MESOSCALE DISCUSSION 0210 NWS STORM PREDICTION CENTER NORMAN OK 0201 PM CDT THU MAR 27 2014 AREAS AFFECTED...ERN TX...WRN LA CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 271901Z - 272100Z PROBABILITY OF WATCH ISSUANCE...40 PERCENT SUMMARY...A CLUSTER OF STORMS ROOTED JUST ABOVE THE SURFACE SHOULD FORM BY LATE AFTERNOON WITHIN A PERSISTENT LOW-LEVEL WAA REGIME AS INHIBITION WANES. ISOLATED SEVERE HAIL SHOULD BE THE PRIMARY THREAT...BUT LOCALLY DAMAGING WINDS AND A BRIEF TORNADO ARE POSSIBLE WITH POTENTIAL FOR EMBEDDED SUPERCELL STRUCTURES. DISCUSSION...MOST CONVECTION-ALLOWING AND CONVECTION-PARAMETRIZED GUIDANCE HAS BEEN TOO QUICK TO DEVELOP SIMULATED STORMS ACROSS E-CNTRL/SERN TX. THIS IS LIKELY DUE TO A STRONG CAPPING INVERSION NOTED IN 12Z CRP RAOBS AND A SPECIAL 15Z RAOB NEAR IAH ALONG WITH LATE MORNING AMDAR DATA. MOST RECENT AMDAR DATA SUGGEST THE INVERSION IS WEAKENING AND A SPECIAL 17Z RAOB NEAR CLL INDICATES LITTLE INHIBITION WITH RICH LOW-LEVEL SATURATION. CONTINUED LOW-LEVEL WAA AND DEEPENING CLOUDS ATOP THE LOW-LEVEL STRATUS DECK SUGGEST THAT STORMS ROOTED ABOVE THE SURFACE WILL INCREASE IN COVERAGE THOUGH LATE AFTERNOON. STEEP MID-LEVEL LAPSE RATES AND MODERATE BUOYANCY WOULD SUPPORT A RISK FOR SEVERE HAIL WITH SUFFICIENT DEEP-LAYER SHEAR FOR ORGANIZED UPDRAFTS. HOWEVER...THE LIKELIHOOD OF A CLUSTER CONVECTIVE MODE WITHIN AN ILL-DEFINED SURFACE PATTERN SHOULD TEMPER LONGEVITY OF INDIVIDUAL UPDRAFTS AND HAIL SIZE. EVEN WITH CONVECTION LIKELY INITIATING ABOVE THE SURFACE...SATURATED LOW-LEVEL THERMODYNAMIC PROFILES WITH NEAR-NEUTRAL LAPSE RATES COULD YIELD LOCALLY DAMAGING WINDS AND A BRIEF TORNADO. ..GRAMS/THOMPSON.. 03/27/2014 ATTN...WFO...LCH...SHV...HGX...FWD...
Posted on: Thu, 27 Mar 2014 19:07:13 +0000
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