Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 240500

Area Forecast Discussion
National Weather Service Bismarck ND
1200 AM CDT Mon Jul 24 2017

Issued at 1159 PM CDT Sun Jul 23 2017

Latest water vapor imagery shows a mid level shortwave working
through northeast Wyoming and southeast Montana. CAM`s having a
difficult time initializing the convection per Bowman and
regional radar summary. The NAMNest and NMM East are the closest.
With the shortwave forecast to scoot along the ND/SD border 12z to
18z Monday, have blended the above solutions and the GFS, which
shows a slightly more expansive precipitation potential in the
southwest. Strengthening low level jet/850mb underway per SPC
Mesoanalysis. Not expecting anything severe with most unstable
cape under 500 J/Kg, and deep layer shear around 20kt. Rest of
forecast is on track for the rest of the overnight.

UPDATE Issued at 915 PM CDT Sun Jul 23 2017

Current forecast looks good no updates required. Regional radars
showing scattered thunderstorms in northeast Wyoming and water
vapor imagery shows the shortwave tracking close to the new 00Z
NAM position. Current trends look ok.

UPDATE Issued at 544 PM CDT Sun Jul 23 2017

Current forecast keeps clear skies over the region tonight. A
developing lee side trough in eastern Montana along with an
elevated mixed layer (EML) should set the stage for warm
temperatures Monday. A developing low level jet of 45kts below
the EML should provide some low level convergence for elevated
non severe convection during the predawn hours Monday, which will
mix out during the day. Current forecast looks good in this
regard. No updates needed.


.SHORT TERM...(This evening through Monday)
Issued at 329 PM CDT Sun Jul 23 2017

Main concern in the short term are elevated non-severe thunderstorms
late tonight in the far southwest, then isolated chances of
thunderstorms Monday afternoon in parts of western and central
ND...possibly severe.

Currently, surface high pressure was over the eastern Dakotas with
the upper level ridge over the Front Range/western Plains of Canada
and the northern US. Regarding smoke aloft from Montana and Canadian
fires, sat pics and web cams not showing any tangible evidence of
smoke aloft (like we saw yesterday from satellite pics).

Tonight a shortwave in the flow aloft is forecast to move east
across Wyoming and southern Montana this evening, and across SD and
far southern ND late tonight and Monday. Expect isolated elevated
thunderstorms associated with this feature in ND.

More concerning is a cold front moving into western ND Monday
afternoon. This feature is associated with a stacked low pressure
system moving from central Alberta eastward into central
Saskatchewan. A low level jet is forecast to develop up the US
Plains well northward into central Canada. Most of the energy with
this system should reside in Canada, but enough instability with
projected CAPE values over 2000 J/Kg along the surface cold front
for SPC to continue a marginal risk for severe storms over ND. Thus
at this time isolated storms - possibly severe - over
western/central ND mid-afternoon and becoming a bit more numerous in
central/eastern ND Monday evening. Best chances of precipitation
over north central ND during the evening.

Along and ahead of the cold front we expect temperatures to climb
into the 90s across western and most of central ND, with upper 90s
in the southwest.

.LONG TERM...(Monday night through Sunday)
Issued at 329 PM CDT Sun Jul 23 2017

Monday night into early Tuesday morning thunderstorms may linger in
parts of south central ND into the eastern part of the state as an
upper level impulse moves across the ND/SD border Monday
night/Tuesday in the wake of the surface cold front.

The strong low pressure system continues moving east across
central/northern Manitoba into Ontario Tuesday/Tuesday night.
This will bring a dry day to western and central ND Tuesday with
westerly winds behind the cold front. Not confident regarding
strength of winds or how low relative humidity values will be
Tuesday...but this will need to be monitored for possible fire
weather concerns.

Upper level ridging builds again over the Rockies. Some shortwaves
move through the flow from time to time, bringing some slight
chances for showers/thunderstorms Thursday. Looking at seasonable
temperatures Tuesday through next weekend with highs mainly in the


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1159 PM CDT Sun Jul 23 2017

A cold front will slide into northwestern ND between 18z and 21x
Monday, then shift southeast Monday night, reaching KJMS between
09z-12z Tuesday. High confidence in thunderstorms developing at
KMOT between 02z-06z Tuesday. Thunderstorms could be severe with
large hail and damaging winds. Much less confidence with thunderstorms
at KDIK/KBIS, and for now, have mentioned a VCTS at KDIK from 23z
Monday through 02Z Tuesday. Expect winds shifting from south to
west, and eventually northwest as the front pushes through. Vfr
cigs/vsbys outside of any thunderstorm activity.




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