Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 200440

Area Forecast Discussion
National Weather Service Bismarck ND
1140 PM CDT Mon Sep 19 2016

Issued at 1140 PM CDT Mon Sep 19 2016

Latest regional radar shows showers and isolated thunderstorms
continuing to develop in southeast MT, lining up with an 850-700mb
frontogenesis region. Per latest NAM, frontogenetical forcing will
translate east overnight, shifting from southwest into south central
06z-13z, and into the James River Valley by 13z-16z Tuesday. The
HRRR details the highest reflectivitys commencing during this time.
Current pops are in good shape, generally following the current
HRRR model from previous discussion. No significant changes in
this update.

UPDATE Issued at 938 PM CDT Mon Sep 19 2016

The 22-01 UTC HRRR and ESRL HRRR, and the 18 UTC NAM NEST
continue to depict elevated convective development generally
along and south of US Highway 2 late tonight into Tuesday morning.
This is in association with a weak impulse aloft and low level
warm air advection via a strengthening low level jet east of a
surface low across western South Dakota and Nebraska. Given steep
lapse rates aloft, thunderstorms are possible. The aforementioned
HRRRs have hinted at possibly organized convection in their
updraft helicity fields given the very high deep layer shear with
the jet aloft.

UPDATE Issued at 631 PM CDT Mon Sep 19 2016

The forecast for the remainder of the night remains on track and
was blended to observed trends through 23 UTC. A similar overnight
is expected tonight as was last night with a chance for showers
across the south with a weak impulse embedded in the fast flow
aloft. Given steep mid level lapse rates, did add a slight chance
mention for thunderstorms. Severe weather is not expected.


.SHORT TERM...(This evening through Tuesday)
Issued at 224 PM CDT Mon Sep 19 2016

Forecast concern through the short term will be chance for
showers across the south associated with a weak shortwave trough.

In the wake of the low that moved across the northern plains on
Sunday, high pressure was the dominant feature today bringing
mostly sunny skies. As the pressure gradient lessens the winds
across the north have also diminished so no wind advisory was
considered for this afternoon.

Relative humidity this afternoon has fallen to around 20 percent
across the southwest but winds not expected much above 15 mph with
some gusts in the lower 20s.

Tonight, a weak shortwave with move across the southern portion of
the state bringing a chance showers to the southern third of the
state. considered adding some isolated thunderstorms but cape is
pretty meager so kept only showers.

On Tuesday the will return to partly to mostly sunny skies as the
shortwave trough moves east. Highs tuesday again in the 70s.

.LONG TERM...(Tuesday night through Monday)
Issued at 224 PM CDT Mon Sep 19 2016

The extended period will be feature a significant upper level low
forecast to move from the Great Basin northeast into the northern
plains by Saturday. This will bring a good chance for showers to
the western portion of the forecast area.

Tuesday night and Wednesday, as the upper flow begins to back to
the southwest, will bring the opportunity for some shortwave
energy to support scattered showers. Once again the instability
remains slight so have limited the chance for thunderstorms to
slight and that across the south.

Thursday and Friday will see increasing chances for showers
across the west as the upper low approaches. The GEFS
climatological QPF supports the best rainfall across Montana with
some in western North Dakota with this weather pattern. This
would tend to support the GFS solution over the ECMWF for best
chances for precipitation across western North Dakota Thursday
night though Saturday. Again the instability appears to slim for
Thursday and wait until Friday and saturday to add chance for

As the upper low lifts out on Sunday the precipitation will trail


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1140 PM CDT Mon Sep 19 2016

A vcsh has been included at KDIK/KBIS until around 12z Tuesday,
with a VCTS at KJMS from 13z-17z Tuesday. Although vfr cigs and
vsbys expected through 06z Wednesday, bkn mid level clouds will
impact all terminals through Tuesday morning before scattered
conditions are once again realized. Winds will generally remain
light and northeasterly.




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