Jan 9, 2013 1630 UTC Day 1 Convective Outlook | |
Updated: Wed Jan 9 16:11:32 UTC 2013 | |
Probabilistic to Categorical Outlook Conversion Table |
Categorical Graphic |
---|
Probabilistic Tornado Graphic |
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. |
Probabilistic Damaging Wind Graphic |
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. |
Probabilistic Large Hail Graphic |
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. |
SPC AC 091608 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1008 AM CST WED JAN 09 2013 VALID 091630Z - 101200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... A POLAR BRANCH SHORT-WAVE TROUGH OVER THE FAR NERN PACIFIC WILL ADVANCE INTO THE PACIFIC NW AND CA THIS PERIOD...AMPLIFYING WITH TIME OWING TO THE EQUATORWARD PROGRESSION OF MID TO UPPER-LEVEL JET STREAKS INTO THE BASE OF THE PARENT TROUGH. THESE DEVELOPMENTS WILL LEAD TO THE NWD ACCELERATION OF A SUBTROPICAL BRANCH UPPER LOW FROM NRN MEXICO INTO W-CNTRL TX. THIS LATTER SYSTEM WILL BE ATTENDED BY A 50-70 KT MIDLEVEL JET STREAK WHICH WILL OVERSPREAD THE ERN HALF OF TX NWD THROUGH THE RED RIVER VALLEY. IN THE LOW LEVELS...A SURFACE LOW ANALYZED ALONG THE TX COAST NEAR PSX AS OF 16Z WILL DEVELOP NWWD INTO THE TX HILL COUNTRY BY 10/00Z...AND INTO NWRN TX BY THE END OF THE D1 PERIOD. MEANWHILE... A WARM FRONT --DELINEATING CP AND MODIFIED CP AIR MASSES-- CURRENTLY FROM THE LOW NEWD THROUGH E-CNTRL TX AND CNTRL LA WILL LIFT SLOWLY NWD. A SECONDARY WARM FRONT --WHICH DEMARCATES THE MODIFIED CP AIR FROM THAT OF TRUE MARITIME ORIGIN-- IS EXPECTED TO REMAIN ALONG THE SHELF WATERS OF THE NRN GOM. FINALLY...A COLD FRONT WILL ADVANCE EWD ALONG THE TX COAST TOWARD THE LOWER SABINE RIVER VALLEY. ...MIDDLE/UPPER TX COAST INTO SWRN LA... AS OF MID-MORNING...A PRE-FRONTAL CONVECTIVE BAND EXISTED FROM NEAR CLL SWD INTO THE NWRN GOM APPROXIMATELY 50-80 NM E OF BRO. THIS ACTIVITY DEFINES THE SRN PORTION OF THE WARM CONVEYOR BELT OF THE SUBTROPICAL BRANCH SYNOPTIC SYSTEM...WITH A BROAD ZONE OF ISENTROPIC ASCENT AND DCVA AHEAD OF THE PARENT UPPER LOW LIKELY BEING THE PRIMARY PROCESSES FORCING THIS ACTIVITY. LATEST CONVECTION-ALLOWING AND MESOSCALE MODEL GUIDANCE ARE IN RELATIVELY GOOD AGREEMENT IN SUGGESTING A GRADUAL EWD PROGRESSION OF THIS CONVECTIVE BAND INTO THE LOWER SABINE RIVER VALLEY BY TONIGHT AS THE PARENT UPPER LOW BEGINS TO LIFT NWD TOWARD THE RED RIVER VALLEY. AS MENTIONED ABOVE...IT APPEARS THAT THE SRN-MOST WARM FRONT WHICH DELIMITS THE NRN EXTENT OF A HIGH THETA-E...MT AIR MASS WILL REMAIN OFFSHORE THROUGH THE PERIOD. THIS COUPLED WITH WIDESPREAD CLOUDS AND PRECIPITATION WILL LIMIT AIR MASS DESTABILIZATION ALONG THE COASTAL PLAINS OF TX INTO SWRN LA. THIS IS CONFIRMED BY MODEL-DERIVED FORECAST SOUNDINGS WHICH SHOW THE MAINTENANCE OF A SHALLOW...NEAR-SURFACE STABLE LAYER AND MLCAPE VALUES GENERALLY LESS THAN 500 J/KG. THUS...DESPITE MODESTLY STRONG LOW-LEVEL AND DEEP-LAYER SHEAR WHICH WILL PERSIST ACROSS THE REGION...THE OVERALL SETUP DOES NOT APPEAR TO WARRANT ANY MORE THAN LOW TORNADO AND DAMAGING WIND PROBABILITIES. ..MEAD/LEITMAN.. 01/09/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z