Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 141153
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
653 AM CDT Thu Sep 14 2017

.UPDATE...
Issued at 653 AM CDT Thu Sep 14 2017

Made some adjustments to pops and weather based on latest radar
and obs trends. Mainly tried to better cover two areas of showers,
one across the west and on moving through the James Valley region.
Otherwise, just blended most recent observations.

&&

.SHORT TERM...(Today and tonight)
Issued at 343 AM CDT Thu Sep 14 2017

Latest water vapor imagery shows an upper low/trough in the
Pacific northwest, continuing to develop/sharpen up, as it is
forecast to migrate into the northern rockies tonight. As a
pronounced west to southwest flow organizes, a couple of lead
shortwaves out ahead of the main trough is producing showers and
isolated thunderstorms early this morning. One upper level
shortwave was located over Grant County which has been producing a
swath of light to moderate rainshowers/isolated thunderstroms
across south central ND. Another shortwave was working across
eastern Montana and this will slide into western ND in the next
few hours. Expect a round of scattered showers with this
shortwave. The smoky conditions, especially across southwestern
and south central ND should continue to improve as the area of
rainshowers push through.

More shortwaves embedded within the southwesterly flow will ride
through eastern Montana and across western/central ND today resulting
in a continued chance of showers/isolated thunderstorms. The better
probability for thunderstorms resides in the southern James River
Valley with mixed layer cape between 500 J/Kg and 1000 J/kg, and
deep layer shear around 40kt. Under this scenario, there could be
a couple strong thunderstorms and/or an isolated severe thunderstorm
later this afternoon across the southern portion of the James
River Valley, per SPC Marginal Risk. As the upper low and associated
trough edge closer tonight, widespread rainshowers will commence
in the west as synoptic scale ascent increases, and overlaps with
low level frontogenetical forcing per NAM/GFS QG.

.LONG TERM...(Friday through Wednesday)
Issued at 343 AM CDT Thu Sep 14 2017

Much needed rain will occur Friday/Friday night across all of
western/central ND as the strongest forcing slides through.
Showers continue Saturday, but more of scattered variety as the
main upper low/trough scoot through. Total rainfall in for most of
western/central ND still looks to range from around 0.50 in the
southern James River Valley, and between 1 and 2 inches for most
of the west and central. Much cooler temperatures with highs
Friday and Saturday in the 50s. This exits the Turtle Mountains
Saturday night. Will monitor how rapidly the clouds move out
Saturday night, especially across the west, where the potential
for frost and lows in the mid 30s looks very possible at this
time.

A break in the wet pattern Sunday, then the next upper trough
takes shape in the Pacific northwest and southwestern Canada. This
is forecast to slowly evolve and move east through the week, with
varying solutions on the depth of the trough in the west from
midweek onward. Will continue with periodic chances of showers
Sunday night through Wednesday. Highs will moderate into the 60s
and 70s Monday through Wednesday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 653 AM CDT Thu Sep 14 2017

VFR conditions expected through the morning, but expect cigs to
deteriorate from west to east this evening and overnight as a
storm system nears our region. MVFR conditions expected at all
locations overnight, eventually affecting KJMS closer to 12z
Friday.

&&

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

$$

UPDATE...JNS
SHORT TERM...KS
LONG TERM...KS
AVIATION...JNS



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