DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0138 PM CST MON DEC 28 2015 VALID 282000Z - 291200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF SOUTHEAST AL AND THE FL PANHANDLE... ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE LOWER OH AND TN VALLEYS TO THE FL PANHANDLE... ...SUMMARY... SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO EARLY EVENING FROM THE LOWER OHIO AND TENNESSEE VALLEYS TO THE FLORIDA PANHANDLE. A FEW STORMS COULD PRODUCE DAMAGING WIND GUSTS AND PERHAPS A TORNADO OR TWO...ESPECIALLY ACROSS SOUTHEAST ALABAMA INTO THE FLORIDA PANHANDLE. ...20Z UPDATE - CENTRAL/ERN GULF COAST INTO THE LOWER OH/TN VALLEYS... THE WESTERN EDGE OF THE OUTLOOK AREA HAS BEEN SHIFTED EASTWARD IN-LINE WITH CURRENT POSITION OF LINE OF CONVECTION OVER THE REGION. ADDITIONALLY...THE SLIGHT RISK AREA HAS BEEN ADJUSTED TO ENCOMPASS PORTIONS OF E-CNTRL/SE AL AND PORTIONS OF THE FL PANHANDLE...WHILE REMOVING MIDDLE TN AND NORTHERN AL...TO REFLECT WHERE MORE FAVORABLE CONDITIONS EXIST FOR POTENTIAL WIND DAMAGE AND/OR A BRIEF TORNADO OR TWO. HERE...TEMPERATURES ARE A BIT WARMER THANKS TO SOME BREAKS IN CLOUD COVER AND OVERALL INSTABILITY PARAMETERS ARE MORE CONDUCIVE TO STRONGER UPDRAFTS. STORM INTENSITY SHOULD GRADUALLY DECREASE WITH EASTWARD EXTENT AND TIME AS UPPER FORCING CONTINUES TO SHIFT NORTHEAST TOWARD LAKE MICHIGAN. ..LEITMAN.. 12/28/2015 .PREV DISCUSSION... /ISSUED 1017 AM CST MON DEC 28 2015/ ...SYNOPSIS... A MID-LEVEL LOW AND ASSOCIATED 100 KT JET STREAK OVER THE OZARK PLATEAU WILL UNDERGO GRADUAL WEAKENING AS IT EJECTS NEWD INTO THE UPPER GREAT LAKES. MEANWHILE...AN ASSOCIATED SURFACE LOW OVER N-CNTRL AR WILL DEVELOP NNEWD THROUGH THE MID-MS VALLEY TO THE VICINITY OF LAKE MI BY 12Z/TUESDAY. THIS CYCLONE WILL BE ACCOMPANIED BY A WARM FRONT LIFTING NWD TO THE OH RIVER WHILE A TRAILING COLD FRONT SURGES EWD THROUGH THE TN VALLEY AND CNTRL GULF STATES. ...CNTRL/ERN GULF COAST INTO THE TN/LOWER-OH VALLEYS... AN ARCING BAND OF CONVECTION /WITH EMBEDDED TSTMS/ IS PRESENT AS OF MID MORNING FROM E-CNTRL MO THROUGH WRN PORTIONS OF TN AND AL. AHEAD OF THIS BAND...SEVERAL SUPERCELLS HAVE EVOLVED OVER S-CNTRL AL AND THE FL PNHDL WHERE THE MOST FAVORABLE OVERLAP OF MODEST INSTABILITY AND STRONG VERTICAL SHEAR RESIDE. WHILE WIDESPREAD CLOUDS WILL LIMIT DAYTIME HEATING...STRONG MOISTURE FLUX ALONG A 60-70 KT LLJ WILL SUPPORT WEAK AIR MASS DESTABILIZATION ACROSS THE TN VALLEY PERHAPS INTO THE LOWER-OH VALLEY...IMMEDIATELY AHEAD OF THE STRONGLY FORCED CONVECTIVE BAND. AND GIVEN THE PRESENCE OF INTENSE VERTICAL SHEAR AND FORCING FOR ASCENT...THE POTENTIAL WILL EXIST FOR EMBEDDED SUPERCELL AND BOWING STRUCTURES CAPABLE OF LOCALLY DAMAGING WINDS AND PERHAPS A COUPLE TORNADOES. FARTHER SOUTH FROM SRN AL INTO SWRN GA AND THE FL PNHDL...BOTH VERTICAL SHEAR AND LARGE-SCALE FORCING FOR ASCENT WILL GRADUALLY WEAKEN THROUGH THE DAY AS THE UPPER-AIR SYSTEM PULLS AWAY FROM THE REGION. HOWEVER...THE CONTINUED INFLUX OF A MARITIME-TROPICAL AIR MASS...DAYTIME HEATING AND STILL AMPLE VERTICAL SHEAR WILL YIELD AN ENVIRONMENT SUPPORTIVE OF A TORNADO AND DAMAGING WIND THREAT PERSISTING THROUGH THIS AFTERNOON...PERHAPS INTO EVENING.Read more
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