Mar 12, 2012 1300 UTC Day 1 Convective Outlook | |
Updated: Mon Mar 12 12:57:25 UTC 2012 | |
Probabilistic to Categorical Outlook Conversion Table |
Categorical Graphic |
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Probabilistic Tornado Graphic |
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 |
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 |
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 121254 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0754 AM CDT MON MAR 12 2012 VALID 121300Z - 131200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF LWR MI AND ADJACENT PARTS OF THE MIDWEST... ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR MS AND LWR TN VLYS... ...SYNOPSIS... IA UPR LOW EXPECTED TO CONTINUE NE TO LK SUPERIOR BY THIS EVE...BEFORE BECOMING ABSORBED WITHIN UPSTREAM TROUGH AMPLIFYING ESE FROM THE CANADIAN PRAIRIES. A LOBE OF VORTICITY EXTENDING SW FROM THE IA LOW...WITH AN ASSOCIATED VORT MAX NOW IN SW OK PER WV IMAGERY...SHOULD CONTINUE ENE INTO OZARKS AND LWR OH VLY BY LATE IN THE DAY. AT THE SFC...A BROAD SWATH OF SWLY FLOW WILL PREVAIL OVER THE CNTRL AND ERN STATES DOWNSTREAM FROM AMPLIFYING LARGER SCALE TROUGH APPROACHING THE W CST. AN AXIS OF LOW LVL CONFLUENCE WITHIN THE SWLY FLOW...ESSENTIALLY MARKING THE WRN FRINGE OF STRONG SFC HIGH OFF THE S ATLANTIC CST...WILL PROGRESS SLOWLY E ACROSS THE LWR MS AND LWR TN VLYS TODAY. ...NRN IL/LWR MI INTO NRN IND/NRN OH THIS AFTN INTO TNGT... IT APPEARS THAT STRONGEST FORCING FOR ASCENT WITH IA UPR SYSTEM WILL TRACK NE ACROSS WI AND NRN MI LATER TODAY...BEYOND AXIS OF LOW LVL AIR MASS RECOVERY NOW OCCURRING NWD THROUGH THE MID MS AND LWR OH VLYS. NEVERTHELESS...SATELLITE SUGGESTS THAT A SECONDARY WAVE OF ASCENT WILL OVERSPREAD MUCH OF IL...NRN IND...AND LWR MI LATER TODAY FOLLOWING MAX HEATING. GIVEN BROAD SFC TROUGH ALREADY IN PLACE ACROSS THE N CNTRL STATES...EXPECT THAT THE MAIN SFC REFLECTION OF THE IA LOW WILL BE AN AXIS OF ENHANCED CONFLUENCE THAT SHOULD EVOLVE BY EARLY AFTN FROM CNTRL/NRN IL NEWD SRN/CNTRL LWR MI. THIS CONFLUENCE AXIS SHOULD SERVE AS THE MAIN FOCUS FOR STORM DEVELOPMENT LATER THIS AFTN AND EVE AS DAYTIME HEATING...CONTINUED LOW LVL MOISTURE INFLOW...AND APPROACH OF SECONDARY UPR IMPULSE DESTABILIZE REGION. SFC DEWPOINTS IN THE MID 50S F BENEATH 500 MB TEMPS AOA MINUS 16C SHOULD YIELD SBCAPE OF 500-1000 J/KG...AMPLE FOR SUSTAINED STORMS/SUPERCELLS GIVEN 50-60 KT WSWLY DEEP SHEAR. A POTENTIAL WILL EXIST FOR BOTH TORNADOES AND BOWING SEGMENTS GIVEN 60+ KT 700 MB FLOW AND SIZABLE LOW LVL DIRECTIONAL SHEAR. THE SVR THREAT SHOULD BE GREATEST FROM MID TO LATE AFTN THROUGH EARLY TNGT IN PARTS OF LWR MI AND ADJACENT NRN IL/IND...ALTHOUGH A MORE LIMITED THREAT MAY PERSIST THROUGH EARLY TUE EWD ACROSS THE LK ERIE REGION. ...MID SOUTH/CNTRL GULF CST THIS AFTN... OVERNIGHT PROGRESSIVE MCS HAS SOMEWHAT STABILIZED THE CNTRL GULF CST REGION THIS MORNING. THE ERN PART OF THE SYSTEM SHOULD CONTINUE FORWARD-PROPAGATING INTO LOW LVL ESELY FLOW OVER THE FL PANHANDLE AND SRN AL. THE STORMS SHOULD WEAKEN AS THE SYSTEM PROPAGATES FARTHER E BEYOND LOW LVL MOIST AXIS OFF THE LA CST. ADDITIONAL STORMS MAY FORM WITH DAYTIME HEATING ALONG WRN SIDE OF MCS...I.E. OVER SRN LA. THESE MAY POSE A LIMITED SVR RISK IN THE FORM OF LOCALLY DMG WIND OR A BRIEF TORNADO GIVEN RICH MOISTURE INFLOW...ALTHOUGH MODEST SHEAR/WEAK FORCING FOR ASCENT SHOULD LIMIT OVERALL THREAT. FARTHER N...EXPECT MODERATE AFTN DESTABILIZATION /SBCAPE AOA 1500 J PER KG/ TO OCCUR OVER PARTS OF MS...WRN TN...AND SRN KY...IN ZONE OF LOW LVL MOISTURE RETURN ALONG AND E OF AFOREMENTIONED CONFLUENCE ZONE. FORCING FOR ASCENT WILL BE WEAK...ALTHOUGH SOME ASCENT MAY OCCUR IN ASSOCIATION WITH CONTINUED EWD MOTION OF OK UPR IMPULSE. THIS SETUP SHOULD SUPPORT ISOLD TO SCTD AFTN SHOWERS/STORMS. GIVEN EXPECTED BUOYANCY AND 30-40 KT WSWLY DEEP SHEAR ON SRN FRINGE OF IA UPR LOW...A FEW STRONG TO SVR STORMS CAPABLE OF SVR HAIL AND/OR WIND COULD OCCUR. ..CORFIDI/SMITH.. 03/12/2012 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z