Area Forecast Discussion
Issued by NWS Bismarck, ND

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297
FXUS63 KBIS 211715
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1215 PM CDT SAT MAY 21 2016

.UPDATE...
Issued at 1215 PM CDT Sat May 21 2016

Latest visible satellite imagery shows a cumulus field across
central North Dakota as southeast winds advect in higher low level
moisture. This trend will continue, although highest dewpoints of
60s will be delayed until Sunday afternoon. Otherwise mid/high
clouds in the west will also move toward central ND this
afternoon. Partly to mostly cloudy conditions expected and have
adjusted sky grids in this direction. Winds in southwest ND
verifying well for the ongoing wind advisory at this time. Latest
12z models keep threat of showers and thunderstorms away from the
western border until at least 03z, and concur, so have removed
mention of precipitation early this evening. Strong cap evolving
in the southwest, with the Bowman NSharp sounding showing a large
CIN layer with maximum temperatures of +13c to +14C within the
layer toward 00z Sunday. This will inhibit convection at least
until the 03z-06z Sunday timeframe. Rest of forecast looks on
track.

UPDATE Issued at 850 AM CDT Sat May 21 2016

Previous forecast is on track, the only update was to add a slight
chance of thunderstorms for the one cell tracking northeast out of
southeastern Montana. However this cell has been decreasing in
intensity as it nears the border.

UPDATE Issued at 637 AM CDT Sat May 21 2016

Scattered light rain showers linger across the far southwest.
Stream of low level moisture showing up in a region of clouds
extending across the southwest quarter of the state. Cloud may
keep the high temperatures cooler southwest, in the lower 70s
today. Current forecast trending ok.

&&

.SHORT TERM...(Today and tonight)
Issued at 300 AM CDT Sat May 21 2016

Main concerns this forecast include a marginal severe weather
threat for large hail and damaging winds saturday evening and
overnight from a few storms. Moderate southeast winds of 25 to 45
mph have also prompted a wind advisory for saturday afternoon and
evening southwest.

Saturday begins with an amplified upper air pattern with a large
upper low centered over the California-Nevada-Oregon border. The
eastern fringe of this upper low extends to eastern Montana and
Wyoming. Downstream an H500 ridge extends across the Dakotas.
Weak ripples in the flow aloft have generated a few showers across
far southwest North Dakota until sunrise which will diminish with
time as a well defined capping inversion develops.

For today, the h500 ridge will enhance the cap and should inhibit
convection through the the day. Eventually some convection will
break through the cap this evening across the west.

A marginal severe risk exists with a few of these storms this
evening and tonight for large hail and damaging wind threats.

.LONG TERM...(Sunday through Friday)
Issued at 300 AM CDT Sat May 21 2016

Sunday will see more organized convection into lines along an
advancing cold front through central North Dakota.

The main forecast concerns will be the continuing threat for
severe weather Sunday afternoon and Sunday night. A slight risk
of severe thunderstorms is expected due to large hail and damaging
winds.

By Sunday, much better shear arrives with the advancing upper low
into North Dakota. Most unstable cape between 2 and 3 thousand is
forecast along an eastward moving cold front that will erode the
remnants of the capping inversion Sunday afternoon. the severe
thunderstorm threat will be focused on central North Dakota late
Sunday afternoon and Sunday night.

By Monday morning the cold front has moved east of the region. The
GFS/ECMWF clear most of the showers out of the area but the NAM
has a lingering short wave trough that supports some convection
Monday afternoon across the east.

Tuesday and Wednesday will have southwest flow aloft with little
to inhibit at least widely scattered convection. Global models
bring a better chance for thunderstorms Thursday and Friday to
the region with an H500 shortwave trough carving out some
instability and cyclonic flow aloft.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1215 PM CDT Sat May 21 2016

Cloud cover will increase across the region through the day from
west to east. A stratus deck is expected to impact western and
central parts of North Dakota, mainly impacting KDIK, KMOT, and
KBIS lowering heights into the MVFR category. Late tonight early
Sunday morning a few thunderstorms will move into western North
Dakota possibly impacting KDIK, KISN, KBIS, and KMOT.

&&

.BIS Watches/Warnings/Advisories...
Wind Advisory until 9 PM MDT this evening for NDZ031>033-040-041-
043-044.

&&

$$

UPDATE...KS
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...MM



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