Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 131448
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
948 AM CDT Wed Sep 13 2017

.UPDATE...
Issued at 937 AM CDT Wed Sep 13 2017

Based on experimental surface smoke forecasts available at
www.airquality.weather.gov, and the 06 UTC HRRR experimental
smoke forecast, reduced visibility in smoke will continue through
today across most of western and central North Dakota, and likely
tonight, with no major airmass exchange .

UPDATE Issued at 641 AM CDT Wed Sep 13 2017

No significant changes were needed with this update. Observations
suggest the most significant surface smoke is settling over south
central ND in the immediate post-frontal region, with a relative
improvement in visibility over northwest and far north central ND
since 09 UTC. This suggests that surface smoke concentration may
indeed slowly be reduced by afternoon, particularly as boundary
layer mixing increases. Otherwise, most areas are 40 to 50 degrees
cooler than they were 12 hours ago thanks to light winds and the
dry atmosphere. We did adjust hourly temperatures this morning to
better reflect the magnitude of cooling that occurred overnight.

&&

.SHORT TERM...(Today through Thursday)
Issued at 343 AM CDT Wed Sep 13 2017

The primary forecast challenge for the day is smoke. How long will
the smoke continue to filter into western and central areas of ND?
The HRRR has struggled to get a good handle on surface smoke
integration. The model from the Naval Research Laboratory (NRL) has
been preforming much better, thus the smoke forecast for today
favors the NRL projections. Chances for showers and isolated
thunderstorms creep into the forecast through the afternoon, which
may help to dampen the smoke. However, it is highly possible the
smoke will linger through the day. Current visibility observations,
across western and central ND, are between three and five miles.
Though visibilities as low as 2 miles have been observed in the
west.

Looking at Thursday, the SPC day two outlook places our far
southeast in a marginal risk for severe thunderstorms. The overall
ingredients for severe weather are not overwhelming. The 00Z GFS has
around 1500 J/Kg of CAPE and close to 40 kts of 0-6 km bulk shear,
so a strong storm or two is possible Thursday afternoon.

.LONG TERM...(Friday through Tuesday)
Issued at 343 AM CDT Wed Sep 13 2017

Fall-like temperatures and frequent chances for rain are expected
in the extended forecast.

A large pattern shift is favored by the 00 UTC global models for
late this week and likely into next week, as a significant longwave
trough is projected to propagate eastward across the northern and
central plains. As a result, drastically cooler temperatures and
frequent chances for rain are expected. Forecast highs, for Friday
and Saturday, are in the 50s and 60s. Widespread rainfall amounts
between one and three inches, with the greatest amounts across
western and north central areas, are favored Friday and Saturday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 937 AM CDT Wed Sep 13 2017

Smoke will continue through most of the 12 UTC TAF cycle across
western and central North Dakota. MVFR/IFR visibility will likely
continue through at least midday, with some small, possible
improvement in the afternoon. The smoke will be thickest with the
lowest visibility across southwest and south central North Dakota.
Isolated showers and thunderstorms are possible across the west
late this afternoon, spreading into central North Dakota this
evening and overnight.

&&

.FIRE WEATHER...
Issued at 343 AM CDT Wed Sep 13 2017

Another seasonably warm day is expected across much of western and
central ND. High temperatures in northern areas are forecast in
the lower 80s, while central and southern areas will be in the
upper 80s and lower 90s. Southwest locations will be dry with
minimum relative humidity values around 15 percent. Although
conditions will be warm and dry in the southwest, winds will be
around 10 mph and generally variable. Through the afternoon,
chances for showers and isolated thunderstorms will spread from
west to east.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...PA
SHORT TERM...AC
LONG TERM...AC
AVIATION...PA
FIRE WEATHER...AC



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