Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 242217
AFDBIS

AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
517 PM CDT TUE MAY 24 2016

.UPDATE...
Issued at 517 PM CDT Tue May 24 2016

Quick update to expand/move up the chance of showers over western
ND from now through the early evening in response to the showers
developing out of the cumulus field in southwestern ND through 22
UTC. We have a slight chance of thunderstorms expanding northward
with time, too, but so far the dry boundary layer is tending to
minimize instability, updraft depth, and thus lightning chances.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 240 PM CDT Tue May 24 2016

Thunderstorm chances highlight the short term.

An upper level low currently located over southern Saskatchewan
will keep the region in southwest cyclonic flow. Most of western
and central North Dakota will remain dry through the afternoon,
but precipitation chances will increase through the late afternoon
and evening hours from west to east as a surface trough and
associated upper level short wave approaches from Montana.

Tonight, showers and some thunderstorms will develop in the
southwest and spread east overnight. Any thunderstorms that
develop will remain sub severe with modest CAPE and shear
forecast.

Wednesday, a more potent shortwave and surface low will approach
the Dakotas as the upper low approaches, bringing widespread rain
and scattered thunderstorms. The 12z NAM and GFS iterations show
more instability than previously forecast. If these solutions were
to verify, potentially anywhere from 1000 J/KG to 2500 J/KG of
MLCAPE will be in place by 21z, along a line from near Bismarck to
Jamestown and south to the state border. This instability will be
collocated with deep layer shear values of 25-35 knots. These
parameters would suggest a conditional severe weather threat in
south central and southeast North Dakota. However, quite a bit of
uncertainty remains about how much destabilization will actually
occur. Widespread precipitation is likely over the area early
Wednesday, potentially limiting daytime heating. If we can get
some breaks in the clouds, then some storms could produce some
marginally severe hail and winds. SPC has placed parts of south
central and southeastern North Dakota in a marginal risk of severe
weather, which matches up well with our current thinking. Clusters
of multicell or marginal supercell structures seem to be the most
likely storm modes.

Overnight Wednesday, rain chances will continue on the back side
of the surface low.

.LONG TERM...(Thursday through Tuesday)
Issued at 240 PM CDT Tue May 24 2016

Persistant southwesterly flow remains through the period with a
variety of short waves sliding through the area. Models are having
a tough time timing out the individual waves, so most periods will
have a broad-brushed chance for showers and thunderstorms.
Temperatures will remain near to slightly above average.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1242 PM CDT Tue May 24 2016

VFR conditions and generally light southwest winds will dominate
the first part of the forecast period. As we turn to late
afternoon and the early evening hours...chances of showers and
thunderstorms will begin to increase from west to east and
continue through the overnight hours and Wednesday. Periods of
MVFR ceilings/visibilities and gustier winds can be expected in
heavier showers or thunderstorms.

&&

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

$$

UPDATE...CJS
SHORT TERM...ZH
LONG TERM...JJS
AVIATION...ZH



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