DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 051731
SWODY2
SPC AC 051730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT TUE JUN 05 2007

VALID 061200Z - 071200Z

..THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF ND...SD...NEB
AND MN...

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE PLAINS AND
UPPER MIDWEST...

..SIGNIFICANT SEVERE THUNDERSTORM EPISODE POSSIBLE ACROSS PARTS OF
THE NRN PLAINS INTO PARTS OF THE CNTRL PLAINS LATE WEDNESDAY
AFTERNOON THROUGH WEDNESDAY NIGHT...

..GREAT PLAINS AND UPPER MIDWEST...
A POWERFUL UPPER-LEVEL LOW IS FORECAST TO MOVE EWD ACROSS THE
PACIFIC NORTHWEST TONIGHT AND INTO THE ROCKIES WEDNESDAY. AN 80 TO
90 KT MID-LEVEL JET ASSOCIATED WITH THIS FEATURE IS FORECAST TO
ROUND THE BASE OF THE TROUGH AND THE EXIT REGION OF THIS FEATURE
WILL EJECT INTO THE PLAINS WEDNESDAY AFTERNOON AND EVENING.
LOW-LEVEL MOISTURE WILL RETURN QUICKLY NWD ACROSS THE CNTRL PLAINS
INTO THE NRN PLAINS ASSOCIATED WITH A STRONG LOW-LEVEL JET. AS A
RESULT...LARGE-SCALE ASCENT...INSTABILITY AND VERTICAL SHEAR SHOULD
BECOME INCREASINGLY FAVORABLE FOR SEVERE STORMS ACROSS THE PLAINS
REGION WEDNESDAY AND WEDNESDAY NIGHT.

ALTHOUGH AN OUTBREAK OF SEVERE STORMS IS POSSIBLE ACROSS PARTS OF
THE MODERATE RISK AREA FROM LATE WEDNESDAY AFTERNOON THROUGH
WEDNESDAY NIGHT...MANY UNCERTAINTIES REMAIN CONCERNING MOISTURE
RETURN AND THE TIMING OF THE UPPER-LEVEL LOW. THE SHORT-TERM MODELS
APPEAR TO BE TOO QUICK WITH RETURNING LOW-LEVEL MOISTURE NWD INTO
THE PLAINS. ALSO...THE MODELS FROM RUN TO RUN HAVE BEEN CONSISTENTLY
TOO FAST AND TOO FAR NORTH WITH THE UPPER-LOW. FOR THESE
REASONS...THUNDERSTORMS THAT DEVELOP ACROSS THE REGION MAY NOT HAVE
ACCESS TO THE GREATEST MOISTURE UNTIL LATER WEDNESDAY NIGHT AND THIS
COULD LIMIT THE OUTBREAK POTENTIAL.

CONCERNING THE SYNOPTIC SETUP...A SFC LOW SHOULD DEVELOP IN THE HIGH
PLAINS WEDNESDAY WITH THE LOW DEEPENING AND MOVING EWD INTO THE NRN
PLAINS BY WEDNESDAY EVENING. WARM MID-LEVEL TEMPS ASSOCIATED WITH AN
ELEVATED MIXED LAYER WILL LIKELY CAP AREAS SOUTH OF THE SFC LOW
ACROSS WCNTRL NEB AND WCNTRL KS WEDNESDAY AFTERNOON. THUNDERSTORMS
SHOULD DEVELOP WEDNESDAY AFTERNOON FROM THE SFC LOW IN WRN SD NWD
ACROSS ERN MT AND WRN ND. INSTABILITY AND VERTICAL SHEAR ON FORECAST
SOUNDINGS IN THIS AREA SUGGEST CONDITIONS WILL BE FAVORABLE FOR
SUPERCELLS. SUPERCELLS SHOULD HAVE ENOUGH INSTABILITY AND VERTICAL
SHEAR TO PRODUCE TORNADOES...LARGE HAIL AND WIND DAMAGE WEDNESDAY
AFTERNOON WITH THE SEVERE WEATHER THREAT SPREADING EWD ACROSS THE
NRN PART OF THE MODERATE RISK AREA LATE WEDNESDAY AFTERNOON INTO THE
EARLY EVENING. CONSIDERING THE STRONG UNIDIRECTIONAL FLOW AND
RELATIVELY DRY BOUNDARY LAYER IN THE WRN DAKOTAS COUPLED WITH THE
VERY STRONG LARGE-SCALE ASCENT COMING OUT WITH THE TROUGH...AN
ENHANCED POTENTIAL FOR WIND DAMAGE MAY ALSO DEVELOP IF A LINEAR MCS
TRACKS EWD ACROSS SRN ND AND NRN SD FROM LATE WEDNESDAY AFTERNOON
INTO THE EVENING. A SIGNIFICANT TORNADO THREAT MAY ALSO DEVELOP
DURING THE LATE EVENING AND OVERNIGHT PERIOD IN ERN ND...ERN SD AND
WRN MN AS THE MCS TRACKS EWD INTO INCREASING LOW-LEVEL MOISTURE AND
NEW SUPERCELLS INITIATE ON THE SOUTH END OF THE MCS.

THUNDERSTORM DEVELOPMENT ACROSS THE SRN PART OF THE MODERATE RISK
APPEARS MORE CONDITIONAL DUE TO A STRONG CAPPING INVERSION THAT WILL
BE IN PLACE. AS THE LARGE-SCALE ASCENT COMES OUT WITH THE
UPPER-LEVEL TROUGH WEDNESDAY EVENING...THUNDERSTORMS MAY FINALLY
INITIATE ACROSS PARTS OF SERN SD...CNTRL NEB SSWWD ACROSS WCNTRL KS
INTO WEST TX. THUNDERSTORMS SHOULD BE MORE ISOLATED SSWWD ALONG THE
DRYLINE. FORECAST SOUNDINGS ALONG AND JUST EAST OF THE DRYLINE
WEDNESDAY EVENING SHOW VERY STEEP LAPSE RATES...HIGH INSTABILITY AND
STRONG LOW-LEVEL FLOW SUGGESTING LARGE HAIL AND A FEW TORNADOES WILL
BE LIKELY. VERY LARGE HAIL WILL ALSO BE POSSIBLE WITH THE MORE
PERSISTENT SUPERCELLS DURING THE LATE EVENING.

..ERN SD/SE GA AND NERN FL...
THUNDERSTORM DEVELOPMENT APPEARS LIKELY ON SEA BREEZE BOUNDARIES
ALONG THE SRN ATLANTIC SEABOARD WEDNESDAY AFTERNOON AND EVENING.
FORECAST SOUNDINGS ACROSS THIS REGION SHOW NWLY FLOW ALOFT WITH
0-6KM SHEAR VALUES IN THE 30 TO 40 KT RANGE. THIS COMBINED WITH THE
INSTABILITY MAY BE ENOUGH FOR A MARGINAL WIND DAMAGE THREAT MAINLY
LATE WEDNESDAY AFTERNOON AND EARLY WEDNESDAY EVENING.

.BROYLES.. 06/05/2007

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