| 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 021937 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0237 PM CDT TUE AUG 02 2011 VALID 022000Z - 031200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY INTO THE GREAT LAKES REGION... ...UPPER MS VALLEY INTO GREAT LAKES... THE AIR MASS CONTINUES TO DESTABILIZE OVER SERN MN/NRN IA/SRN WI...WHERE THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE NEXT FEW HOURS. FORECAST APPEARS ON TRACK WITH STORMS GROWING UPSCALE AND SURGING SOUTHEASTWARD INTO PARTS OF LWR MI/IL/IND DURING THE EVENING. DAMAGING WINDS APPEAR TO BE THE MAIN THREAT. HOWEVER...SUFFICIENT VERTICAL SHEAR IS PRESENT FOR A RISK OF SUPERCELLS CAPABLE OF LARGE HAIL AND AN ISOLATED TORNADO OR TWO. ...NEW ENGLAND... THE INITIAL BAND OF INTENSE STORMS HAS MOVED OFF THE ME COAST...AHEAD OF MID/UPPER LOW MOVING INTO AREA. RESIDUAL STORMS BENEATH UPPER COLD POOL WILL CONTINUE TO POSE A RISK OF HAIL AND GUSTY WINDS...BUT THE PRIMARY SEVERE THREAT APPEARS TO HAVE PASSED. ..HART.. 08/02/2011 .PREV DISCUSSION... /ISSUED 1112 AM CDT TUE AUG 02 2011/ ...UPPER MS VALLEY/UPPER MIDWEST ACROSS THE GREAT LAKES... A COUPLE OF NOCTURNAL MCSS ARE ONGOING ACROSS WI...AIDED BY ENHANCED INFLOW AT THE TERMINUS OF A 30-40 KT LLJ...AND FORCING ATTENDANT TO MCV NEAR MSP. THIS ACTIVITY MAY UNDERGO SOME DIURNAL WEAKENING LATE THIS MORNING/EARLY AFTERNOON BEFORE REFORMING AND/OR RE-INTENSIFYING FARTHER S/SW ALONG TRAILING OUTFLOW BOUNDARY AND COLD FRONT APPROACHING FROM THE W. WARM SECTOR AIR MASS IS EXPECTED TO BECOME STRONGLY TO EXTREMELY UNSTABLE BY AFTERNOON /I.E. MLCAPE OF 3000-4000 J PER KG/ OWING TO THE PRESENCE OF A MOIST BOUNDARY LAYER AND STRONG DAYTIME HEATING S OF CONVECTIVE CIRRUS CANOPY. WHEN COUPLED WITH 30-40 KT OF DEEP NWLY SHEAR...SETUP WILL FAVOR ORGANIZED STORM MODES...INCLUDING SUPERCELLS AND BOWING STRUCTURES...WITH THE PRIMARY HAZARDS BEING DAMAGING WINDS AND LARGE HAIL. UPSCALE GROWTH INTO A SEWD-MOVING MCS IS ANTICIPATED WITH A CONTINUED THREAT FOR DAMAGING WINDS AND HAIL SPREADING INTO THE OH VALLEY TONIGHT. ...ERN NEW ENGLAND... TSTMS WILL CONTINUE TO INCREASE IN COVERAGE AND INTENSITY THIS AFTERNOON IN ADVANCE OF MIDLEVEL VORTICITY MAXIMUM TRANSLATING SEWD THROUGH VT/NH. 12Z GYX/CHH SOUNDINGS SAMPLED THE PRESENCE OF MODERATE ELEVATED INSTABILITY WITH MUCAPE OF 1500-2000 J/KG. DAYTIME HEATING COMBINED WITH MIDLEVEL COOLING ATTENDANT TO VORTICITY MAXIMUM SHOULD SUPPORT AN INCREASE IN SURFACE-BASED POTENTIAL INSTABILITY WITH MLCAPE VALUES APPROACHING 1000-1500 J/KG BY LATE AFTERNOON. NRN EXTENT OF SLIGHT RISK AREA WILL LIKELY EXPERIENCE MORE DISORGANIZED STORM MODES WITH HAIL BEING THE PRIMARY HAZARD. FARTHER S...THE PRESENCE OF 50+ KT MIDLEVEL JET STREAK ROUNDING LARGE-SCALE UPPER-LOW WILL RESULT IN SUFFICIENT VERTICAL SHEAR FOR SUPERCELLS AND BOWING STRUCTURES WITH RISKS FOR LARGE HAIL AND DAMAGING WINDS. ...MID/LOWER MO VALLEY INTO CNTRL HIGH PLAINS... AN INCREASE IN DIURNAL STORMS IS EXPECTED TODAY ALONG COLD FRONT WITHIN A THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY STEEP LAPSE RATES AND MLCAPE VALUES OF 1500-3000 J/KG. WEAK VERTICAL SHEAR WILL LIMIT STORM ORGANIZATION...THOUGH LOCALLY DAMAGING WIND GUSTS WILL BE POSSIBLE WITH THE MOST INTENSE STORMS. CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z