DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0300 PM CDT MON MAR 09 2015 VALID 092000Z - 101200Z ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS SOUTHEAST LA AND FAR SRN MS FOR LATE TONIGHT/EARLY TUESDAY MORNING... ...SUMMARY... A FEW STRONG TO POSSIBLY SEVERE THUNDERSTORMS MAY AFFECT PORTIONS OF SOUTHEAST LOUISIANA AND FAR SOUTHERN MISSISSIPPI TONIGHT. OTHER THUNDERSTORMS ARE POSSIBLE OVER THE SOUTHERN ROCKIES INTO FAR WESTERN TEXAS...AND ACROSS PARTS OF SOUTH AND EAST TEXAS. ...SRN/ERN TX TO THE LOWER MS VALLEY... TSTMS ARE EXPECTED TO DEVELOP INTO TONIGHT ACROSS PORTIONS OF THE TX GULF COAST INTO THE LOWER MS VALLEY. ALTHOUGH INSTABILITY IS EXPECTED TO REMAIN MARGINAL THROUGH 12Z...ESPECIALLY GIVEN POOR LAPSE RATES...18Z RAP AND RECENT HRRR SUGGEST THE POTENTIAL FOR TSTMS TO BECOME SURFACE-BASED FROM SERN LA INTO FAR SRN MS TOWARD 12Z. A SLY LLJ IS EXPECTED TO STRENGTHEN TONIGHT FROM EAST TX INTO THE ADJACENT LOWER MS VALLEY RESULTING IN ENHANCED LOW-LEVEL HODOGRAPH CURVATURE. THIS WOULD SUPPORT A MARGINAL SEVERE RISK FOR LOCALLY STRONG WIND GUSTS AND A BRIEF TORNADO COULD NOT BE RULED OUT. ...SOUTHERN ROCKIES EAST INTO FAR WEST TEXAS... NO CHANGES ARE NEEDED ACROSS THIS REGION. TSTMS HAVE DEVELOPED AS EXPECTED ACROSS THE HIGHER TERRAIN OF NEW MEXICO INTO SOUTHWEST TX...WITH THIS TSTM THREAT FORECAST TO BE PRIMARILY DIURNAL. ..PETERS.. 03/09/2015 .PREV DISCUSSION... /ISSUED 1119 AM CDT MON MAR 09 2015/ ...SYNOPSIS... A BROAD SOUTHERN-STREAM UPPER TROUGH WILL REMAIN ESSENTIALLY STATIONARY THROUGH 12Z TUESDAY AS TWO VORTICITY MAXIMA OF PROMINENCE ROTATE THROUGH THE TROUGH. THE FIRST WILL LIFT NORTHEAST ACROSS TEXAS TODAY AND INTO THE OZARK PLATEAU TONIGHT. THE SECOND WILL MOVE SOUTHWARD THROUGH THE SOUTHERN GREAT BASIN INTO THE SONORA/CHIHUAHUA PROVINCES REGION OF NORTHERN MEXICO BY TUESDAY MORNING. A WEAK SURFACE LOW ASSOCIATED WITH THE LEAD DISTURBANCE WILL MOVE NORTHEAST FROM SOUTHERN TEXAS THIS MORNING INTO SOUTHERN ARKANSAS BY THE END OF THE PERIOD AS A COLD FRONT MOVES EAST TO NEAR THE TEXAS/LOUISIANA BORDER. ...SOUTHERN/EASTERN TEXAS INTO THE LOWER MISSISSIPPI VALLEY... WIDESPREAD CLOUDS/RAIN PERSISTS THIS MORNING WITHIN A ZONE OF ISENTROPIC ASCENT FROM MUCH OF CENTRAL/EASTERN TEXAS INTO THE LOWER MISSISSIPPI VALLEY REGION...AND THIS WILL LIKELY PERSIST THROUGH MUCH OF THE DAY. WITH TIME...PARTIALLY MODIFIED GULF MOISTURE SHOULD BEGIN TO ADVECT NORTHWARD ON STRENGTHENING LOW-LEVEL FLOW AS THE WEAK SURFACE LOW LIFTS NORTHEAST...WITH LOWER TO MID 60S DEW POINTS AS FAR NORTH AS CENTRAL MS BY 12Z TUE. A FEW THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON AND TONIGHT ALONG AND EAST OF THE COLD FRONT FROM SOUTHERN/SOUTHEAST TEXAS INTO THE LOWER MISSISSIPPI VALLEY AS MOISTURE ADVECTION CONTRIBUTES TO WEAK INSTABILITY /MUCAPE 200-300 J/KG/ AND MODEST LARGE-SCALE FORCING FOR ASCENT WITH THE LEAD SHORTWAVE GLANCES THE AREA. A WEAK CONFLUENCE ZONE EXPECTED TO EXTEND FROM FAR SOUTHEAST LOUISIANA NORTHWARD INTO SOUTHWESTERN MISSISSIPPI TONIGHT MAY ALSO FOCUS ADDITIONAL DEVELOPMENT IN THAT AREA. WEAK LAPSE RATES AND THE LIKELIHOOD THAT THUNDERSTORMS WILL BE SLIGHTLY ELEVATED SUGGEST THAT ORGANIZED SEVERE WEATHER IS UNLIKELY...HOWEVER A COUPLE OF WEAKLY-ROTATING STRONG STORMS WITH GUSTY WINDS WILL BE POSSIBLE. ...SOUTHERN ROCKIES EAST INTO FAR WEST TEXAS... DAYTIME HEATING COUPLED WITH THE COOL MID-LEVEL TEMPERATURES WITH THE UPSTREAM SHORTWAVE WILL RESULT IN SUFFICIENT INSTABILITY FOR A FEW THUNDERSTORMS MAINLY THIS AFTERNOON AND EVENING...AIDED IN PART BY TOPOGRAPHIC FORCING.
lundi 9 mars 2015
Mar 9, 2015 2000 UTC Day 1 Convective Outlook
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