Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 290831

Area Forecast Discussion
National Weather Service Bismarck ND
331 AM CDT Sat Jul 29 2017

.SHORT TERM...(Today and tonight)
Issued at 328 AM CDT Sat Jul 29 2017

Currently, an upper level ridge over the Rockies had flattened with
a large shortwave moving east across northern/central Canada. A
trailing surface cold front extended from near Hudson Bay
southwestward across Manitoba and to the border of
Saskatchewan/Montana/North Dakota. A weaker upper level shortwave
was also in the flow over the intermountain west near
Idaho/Montana/Wyoming early this morning. Broad surface low pressure
remained over the eastern Rockies and Front Range.

A few isolated thunderstorms in southeastern Saskatchewan
developed in the past hour or so...and put a slight chance mention
in far northwestern ND before sunrise. This convection is likely
associated with the aforementioned trailing cold front across
northern/central Canada.

A cluster of upper level impulses associated with the intermountain
west shortwave were over western/central Wyoming/Montana early this
morning, and are forecast to move east today, entering the western
Dakotas this afternoon and expanding across the Dakotas tonight. The
lingering Canadian cold front is forecast to stall over southern
Manitoba/northwestern ND, and diminish/wash out with time by this
evening. There will be an increasing chance of shower and
thunderstorm development this afternoon across western and central
North Dakota associated with these surface and upper level features.

Enough lower level moisture for decent MU CAPE values around 2500
J/Kg this afternoon, but 0-6km bulk shear is weak. Thus good
potential for thunderstorms, but not expecting much in the way of
severe storms. SPC has western and central ND in the "general"
category for thunderstorms - meaning not in the marginal or slight
risk for severe storms today.

Another warm day today with highs from the mid 80s to lower 90s, and
lows tonight again in the 60s.

.LONG TERM...(Sunday through Friday)
Issued at 328 AM CDT Sat Jul 29 2017

Daily chances for showers and thunderstorms exist through mid-week.
An upper level ridge to the west will keep North Dakota firmly
entrenched in northwest flow, leading to frequent upper level waves
moving overhead. While this ridge remains west we will see a fairly
stagnant pattern with temperatures in the 80s/90s each day and
isolated to scattered showers and thunderstorms.

On Sunday the models are not forecasting much in the way of forcing
for shower or thunderstorm development. Plenty of low level moisture
with dewpoints in the 60s over much of western and central ND but
not seeing much in the way of upper level impulses or steep mid-
level lapse rates. Model consensus still yielded a slight chance
mention of thunderstorms southwest and south central.

On Monday a cold front moves into northwestern North Dakota in the
afternoon, reaching a Minot-to-Bowman line by evening, then making
its way south and east overnight. This front and associated upper
level impulses will be the focus for scattered showers and
thunderstorms - mainly across central and southwestern North Dakota
Monday afternoon/night. Forecast CAPE values above 2000 J/kg will be
present, but with low 0-6km bulk shear. However, shear values
increase in the vicinity of the front over north central ND and into
Manitoba by late afternoon/evening. SPC has placed north central and
northeastern ND in a "marginal" risk for severe storms on Monday.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1230 AM CDT Sat Jul 29 2017

A few showers and and a couple isolated lightning strikes have
entered the northwestern part of North Dakota and may impact KISN
over the next couple of hours. Convective trends have been
diminishing but lightning flashes have continued to be observed. For
tomorrow, more numerous scattered showers and thunderstorms will
develop along a line roughly from near KDIK to KMOT and gradually
move east, potentially reaching KBIS. For now, elected to leave KBIS
with a VCSH by the evening. Otherwise, VFR conditions are expected
through the TAF period with generally light and variable winds.




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