SWODY1
SPC AC 100552
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1252 AM CDT TUE MAY 10 2011
VALID 101200Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE OH
VALLEY...SRN TO CNTRL APPALACHIAN MTNS AND CAROLINAS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN PLAINS
AND UPPER MS VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NORTHWEST TX...
...OH VALLEY/SRN APPALACHIAN MTNS/CAROLINAS...
AN UPPER-LEVEL RIDGE WILL BE IN PLACE TODAY ACROSS THE MS VALLEY
WITH NNWLY FLOW LOCATED ACROSS THE UPPER OH VALLEY...SRN TO CNTRL
APPALACHIAN MTNS AND CAROLINAS. SEVERAL MODEL FORECASTS SUGGEST A
SUBTLE SHORTWAVE TROUGH WILL MOVE SEWD ACROSS THE REGION. THIS ALONG
WITH WARMING SFC TEMPS...SHOULD RESULT IN SCATTERED THUNDERSTORM
INITIATION FROM ERN KY SEWD ACROSS THE CAROLINAS. SFC DEWPOINTS IN
THE LOWER 60S F SHOULD ENABLE MODERATE TO STRONG INSTABILITY TO
DEVELOP WHICH ALONG WITH SUBSTANTIAL DIRECTIONAL SHEAR SHOULD BE
FAVORABLE FOR SEVERE THUNDERSTORM DEVELOPMENT.
FORECAST SOUNDINGS ACROSS WRN NC AND CNTRL SC AT 00Z WEDNESDAY SHOW
MLCAPE VALUES FROM 2000 TO 3000 J/KG WITH ABOUT 50 KT OF DEEP LAYER
SHEAR. THIS ENVIRONMENT ALONG WITH 700 TO 500 MB LAPSE RATES AROUND
8.0 C/KM SHOULD BE SUPPORTIVE OF SUPERCELL DEVELOPMENT WITH A THREAT
FOR LARGE HAIL. SUPERCELLS THAT HAVE ACCESS TO LOCALLY ENHANCED
INSTABILITY MAY ALSO HAVE AN ISOLATED THREAT FOR TORNADOES AND HAIL
STONES GREATER THAN 2 INCHES IN DIAMETER. A WIND DAMAGE THREAT MAY
ALSO DEVELOP ESPECIALLY IF LINE-SEGMENTS BECOME THE FAVORED STORM
MODE. AT THIS POINT...MODEL FORECASTS DIFFER ON CONVECTIVE COVERAGE
WITH THE GFS BEING THE MOST AGGRESSIVE SOLUTION. THE GFS APPEARS
REASONABLE AND HAVE CONTINUED AN ENHANCED THREAT FOR WIND DAMAGE IN
WRN NC AND CNTRL SC WHERE THE LOW-LEVEL FLOW AND DEEP LAYER SHEAR IS
FORECAST TO BE THE STRONGEST.
...NRN PLAINS/UPPER-MS VALLEY...
SOUTH SOUTHWEST FLOW WILL BE IN PLACE ACROSS THE GREAT PLAINS AND
UPPER MS VALLEY TODAY AS A 55 TO 70 KT MID-LEVEL JET MOVES NEWD INTO
THE NRN PLAINS. THIS FEATURE WILL HELP TO CREATE STRONG DEEP LAYER
SHEAR ACROSS THE NRN PLAINS AND UPPER MS VALLEY WHERE SCATTERED
THUNDERSTORMS ARE FORECAST TO DEVELOP. STORM INITIATION WILL MOST
LIKELY OCCUR LATE THIS AFTERNOON ON THE NOSE OF THE MID-LEVEL JET IN
ERN ND AND NW MN. THE MODELS ARE ALSO IN AGREEMENT THAT SCATTERED
THUNDERSTORMS WILL ALSO INITIATE SSEWD ALONG THE INSTABILITY AXIS
FROM CNTRL MN TO NERN IA BY EARLY EVENING.
FORECAST SOUNDINGS ALONG THIS CORRIDOR AT 00Z WEDNESDAY SHOW MLCAPE
VALUES RANGING FROM 2000 J/KG IN NRN MN TO AROUND 4500 J/KG IN NRN
IA WITH DEEP LAYER SHEAR DECREASING WITH SEWD EXTENT. THE
COMBINATION OF SHEAR AND INSTABILITY SHOULD EASILY SUPPORT A LARGE
HAIL THREAT ESPECIALLY WITH SUPERCELLS THAT DEVELOP. A WIND DAMAGE
THREAT MAY ALSO DEVELOP ESPECIALLY IF A STORM CLUSTER CAN PERSIST
INTO THE EARLY TO MID EVENING WITH LOW-LEVEL FLOW IS FORECAST TO
STRENGTHEN.
...NORTHWEST TX...
A HIGH-AMPLITUDE UPPER-LEVEL TROUGH WILL MOVE SLOWLY EWD ACROSS THE
FOUR CORNERS REGION TODAY AS LOW-LEVEL FLOW INCREASES ACROSS THE SRN
PLAINS. A LARGE CORRIDOR OF MODERATE INSTABILITY WILL BE IN PLACE BY
MIDDAY WITH A RETREATING DRYLINE SHIFTING NWWD INTO NORTHWEST TX
DURING THE AFTERNOON. SEVERE THUNDERSTORM DEVELOPMENT MAY OCCUR IN
NORTHWEST TX ON THE ERN EDGE OF A 50 TO 65 KT MID-LEVEL JET. THE
MID-LEVEL JET WILL HELP TO CREATE MODERATE DEEP LAYER SHEAR WHICH
COMBINED WITH THE INSTABILITY AND VERY STEEP LAPSE RATES SHOULD BE
SUFFICIENT FOR SUPERCELL DEVELOPMENT. A LARGE HAIL THREAT MAY EXIST
IN THE LATE AFTERNOON AND EARLY EVENING AS THE LOW-LEVEL JET BECOMES
BETTER DEFINED HELPING TO SUPPORT CONVECTIVE INITIATION. AT THIS
POINT...THE MODELS KEEP CONVECTIVE DEVELOPMENT ISOLATED SUGGESTING
THE SEVERE THREAT SHOULD REMAIN CONFINED TO THE LOW ROLLING PLAINS
WHERE A NARROW SLIGHT RISK HAS BEEN OUTLOOKED.
..BROYLES/STOPKOTTE.. 05/10/2011
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