USA Weather — Severe Weather Division
This outlook is expired and is no longer valid.
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER NORTH-CENTRAL TEXAS INTO CENTRAL OKLAHOMA...AND ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY...
...SUMMARY...
ISOLATED SEVERE THUNDERSTORMS, WITH A TORNADO/DAMAGING WIND THREAT MAY CONTINUE THIS MORNING OVER PARTS OF TEXAS INTO OKLAHOMA. ISOLATED TO SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY, WITH A FEW TORNADOES AND DAMAGING WINDS THE MAIN THREAT.
...SYNOPSIS...
A SHARP, NEGATIVELY-TILTED SHORTWAVE TROUGH IS CURRENTLY LOCATED OVER SOUTHWESTERN TEXAS/NEW MEXICO. THIS TROUGH WILL RAPIDLY EJECT NORTHEASTWARD INTO THE UPPER GREAT PLAINS/MISSISSIPPI VALLEY THROUGHOUT THE PERIOD, WITH AN ASSOCIATED SURFACE LOW RAPIDLY DEEPENING/PUSHING NORTH-NORTHEAST WITH THIS SHORTWAVE. A COLD FRONT SWEEPS EASTWARD WITH TIME ACROSS THE PLAINS/MS VALLEY. A POWERFUL MID-LEVEL JET AND A STRONG LOW-LEVEL JET WILL SUPPORT RAPID MOISTURE TRANSPORT NORTHWARD INTO THE MID-WEST BY THIS EVENING, IN ADDITION TO A HIGHLY SHEARED PROFILE.
...OK/TX THIS MORNING...
A HIGHLY FORCED SQUALL LINE EXTENDING ACROSS CENTRAL OKLAHOMA INTO TEXAS WILL CONTINUE MOVING EASTWARD THIS MORNING WITHIN A MODESTLY UNSTABLE AND HIGHLY SHEARED ENVIRONMENT, CHARACTARIZED BY 500-1000 J/KG MLCAPE AND A 50-65KT LLJ. LONG/CURVED HODOGRAPHS WILL SUPPORT CONTINUED POTENTIAL FOR A FEW BRIEF TORNADOES AND DAMAGING GUSTS WITHIN EMBEDDED BOWING SEGMENTS. WHILE LOW-LEVEL MOISTURE TRANSPORT COULD SUPPORT SOME DESTABALIZATION, MODEL GUIDANCE IS IN AGREEMENT THAT THE SQUALL WILL OUTPACE BETTER THERMODYNAMICS AND THEREFORE GRADUALLY WEAKENING BY MID-MORNING. A SLIGHT RISK IS CONTINUED FOR NOW TO ACCOUNT FOR THE NEXT FEW HOURS.
...LOWER MISSISSIPPI VALLEY...
AHEAD OF THE SOUTHERN PORTION OF THE SQUALL LINE, INCREASING LOW-LEVEL MOISTURE WITH DEWPOINTS IN THE LOW 70S WILL SUPPORT A PLUME OF 1000-1500 J/KG MLCAPE SPREADING NORTHWARD INTO SOUTHERN ARKANSAS. MID-LEVEL LAPSE RATES WILL BE RATHER POOR GIVEN NEAR MOIST AIDABATIC TEMPERATURE PROFILES. STILL, THE COMBINATION OF THIS BUOYANCY WITH A STRONG LOW-LEVEL JET SUPPORTING 50KT DEEP LAYER SHEAR WILL SUPPORT THE POTENTIAL FOR THIS PART OF THE SQUALL TO STRENGTHEN AS IT ENTERS EAST TEXAS AND THE LOWER MISSISSIPPI VALLEY THIS AFTERNOON. CURVED/ELONGATED HODOGRAPHS SHOULD SUPPORT POTENTIAL FOR A FEW EMBEDDED SUPERCELL STRUCTURES AND BOWING SEGMENTS ALONG THE SQUALL LINE AS IT PROGRESSES EASTWARD THIS AFTERNOON/EVENING, WITH A THREAT FOR DAMAGING WINDS AND A FEW TORNADOES EXPECTED WITH THE STRONGER ACTIVITY. BY THE OVERNIGHT HOURS, BETTER FORCING RAPIDLY MOVES WELL NORTH OF THE REGION, LIKELY RESULTING IN A WEAKENING TREND ENHANCED BY DECREASING LOW-LEVEL INSTABILITY AND EVEN WORSE LAPSE RATES. STILL, A BRIEF TORNADO/DAMAGING GUST WILL BE POSSIBLE WITH ANY SURFACE-BASED PORTION OF THE LINE THAT REMAINS THROUGH DAYBREAK TUESDAY.
...MID MS VALLEY...
AHEAD OF THE COLD FRONT AND NEAR THE SURFACE LOW, AN AREA OF STEEP MID-LEVEL LAPSE RATES SHOULD PROMOTE MODESTLY BUOYANT 500-1000 J/KG MLCAPE. POWERFUL DEEP-LAYER SHEAR IN EXCESS OF 60-70KT COULD RESULT IN A FEW LOW-TOPPED SUPERCELLS CAPABLE OF PRODUCING AN ISOLATED/BRIEF TORNADO, DAMAGING GUSTS, AND MARGINALLY SEVERE HAIL THIS AFTERNOON/EVENING.