WATCHES: Severe Thunderstorm Watch Number 172

WWUS20 KWNS 182057
SEL2
SPC WW 182057
SDZ000-190400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 172
NWS STORM PREDICTION CENTER NORMAN OK
255 PM MDT SAT MAY 18 2013

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
WESTERN SOUTH DAKOTA

* EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 255 PM UNTIL
1000 PM MDT.

* PRIMARY THREATS INCLUDE...
SEVERAL LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE
A FEW DAMAGING WIND GUSTS TO 60 MPH POSSIBLE

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95
STATUTE MILES EAST AND WEST OF A LINE FROM LEMMON SOUTH DAKOTA TO
75 MILES SOUTH SOUTHWEST OF PHILIP SOUTH DAKOTA. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU2).

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 170...WW 171...

DISCUSSION...STORM COVERAGE IS IN THE PROCESS OF INCREASING
NEAR/NORTH AND EAST OF THE BLACK HILLS AREA...WHERE STEEP LAPSE
RATES ARE CONTRIBUTING TO A RISK FOR AT LEAST SEVERE HAIL...AIDED BY
MODEST DEEP LAYER SHEAR BENEATH 30-40 KT SOUTHERLY 500 MB FLOW.
THIS ACTIVITY LIKELY WILL PERSIST INTO THE EVENING HOURS...BEFORE
WEAKENING/SHIFTING EAST OF REGION.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 50
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 24035.


...KERR

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