SPC AC 160600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT WED JUN 16 2010
VALID 161200Z - 171200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN AND
CNTRL HIGH PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL
APPALACHIAN MTNS AND MID-ATLANTIC...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CAROLINAS
AND ERN GULF COAST STATES...
...NRN AND CNTRL HIGH PLAINS/SRN PLAINS...
AN UPPER-LEVEL LOW AND ASSOCIATED TROUGH WILL MOVE SEWD ACROSS THE
PACIFIC NORTHWEST AND INTERMOUNTAIN WEST AS A 60 TO 75 KT MID-LEVEL
JET ROUNDS THE BASE OF THE TROUGH. THE EXIT REGION OF THE JET WILL
OVERSPREAD A MODERATELY UNSTABLE AIRMASS ACROSS THE NRN ROCKIES AND
NRN HIGH PLAINS WITH SCATTERED THUNDERSTORMS INITIATING THIS
AFTERNOON FROM CNTRL/ERN MT SEWD ACROSS NRN/ERN WY INTO SWRN SD AND
WRN NEB. SEVERAL CLUSTERS OF STORMS APPEAR LIKELY TO ORGANIZE ON THE
NRN END OF THIS CORRIDOR. ON THE SRN END IN WRN NEB...STORM COVERAGE
IS MORE UNCERTAIN DUE TO MODEL VARIANCE AND WARM AIR ALOFT WHICH
COULD KEEP CONVECTION RELATIVELY ISOLATED.
CONCERNING THE SEVERE THREAT...THE EXIT REGION OF THE MID-LEVEL JET
WILL CREATE MODERATE TO STRONG DEEP LAYER SHEAR PROFILES ACROSS THE
WRN EDGE OF THE SLIGHT RISK AREA WHICH ALONG WITH VERY STEEP
MID-LEVEL LAPSE RATES WILL BE FAVORABLE FOR SUPERCELLS WITH LARGE
HAIL. THE MORE DOMINANT SUPERCELLS SHOULD BE CAPABLE OF PRODUCING
ISOLATED VERY LARGE HAIL AND A COUPLE TORNADOES FROM SE MT SEWD INTO
WRN SD WHERE THE HIGHEST PROBABILITY OF SCATTERED STORM COVERAGE
COINCIDES WITH A STRONG INSTABILITY/SHEAR COMBINATION. MCS
DEVELOPMENT APPEARS MOST LIKELY ACROSS ERN MT WHERE LARGE-SCALE
ASCENT SHOULD BE GREATEST WITH THE UPPER-LEVEL TROUGH. IF AN MCS CAN
ORGANIZE...THEN A WIND DAMAGE POTENTIAL WOULD EXIST WITH ANY
LINE-SEGMENT.
FURTHER SSEWD ACROSS THE CNTRL HIGH PLAINS STORM COVERAGE SHOULD BE
INCREASINGLY ISOLATED INTO WRN KS...FAR ERN CO AND THE TX PANHANDLE.
MODERATE INSTABILITY SHOULD BE PRESENT ACROSS THE CORRIDOR BY LATE
AFTERNOON WITH ETA-KF FORECAST SOUNDINGS SHOWING 30 TO 40 KT OF DEEP
LAYER SHEAR. THIS ALONG WITH STEEP MID-LEVEL LAPSE RATES SHOULD BE
SUFFICIENT FOR SUPERCELLS AND LARGE HAIL BUT WITH VERY ISOLATED
COVERAGE. FOR THIS REASON...WILL NOT OUTLOOK A SLIGHT IN WRN KS AND
TX PANHANDLE ATTM.
...CNTRL APPALACHIAN MTNS/MID-ATLANTIC...
A WELL-FOCUSED UPPER-LEVEL TROUGH OVER THE GREAT LAKES REGION WILL
MOVE EWD INTO THE CNTRL APPALACHIAN MTNS TODAY. AT THE SFC...A COLD
FRONT WILL MOVE EWD ACROSS THE OH VALLEY WITH STORMS DEVELOPING
ALONG THE FRONT AND MOVING INTO SRN NY AND CNTRL PA LATE THIS
AFTERNOON. ETA-KF FORECAST SOUNDINGS ALONG THE MOIST AXIS IN CNTRL
PA AT 00Z SHOW 0-6 KM SHEAR VALUES AROUND 40 KT ALONG WITH STRONG
DIRECTIONAL SHEAR IN THE LOW-LEVELS SUGGESTING A SUPERCELL AND
ISOLATED TORNADO THREAT MAY DEVELOP. LARGE HAIL WOULD BE POSSIBLE
WITH ANY SUPERCELLS. HOWEVER...THE DOMINANT STORM MODE REMAINS
UNCERTAIN AND A BOWING LINE-SEGMENT WILL ALSO BE POSSIBLE AS THE
FRONT MOVES QUICKLY EWD. IF A LINEAR MCS CAN DEVELOP...THEN AN
ENHANCED WIND DAMAGE THREAT COULD OCCUR ACROSS PARTS OF CNTRL AND
ERN PA SWD INTO NRN MD.
...CAROLINAS AND ERN GULF COAST STATES...
A VERY MOIST AIRMASS WILL AGAIN BE IN PLACE ACROSS THE CAROLINAS
EXTENDING SWWD INTO GA AND ERN AL THIS AFTERNOON. SFC DEWPOINTS IN
THE LOWER TO MID 70S F SHOULD YIELD STRONG INSTABILITY WITH MLCAPE
VALUES IN THE 2000 TO 3000 J/KG RANGE. SCATTERED TO NUMEROUS
THUNDERSTORMS SHOULD INITIATE IN A WEAKLY SHEARED ENVIRONMENT BY
EARLY TO MID-AFTERNOON WHEN LOW-LEVEL LAPSE RATES WILL BE VERY
STEEP. THIS COMBINATION OF PARAMETERS SHOULD BE FAVORABLE FOR SEVERE
PULSE STORMS WITH WET DOWNBURSTS POTENTIAL. THE THREAT APPEARS TO BE
GREAT ENOUGH TO WARRANT A SLIGHT RISK FROM NC SSWWD INTO SRN/CNTRL
GA...SE AL AND THE NRN FL PANHANDLE.
..BROYLES/GARNER.. 06/16/2010
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