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Apr 4, 2014 1630 UTC Day 1 Convective Outlook

April 4, 2014

Apr 4, 2014 1630 UTC Day 1 Convective Outlook

day1otlk

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1116 AM CDT FRI APR 04 2014

VALID 041630Z – 051200Z

…THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON ACROSS A PART OF THE CNTRL GULF COAST…

…SYNOPSIS…

AN INTENSE NEGATIVELY TITLED SHORT-WAVE TROUGH AND ASSOCIATED MIDLEVEL JET STREAK OVER THE UPPER MIDWEST INTO LOWER OH VALLEY WILL TRANSLATE NEWD INTO ERN ONTARIO/WRN QUEBEC AND LOWER GREAT LAKES BY 05/12Z. ELSEWHERE…A SHORT-WAVE TROUGH WILL AMPLIFY OVER THE LOWER CO VALLEY INTO BAJA AND NWRN MEXICO.

AT THE SURFACE…AN OCCLUDED LOW OVER CNTRL LAKE MI WILL DEVELOP NEWD INTO WRN QUEBEC WHILE A TRAILING COLD FRONT ADVANCES EWD THROUGH THE UPPER OH/TN VALLEYS AND CNTRL APPALACHIANS TO OFF THE MID ATLANTIC COAST BY DAYBREAK SATURDAY. THE COLD FRONT WILL PROGRESSIVELY OVERTAKE A WARM FRONT LIFTING NWD THROUGH THE MID ATLANTIC STATES WITH WEAK CYCLOGENESIS FORECAST AT THE INTERSECTION OF THESE TWO BOUNDARIES. MEANWHILE…THE TRAILING EXTENSION OF THE COLD FRONT WILL MOVE MORE SLOWLY EWD/SEWD THROUGH THE GULF COAST STATES AND SRN APPALACHIANS WITH THIS FEATURE LIKELY EXTENDING FROM THE TIDEWATER REGION SWWD THROUGH THE FL PNHDL TO THE NEAR-SHORE WATERS OFF THE SERN LA COAST BY THE END OF THE PERIOD.

…CNTRL GULF COAST THIS AFTERNOON…

THE TRAILING EXTENSION OF A NOCTURNAL QLCS IS ONGOING OVER S-CNTRL/SERN LA AND SRN MS AS OF MID MORNING. THE INFLOW AIR MASS TO THIS CONVECTIVE SYSTEM IS QUITE MOIST WITH BOUNDARY LAYER DEWPOINTS IN THE MID 60S TO LOWER 70S. WHEN COUPLED WITH DAYTIME HEATING AND MODESTLY STEEP MIDLEVEL LAPSE RATES…EXPECT POCKETS OF MODERATE AFTERNOON INSTABILITY TO DEVELOP WITH MLCAPE APPROACHING 1000-2000 J/KG. THE RECENT EVOLUTION OF AN MCV ON THE NWRN FLANK OF THE QLCS MAY PROMOTE SOME BOWING CHARACTERISTICS AND A RESULTANT ENHANCEMENT OF DAMAGING WIND POTENTIAL ACROSS THE SLIGHT RISK AREA THIS AFTERNOON.

…UPPER OH VALLEY INTO MID ATLANTIC THIS AFTERNOON/EVENING…

THE QLCS WHICH FORMED LAST NIGHT HAS SINCE WEAKENED CONSIDERABLY WHILE ADVANCING WELL AHEAD OF THE SYNOPTIC COLD FRONT WITH THE LEADING EDGE OF THE COLD POOL EXTENDING FROM ERN WV SSWWD TO FAR WRN NC AS OF 1530Z. DOWNSTREAM 12Z SOUNDINGS E OF THE APPALACHIANS INDICATE THAT THE LACK OF MORE ROBUST MOISTURE RETURN IN THE BOUNDARY LAYER WILL LIMIT THE DEGREE OF AIR MASS DESTABILIZATION THIS AFTERNOON DESPITE THE PRESENCE OF RELATIVELY STEEP MIDLEVEL LAPSE RATES.

CURRENT INDICATIONS ARE THAT STORMS MAY RE-INTENSIFY AND/OR DEVELOP BY AFTERNOON ALONG THE RESIDUAL COLD POOL ATTENDANT TO THE DECAYED MCS AS WELL AS ALONG A DEVELOPING LEE TROUGH AS THE BOUNDARY LAYER WARMS AND PROMOTES A WEAKLY UNSTABLE ENVIRONMENT. LOCALLY DAMAGING WIND GUSTS WILL BE POSSIBLE WITH THE STRONGEST STORMS GIVEN THE STEEPENING OF LOW-LEVEL LAPSE RATES WHICH WILL PROMOTE THE DOWNWARD TRANSFER OF HIGH-MOMENTUM WESTERLY FLOW. HOWEVER…THIS RISK APPEARS TOO MARGINAL TO WARRANT INCLUSION OF A SLIGHT RISK AREA.

FARTHER TO THE NW OVER THE UPPER OH VALLEY INTO LOWER GREAT LAKES…CONSIDERABLE CLOUDINESS ALONG AND AHEAD OF THE COLD FRONT WILL LIMIT BOUNDARY LAYER HEATING AND THE POTENTIAL FOR MORE ROBUST AIR MASS DESTABILIZATION THIS AFTERNOON. LARGE-SCALE FORCING FOR ASCENT AND VERTICAL SHEAR WILL REMAIN STRONG AND SOME POTENTIAL WILL EXIST FOR LOW-TOPPED STORMS CAPABLE OF LOCALLY DAMAGING WINDS AND/OR SOME HAIL INTO THIS EVENING.

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