Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 242308

Area Forecast Discussion
National Weather Service Bismarck ND
608 PM CDT Mon Jul 24 2017

Issued at 601 PM CDT Mon Jul 24 2017

Showers and isolated thunderstorms are forming along the advancing
cold front in western North Dakota at this time. Current forecast
has the location pretty well defined but will add some 20-30 POPs
to account for what may become a line of showers and scattered
thunderstorms in west central North Dakota. Otherwise current
forecast looks good.


.SHORT TERM...(This evening through Tuesday)
Issued at 237 PM CDT Mon Jul 24 2017

A compact upper level shortwave trough was noted on water vapor
imagery over south central North Dakota, sparking some showers and
isolated thunderstorms near the South Dakota border over the
south central and James River Valley. As this circulation moves
east, clouds will begin to dissipate with rapidly warming
temperatures in it`s wake. Additionally, a closed upper low
located near the central Alberta Saskatchewan border will push
another shortwave towards North Dakota late this afternoon and

At the surface, a cold front was moving through northwestern North
Dakota, extending from a surface low over central Saskatchewan.
This cold front will be the focus for isolated to scattered
showers and thunderstorms later this afternoon and evening, some
of which may become severe. The main question with regards to
thunderstorms will be coverage. Strong capping was noted on the
12z Bismarck sounding with an 850mb temperature near 21 degrees
Celsius. Early morning cloud cover may also limit high temperature
potential in the south and we may struggle to reach our
convective temperature of 95 degrees Fahrenheit here in Bismarck.

The better chance for thunderstorms appears to be over the north,
initiating in the 21 to 23z time frame from just west of Minot to
the international border. It should be noted that there is
disagreement in the high resolution models. The operational HRRR
has kept any convection relegated to the very northern tier of
our counties for numerous runs, while the 12z NAM nest and
experimental HRRR initiate storms much further south. At this
time, the best guess is somewhere in between and have tried to
reflect that in the precipitation chances. The 18z RAP shows a
narrow corridor of MLCAPE approaching 2000+ J/kg along and ahead
of the front co-located with 35 to 40 knots of 0-6km shear.
Therefore, if any thunderstorms can break the cap, there will be
a chance for some high based supercells. Large hail and damaging
winds would be the greatest threats.

The cold front continues to sweep southeast overnight. Tuesday
will see cooler high temperatures for most of the forecast area,
with another chance for a strong to severe storm across our far
southeast in the afternoon along the front.

.LONG TERM...(Tuesday night through Monday)
Issued at 237 PM CDT Mon Jul 24 2017

Precipitation chances will fade by Tuesday night and Wednesday and
Thursday should remain dry as upper level ridging once again
builds to the west placing North Dakota in northwest flow aloft.
As the ridge moves east, return flow sets back in as does a slight
chance of showers and thunderstorms on Thursday. Over the
weekend, ridging builds once again, increasing temperatures with
only slight chances of periodic hit and miss thunderstorms.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 601 PM CDT Mon Jul 24 2017

At 6 PM CDT a cold front extended across northwest into west
central North Dakota. The front will move east and will be the
focus for showers and scattered thunderstorms tonight which will
be the main hazard to aviation. VFR is forecast for all TAF
sites. Low confidence in timing and location of thunderstorms so
have used VCTS at KDIK only this evening.




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