Special Weather Statement, NWS Bismarck, ND

Area Forecast Discussion
National Weather Service Bismarck ND
1228 AM CDT SAT JUN 11 2016

.UPDATE...
Issued at 1227 AM CDT Sat Jun 11 2016

Thunderstorms in eastern Montana continue to slowly make their way
east towards western North Dakota. There has been some weakening
to the northern part of the line, while in the south, closer to
the better instability, the storms remain strong to severe. The
latest hi-res models continue to move the storms across parts of
western and central North Dakota this morning, so have followed
that general trend which has been consistent. The Hazardous
Weather Outlook already highlights the chance of a few strong
storms as they move across which looks reasonable.

UPDATE Issued at 947 PM CDT Fri Jun 10 2016

Once again, only minor changes were made to the overnight forecast
with this update cycle. Extrapolating upstream storms entering the
northeast part of MT as of 0245 UTC still brings the leading cells
into ND after 05 UTC, consistent with our hourly PoP forecasts. We
earlier added the possibility of a strong storm to our hazardous
weather outlook tonight, and there's a small risk of severe storms,
too. The near-storm environment upstream in northeast MT contains
strong deep-layer shear (effective bulk wind differences in excess
of 60 kt per the RAP-based/SPC mesoscale analysis) and modest CAPE
on the northern axis of a reservoir of strong instability. RAP
forecast soundings across western and central ND suggest similarly
strong deep-layer shear later tonight, but with less bouyancy. We
believe the modest (albeit increasing) MUCAPE values will tend to
keep any severe risk in check tonight.

UPDATE Issued at 657 PM CDT Fri Jun 10 2016

Only minor changes were made with this forecast update. Applying a
simple speed/time of arrival method to the thunderstorms impacting
central MT at 2345 UTC would bring them into western ND after 05
UTC, so our overnight PoP forecast is on track, and also has the
support of a 40 kt low-level jet that is expected to develop and
impinge on a mid-level frontal zone. Recent HRRR and ESRL-HRRR
simulations are more aggressive and faster bringing storms out of
MT and into ND, but both appear to be overzealous with deep
convection in south central MT compared to radar trends as of
early evening. That in turn lowers our confidence a bit in those
solutions for the time being.

&&

.SHORT TERM...(This evening through Saturday Night)
Issued at 402 PM CDT Fri Jun 10 2016

The potential for severe weather late Saturday afternoon
into Saturday night highlights the short term.

The latest model package (GFS20/ECMWF/SREF/Canadian) project quasi-
zonal flow aloft transitioning into southwest flow through Saturday,
as an upper level trough pushes inward from the Pacific NW.
Meanwhile, at the surface, low pressure will deepen over the
southeast Montana/northeast Wyoming corner, moving northeastward
through Saturday. Sufficient instability coupled with favorable 0-6
Km agl bulk shear of around 40 kts and dewpoints near 60F, will aid
in thunderstorm development. Models are also in fairly good
agreement with painting a band of CAPE between 5500 and 4000 joules
in west central and south central areas.

The current SPC convective outlook places much of western and
central ND in a slight risk for severe thunderstorms Saturday, with
a highlighted area for an enhanced risk over the west, late Saturday
afternoon into Saturday night. The main threats will be very large
hail, damaging winds, with a few tornadoes possible.

Supporting the probability for tornadoes are the 12Z NAM forecast
soundings in the southwest, which are projecting strong 0-1 km
storm relative helicity over 200 m2/s2 for Saturday evening. The
soundings also show low lcl heights around 1200 m agl for Saturday
evening.

.LONG TERM...(Sunday through Friday)
Issued at 402 PM CDT Fri Jun 10 2016

Seasonable temperatures along with chances for thunderstorms
continuing into Wednesday, highlights the long term.

Southwest flow, with embedded shortwaves, will keep a chance of
thunderstorms in the forecast in many areas through the middle of
next week. The latest deterministic and ensemble models suggest mid-
level flow may amplify again with ridging becoming more prevalent by
late next week, leading to a drier period, at least temporarily.
Highs will generally be in the 70s and 80s F over western and
central areas from Sunday through Friday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1227 AM CDT Sat Jun 11 2016

Thunderstorms in eastern Montana will continue to move east into
parts of western and central North Dakota. The storms could
eventually work their way across some of the TAF sites, and for
now covered that with VCTS. Another round of thunderstorms is
expected to develop this afternoon in eastern Montana / western
North Dakota. Those could impact the terminal locations later
tonight.

&&

.BIS Watches/Warnings/Advisories...
NONE.
&&

UPDATE...CK
SHORT TERM...AC
LONG TERM...AC
AVIATION...CK

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
956 PM CDT FRI JUN 10 2016

NDZ001>005-009>013-017>023-025-031>037-040>048-050-051-120300-
DIVIDE-BURKE-RENVILLE-BOTTINEAU-ROLETTE-WILLIAMS-MOUNTRAIL-WARD-
MCHENRY-PIERCE-MCKENZIE-DUNN-MERCER-OLIVER-MCLEAN-SHERIDAN-WELLS-
FOSTER-GOLDEN VALLEY-BILLINGS-STARK-MORTON-BURLEIGH-KIDDER-
STUTSMAN-SLOPE-HETTINGER-GRANT-BOWMAN-ADAMS-SIOUX-EMMONS-LOGAN-
LA MOURE-MCINTOSH-DICKEY-
956 PM CDT FRI JUN 10 2016 /856 PM MDT FRI JUN 10 2016/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
NORTH DAKOTA...NORTHWEST NORTH DAKOTA...SOUTH CENTRAL NORTH
DAKOTA...SOUTHEAST NORTH DAKOTA AND SOUTHWEST NORTH DAKOTA.

.DAY ONE...TONIGHT

THERE IS A CHANCE OF THUNDERSTORMS OVER PARTS OF WESTERN AND
CENTRAL NORTH DAKOTA AFTER MIDNIGHT TONIGHT. FEW STORMS COULD
BE STRONG...BUT WIDESPREAD SEVERE WEATHER IS NOT EXPECTED.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS ARE POSSIBLE SATURDAY AND SATURDAY NIGHT. SOME
THUNDERSTORMS MAY BE SEVERE WITH LARGE HAIL...DAMAGING
WINDS...AND POSSIBLY A FEW TORNADOES.

CHANCES FOR THUNDERSTORMS CONTINUE OVER PARTS OF THE AREA FROM
SUNDAY THROUGH THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATE SATURDAY AFTERNOON AND
SATURDAY EVENING.

CJS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BISMARCK ND
104 AM CDT SAT JUN 11 2016

NDZ017-031-110645-
MCKENZIE ND-GOLDEN VALLEY ND-
104 AM CDT SAT JUN 11 2016

...A STRONG THUNDERSTORM WILL AFFECT NORTH CENTRAL GOLDEN VALLEY AND
SOUTHWESTERN MCKENZIE COUNTIES UNTIL 145 AM CDT/1245 AM MDT/...

AT 104 AM CDT/1204 AM MDT/...DOPPLER RADAR WAS TRACKING A STRONG
THUNDERSTORM 6 MILES NORTHEAST OF SKAAR...OR 22 MILES SOUTHEAST OF
SIDNEY...MOVING EAST AT 45 MPH.

PENNY SIZE HAIL AND WIND GUSTS TO 55 MPH WILL BE POSSIBLE WITH THIS
STORM.

LOCATIONS IMPACTED INCLUDE...
GRASSY BUTTE...THEODORE ROOSEVELT NATIONAL PARK NORTH UNIT AND
TROTTERS.

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO
STATIONS AND AVAILABLE TELEVISION STATIONS FOR ADDITIONAL INFORMATION
AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

LAT...LON 4759 10404 4777 10309 4733 10311 4733 10367
      4730 10367 4728 10404
TIME...MOT...LOC 0604Z 261DEG 41KT 4743 10392

SCHILD