The SPC is forecasting ...the most significant threat for severe thunderstorms is expected over parts of the ozark region and the lower mississippi valley this evening through tonight.... Please read the latest public statement about this event. View What is a Watch? clip.
| 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 291250 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0650 AM CST TUE JAN 29 2013 VALID 291300Z - 301200Z ...THERE IS A MDT RISK OF SVR TSTMS THIS EVENING INTO TONIGHT FOR MUCH OF AR...FAR NERN TX...FAR NRN LA...WEST CENTRAL AND NW MS...FAR SWRN TN AND PART OF SERN MO... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM THE SRN PLAINS TO CENTRAL GULF COAST STATES AND NNEWD INTO THE MID MS AND LOWER OH VALLEYS... ...SYNOPSIS... A DEEP LONGWAVE TROUGH...CURRENTLY CENTERED OVER THE ROCKIES INTO NRN MEXICO PER WATER VAPOR IMAGERY...WILL CONTINUE TO SHIFT E TOWARD THE PLAINS STATES THIS FORECAST PERIOD. A STRONG SHORTWAVE TROUGH WILL EJECT NEWD FROM THE BASE OF THE LONGWAVE TROUGH THROUGH THE SRN PLAINS...REACHING THE LOWER MO/MID MS VALLEYS LATER TONIGHT/EARLY WED MORNING. A STRONG 90-100 KT SWLY MIDLEVEL JET WILL ACCOMPANY THE LEAD SHORTWAVE TROUGH. FURTHER STRENGTHENING OF THIS SWLY WIND FIELD IS EXPECTED DURING THE SECOND HALF OF THE PERIOD FROM CENTRAL TX THROUGH AR TO THE LOWER OH VALLEY. THIS WILL OCCUR AS A STRONG UPSTREAM JET OVER THE PACIFIC NW TO GREAT BASIN TRANSLATES THROUGH THE BASE OF THE PARENT LONGWAVE TROUGH AND EMERGES ACROSS TX TO THE LOWER OH VALLEY THIS EVENING AND TONIGHT. EARLY MORNING SURFACE ANALYSIS SHOWED A SYNOPTIC LOW CENTERED OVER IA WITH A POLAR FRONT EXTENDING SSWWD THROUGH FAR NWRN MO...ERN KS TO NWRN OK...AND THEN WWD THROUGH THE OK PANHANDLE TO AN AREA OF LOW PRESSURE IN SERN CO. A WARM FRONT EXTENDED EWD FROM IA ALONG THE IL/WI BORDER TO N OF CHICAGO INTO FAR NRN OH. MEANWHILE...A DRY LINE EXTENDED SWD ACROSS FAR WRN OK TO THE TX BIG BEND REGION TO THE NW OF DRT...WITH A PACIFIC COLD FRONT EXTENDING SWD THROUGH THE TX PANHANDLE AND W TO SW TX. PRIOR THE PACIFIC NW/GREAT BASIN JET EMERGING ENE OF THE SWRN STATES...THE POLAR FRONT AND DRY LINE WILL MOVE SLOWLY EWD...WHILE THE WARM FRONT MOVES NWD THROUGH SERN WI AND LOWER MI. BY THIS EVENING...THE PACIFIC FRONT WILL OVERTAKE THE DRY LINE AND ADVANCE MORE QUICKLY EWD...CONCURRENT WITH THE ADVANCEMENT OF THE POLAR FRONT. BY 12Z WED...A SYNOPTIC LOW SHOULD BE LOCATED OVER LOWER MI WITH COLD FRONT EXTENDING SSWWD THROUGH INDIANA TO MIDDLE TN...MS...SERN LA TO THE WRN GULF. ...SRN PLAINS TO CENTRAL GULF COAST STATES TO MID MS AND LOWER OH VALLEYS... A MOIST AIR MASS ALREADY IN PLACE ACROSS THE SRN PLAINS IS SUPPORTING AN INCREASINGLY UNSTABLE ENVIRONMENT WITH MLCAPE UP TO 1000 J/KG EXTENDING FROM NORTH TX INTO CENTRAL OK...ALONG AND EAST OF THE DRY LINE. STRONG HEIGHT FALLS SPREADING EWD WITH THE LONGWAVE TROUGH AND LEAD SHORTWAVE TROUGH MOVING ENEWD THROUGH THE SRN HIGH PLAINS HAS SUPPORTED THE ONSET OF STRONG TO SEVERE ORGANIZED STORMS PRIOR TO THE START OF DAY 1 OVER WRN OK. THIS INCREASE IN DEEP LAYER ASCENT IS ALSO EVIDENT FARTHER TO THE NORTHEAST JUST AHEAD OF THE POLAR FRONT IN NRN OK TO SERN KS AND SWRN MO WHERE STORMS HAVE BEEN INCREASING IN COVERAGE AND INTENSITY SINCE 10-11Z. THE TORNADO AND DAMAGING WIND PROBABILITIES AND SLIGHT RISK AREA HAVE BEEN EXTENDED WWD TO INCLUDE MORE OF NORTHWEST TX...WRN AND NRN OK INTO ERN KS. THIS CHANGE IS DUE TO THE ONGOING STRONG TO SEVERE STORMS AND THE LIKELIHOOD FOR ADDITIONAL ACTIVITY WITH SWD AND NEWD EXTENT ALONG THE DRY LINE AND POLAR FRONT...RESPECTIVELY. STRONG-EXTREME HEIGHT FALLS SPREADING FROM THE SRN/CENTRAL PLAINS TO THE MS RIVER VALLEY TODAY/TONIGHT WILL RESULT IN A RELATIVELY BROAD SSWLY LLJ UNDERGOING STRENGTHENING AS IT SHIFTS ENEWD AHEAD OF THE POLAR FRONT/DRY LINE. THIS WILL ALLOW MOISTURE TO SPREAD FAIRLY FAR N FOR THIS TIME OF YEAR...WITH SURFACE DEWPOINTS IN THE UPPER 50S TO NEAR 60 F REACHING NRN IL AND INDIANA. FARTHER S...MID 60S DEWPOINTS WILL SPREAD INTO SERN OK...CENTRAL AR TO WRN TN THIS AFTERNOON THROUGH TONIGHT. MODEST MIDLEVEL LAPSE RATES WITH NWD EXTENT WILL TEND TO LIMIT THE DEVELOPMENT OF STRONGER INSTABILITY...ESPECIALLY INTO THE LOWER MO AND MID MS VALLEYS. MODIFIED FORECAST SOUNDINGS INTO NRN IL SUGGEST THE POTENTIAL FOR MUCAPE AROUND 400 J/KG THIS AFTERNOON. FARTHER S...MIDLEVEL LAPSE RATES CLOSER TO 8 C/KM PER 12Z SOUNDING AT FORT WORTH TEXAS IS SUPPORTING THE AFOREMENTIONED MUCAPE TO AROUND 1000 J/KG EXTENDING INTO CENTRAL OK. SIMILAR MUCAPE VALUES ARE EXPECTED INTO NERN TX/SERN OK TO SRN AR WHERE GREATER MOISTURE IS FORECAST THIS AFTERNOON AND EVENING. STRENGTHENING DEEP LAYER WIND FIELDS WITH EFFECTIVE BULK SHEAR EXCEEDING 50 KT AS FAR N AS THE LOWER MO TO LOWER OH VALLEYS AND SHEAR VECTORS ORIENTED NEARLY PARALLEL TO THE POLAR FRONT AND DRY LINE SUGGEST PRIMARILY A LINEAR STORM MODE. HOWEVER...GIVEN THE STRENGTH OF THE BULK SHEAR AND INCREASING LOW LEVEL HODOGRAPH CURVATURE...TORNADOES WILL BE POSSIBLE IN ADDITION TO DAMAGING WINDS. MODELS CONTINUE TO INDICATE A STRONG INCREASE IN DEEP LAYER WINDS AS THE UPSTREAM PACIFIC NW/GREAT BASIN JET ADVANCES INTO THE SRN EXTENT OF THE OUTLOOK AREA INCLUDING THE MODERATE RISK. THIS WILL FURTHER INCREASE LOW LEVEL SHEAR/HODOGRAPH CURVATURE FOR AN ENHANCED THREAT FOR STRONGER TORNADOES INCLUDING THE METRO AREAS OF LITTLE ROCK AND MEMPHIS AFTER DARK THIS EVENING/TONIGHT. GIVEN THE STRENGTHENING DEEP LAYER SSWLY WINDS TONIGHT ACROSS A MODESTLY UNSTABLE WARM SECTOR...MODELS CONTINUE TO ADVERTISE THE DEVELOPMENT OF A WELL DEFINED QLCS ADVANCING E OF THE MID-LOWER MS RIVER. THIS SCENARIO IS ALSO SUPPORTED BY THE 00Z 4KM WRF-NSSL SUGGESTING THE QLCS WITH A THREAT FOR DAMAGING WINDS AND A FEW TORNADOES REACHES PARTS OF THE LOWER OH VALLEY TO CENTRAL GULF COAST STATES. THUS...THE SLIGHT RISK AND SEVERE WIND AND TORNADO PROBABILITIES HAVE BEEN EXTENDED EWD SOME WITH THIS OUTLOOK ISSUANCE. THE SLIGHT RISK HAS ALSO BEEN EXTENDED NWD TO INCLUDE THE REST OF NRN IL TO ACCOUNT FOR A THREAT FOR DAMAGING WINDS AND EVEN A TORNADO THREAT...GIVEN THE PRESENCE OF FAVORABLE DEEP LAYER AND LOW LEVEL SHEAR...DESPITE WEAKER INSTABILITY THIS AFTERNOON. ..PETERS/ROGERS.. 01/29/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z