Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 240803

Area Forecast Discussion
National Weather Service Bismarck ND
303 AM CDT Thu Aug 24 2017

.SHORT TERM...(Today and tonight)
Issued at 303 AM CDT Thu Aug 24 2017

Potential for early morning low clouds/patchy fog in portions of
western and central ND, and increasing chances for showers and
thunderstorms late tonight are the highlights in the near/short
term periods.

For the near term period, now through mid morning, latest suite of
satellite imagery and surface observations continue with a moist
low level easterly upslope wind across northern ND and into the
James River Valley. Still expect a widespread area of low clouds
within a corridor from Minot to Jamestown and north to Rolla.
Rolla already has cloud bases at 300ft agl, and will monitor a
westward expansion over the next few hours. Will also monitor
portions of southwestern ND, as the HRRR and RAP13 both indicate
potential for clouds and/or fog from Hettinger to Dickinson
through mid morning.

Otherwise for the rest of the short term period, a mid/upper
level transitory ridge will slide into western and central ND,
resulting in plenty of sunshine, dry and warm weather. Expect
breezy low level southeasterly winds this afternoon around 15 mph
for most of western and central ND. The far southwest will have
sustained winds of around 20 mph this afternoon. Highs today will
range from the 70s in the Turtle Mountains south into the James
River Valley, with lower 80s in central ND, and upper 80s west.

The latest water vapor imagery loop shows just upstream from the
ridge axis this morning, are multiple shortwaves, one located
over eastern Idaho, another in western Wyoming, and also in southern
Montana. These will move northeast today, reaching far western ND
late tonight/after midnight. A chance for showers and thunderstorms
remains in the forecast in the far west, with dry conditions elsewhere.

.LONG TERM...(Friday through Wednesday)
Issued at 303 AM CDT Thu Aug 24 2017

Moderate Instability per NAM/GFS Mixed Layer Cape mainly along and south
of Interstate 94 Friday, combined with Effective Bulk Shear of around
30kt, and conditionally unstable lapse rates, will allow for strong
to possibly isolated severe thunderstorms Friday. The latest SPC
21z SREF 3hr Calibrated Severe Thunderstorm potential for Friday does
weakly support this possibility, so continuing to mention an isolated
strong to severe thunderstorm in the HWO remains warranted at this
time. This may extend into Saturday as another mid level shortwave
slides through, which also supports a weak frontal system sliding
through the southwest Saturday. With instability/shear elements
mentioned above remaining mostly in place from Friday into Saturday,
we could see strong to possibly isolated severe thunderstroms in
southern ND Saturday as well. Will pass this along to the dayshift
and allow subsequent shifts to monitor the latest trends.

Beyond Saturday, upper level ridging in the west amplifies through
early next week, with heights rising Sunday and remaining largely
in tact through Wednesday. The end result is a dry and warm
forecast with highs in the 80s Monday through Wednesday across
western and central ND.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 303 AM CDT Thu Aug 24 2017

An easterly to southeasterly wind this TAF period will result in
mvfr/ifr cigs and possibly vsbys for KMOT/KJMS/KDIK in the 09z
through 16z Thursday timeframe. For now, KISN/KBIS have much
lower probabilities for sub-vfr conditions, but will monitor
closely. Current satellite imagery and latest model guidance
suggests that KMOT mvfr/ifr timeframe would be between 09z-16z
Thursday, and at KJMS 12z-16z Thursday. Not totally confident the
same will occur at KDIK, so have added a vcfg and hinted at
sct005 until evidence is seen that deteriorating cigs are in fact
beginning to occur.




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