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| Probability of severe weather within 25 miles of a point. Hatched Area: 10% or greater probability of significant severe within 25 miles of a point. |
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SPC AC 221730 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT FRI MAR 22 2013 VALID 231200Z - 241200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE LOWER MS VALLEY EWD ACROSS THE CENTRAL GULF COAST REGION... ...SYNOPSIS... A WRN U.S. TROUGH WILL DIG SEWD FROM THE CENTRAL ROCKIES/FOUR CORNERS INTO THE CENTRAL/SRN PLAINS DURING THE FIRST HALF OF DAY2. THIS FEATURE WILL THEN TRACK EWD AND BEGIN TO TAKE ON A NEGATIVE TILT BY 12Z SUN AS IT APPROACHES THE MID/LOWER MS VALLEY. AS THE TROUGH DIGS EARLY IN THE PERIOD...A SURFACE LOW INITIALLY OVER THE WRN HALF OF TX IS FORECAST TO REDEVELOP OVER THE LOWER MS VALLEY DURING THE EVENING REACHING WRN TN BY 12Z SUN. AS THIS OCCURS...A COLD FRONT IS FORECAST TO SURGE SEWD ACROSS THE SRN PLAINS. MEANWHILE...GIVEN THE TRACK OF THE SYNOPTIC LOW AND BACKED LOW LEVEL FLOW ACROSS THE NWRN GULF INTO THE LOWER MS VALLEY...A WARM FRONT IS EXPECTED TO MAKE THE GREATEST NWD MOVEMENT ACROSS THE WRN PART OF THE SLIGHT RISK AREA. FARTHER E...ONGOING ELEVATED SHOWERS/EMBEDDED TSTMS WILL SHIFT EWD THROUGH THE SERN STATES...AND COMBINED WITH EXTENSIVE CLOUDINESS SHOULD TEND TO MAINTAIN THE ERN PART OF THE WARM FRONT ALONG OR JUST S OF THE FL PANHANDLE. THIS PART OF THE FRONT SHOULD SHIFT NWD INTO SERN AL/SRN GA LATER SAT NIGHT IN RESPONSE TO GREATER SURFACE PRESSURE FALLS INLAND OVER CENTRAL/NRN GA. ...LOWER MS VALLEY AND CENTRAL GULF COAST REGION... MODELS CONTINUE TO INDICATE THE SEVERE WEATHER POTENTIAL WILL BECOME WIDESPREAD AND SUBSTANTIAL ENOUGH...MAINLY FROM LATE SAT AFTERNOON THROUGH SAT NIGHT...TO MAINTAIN AN ENHANCED SLIGHT RISK AREA /UP TO 30 PERCENT SEVERE WEATHER PROBABILITY/ ACROSS THE LOWER MS VALLEY AND CENTRAL GULF COAST STATES. SRN AL AND THE WRN FL PANHANDLE REMAIN IN THIS ENHANCED THREAT AREA...ESPECIALLY FOR SAT NIGHT. HOWEVER...LATEST GUIDANCE SUGGESTS GREATER UNCERTAINTY WITH THE DEGREE OF DESTABILIZATION WITH NNEWD EXTENT IN AL SUCH THAT THE NRN EXTENT OF THE 30 PERCENT PROBABILITY HAS BEEN SHIFTED S I-20. THE AFOREMENTIONED BACKED LOW LEVEL FLOW INTO THE LOWER MS VALLEY WILL SUPPORT MOISTURE RETURN BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES EXPECTED TO SPREAD EWD ACROSS THE GULF COAST REGION DURING DAY2. DESPITE LIMITED SURFACE HEATING...MLCAPE OF 1000-1500 J/KG IS EXPECTED ACROSS THE SRN EXTENT OF THE LOWER MS VALLEY WITH FURTHER DESTABILIZATION FORECAST INLAND ACROSS CENTRAL/ERN MS AND SRN AL AS THE WARM SECTOR ADVANCES FARTHER INLAND AFTER DARK. WEAKENING INHIBITION WILL ALLOW FOR TSTMS TO DEVELOP ALONG THE WARM FRONT...TRIPLE POINT AND SWD EXTENDING PRE-FRONTAL TROUGH BEING THE PRIMARY FOCI. DEGREE OF INSTABILITY AND EFFECTIVE BULK SHEAR EXCEEDING 50 KT WILL SUPPORT ORGANIZED STORMS. IN ADDITION TO HEIGHT FALLS INCREASING SAT NIGHT FROM THE LOWER-MID MS VALLEY EWD ACROSS THE GULF COAST STATES IN ADVANCE OF THE EWD MOVING CENTRAL/SRN PLAINS UPPER TROUGH...FORCING FOR ASCENT WILL BE ENHANCED INTO THE LOWER MS VALLEY/CENTRAL GULF COAST STATES. THIS LATTER FACTOR WILL BE ATTENDANT TO DCVA SPREADING ACROSS THE WRN EXTENT OF THE SLIGHT RISK AREA AFTER 24/00Z...AS A MIDLEVEL IMPULSE TRANSLATES EWD THROUGH THE BASE OF THE PARENT LARGE SCALE TROUGH. THIS COMBINED WITH ASCENT WITHIN THE EXIT REGION OF A 110-130 KT WSWLY UPPER LEVEL JET SPREADING INTO SRN AL TO SRN GA LATE SAT NIGHT WILL ALLOW FOR AN INCREASE IN TSTM DEVELOPMENT/COVERAGE WITH ACTIVITY SPREADING EWD. STORM MODE MAY REMAIN MIXED EVEN INTO THE OVERNIGHT PERIOD WITH ALL FACETS OF SEVERE WEATHER EXPECTED...WITH GREATER COVERAGE FROM SRN AL TO SRN GA WHERE DEEP LAYER WIND FIELDS WILL BE STRENGTHENING. ..PETERS.. 03/22/2013 CLICK TO GET WUUS02 PTSDY2 PRODUCT NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z |