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SPC Day 1 Outlook Text Only
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Forecast DiscussionSPC AC 110531 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1131 PM CST WED MAR 10 2010 VALID 111200Z - 121200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF FL... ...SYNOPSIS... BROAD UPPER LOW WILL PERSIST OVER THE CNTRL U.S. THURSDAY. SEVERAL VORTICITY MAXIMA WILL CONTINUE TO ROTATE THROUGH THIS FEATURE. THE VORT MAX OVER ERN KS/WRN MO AS OF WEDNESDAY EVENING IS FORECAST TO LIFT NWD INTO ERN NEB/IA...WHILE VORT MAX CURRENTLY OVER THE SWRN U.S. WILL CONTINUE ESEWD...REACHING THE LOWER MS VALLEY BY THE END OF THE PERIOD. INITIAL SURFACE LOW WILL OCCLUDE OVER THE UPPER MS VALLEY WITH TRAILING FRONT EXTENDING SWD THROUGH WRN PARTS OF THE TN AND LOWER MS VALLEY. SECONDARY LOW SHOULD DEVELOP OVER THE LOWER MS VALLEY THURSDAY NIGHT IN ASSOCIATION WITH APPROACHING IMPULSE. A QUASI-STATIONARY BOUNDARY WILL LIKELY PERSIST FROM SRN GA NWWD THROUGH CNTRL AL. ...SRN PARTS OF THE GULF COASTAL STATES AND FL... SWLY LOW-LEVEL JET LOCATED WITHIN THE DIVERGENT EXIT REGION OF A STRONG SUBTROPICAL UPPER JET IS FORECAST TO SHIFT EWD THROUGH THE NERN GULF AND THE FL PENINSULA THURSDAY. THIS FEATURE WILL HELP TRANSPORT RICHER BOUNDARY LAYER MOISTURE WITH UPPER 60S DEWPOINTS NEWD THROUGH THE PENINSULA. WEAK LAPSE RATES AND WIDESPREAD CLOUDS WILL LIMIT MLCAPE IN MOST AREAS TO BELOW 1000 J/KG. STORMS WILL BE ONGOING THURSDAY WITHIN THE BROAD ZONE OF ISENTROPIC LIFT AND THETA-E ADVECTION OVER THE SRN PORTIONS OF THE GULF COASTAL STATES. THESE STORMS WILL BE EMBEDDED WITHIN STRONG VERTICAL SHEAR WITH LARGE LOW HODOGRAPHS SUPPORTIVE OF SUPERCELLS. HOWEVER...THE ACTIVITY MAY BE SLIGHTLY ELEVATED...WHICH ALONG WITH A THE MARGINAL THERMODYNAMIC ENVIRONMENT WOULD SERVE AS A LIMITING FACTOR FOR SEVERE STORMS. A GREATER THREAT FOR SEVERE STORMS WILL MATERIALIZE AS ACTIVITY DEVELOPS EWD THROUGH THE FL PENINSULA WHERE INFLUX OF RICHER MOISTURE AND GRADUAL DESTABILIZATION OF THE BOUNDARY LAYER WILL OCCUR. LARGE HODOGRAPHS AND BULK SHEAR WILL SUPPORT A THREAT FOR EMBEDDED SUPERCELLS AND BOWING SEGMENTS WITH ISOLATED DAMAGING WIND AND TORNADOES POSSIBLE. SEVERE THREAT MAY UNDERGO A TEMPORARY DECREASE THURSDAY EVENING...BUT MAY INCREASE AGAIN LATER THURSDAY NIGHT AS THE LOW-LEVEL JET REDEVELOPS OVER THE PENINSULA DOWNSTREAM FROM ADVANCING SRN STREAM IMPULSE. ...MID MS AND OH VALLEY AREAS... DIABATIC WARMING WITHIN DRY SLOT AND BENEATH UPPER THERMAL TROUGH ACCOMPANYING NWD EJECTING VORT MAX WILL CONTRIBUTE TO A ZONE OF STEEP MID LEVEL LAPSE RATES ACROSS IL THROUGH WRN PARTS OF THE TN VALLEY. AN AXIS OF MODEST INSTABILITY WITH MLCAPE BELOW 800 J/KG WILL BE POSSIBLE IN THIS REGION. ADDITIONAL STORMS MAY DEVELOP ALONG AND EAST OF OCCLUDED FRONT AS THE ATMOSPHERE DESTABILIZES DURING THE AFTERNOON. VERTICAL SHEAR WILL REMAIN SUFFICIENT FOR UPDRAFT ROTATION WITH ISOLATED LARGE HAIL AND PERHAPS A COUPLE OF TORNADOES. THIS AREA WILL CONTINUE TO BE MONITORED FOR A POSSIBLE SLIGHT RISK IN LATER UPDATES. ...LOWER MS VALLEY AND WRN TN VALLEY AREA... TRAILING PORTIONS OF FRONT WILL LIKELY STALL OVER THE LOWER MS VALLEY. VORT MAX NOW OVER THE SWRN STATES WILL REACH THIS REGION THURSDAY NIGHT. ASCENT AND STEEPER LAPSE RATES ACCOMPANYING THE IMPULSE WILL OVERTAKE THIS BOUNDARY AND CONTRIBUTE TO DESTABILIZATION AND THUNDERSTORM INITIATION. GIVEN TIME OF DAY AND MODEST LOW-LEVEL MOISTURE...STORMS WILL LIKELY REMAIN ELEVATED...BUT STEEP LAPSE RATES AND A RELATIVELY DRY BOUNDARY LAYER WILL CONTRIBUTE TO A THREAT FOR ISOLATED HAIL AND STRONG WIND GUSTS. ..DIAL/HURLBUT.. 03/11/2010 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z