Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 260833

Area Forecast Discussion
National Weather Service Bismarck ND
333 AM CDT Mon Jun 26 2017

.SHORT TERM...(Today and tonight)
Issued at 333 AM CDT Mon Jun 26 2017

Tranquil and pleasant conditions in the short term period. Surface
high pressure over the James River Valley early this morning will
nudge farther southeast today. Expect a sunny sky along with
light southerly winds/warm air advection. High temperatures will
reach into the 70s this afternoon, with around 80F along the
western border. Used the experimental HRRR for Min RH today which
best captured the expectations of relative humidities in the mid
teens this afternoon across southwest ND. Aloft, a mid to upper
level ridge axis/700-500mb, will crest the western border shortly
after 00z Tuesday. Low level southerly winds and warm air advection
increase overnight, out ahead of a developing surface low and
attending cold front in eastern Montana. It will remain precipitation
free through the short term period, with overnight lows tonight in
the upper 40s southern James River Valley to upper 50s in the west.

.LONG TERM...(Tuesday through Sunday)
Issued at 333 AM CDT Mon Jun 26 2017

A brief/significant warmup into the lower 90s southwest and south
central ND Tuesday, followed by isolated severe thunderstorms
central ND Tuesday evening/night. Thereafter, unsettled weather
continues through the weekend.

A deepening mid level trough and strengthening surface low
pressure/attending cold front in eastern Montana Tuesday morning,
will scoot into southwest ND 00z Wednesday, then into south
central ND 06z Wednesday. An 850mb thermal ridge with temperatures
between +22C and +28C will result in afternoon highs in the lower
90s southwest into south central ND. Followed the mean 2meter
Temperature GEFS Plumes, which are higher than the operational
GFS, and most other statistical guidance. Expectations are for
high temperatures in the lower 90s from Dickinson to Bismarck.
BUFKIT soundings show increasing high level moisture(above 20kft)
late in the afternoon, but unless a thick cirrus canopy develops
and slides over southern ND, believe at this time we will be able
to achieve highs in the lower 90s given max solar strength,and
somewhat modest surface moisture, with dewpoints in the upper 50s
to lower 60s. Per KBIS Tuesday afternoon sounding, a vigorous
EML/Elevated Mixed Layer (700mb-500mb) with absolutely unstable lapse
rates of 9.5C/km will be located above a strong capping inversion
(800mb-700mb). As cooling aloft commences with the approach of
the mid level shortwave mentioned above, the inversion weakens,
allowing for a breaking point to occur right around 00z. Fully
expect a quick upscale growth in thunderstorms/and severe weather
mostly south central ND, peaking between 00z-03z, as a narrow
corridor of moderate instability per ML Cape/mixed layer Cape of
around 2200 J/kg is just ahead of the surface cold front. 0-6m
Bulk Shear will be on the increase from around 25kt at 00z to 40kt
by 03z in south central ND. Main threats will be large hail and
strong winds. Hail Cape around 800 J/kg and freezing levels
approximately 13kft. Equilibrium levels/thunderstorm tops are
forecast near 40kft per Bismarck sounding Tuesday evening.
Inverted V-type soundings initially will support evaporational
cooling and strong winds.

Any severe thunderstorms will be on the decrease after midnight,
however ongoing showers/thunderstorms will continue, but wane
towards 12z Wednesday as the surface low and mid level shortwave
slide just outside the James River Valley by 12z Wednesday.

Brief transitory ridge moves through Wednesday with northwest
flow and cooler temperatures with highs 75F-80F. Another surface
low and cold front enter western ND Thursday morning, then shift
through Thursday night. The upper trough lags and slowly moves
through Friday/Friday night. Thus will continue to mention a
chance of showers/thunderstorms during the Thursday/Friday time
period. Highs in the 70s Thursday/Friday.

No change for the weekend, as chances for showers continue with
weak shortwaves traversing through. Highs in the 70s Saturday,
then upper 70s and lower 80s Sunday.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 333 AM CDT Mon Jun 26 2017

Skc next 24hr with winds at or below 10kt.




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