DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 180601
SWODY2
SPC AC 180559

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT WED APR 18 2007

VALID 191200Z - 201200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...
WHILE CYCLONIC FLOW ALOFT OVER THE ERN CONUS WILL CONTINUE TO SHIFT
EWD INTO THE ATLANTIC...LARGE/COMPLEX UPPER TROUGH WILL CONTINUE TO
INTENSIFY/EXPAND OVER THE WEST. A NEGATIVELY-TILTED SHORT-WAVE
TROUGH WITHIN THE EVOLVING LARGER-SCALE TROUGH WILL CONTINUE TO BE
SHUNTED NEWD ACROSS THE NRN PLAINS...AS IT IMPINGES ON THE RIDGE
OVER THE PLAINS. MEANWHILE...A SECOND/STRONGER SHORT-WAVE FEATURE
SHOULD MOVE RAPIDLY SSEWD ALONG THE W COAST.

AT THE SURFACE...LEE TROUGH IS FORECAST TO MOVE EWD INTO THE PLAINS
AND WEAKEN WITH TIME...BUT STILL MAY PROVIDE A FOCUS FOR SCATTERED
AFTERNOON STORMS.

..NRN PLAINS SEWD INTO THE MID MO VALLEY/KS/NRN OK...
SHOWERS AND A FEW THUNDERSTORMS SHOULD BE ONGOING AT THE START OF
THE PERIOD AHEAD OF LEE TROUGH/SHORT-WAVE UPPER FEATURE OVER THE NRN
HIGH PLAINS AND VICINITY. THIS CONVECTION SHOULD CONTINUE MOVING
EWD THROUGH THE DAY...LIKELY REMAINING WEAK DUE TO LIMITED
INSTABILITY.

FURTHER S...INSTABILITY SHOULD INCREASE...THOUGH SUBSIDENCE/CAPPING
WILL LIKEWISE INCREASE WITH SWD EXTENT WHERE THE UPPER RIDGE WILL
PREVAIL.

ATTM...IT APPEARS THAT SOMEWHERE BETWEEN THE STRONGER UVV TO THE N
AND STRONGER CAP TO THE S...A SMALL ZONE OF SUFFICIENT INSTABILITY
AND A WEAKENING CAP ON THE SRN FRINGES OF THE UPPER FEATURE MAY
ALLOW A FEW AFTERNOON STORMS TO DEVELOP -- MOST LIKELY ACROSS
CENTRAL AND ERN KS. WITH 500 J/KG MEAN-LAYER CAPE AND 40 TO 50 KT
DEEP-LAYER SHEAR...A FEW STRONGER/POSSIBLY-ROTATING STORMS MAY
EVOLVE. GIVEN CAP ISSUES AND LIKELIHOOD THAT STORMS WILL REMAIN
ISOLATED...WILL INTRODUCE ONLY 5% SEVERE PROBABILITY ATTM.
CONVECTION/SEVERE THREAT SHOULD DECREASE INTO THE EVENING WITH THE
ONSET OF DIURNAL STABILIZATION.

.GOSS.. 04/18/2007

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