ACUS02 KWNS 121728
SWODY2
SPC AC 121727

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1227 PM CDT TUE JUL 12 2011

VALID 131200Z - 141200Z

....THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN
ROCKIES...NRN HIGH PLAINS...CNTRL ROCKIES AND CNTRL PLAINS...

....NRN ROCKIES/NRN HIGH PLAINS...
AN UPPER-LEVEL LOW WILL MOVE VERY SLOWLY ACROSS THE PACIFIC
NORTHWEST WEDNESDAY AS A 45 TO 60 KT MID-LEVEL JET MOVES NEWD ACROSS
THE NRN ROCKIES. THE JET MAX WILL HELP CREATE MODERATE DEEP LAYER
SHEAR ALONG AN AXIS OF INSTABILITY FROM CNTRL ID NEWD INTO WCNTRL MT
WHERE A SEVERE THREAT SHOULD DEVELOP LATE WEDNESDAY AFTERNOON INTO
THE EARLY EVENING. FORECAST SOUNDINGS AT 00Z ALONG THE INSTABILITY
AXIS SHOW MLCAPE VALUES IN THE 1000 TO 2000 J/KG RANGE WITH 0-6 KM
SHEAR VALUES OF 35 TO 45 KT AND STEEP MID-LEVEL LAPSE RATES. THIS
ENVIRONMENT MAY SUPPORT A LARGE HAIL THREAT IF SUPERCELLS CAN
DEVELOP. HOWEVER...THE STORMS MAY TEND TO LINE OUT ALONG A SEWD
MOVING COLD FRONT ON WHICH THE MODELS FORECAST STRONG LOW-LEVEL
CONVERGENCE. THIS COULD RESULT IN A WIND DAMAGE THREAT DEVELOPING AS
LOW-LEVEL LAPSE RATES BECOME STEEP IN THE LATE AFTERNOON.

A SEVERE THREAT MAY ALSO DEVELOP EWD ACROSS ERN MT ALONG AN AXIS OF
MODERATE INSTABILITY. HOWEVER...DEEP LAYER SHEAR IS FORECAST TO BE
MUCH WEAKER ACROSS ERN MT SUGGESTING THE THREAT SHOULD REMAIN
ISOLATED.

....CNTRL ROCKIES AND CNTRL HIGH PLAINS...
AN UPPER-LEVEL RIDGE WILL BE IN PLACE ACROSS THE GREAT PLAINS AND MS
VALLEY WEDNESDAY. A SUBTLE SHORTWAVE TROUGH IS FORECAST TO MOVE
ENEWD ACROSS THE CNTRL HIGH PLAINS INTO THE WRN PART OF THE
UPPER-LEVEL RIDGE. LARGE-SCALE ASCENT ASSOCIATED WITH THIS SHORTWAVE
TROUGH MAY AID THUNDERSTORM DEVELOPMENT IN THE CNTRL HIGH PLAINS
WITH CONVECTION ALSO INITIATING IN THE HIGHER TERRAIN OF SE WY AND
ECNTRL CO. FORECAST SOUNDINGS AT 00Z FROM ECNTRL CO EWD INTO CNTRL
NEB SHOW MODERATE TO STRONG INSTABILITY WITH 35 TO 45 KT OF DEEP
LAYER SHEAR. THIS ENVIRONMENT ALONG WITH STEEP MID-LEVEL LAPSE RATES
SHOULD SUPPORT A LARGE HAIL THREAT WITH SUPERCELLS THAT DEVELOP. THE
LARGE HAIL THREAT SHOULD BE GREATEST CLOSER TO THE MTNS WHERE
MID-LEVEL LAPSE RATES ARE FORECAST TO BE THE STEEPEST. THE SEVERE
THREAT ACROSS CNTRL NEB APPEARS MORE CONDITIONAL DUE TO A CAPPING
INVERSION THAT IS FORECAST TO BE IN PLACE MUCH OF THE DAY. IF
SFC-BASED STORMS CAN INITIATE IN CNTRL NEB WHERE WINDS ARE FORECAST
TO BE LOCALLY BACKED...THEN SUPERCELLS OR BOWING LINE-SEGMENTS MAY
DEVELOP LATE WEDNESDAY AFTERNOON OR EARLY WEDNESDAY EVENING. BECAUSE
OF A CONDITIONAL THREAT FOR WIND DAMAGE AND HAIL IN THE CNTRL
PLAINS...A SLIGHT RISK HAS BEEN ADDED.

....OZARKS/MID-MS VALLEY/GULF COAST STATES...
MODERATE TO STRONG INSTABILITY IS AGAIN FORECAST WEDNESDAY AFTERNOON
FROM THE OZARKS SEWD INTO THE TN VALLEY WHERE THE MODELS DEVELOP
SCATTERED THUNDERSTORMS. FORECAST SOUNDINGS ALONG THIS CORRIDOR AT
21Z WEDNESDAY SHOW MLCAPE VALUES IN THE 2000 TO 3500 J/KG RANGE
ALONG WITH STEEP LOW-LEVEL LAPSE RATES. THIS ENVIRONMENT SHOULD
SUPPORT A THREAT FOR ISOLATED WET DOWNBURSTS ASSOCIATED WITH THE
MORE INTENSE PULSE STORMS THAT DEVELOP NEAR MAXIMUM DESTABILIZATION.


....MID-ATLANTIC AND SRN NEW ENGLAND...
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE ACROSS THE ERN SEABOARD
WEDNESDAY. JUST AHEAD OF THE TROUGH...AN AXIS OF INSTABILITY IS
FORECAST FROM ERN VA NEWD INTO SRN NEW ENGLAND. AS THUNDERSTORMS
INITIATE ALONG THE INSTABILITY AXIS WEDNESDAY AFTERNOON...30 TO 40
KT OF DEEP LAYER SHEAR SHOULD BE ENOUGH FOR A MARGINAL SEVERE
THREAT. MARGINALLY SEVERE WIND GUSTS AND HAIL WILL BE POSSIBLE WITH
THE MORE INTENSE CELLS BUT WEAK INSTABILITY SHOULD KEEP THE SEVERE
THREAT ISOLATED.

...BROYLES.. 07/12/2011

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