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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. |
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| 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. |
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| 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. |
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SPC AC 271244 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0744 AM CDT SUN OCT 27 2013 VALID 271300Z - 281200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... IN MID-UPPER LEVELS...BROAD AREA OF CYCLONIC FLOW WILL COVER ERN CONUS EARLY IN PERIOD...THOUGH RELATED SYNOPTIC TROUGHING SHOULD DEAMPLIFY WITH TIME. SHORTWAVE PERTURBATION INITIALLY OVER ARKLATEX REGION EXHIBITS PRONOUNCED MID-UPPER LEVEL DRY SLOT OVER CENTRAL-E TX. TROUGH SHOULD MOVE ESEWD ACROSS LOWER MS VALLEY TO AL AND CENTRAL GULF COAST THROUGH REMAINDER PERIOD...WHILE GRADUALLY WEAKENING. ASSOCIATED SFC FRONTAL ZONE FROM KY TO SW TX WILL LOSE DEFINITION AS UPPER SYSTEM DEPARTS...AND AS GREATER CONTRIBUTION TO REGIONAL BAROCLINICITY CONTINUES TO ARISE FROM MESOSCALE CONVECTIVE PROCESSES. MEANWHILE...STG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER BC -- IS FCST TO EXPERIENCE INTENSE AMPLIFICATION THROUGH PERIOD AS IT DIGS SWD ACROSS NWRN CONUS. NET RESULT BY 12Z SHOULD BE LARGE...CLOSED 500-MB CYCLONE CENTERED OVER NERN NV...WITH RELATED CYCLONIC FLOW COVERING MOST OF WRN CONUS FROM ROCKIES WWD. STG DCVA AND WAA WILL PRECEDE THIS SYSTEM...WITHIN REGIME OF PRONOUNCED HEIGHT FALLS. STEEPENED MIDLEVEL LAPSE RATES AND MRGL LOW-MIDDLE LEVEL MOISTURE MIGHT BE SUFFICIENT TO YIELD LOW-CAPE CONVECTION APCHG ICING LAYERS SUITABLE FOR LTG PRODUCTION. AS SUCH...A FEW LTG STRIKES CANNOT BE RULED OUT SOMEWHERE ACROSS BROAD SWATH OF CENTRAL/NRN GREAT BASIN REGION OR SRN ID. HOWEVER...LOW-LEVEL THETAE WILL REMAIN WEAK...AND COVERAGE/DURATION OF ANY THUNDER THREAT APPEAR TOO SPARSE TO ASSIGN SPECIFIC AREA OF AOA 10% TSTM RISK ATTM. ...MID-SOUTH/DELTA REGION...S TX... MCS WITH EMBEDDED STG TSTMS IS EVIDENT FROM UPPER TX COAST WNWWD ACROSS PORTIONS S-CENTRAL TX...AND IS PRECEDED BY SERIES OF GUST FRONTS PER RADAR REFLECTIVITY ANIMATIONS. WHILE ISOLATED GUSTS APCHG SVR LEVELS ARE POSSIBLE WITH THIS ACTIVITY...OVERALL THREAT APPEARS TOO LOW AND CONDITIONAL TO ASSIGN PROBABILITIES ATTM...GIVEN 1. OFFSHORE MOTION OF MOST INTENSE PART ONGOING... 2. DEPARTURE OF MID-UPPER WAVE AWAY FROM AREA...LEADING TO HEIGHT RISES AND WEAKENING OF BOTH LOW-LEVEL AND DEEP SHEAR...AND 3. CONTINUED ADVECTION FROM MEX PLATEAU OF ELEVATED MIXED-LAYER AIR CAPPING BOUNDARY LAYER...WHICH WILL FORTIFY THAT CONTRIBUTION TO CINH. STABLE LAYERS ALOFT WERE EVIDENT IN 12Z RAOBS FROM LCH...CRP...BRO AND DRT. STILL...THREAT FOR AT LEAST ISOLATED TO WIDELY SCATTERED TSTMS SHOULD LINGER THROUGH AT LEAST LATE AFTN ALONG RESULTING OUTFLOW/DIFFERENTIAL HEATING BOUNDARY...UNTIL BOUNDARY BECOMES TO WEAK/SHALLOW TO PROVIDE FAVORABLE LIFT. FARTHER N...WIDELY SCATTERED TO ISOLATED TSTMS ARE POSSIBLE LATE MORNING THROUGH AFTN...IN REGIME OF DCVA...WEAKENING FRONTAL FORCING AND MRGL LOW-LEVEL THETAE PRECEDING MID-UPPER SHORTWAVE TROUGH. GEN TSTM AREA HAS BEEN BIFURCATED IN BETWEEN THESE TWO REGIMES...WHERE COMBINATION OF DRY-SLOTTING/STABILIZATION ALOFT AND WEAK LOW-LEVEL INSTABILITY WILL PREVAIL. ..EDWARDS/COHEN.. 10/27/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z |
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