Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 261718

Area Forecast Discussion
National Weather Service Bismarck ND
1218 PM CDT Sat May 26 2018

Issued at 1208 PM CDT Sat May 26 2018

Forecast remains on track this afternoon. See earlier discussions
for further details.

UPDATE Issued at 1005 AM CDT Sat May 26 2018

Latest suite of satellite imagery shows scattered high clouds
now into southwestern North Dakota with a clear sky elsewhere.
A mid to upper level ridge axis over western/central North Dakota
will maintain warm and dry conditions into the evening. Only
update was to increase highs by another couple degrees, as 850mb
temperatures averaging 2 degrees Celsius warmer at 12z Saturday
versus 12z Friday. Temperatures tracking identical as of this
writing when compared to yesterday, which yielded a high of 92F
Friday afternoon in Bismarck. Mixing heights today adequate to
tap into the warmer H850mb temperatures this afternoon, and with
compressional warming, expecting highs in the lower to mid 90s.
As mentioned in an earlier discussion, the record high temperature
for this date in Bismarck is 92F. Fully expect to break this
record late this afternoon.

A couple of mid level shortwaves from northern Wyoming into south
central Montana west of the ridge axis will eventually shift into
western North Dakota between 03z-06z Sunday, increasing the threat
for showers and thunderstorms. Forecast is on track with this idea.

UPDATE Issued at 631 AM CDT Sat May 26 2018

Clear skies and light winds cover the region this morning. 12Z
sounding shows a strong inversion with 24C at 911 mb, which is
about 1C warmer than the NAM/GFS forecast soundings for 11Z. This
gives some confidence we will tie or break the record high today.

Current forecast looks ok with no changes needed.


.SHORT TERM...(Today and tonight)
Issued at 229 AM CDT Sat May 26 2018

A very warm day remains in the forecast for Saturday, with a
potential record high possible at Bismarck, whose current record
stands at 92 set in 2006 as a strong h850 thermal ridge builds
into western North Dakota. Other locations have warmer records
for this date so are not likely to be broken.

There will be increasing chances for thunderstorms Saturday night
across the west. Short range models focus Updraft Helicity across
eastern Montana into western North Dakota, indicating more
likelihood of Supercell formation, with the severe potential
mainly large hail and string winds across the far west after 7 PM

.LONG TERM...(Sunday through Friday)
Issued at 229 AM CDT Sat May 26 2018

An active convective weather pattern continues to be favored for
Sunday through Tuesday, with severe thunderstorms possible as an
upper low migrates northeast toward the upper plains. Increasing
low level moisture ahead of the low and falling h500 heights will
destabilize the atmosphere and abundant Cape and Bulk Shear will
be be available.

The remnants of Saturday nights convection will be exiting the
region Sunday. The next round of storms associated with a
shortwave trough embedded within the upper low rotating northward
into the northern plains Sunday night and Memorial Day will
develop Sunday night. More widespread thunderstorms are seen
across the region Sunday night and Monday, with the precipitable
water supporting some heavy rain. Stronger Bulk Shear and high
cape values will also support more widespread severe
thunderstorms, with a slight risk identified by the SPC across
portions of west and central North Dakota both Sunday and Monday.

Cooler, but more normal temperatures will follow Memorial day,
bringing more normal highs in the 70s to lower 80s. The next
chance for thunderstorms will Thursday night into Friday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1218 PM CDT Sat May 26 2018

An area of showers and thunderstorms will shift from eastern
Montana this evening and into western North Dakota between
03z-06z Sunday. KISN has the highest chance and confidence for
showers/thunderstorms, thus have gone predominate from 06z-12z
Sunday. Would anticipate some severe weather within the timeframe
mentioned above at KISN. A vcts was utilized at the remaining
terminals at this time. Cloud bases will initially be high (9kft
to 10kft), and lower with time towards 12z, still remaining vfr.
The exception wold be at KISN where a period of stratus is
forecast from 15z-18z Sunday.




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