SPC AC 090529 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1229 AM CDT FRI MAY 09 2008 VALID 101200Z - 111200Z ...THERE IS A MDT RISK OF SVR TSTMS FROM ERN OK INTO NWRN AL... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM SERN TX AND SRN MO INTO WRN GA... ...ERN OK/TX TO CNTRL GULF STATES... LARGE SCALE PATTERN WILL BECOME INCREASINGLY FAVORABLE FOR ORGANIZED SEVERE THUNDERSTORMS ACROSS A GOOD PORTION OF THE GULF STATES DURING THE DAY2 PERIOD...POTENTIALLY AS FAR WEST AS THE ERN SECTIONS OF THE SRN PLAINS. LATEST MODEL GUIDANCE SUGGEST TWO MAIN BRANCHES OF HIGH LEVEL FLOW...WHILE MAINTAINING THEIR SEPARATE IDENTITY...WILL PHASE SOMEWHAT OVER THE LOWER MS VALLEY DURING THE LATTER HALF OF THE PERIOD. STRONG NRN STREAM SHORTWAVE WILL DIG SEWD ACROSS THE CNTRL PLAINS EARLY BEFORE A CLOSED CIRCULATION EVOLVES OVER MO. ANOTHER SIGNIFICANT SPEED MAX WILL RACE ENEWD WITHIN THE SLY BRANCH ACROSS TX...OVERSPREADING THE CNTRL GULF STATES BY MID DAY. BUOYANCY WILL BE GREATLY ENHANCED ACROSS THE WARM SECTOR SATURDAY AS MARITIME TROPICAL AIRMASS SPREADS ACROSS THE WRN GULF OF MEXICO BEFORE ADVECTING INTO SERN TX/LOWER MS VALLEY REGION. WITH DEEPENING WLY FLOW THERE WILL LIKELY BE A SIGNIFICANT...BUT BREAKABLE EML DEVELOP ACROSS TX THAT WILL SPREAD DOWNSTREAM ACROSS MUCH OF THE OUTLOOK. STORMS WILL STRUGGLE INITIALLY ALONG THE DRYLINE BUT SHOULD EASILY DEVELOP ALONG WARM FRONT THAT SHOULD BE ORIENTED FROM NRN GA INTO AR. WARM FRONTAL INITIATION WILL BE DIFFICULT TO TIME...BUT AFTERNOON HEATING SHOULD CERTAINLY AID DEVELOPMENT AND FOCUS MORE INTENSE UPDRAFTS. UPSTREAM...A STRONG COLD FRONT WILL SURGE SEWD ACROSS OK WHERE IT WILL INTERSECT A WELL PRONOUNCED DRYLINE NEAR THE RED RIVER. EXTREME INSTABILITY COULD DEVELOP ACROSS SERN OK/SWRN AR INTO ERN TX WHERE AFOREMENTIONED CAP SHOULD SUPPRESS THUNDERSTORM DEVELOPMENT UNTIL LATE IN THE AFTERNOON. AS TEMPERATURES SOAR CONVECTION SHOULD FIRE INITIALLY ALONG COLD FRONT OVER OK...THEN IN A MORE ISOLATED FASHION ALONG DRYLINE INTO TX. SHEAR PROFILES ACROSS THIS REGION STRONGLY SUGGEST DISCRETE SUPERCELLS...THOUGH PROFILES ARE SOMEWHAT VEERED SOUTH OF THE WARM FRONT. MULTIPLE SEVERE THUNDERSTORM CLUSTERS COULD EASILY DEVELOP FROM ERN OK/AR...ESEWD INTO THE NRN GULF STATES AS UPPER TROUGH DEEPENS OVER THE MS VALLEY DURING THE OVERNIGHT HOURS. VERY LARGE HAIL...DAMAGING WINDS AND ISOLATED TORNADOES ARE ALL POSSIBLE SEVERE THREATS WITHIN MULTI FACETED CONVECTIVE EVENT. ..DARROW.. 05/09/2008
SPC AC 090719 DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0219 AM CDT FRI MAY 09 2008 VALID 111200Z - 121200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE CNTRL/ERN GULF STATES INTO THE CAROLINAS... ...SERN U.S... 00Z MODEL GUIDANCE IS IN GENERAL AGREEMENT ALLOWING DIGGING SHORTWAVE OVER THE MID MS VALLEY TO DEEPEN AS IT MOVES INTO THE CNTRL APPALACHIANS BY THE END OF THE DAY3 PERIOD. THIS FEATURE WILL INDUCE SIGNIFICANT DEEPENING AT THE LOWER LEVELS OVER THE OH VALLEY WHERE SFC LOW SHOULD OCCLUDE. ALTHOUGH A FEW THUNDERSTORMS SHOULD DEVELOP AHEAD OF THIS FEATURE...WITHIN MEAGER MOISTURE FROM IND INTO OH...MORE SIGNIFICANT THUNDERSTORM DEVELOPMENT IS ANTICIPATED ACROSS THE CNTRL/ERN GULF STATES INTO THE COASTAL CAROLINAS. DEEP CYCLONIC FLOW WILL EVOLVE ACROSS THE ERN U.S. DURING THE DAY3 PERIOD. THIS LARGE SCALE EVOLUTION WILL TRANSPORT STEEP LAPSE RATE ENVIRONMENT ACROSS THE SRN PLAINS INTO THE GULF STATES AS WLY FLOW DEEPENS ALONG SRN PERIPHERY OF OH VALLEY LOW PRESSURE SYSTEM. LATEST MODEL GUIDANCE SUGGEST PW'S ON THE ORDER OF 1.5-1.75 INCHES WILL BE TRANSPORTED AHEAD OF SHARP FRONTAL BOUNDARY FROM MS/AL...EWD INTO SC/NC. THIS MOISTURE SURGE WILL CERTAINLY AID BUOYANCY WITHIN STRONGLY VEERED WIND REGIME...ESPECIALLY AS DAYTIME HEATING DEEPENS BOUNDARY LAYER. SEVERE THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS THE CNTRL GULF STATES...ESPECIALLY NEAR THE WARM FRONT INTERSECTION AT THE BEGINNING OF THE PERIOD. FORECAST SHEAR PROFILES SUGGEST CELL MOTIONS OF 40-50KT...WITH MLCAPE VALUES APPROACHING 2000 J/KG BY MID DAY. IF CONVECTIVE CONTAMINATION DOES NOT OCCUR FROM DAY2 ACTIVITY...A POTENTIALLY SIGNIFICANT SEVERE EVENT COULD OCCUR ACROSS THE OUTLOOK REGION AS PROFILES FAVOR VERY FAST MOVING SUPERCELL STRUCTURES. AN UPGRADE MAY BE REQUIRED IN LATER OUTLOOKS IF MODEL DATA CONTINUES TO SUPPORT THIS EVOLUTION.
