Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 262024
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
324 PM CDT TUE JUL 26 2016

.SHORT TERM...(This evening through Wednesday)
Issued at 325 PM CDT Tue Jul 26 2016

The main forecast issue in the short term period will be
thunderstorm chances and the potential for severe storms.

Currently, low pressure is situated over north central South
Dakota with high pressure over Saskatchewan and nosing into
northwest North Dakota. In the mid and upper levels northern
portions of the forecast area are within the right entrance region
of a strong upper level jet situated over southern Manitoba and
Ontario. Numerous impulses also continue to track across the
Rockies and into the northern plains within a quasi-zonal upper
level flow. Thus we remain slightly to moderately unstable across
the forecast area. Meager low level lapse rates over areas of
morning convection and low mid level lapse rates and lack of bulk
shear across the north are the limiting factors. An axis of high
pwats extends from south central into northwest ND so any storms
that do develop will have the potential to produce very heavy
rainfall. And a severe storm can not be completely ruled out
either.

Short term models are not completely out of line but are having a
hard time pinpointing convection this afternoon. Will likely
utilize a blend of short term models with current forecast pops to
depict isolated to scattered convection across the north and over
the south central this afternoon with overall trend in convection
sliding south. Medium range models as well as short term models
are pointing to convection tonight along the ND/SD border and
southward as a couple of shortwaves move across the northern
rockies and into the plains. Thus have trended pops down across
the north this evening, and higher across the far south central
into the James River Valley from mid to late evening.

Late tonight and through Wednesday surface high pressure builds
over the eastern Dakotas which pushes the instability axis sitting
along the ND/SD border, west into the western dakotas and eastern
Montana. Shower and thunderstorm activity will be suppressed to
only western ND. Highs are expected to be mainly in the 70s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 325 PM CDT Tue Jul 26 2016

Wednesday night through Friday, surface high pressure moves
slowly east across the forecast area with building upper level
ridging over the region downstream of a digging upper trough
moving onto the British Columbia coast. This will keep shower and
thunderstorm activity mostly confined to western ND. Morning lows
will be in the mid 50s to lower 60s with daytime highs in the mid
70s to mid 80s.

Upper ridging remains over the area through the weekend but upper
flow backs and thermal ridging pushes into western ND. Daytime
highs will climb back into the 80s to lower 90s with increasing
humidity as low level flow turns southerly ahead of lee side
troughing in the northern rockies. We likely become unstable each
afternoon but probably with some capping issues. Overnight
convection can not be ruled out either. But in general, with
upper ridging still over the area, our current slight chance pops
look reasonable for now.

Late Sunday night through monday, the upper low to our north
pushes a cold front through the area, with another upper trough
trailing the first, providing a chance of thunderstorms into
Tuesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 325 PM CDT Tue Jul 26 2016

There is low confidence on when a shower/thunderstorm will impact
any one terminal through the TAF period. However the best chances
appear to be at KBIS/KJMS today. KMOT may remain completely dry, but
a few short-range models are depicting showers/thunderstorms moving
into the KMOT terminal later today, so put a mention of vicinity
thunderstorms in the TAF.


&&

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

$$

SHORT TERM...TWH
LONG TERM...TWH
AVIATION...AJ


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