Area Forecast Discussion
Issued by NWS Bismarck, ND

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359
FXUS63 KBIS 210600
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
100 AM CDT Sun Apr 21 2019

.UPDATE...
Issued at 1246 AM CDT Sun Apr 21 2019

Latest radar imagery show convection continuing to barely hold on
over the far south central into the James River Valley. Added a
mention of thunder 06-09Z. Latest iterations of the CAMS are
slower in bringing showers into the southwest late tonight.
Utilized a blend of short term model guidance late tonight into
Sunday morning across the southwest. CAMS also showing a potential
for fog north central. Not convinced it will happen with quite a
bit of mid clouds around, but will leave it in for now as
temp/dwpt spreads are very close and winds are light.

UPDATE Issued at 932 PM CDT Sat Apr 20 2019

Latest local radar imagery shows convective development southeast
of Bismarck, along an outflow boundary that passed through
Bismarck about one hour ago. That boundary is now located from
northern Emmons County into southern Kidder and western Stutsman.
Have adjusted PoPs based on this new development. The convective
environment surrounding the outflow boundary per SPC mesoanalysis
is effective deep layer shear of 40kt with mid level lapse rates
of around 7.5C/Km. Some further growth is anticipated with the
potential of small hail and gusty winds. Otherwise, increasing
showers and some thunderstorms in south central Montana associated
with a mid level shortwave will continue to approach southwest ND.
Current forecast with increasing PoPs overnight remain on track.

UPDATE Issued at 524 PM CDT Sat Apr 20 2019

700mb frontogenetical forcing and marginally weak low/mid level
lapse rates per SPC mesoanalysis continues to support a broad area
of light scattered rainshowers stretching from north central
Montana into north central North Dakota. Frontogenetical forcing
is forecast to gradually wane per NAM80 through 06z, thus the
trends of diminishing showers remains on track across the north.
Weak 700-500mb shortwave per water vapor imagery now approaching
Sioux County has played a part in developing a couple showers over
McIntosh County. Expecting to see a bit more activity southern
James River Valley this evening as the shortwave moves through,
in concert with weak instability/moderate deep layer shear per SPC
mesoanalysis. Upstream, another couple of shortwaves ejecting
from northern Wyoming will slide toward the North/South Dakota
border later this evening and affect southern North Dakota tonight
into Sunday morning. PoPs also increase with these shortwaves per
previous forecast, mainly after 06z. Minor adjustments to ongoing
precipitation and PoPs this evening based on current radar and
surface observations, otherwise, everything is on track.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 233 PM CDT Sat Apr 20 2019

Todays forecast includes a cold front sliding south through the
region that will be the focus for scattered showers and isolated
thunderstorms tonight. A mid level wind max will aid in broad
scale lift as the cold front moves through southern North Dakota
this evening. The best location for isolated thunderstorms still
appears to be the southern James River Valley. A few storms could
have brief heavy rain and some gusty winds there. Tonights low
will be in the upper 30s to mid 40s.

On Sunday, cooler temperatures will be found across the state
behind the front. The baroclinic zone will remain along and just
south of the state. An approaching h500 trough will support fairly
widespread showers across southwest North Dakota late tonight and
Sunday morning. Isolated thunderstorms also may be possible in
this area. Highs Sunday will be in the mid 50s to lower 60s.

.LONG TERM...(Sunday night through Saturday)
Issued at 233 PM CDT Sat Apr 20 2019

Broad scale h500 ridging will bring a dry warming trend Monday
through Wednesday, with highs returning to the 60s to lower 70s.
This will be followed by a fairly fast progressive h500 flow for
Thursday through Saturday that will bring scattered showers and
possibly an isolated thunderstorm. Highs will cool into the 50s to
around 60.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1246 AM CDT Sun Apr 21 2019

For the most part VFR conditions are expected through the forecast
period. Exceptions are at KMOT with the potential for fog later
tonight into Sunday morning, especially if we could get some
thinning of the mid clouds currently over the area. For now, kept
the VCFG introduced earlier, from 10-14 UTC. KDIK will see the
best chance for steady rain showers late tonight and early Sunday
morning. Model blended guidance brings some MVFR ceilings into
KDIK for a few hours this morning. For now kept a scattered layer
at 2500 ft and 6sm in rain showers from 10-13 UTC. KJMS will see a
tempo -shra early 06-07 as line of shower activity moves across
the Aerodrome in the next hour. Otherwise north to northeast flow
across the area today, may get a little gusty this afternoon
especially at KJMS.

&&

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

$$

UPDATE...TWH
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...TWH



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