| Categorical Graphic |
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| Probabilistic Tornado Graphic |
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| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
| Probabilistic Damaging Wind Graphic |
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| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
| Probabilistic Large Hail Graphic |
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
SPC AC 291642
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1142 AM CDT TUE MAY 29 2012
VALID 291630Z - 301200Z
...THERE IS A MDT RISK OF SVR TSTMS CNTRL/ERN NY...EXTREME W CNTRL
VT AND N CNTRL/NERN PA...
...THERE IS A SLGT RISK OF SVR TSTMS UPPER OH VALLEY AND MID
ATLANTIC STATES INTO MOST OF NEW ENGLAND...
...THERE IS A SLGT RISK OF SVR TSTMS CNTRL/SRN PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS FL/ERN GA/SRN SC/NC...
...SYNOPSIS...
AN UPPER-LEVEL LOW ALONG THE MN/ONTARIO BORDER WILL GRADUALLY EVOLVE
INTO AN OPEN WAVE DURING THE D1 PERIOD AS IT PROGRESSES ENEWD INTO
WRN QUEBEC. THIS SYSTEM WILL BE ATTENDED BY A BELT OF 50-60 KT
MIDLEVEL FLOW AND 500-MB HEIGHT FALLS OF 60-120 M/12-HR WHICH WILL
OVERSPREAD THE ST. LAWRENCE VALLEY...LOWER GREAT LAKES...AND NEW
ENGLAND. ELSEWHERE...MIDLEVEL HEIGHTS WILL REBOUND SLIGHTLY ACROSS
THE GREAT PLAINS IN THE WAKE OF THE GREAT LAKES SYSTEM...AND AHEAD
OF AN UPSTREAM UPPER SHORT-WAVE TROUGH TRANSLATING SEWD FROM SRN
BRITISH COLUMBIA THROUGH THE NRN ROCKIES.
AT THE SURFACE...A COLD FRONT INITIALLY FROM LOW PRESSURE OVER WRN
QUEBEC SWWD THROUGH SWRN ONTARIO INTO THE MID-MS VALLEY WILL ADVANCE
EWD INTO NEW ENGLAND AND THE MID-ATLANTIC STATES BY 30/12Z. THE WRN
EXTENSION OF THIS BOUNDARY WILL REMAIN QUASI-STATIONARY...STRETCHING
FROM THE OZARKS WWD TO AN AREA OF LOW PRESSURE OVER WRN OK AT
30/00Z. A DRYLINE IS FORECAST TO EXTEND SWD FROM THE LOW PRESSURE
INTO W-CNTRL TX AND WRN PARTS OF THE EDWARDS PLATEAU REGION AT THIS
TIME. MEANWHILE...TROPICAL DEPRESSION BERYL WILL BEGIN TO
ACCELERATE NEWD FROM S-CNTRL GA THROUGH THE LOWER SAVANNAH RIVER
VALLEY.
...NEW ENGLAND INTO THE LOWER GREAT LAKES AND MID-ATLANTIC STATES...
AN EXPANSIVE PRE-FRONTAL BAND OF TSTMS IS ONGOING ACROSS PORTIONS OF
WRN NY INTO THE KY/TN VALLEYS...FORCED BY THE LEADING EDGE OF
STRONGER HEIGHT FALLS ASSOCIATED WITH THE UPPER SYSTEM MOVING
THROUGH THE GREAT LAKES. AREAS OF CLEARING ACROSS MUCH OF THE
NORTHEAST HAVE LED TO AMPLE SURFACE-BASED DESTABILIZATION. LITTLE IF
ANY CONVECTIVE INHIBITION REMAINS GIVEN THE VERY WEAK LOW LEVEL
INVERSION NOTED ON THE 12Z BUF AND ALBANY SOUNDINGS. DEW POINTS IN
THE 60S TO LOWER 70S F COUPLED WITH MIDLEVEL LAPSE RATES AROUND 7
C/KM WILL CONTRIBUTE TO A MODERATELY-STRONGLY UNSTABLE AIR MASS WITH
MLCAPE VALUES INCREASING TO 2000-3000 J/KG. THIS DESTABILIZATION
ALONG WITH THE EWD PROGRESSION OF THE UPPER TROUGH WILL SUPPORT A
MARKED INCREASE IN STORM VIGOR AND COVERAGE BY EARLY AFTERNOON ALONG
THE COLD FRONT AND/OR LEADING EDGE OF THE COLD POOL ASSOCIATED WITH
THE ONGOING STORMS. ADDITIONAL DEVELOPMENT IS POSSIBLE ALONG A
REMNANT OUTFLOW BOUNDARY ACROSS THE MOHAWK VALLEY...AND A
PRE-FRONTAL TROUGH OVER ERN NY/PA.
ALTHOUGH THE STRONGEST MID- AND HIGH-LEVEL WIND FIELD ASSOCIATED
WITH THE TROUGH IS FORECAST TO LAG THE WARM SECTOR TO THE W...LOW
LEVEL WINDS WILL STRENGTHEN SOME ACROSS ERN NY AND WRN NEW ENGLAND.
SHEAR PROFILES WILL BE SUFFICIENT FOR DMGG WINDS AND POTENTIALLY
SUPERCELLS...ESPECIALLY INVOF THE HUDSON VALLEY. A TORNADO THREAT
WILL ALSO EXIST ALONG THE WARM FRONT OVER PORTIONS OF NEW ENGLAND
WHERE LOW-LEVEL SHEAR WILL BE ENHANCED.
THE SEVERE WEATHER THREAT WILL SPREAD EWD TOWARD THE MID-ATLANTIC
COAST AND WRN NEW ENGLAND BY LATE AFTERNOON INTO THIS EVENING BEFORE
GRADUALLY DIMINISHING LATER TONIGHT WITH THE STABILIZATION OF THE
BOUNDARY LAYER.
...CNTRL/SRN PLAINS...
AS MENTIONED ABOVE...MIDLEVEL HEIGHTS WILL REBOUND SLIGHTLY TODAY
WITH PASSAGE OF SYNOPTIC SYSTEM TO THE NE. AS SUCH...DAYTIME
HEATING AND LOW-LEVEL CONVERGENCE ALONG STATIONARY FRONT AND DRYLINE
WILL BE THE PRIMARY MECHANISMS FORCING TSTM DEVELOPMENT THIS
AFTERNOON. LATEST CONVECTION-ALLOWING AND MESOSCALE MODEL GUIDANCE
INDICATE THAT THE HIGHEST PROBABILITY OF STORM INITIATION WILL BE
ALONG FRONT OVER SRN KS/NRN OK BETWEEN 29/21Z-30/00Z. OTHER ISOLATED
STORMS WILL BE POSSIBLE AT THIS TIME SWWD ALONG THE DRYLINE INTO
W-CNTRL TX.
THE COMBINATION OF STRONG DAYTIME HEATING...BOUNDARY LAYER DEWPOINTS
IN THE 60S...AND STEEP MIDLEVEL LAPSE RATES ARE EXPECTED TO YIELD A
MODERATE-STRONGLY UNSTABLE AIR MASS BY MID-LATE AFTERNOON WITH
MLCAPE VALUES OF 2000-3500 J/KG. WHEN COUPLED WITH A VERTICALLY
VEERING WIND PROFILE AND 40-50 KT OF EFFECTIVE BULK SHEAR...SETUP
WILL BE QUITE FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE HAIL
AND PERHAPS A COUPLE TORNADOES WITHIN THE FIRST FEW HOURS AFTER
STORM INITIATION. WITH TIME...CONVECTION-ALLOWING MODEL GUIDANCE IS
SUGGESTIVE OF UPSCALE GROWTH INTO A SEWD-MOVING BOW ECHO SYSTEM
WHICH WOULD SIGNAL A TRANSITION TO A MORE WIDESPREAD DAMAGING WIND
THREAT ACROSS PORTIONS OF OK...PERHAPS INTO NRN TX TONIGHT.
...FL/ERN GA/SRN SC/NC...
THE COMBINATION OF A MOIST BOUNDARY LAYER AND BREAKS IN CLOUD COVER
WILL YIELD POCKETS OF MODEST DESTABILIZATION TODAY INVOF BERYL.
GIVEN A STILL MODESTLY STRONG WIND FIELD...A LOW PROBABILITY RISK
FOR DMGG WINDS AND A TORNADO WILL CONTINUE THROUGH THIS AFTERNOON.
SEVERAL WEAKER CIRCULATIONS WERE NOTED ACROSS SC THIS MORNING. THIS
EVENING INTO TONIGHT...BERYL IS EXPECTED TO DRIFT UP THE
COAST...WITH LOW LEVEL VEERING ALONG THE CAROLINA COAST LATE IN THE
PERIOD. AN ISOLATED TORNADO REMAINS POSSIBLE AFTER DARK.
..WEISS/HURLBUT.. 05/29/2012
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z