SPC AC 210818
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0218 AM CST WED FEB 21 2007
VALID 231200Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NRN
TX...OK...KS AND CNTRL NEB...
...GREAT PLAINS...
AN IMPRESSIVE UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS THE WRN U.S.
FRIDAY CLOSING OFF OVER THE SCNTRL ROCKIES FRIDAY NIGHT. AHEAD OF
THE UPPER-LEVEL SYSTEM...A VERY STRONG 70 KT LOW-LEVEL JET WILL
DEVELOP IN THE SRN PLAINS AND A MOIST AXIS WILL SET UP FROM NW TX
EXTENDING NWD ACROSS WRN OK INTO WCNTRL KS FRIDAY AFTERNOON. SFC
DEWPOINTS BY LATE FRIDAY AFTERNOON SHOULD REACH THE 55 TO 58 F RANGE
ALLOWING FOR POCKETS OF MODERATE INSTABILITY JUST EAST OF A
WELL-DEFINED DRYLINE. ALTHOUGH PARTS OF THE MOIST AXIS MAY REMAIN
CAPPED FRIDAY AFTERNOON...SOME THUNDERSTORM ACTIVITY SHOULD INITIATE
BY LATE AFTERNOON OR EARLY EVENING ON FRIDAY ACROSS WRN OK AND THE
LOW-ROLLING PLAINS OF NORTHWEST TX. ONCE CONVECTION
INITIATES...SUPERCELL DEVELOPMENT SHOULD QUICKLY OCCUR DUE TO STRONG
VERTICAL SHEAR OF 60-70 KT. IN ADDITION...STORM DEVELOPMENT WILL BE
AIDED BY VERY STRONG DYNAMICS ASSOCIATED WITH THE EXIT REGION OF AN
EJECTING 100 KT MID-LEVEL JET.
FORECAST SOUNDINGS ACROSS NW TX AND WRN OK LATE FRIDAY AFTERNOON
SHOW CLASSIC LOADED-GUN TYPE SOUNDINGS WITH 0-3 KM SRH INCREASING TO
ABOVE 500 M2/S2 DURING THE EVENING. THIS SUGGESTS SUPERCELLS WILL BE
CAPABLE OF PRODUCING TORNADOES. THIS COMBINED WITH 0-1 KM SHEAR
VALUES EXCEEDING 30 KT WILL MAKE STRONG TORNADOES A POSSIBILITY
FRIDAY EVENING...SHOULD STRONG CAPPING BE OVERCOME. VERY LARGE HAIL
AND WIND DAMAGE WILL ALSO BE POSSIBLE WITH SUPERCELLS THAT DEVELOP.
A BROKEN LINE OF SUPERCELLS AND/OR BOW ECHOES SHOULD MOVE EWD ACROSS
WCNTRL KS...CNTRL OK AND NRN TX DURING THE OVERNIGHT PERIOD.
SQUALL-LINE DEVELOPMENT APPEARS LIKELY AND SEVERE STORMS COULD OCCUR
AS FAR EAST AS ERN OK/ECNTRL KS/NERN TX LATE IN THE PERIOD. ALSO...A
FEW SEVERE STORMS COULD OCCUR IN CNTRL NEB BUT THIS WILL DEPEND ON
THE AMOUNT OF MOISTURE RETURN THAT TAKES PLACE IN THE CNTRL PLAINS
FRIDAY. IF MOISTURE RETURN ENDS UP BEING STRONGER THAN FORECAST...AN
UPGRADE MAY BECOME NECESSARY IN LATER OUTLOOKS.
..BROYLES.. 02/21/2007
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z
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