...THERE IS A SLGT RISK OF SVR TSTMS MAINLY TONIGHT FROM THE ARKLATEX EWD ACROSS MS/SRN AL... ...LOWER MS VALLEY AREA THIS EVENING INTO TONIGHT... A SRN STREAM MID LEVEL TROUGH NOW EMERGING OVER THE SRN HIGH PLAINS AND AN ASSOCIATED SURFACE CYCLONE IN NRN KS WILL PROGRESS EWD TO THE LOWER MS AND LOWER OH VALLEYS AND AMPLIFY TONIGHT IN RESPONSE TO PHASING OF THE SRN AND NRN STREAMS. THIS SYSTEM WILL BE ACCOMPANIED BY A PLUME OF STEEP MID LEVEL LAPSE RATES ALREADY OVER THE SRN PLAINS. BENEATH THE STEEP LAPSE RATES...INDUCED SLY FLOW IN THE WARM SECTOR WILL DRAW BOUNDARY LAYER DEWPOINTS IN THE 60S NWD ACROSS THE NW GULF COAST TOWARD THE ARKLATEX. THIS DIFFERENTIAL ADVECTION...ALONG WITH DAYTIME HEATING INVOF A DEVELOPING DRYLINE ACROSS TX...WILL RESULT IN MLCAPE VALUES OF 1000-1500 J/KG IN A NARROW CORRIDOR FROM THE MIDDLE TX COAST TO THE ARKLATEX BY THIS EVENING. AN INITIALLY SHALLOW MOIST BOUNDARY LAYER...RELATIVELY LATE ARRIVAL OF THE RICHER LOW-LEVEL MOISTURE...AND STRONG CONVECTIVE INHIBITION ASSOCIATED WITH THE ELEVATED MIXED LAYER WILL LIKELY DELAY CONVECTIVE INITIATION UNTIL 00-03Z INVOF THE DRYLINE/COLD FRONT INTERSECTION. THEREAFTER...CONVECTION SHOULD SPREAD QUICKLY EWD OVERNIGHT ACROSS SE AR/NRN LA/MS/TN/AL. DESPITE THE LOSS OF DAYTIME HEATING...LOW-LEVEL MOISTENING SHOULD BE SUFFICIENT TO MAINTAIN DEEP CONVECTION THROUGH THE NIGHT AS BOUNDARY LAYER DEWPOINTS IN THE 60S SPREAD NWD FARTHER E INTO MS AND SRN AL. LOW-LEVEL SWLY FLOW NEAR 50 KT AND MID LEVEL WSWLY FLOW OF 70-90 KT WILL CONTRIBUTE TO STRONG VERTICAL SHEAR IN THE WARM SECTOR.
THE INITIAL CONVECTION MONDAY EVENING MAY CONSIST OF SUPERCELLS WITH AN ATTENDANT THREAT FOR A COUPLE OF TORNADOES...DAMAGING WINDS...AND LARGE HAIL. THE SEVERE THREAT SHOULD TRANSITION PRIMARILY TO DAMAGING WINDS OVERNIGHT WITH MORE LINEAR CONVECTIVE STRUCTURES IN AN ENVIRONMENT WITH ONLY LIMITED INSTABILITY.
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