Category Archives: North Dakota

Severe Thunderstorm Watch (North Dakota, South Dakota)

ww0463_radar

URGENT – IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 463
NWS STORM PREDICTION CENTER NORMAN OK
355 PM CDT SUN AUG 17 2014

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
WESTERN AND CENTRAL NORTH DAKOTA
NORTH CENTRAL SOUTH DAKOTA

* EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 355 PM UNTIL
1000 PM CDT.

* PRIMARY THREATS INCLUDE…
SCATTERED LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE
ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES WEST OF
MOBRIDGE SOUTH DAKOTA TO 60 MILES NORTH NORTHWEST OF DEVILS LAKE
NORTH DAKOTA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS…

REMEMBER…A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

&&

OTHER WATCH INFORMATION…CONTINUE…WW 462…

DISCUSSION…WIDELY SCATTERED STORMS ARE BEGINNING TO INCREASE OVER
SWRN AND NORTH CENTRAL ND IN ADVANCE OF A SHORT WAVE TROUGH MOVING
EWD FROM MT. THE ENVIRONMENT IS MODERATELY UNSTABLE WITH CAPE TO
2000 J/KG…AND SUFFICIENT VERTICAL SHEAR IS PRESENT TO SUPPORT
ORGANIZED MULTICELL AND ISOLATED SUPERCELL STORM STRUCTURES.
ACTIVITY SHOULD SPREAD EWD INTO THE EVENING WITH A THREAT FOR LARGE
HAIL AND STRONG WIND GUSTS.

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Mesoscale Discussion – Watch Likely (Iowa, Minnesota, North Dakota, South Dakota)

MD 1766 graphic

MESOSCALE DISCUSSION 1766
NWS STORM PREDICTION CENTER NORMAN OK
0256 PM CDT WED AUG 15 2012

AREAS AFFECTED…EXTREME SE ND…FAR ERN SD…NW IA…MUCH OF
MN…FAR WRN WI

CONCERNING…SEVERE POTENTIAL…WATCH LIKELY

VALID 151956Z – 152100Z

PROBABILITY OF WATCH ISSUANCE…80 PERCENT

SUMMARY…ADDITIONAL THUNDERSTORM DEVELOPMENT IS EXPECTED BY 21Z.
SEMI-DISCRETE CELLS ARE EXPECTED TO TRANSITION INTO LINEAR SEGMENTS
ALONG COLD FRONT. LARGE HAIL MAY INITIALLY BE POSSIBLE IN ADDITION
TO DAMAGING WIND THREAT. WW WILL LIKELY BE NEEDED IN THE NEXT HOUR
OR SO.

DISCUSSION…AN EASTWARD ADVANCING COLD FRONT WAS LOCATED FROM FAR
NW MN INTO ERN SD AS OF 1930Z. TEMPERATURES HAVE WARMED INTO THE MID
70S TO LOW 80S AHEAD OF THE FRONT WITH DEWPOINTS INCREASING INTO THE
LOW TO MID 60S. AS SUCH…ENVIRONMENT HAS BECOME MODERATELY UNSTABLE
AND UNCAPPED. CONVECTION HAS BEEN SLOW TO DEVELOP IN THE VICINITY OF
THE FRONT AND THIS IS LIKELY DUE TO LOW TO MIDLEVEL CLOUD COVER THAT
DEVELOPED ACROSS CENTRAL MN THIS MORNING. HI-RES WRF-NMM…NSSL WRF
AND HRRR ALL INDICATE CONVECTIVE DEVELOPMENT BY AROUND 20-21Z
HOWEVER. LATEST RADAR DATA ALSO SEEMS TO BE INDICATING A SLOW UPWARD
TREND WITH STRONGER CORES DEVELOPING FROM NEAR BELTRAMI TO MAHNOMEN
COUNTY IN NW MN. SO…WHILE CONVECTIVE INITIATION HAS LIKELY BEEN
DELAYED DUE TO THE AFOREMENTIONED CLOUD COVER…STORMS ARE STILL
EXPECTED BY 21Z. STRONG DEEP LAYER SHEAR OF AROUND 30-50 KT WILL AID
IN ORGANIZATION OF CELLS…WHICH MAY REMAIN SEMI-DISCRETE
INITIALLY…INTO LINEAR SEGMENTS ALONG THE FRONT. STEEPENING LAPSE
RATES AND STRONG MIDLEVEL FLOW WILL RESULT IN DAMAGING WIND
THREAT…ESPECIALLY ONCE LINEAR ORGANIZATION OCCURS.
OTHERWISE…STRONGER CELLS MAY INITIALLY ALSO POSE A LARGE HAIL
THREAT.

A WW WILL LIKELY BE NEEDED IN THE NEXT HOUR OR SO. THERE MAY BE THE
NEED FOR TWO SEPARATE WATCHES WHERE CONVECTION FURTHER SOUTH ACROSS
FAR ERN SD INTO NW IA/SW MN MAY BE SLOWER TO DEVELOP THAN THAT
ACROSS NORTHERN AND CENTRAL MN.

..LEITMAN/CARBIN.. 08/15/2012

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