SWODY2
SPC AC 101724
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1224 PM CDT SUN AUG 10 2008
VALID 111200Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL HIGH
PLAINS...CNTRL PLAINS AND NRN PLAINS...
...CNTRL HIGH PLAINS/CNTRL AND NRN PLAINS...
THE UPPER-LEVEL RIDGE OVER THE HIGH PLAINS IS FORECAST TO QUICKLY
BREAK DOWN TONIGHT AS AN UPPER-LEVEL TROUGH MOVES EWD ACROSS THE NRN
AND CNTRL PLAINS MONDAY. AT THE SFC...A COLD FRONT WILL ADVANCE SEWD
ACROSS THE CNTRL HIGH PLAINS. SOUTH AND EAST OF THE BOUNDARY...MODEL
FORECASTS DEVELOP MODERATE INSTABILITY ALONG AN AXIS FROM ERN CO AND
WRN KS NWD INTO WRN AND CNTRL NEB BY AFTERNOON. THUNDERSTORMS APPEAR
LIKELY TO DEVELOP ALONG THE AXIS OF THE LOW-LEVEL JET OVER CNTRL AND
ERN NEB BY MIDDAY WITH OTHER STORMS INITIATING ALONG THE COLD FRONT
DURING THE EARLY TO MID AFTERNOON. CONVECTIVE COVERAGE SHOULD EXPAND
SWD AS STORMS ALSO INITIATE ALONG THE INSTABILITY AXIS IN THE
AFTERNOON. MCS DEVELOPMENT MAY OCCUR DURING THE EVENING AS SUGGESTED
BY THE NAM AND NAMKF SOLUTIONS.
CONCERNING THE SEVERE POTENTIAL...FORECAST SOUNDINGS ALONG THE
INSTABILITY AXIS AT 21Z SHOW 30 TO 40 KT OF VERTICAL SHEAR
ASSOCIATED WITH STRONGLY VEERING WINDS WITH HEIGHT IN THE LOW LEVELS
AND SPEED SHEAR IN THE MID-LEVELS. THIS ALONG WITH 850 TO 500 MB
LAPSE RATES EXCEEDING 7.5 C/KM SHOULD BE SUFFICIENT FOR SUPERCELLS
WITH ISOLATED LARGE HAIL. THE HAIL THREAT SHOULD BE GREATEST WITH
SUPERCELLS THAT REMAIN DISCRETE. LINEAR CONVECTION WILL ALSO BE
POSSIBLE ESPECIALLY AS LOW-LEVEL FLOW INCREASES AND CONVECTION
CONGEALS IN THE EARLY EVENING. IF THIS OCCURS...AN ISOLATED WIND
DAMAGE THREAT WOULD BE POSSIBLE AS WELL. NUMEROUS THUNDERSTORMS
SHOULD ALSO DEVELOP ALONG THE BOUNDARY FURTHER NORTH ACROSS CNTRL ND
BUT THE SEVERE THREAT SHOULD REMAIN MARGINAL DUE TO WEAKER VERTICAL
SHEAR.
...SRN PLAINS...
NORTHWEST FLOW WILL CONTINUE ACROSS THE SRN PLAINS MONDAY AS AN
UPPER-LEVEL TROUGH MOVES EWD INTO THE CNTRL PLAINS. THE SRN FRINGE
OF THIS FEATURE MAY AFFECT THE SRN PLAINS ALTHOUGH FLOW SHOULD
REMAIN RELATIVELY WEAK. BY MIDDAY ON MONDAY...MODEL FORECASTS
DEVELOP AN AXIS OF MODERATE INSTABILITY ALONG AND SOUTH OF A COLD
FRONT FROM WEST TX EWD INTO THE ARKLATEX. SCATTERED TO NUMEROUS
THUNDERSTORMS APPEAR LIKELY TO DEVELOP ALONG THE FRONT AS SFC TEMPS
WARM EARLY MONDAY AFTERNOON WITH CONVECTIVE COVERAGE PEAKING NEAR
MAX HEATING. FORECAST SOUNDINGS NEAR THE BOUNDARY AT 21Z MONDAY
GENERALLY SHOW 20 TO 30 KTS OF VERTICAL SHEAR MOSTLY DUE TO AN
ABRUPT WIND DIRECTION CHANGE AROUND 850 MB. THIS SUGGESTS AN
ORGANIZED SEVERE THREAT WILL BE UNLIKELY. HOWEVER...THE STRONGER
MULTICELLS MAY PRODUCE STRONG GUSTY WINDS CONSIDERING THE AMOUNT OF
INSTABILITY AS LOW-LEVEL LAPSE RATES STEEPEN MONDAY AFTERNOON. HAIL
MAY ALSO OCCUR WHERE CELLS HAVE ACCESS TO LOCALLY MAXIMIZED
INSTABILITY.
...DELAWARE RIVER VALLEY/SRN NEW ENGLAND...
AN UPPER-LEVEL LOW WILL MOVE SEWD ACROSS THE CNTRL APPALACHIANS
TONIGHT INTO THE MID-ATLANTIC MONDAY. AT THE SFC...A LOW WILL BE IN
PLACE JUST SOUTH OF LONG ISLAND. SCATTERED THUNDERSTORMS WILL LIKELY
BE ONGOING IN THE NRN QUADRANT OF THE LOW EARLY IN THE PERIOD WITH
CONVECTIVE COVERAGE INCREASING BY AFTERNOON. ALTHOUGH FORECAST
SOUNDINGS SUGGEST VERTICAL SHEAR WILL BE RELATIVELY WEAK /0-6 KM
SHEAR VALUES AROUND 20 KT/ COLD AIR ALOFT NEAR THE CORE OF THE
UPPER-LEVEL LOW WITH 500 MB TEMPS AROUND -18C COMBINED WITH SFC
HEATING MAY BE ENOUGH FOR A HAIL THREAT EARLY MONDAY AFTERNOON.
..BROYLES.. 08/10/2008
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