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Feb 18, 2014 1630 UTC Day 1 Convective Outlook

February 18, 2014

Feb 18, 2014 1630 UTC Day 1 Convective Outlook

day1otlk

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1022 AM CST TUE FEB 18 2014

VALID 181630Z – 191200Z

…NO SVR TSTM AREAS FORECAST…

…TN/OH VALLEY REGION TO THE CAROLINAS TONIGHT…
LOW-LEVEL MOISTURE CONTINUES TO INCREASE IN CONJUNCTION WITH AIR MASS MODIFICATION ACROSS THE GULF BASIN…WITH 100-MB MEAN MIXING RATIOS NOW UP TO 12-13 G/KG ACROSS THE NW GULF COAST /BOUNDARY LAYER MEAN DEWPOINTS IN THE MID 60S/. THIS MOISTURE RESIDES S OF A WARM FRONT THAT WILL DRIFT NWD TO THE MID SOUTH AND RED RIVER VALLEY THROUGH TONIGHT…AND BELOW A WARM LAYER FROM 850-700 MB. THE WARM LAYER/INHIBITION AND LITTLE FOCUS FOR INITIATION ALL SUGGEST THAT CONVECTIVE INITIATION TODAY IS IN QUESTION. LATER THIS EVENING INTO TONIGHT…AN UPSTREAM SHORTWAVE TROUGH OVER THE NRN HIGH PLAINS WILL APPROACH THE OH VALLEY…WHILE A SEPARATE SPEED MAX OVER THE SRN HIGH PLAINS REACHES THE LOWER MS VALLEY. IN RESPONSE…A SWLY LLJ WILL STRENGTHEN BY EARLY TONIGHT…LEADING TO INCREASING LOW-LEVEL WAA AND THE POTENTIAL FOR ELEVATED THUNDERSTORM DEVELOPMENT OVER THE TN VALLEY. CONVECTION WILL THEN SPREAD NEWD INTO THE OH VALLEY…AND EWD INTO THE CAROLINAS. GIVEN OBSERVED UPSTREAM MIDLEVEL LAPSE RATES OF 7-8 C/KM AND EXPECTED STRONG VERTICAL SHEAR…THE INCREASING LOW-LEVEL MOISTURE WILL CONTRIBUTE TO SUFFICIENT BUOYANCY FOR A MARGINAL HAIL RISK OVERNIGHT ACROSS THE TN VALLEY.

…PAC NW COAST THIS AFTERNOON INTO TONIGHT…
ANOTHER IN A SERIES OF MIDLEVEL SHORTWAVE TROUGHS WILL PROGRESS INLAND OVER WA THIS AFTERNOON. SATELLITE IMAGERY AND LIGHTNING DETECTION DATA HAVE SHOWN SOME LOW-TOPPED CONVECTION/ISOLATED LIGHTNING STRIKES W OF VANCOUVER ISLAND. ISOLATED STRIKES WILL BE POSSIBLE WITHIN THE INITIAL BAROCLINIC BAND…AND INTO TONIGHT IN THE POST-FRONTAL ONSHORE FLOW WITH STEEP LAPSE RATES.

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