Apr 6, 2014 2000 UTC Day 1 Convective Outlook | |||||||||
Updated: Sun Apr 6 19:59:35 UTC 2014 ( | ) | |||||||||
Probabilistic to Categorical Outlook Conversion Table |
Categorical Graphic | |||||||||
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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. |
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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. |
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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. |
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SPC AC 061956 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0256 PM CDT SUN APR 06 2014 VALID 062000Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS ERN TX...LA...MS AND AL... THE ONLY CHANGE TO THE OUTLOOK IS TO REMOVE THE SLIGHT RISK AREA FROM PARTS OF CNTRL AND EAST TX. THUNDERSTORMS HAVE MARKEDLY DECREASED IN COVERAGE TO THE WEST OF A LINE FROM JUST WEST OF HOUSTON EXTENDING NWD TO TYLER. THIS AREA IS BEING IMPACTED BY SUBSIDENCE IN THE WAKE OF A VORTICITY MAX OVER THE ARKLATEX AND WILL BE AFFECTED BY DRIER AIR ADVECTING IN FROM THE NORTHWEST THIS AFTERNOON. TO THE EAST ACROSS LA...MS AND AL...A SEVERE THREAT WILL CONTINUE FROM THIS AFTERNOON INTO THE OVERNIGHT PERIOD AS A WELL-DEFINED 70 TO 90 KT MID-LEVEL JET MOVES INTO THE REGION FROM THE SOUTHWEST. THIS FEATURE WILL CREATE STRONG DEEP LAYER SHEAR PROFILES OVER THE TOP OF A MOIST AIRMASS CREATING CONDITIONS FAVORABLE FOR ROTATING STORMS. ..BROYLES.. 04/06/2014 .PREV DISCUSSION... /ISSUED 1128 AM CDT SUN APR 06 2014/ ...SYNOPSIS... THE PRIMARY FEATURE OF INTEREST DURING THE DAY ONE PERIOD IS A SRN-STREAM SHORT-WAVE TROUGH OVER THE SRN PLAINS INTO NWRN MEXICO WHICH WILL SHIFT EWD INTO THE SRN PLAINS AND LOWER MS VALLEY. AN ASSOCIATED 500-MB JET STREAK WILL STRENGTHEN TO 90-100 KT AS IT EMERGES FROM THE BASE OF THE PARENT TROUGH BEFORE MOVING INTO THE LOWER MS VALLEY TONIGHT IN TANDEM WITH A LEAD VORTICITY MAXIMUM. IN RESPONSE TO THE PROGRESSION OF THIS UPPER-AIR SYSTEM...A SSWLY LLJ WILL BROADEN AND INTENSIFY TO 50+ KT WHILE MIGRATING FROM THE WRN GULF OF MEXICO THROUGH THE LOWER MS AND TN VALLEYS INTO THE CNTRL/SRN APPALACHIANS BY 07/12Z. AT THE SURFACE...LOW PRESSURE OVER THE LOWER TX COAST WILL DEEPEN WHILE DEVELOPING NEWD INTO WRN PARTS OF KY/TN BY DAYBREAK MONDAY. AN ASSOCIATED WARM FRONT WILL LIFT NWD THROUGH MS AND AL INTO TN WITH THE ERN EXTENSION OF THIS BOUNDARY SHIFTING MORE SLOWLY NWD THROUGH PARTS OF GA AND SC. MEANWHILE...A COLD FRONT WILL STRENGTHEN WHILE ADVANCING EWD/SEWD INTO THE LOWER MS VALLEY. ...CNTRL/ERN TX INTO THE CNTRL GULF COAST STATES THIS AFTERNOON THROUGH TONIGHT... A CORRIDOR OF ELEVATED TSTMS ARE ONGOING AS OF MID MORNING FROM PORTIONS OF N-CNTRL/CNTRL TX INTO CNTRL MS WITH THIS ACTIVITY LARGELY BEING FORCED BY WARM AND MOISTURE ADVECTION OCCURRING AT THE TERMINUS OF THE LLJ ABOVE THE SURFACE WARM FRONT. THIS REGIME IS EXPECTED TO PERSIST TODAY WHILE GRADUALLY SHIFTING EWD/NEWD INTO THE LOWER MS VALLEY WITH MARGINALLY SEVERE HAIL BEING THE PRIMARY SEVERE WEATHER THREAT. THE INLAND DEVELOPMENT AND INTENSIFICATION OF THE LLJ WILL PROMOTE THE POLEWARD FLUX OF A SEASONABLY MOIST AIR MASS /I.E. PW VALUES OF 1.50-1.75 INCHES/ ALONG AND SOUTH OF THE WARM FRONT AND MIGRATORY SURFACE LOW WITH MLCAPE INCREASING TO 500-1000 J/KG WITHIN THE EXPANDING WARM SECTOR. INCREASING HEIGHT FALLS/DCVA AHEAD OF THE MIDLEVEL TROUGH COUPLED WITH LOW-LEVEL CONVERGENCE/UPLIFT INVOF SURFACE LOW AND ASSOCIATED WARM/COLD FRONTS WILL FOSTER INITIAL SURFACE-BASED STORM DEVELOPMENT BY MID TO LATE AFTERNOON OVER PARTS OF SERN TX INTO SRN LA WITH THIS ACTIVITY MOVING/DEVELOPING EWD/NEWD THROUGH A LARGE PART OF MS...AL AND THE WRN FL PNHDL THIS EVENING THROUGH THE OVERNIGHT HOURS. THE COLOCATION OF THE ABOVE-MENTIONED LOW AND MIDLEVEL WIND MAXIMA WILL RESULT IN STRONG LOW-LEVEL AND DEEP-LAYER SHEAR...PARTICULARLY FROM SERN LA THROUGH MS/AL DURING THE LATTER HALF OF THE FORECAST PERIOD. WHEN COUPLED WITH THE MOIST/LOW LCL BOUNDARY LAYER AND AT LEAST MODEST INSTABILITY...THE SETUP WILL BE SUPPORTIVE OF SUPERCELLS AND BOWING STRUCTURES CAPABLE OF TORNADOES /SOME POSSIBLY EF-2+/ AND WIND DAMAGE...NAMELY ALONG AND SOUTH OF THE I-20 CORRIDOR. ...W-CNTRL TX THIS AFTERNOON INTO EVENING... DAYTIME HEATING ALONG THE WRN EDGE OF PERSISTENT LOW CLOUDS COUPLED WITH COOLING MIDLEVEL TEMPERATURES WILL YIELD STEEPENING LAPSE RATES AND THE DEVELOPMENT OF WEAK INSTABILITY BY AFTERNOON ALONG AND AHEAD OF A TROUGH/WEAK FRONT MOVING THROUGH WRN TX. ISOLATED TO WIDELY SCATTERED TSTMS ARE LIKELY TO DEVELOP ALONG THIS BOUNDARY BY MID TO LATE AFTERNOON WITH THE STEEP LAPSE RATES AND COOL MID-TROPOSPHERIC TEMPERATURE PROFILES SUPPORTIVE OF SMALL HAIL AND LOCALLY GUSTY WINDS INTO THIS EVENING. CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z |