Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 211351

Area Forecast Discussion
National Weather Service Bismarck ND
851 AM CDT SAT MAY 21 2016

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

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 12Z TAFS through 12Z Sunday morning)
Issued at 637 AM CDT Sat May 21 2016

Low pressure across Montana will continue to bring increasing
southeast winds of 20 to 35 kts to southwest North Dakota during
the daytime hours Saturday, impacting KDIK. The low will also
bring a brief period of IFR ceilings to KDIK...improving to vfr
after 15z. Then after 03z some MVFR ceilings will re-appear at
KDIK and extend to KBIS. Scattered thunderstorms are possible
late in the evening but to uncertain to include in TAFs at this
time. Instead added VCTS to KISN-KDIK after 06z.


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



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