and into Manitoba Heading into Saturday
morning. This will facilitate another shortwave passage with an
associated cold front that will dive southeastward out of Canada. We
will likely reach our high temperatures early Saturday, with middle
40s along the International Border to upper 50s in south-central
North Dakota along the South Dakota border. Precipitation is
possible with the frontal passage; however, with rather dry
antecedent conditions and overall lack of available moisture, our
precipitation amounts will be quite low.

Temperatures will fall dramatically following the front, with highs
in the upper 20s to lower 30s Sunday through Tuesday. Lows during
this time will be in the teens and 20s. The 850 mb temps for the
Sunday through Tuesday period will range from -10C to -14C, focused
especially on Sunday morning. A secondary push of cold air follows
the first, with 850 mb temps as cold as -16C per the current
guidance.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 714 PM CDT Tue Oct 22 2019

MVFR, transitioning to IFR, cigs possible for KDIK beginning at
05Z with rain transitioning to snow. Reduced visibilities will
accompany the transition to snow overnight as well. Light snow
possible at KISN and KBIS at 05Z-12Z, though less likely.

&&

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

$$

UPDATE...AE
SHORT TERM...TLynch-FGF
LONG TERM....TLynch-FGF
AVIATION...AE



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