SWODY2
SPC AC 060546
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CDT THU MAY 06 2010
VALID 071200Z - 081200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF THE OH VALLEY INTO
LOWER GREAT LAKES...
...SYNOPSIS...
THE PRIMARY FEATURE OF INTEREST DURING THE DAY TWO PERIOD WILL BE A
POWERFUL MIDLEVEL TROUGH TRANSLATING FROM THE NRN PLAINS/UPPER MS
VALLEY EWD ACROSS THE GREAT LAKES REGION. THIS SYSTEM WILL BE
ATTENDED BY A MIDLEVEL JET STREAK WHICH WILL INTENSIFY TO 80-100
KT...AS WELL AS A CONCENTRATED ZONE OF HEIGHT FALLS OF 120-150 M/12
HRS.
AT THE SURFACE...THE CYCLONE ASSOCIATED WITH THE UPPER SYSTEM
INITIALLY OVER CNTRL OR NERN MO WILL UNDERGO SLIGHT DEEPENING WHILE
DEVELOPING NEWD INTO UPSTATE NY BY SATURDAY MORNING. THIS LOW WILL
BE PRECEDED BY A WARM FRONT LIFTING NWD THROUGH THE UPPER OH VALLEY
AND MID ATLANTIC STATES...WHILE TRAILING COLD FRONT PUSHES EWD/SEWD
THROUGH THE OH AND TN VALLEYS.
...OH VALLEY INTO LOWER GREAT LAKES...
06/00Z MESOSCALE MODEL GUIDANCE REMAINS SUGGESTIVE THAT A MODESTLY
MOIST BOUNDARY LAYER WILL EXIST AHEAD OF COLD FRONT WITH DEW POINTS
IN THE 50S...TO PERHAPS LOW 60S WITHIN IMMEDIATE FRONTAL ZONE. THIS
MOISTURE COUPLED WITH AFTERNOON TEMPERATURES IN THE MID 70S TO
LOWER/MID 80S WILL CONTRIBUTE TO A MODERATELY UNSTABLE AIR MASS WITH
MLCAPE OF 1000-1500 J/KG.
SURFACE-BASED TSTM DEVELOPMENT IS EXPECTED BY MID/LATE AFTERNOON
INITIALLY INVOF SURFACE LOW WHERE LOW-LEVEL CONVERGENCE WILL BE THE
STRONGEST. SUBSEQUENT STORM FORMATION WILL LIKELY OCCUR SWWD ALONG
THE COLD FRONT AS THE STRONGER HEIGHT FALLS/DYNAMIC FORCING FOR
ASCENT ASSOCIATED WITH THE MIDLEVEL TROUGH BEGIN TO OVERSPREAD THE
WARM SECTOR. GIVEN THE COMPACT NATURE OF THE UPPER SYSTEM AND THE
PRESENCE OF AN EML AND ASSOCIATED CAP TO IT/S SOUTH...THERE IS SOME
QUESTION HOW FAR S OF THE OH RIVER DIURNAL STORMS WILL FORM.
WARM SECTOR FORECAST HODOGRAPHS INDICATE A STEADILY STRENGTHENING
SWLY-WLY WIND FIELD THROUGH THE DAY WITH 50+ KT FLOW DESCENDING TO 2
KM AGL. WHEN COUPLED WITH THE MODERATE INSTABILITY...THE
ENVIRONMENT WILL FAVOR THE DEVELOPMENT OF SUPERCELLS AND BOWING
STRUCTURES WITH EVENTUAL UPSCALE GROWTH INTO A LINEAR CONVECTIVE
SYSTEM. THE GREATEST TORNADO THREAT WILL BE WITH ANY SUPERCELLS
DEVELOPING ALONG THE SURFACE LOW TRACK WHERE ISALLOBARICALLY BACKED
WINDS WILL ENHANCE LOW-LEVEL SHEAR. OTHERWISE...THE SETUP SUGGESTS
THE POTENTIAL FOR CORRIDORS OF WIND DAMAGE AND SOME HAIL WHICH MAY
CONTINUE INTO FRIDAY NIGHT ACROSS PARTS OF NY AND PA.
ISOLATED SEVERE STORMS /LIKELY ELEVATED AND CAPABLE OF SOME HAIL/
MAY CONTINUE THROUGH FRIDAY NIGHT AS FAR E AS THE MID ATLANTIC
COAST/SRN NEW ENGLAND. HERE...ACTIVITY WILL BE DRIVEN BY
ASCENT/MOISTURE FLUX OCCURRING ALONG THE LLJ AXIS...TO THE N/E OF
RETREATING SURFACE WARM FRONT.
..MEAD.. 05/06/2010
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