000 FXUS64 KMEG 241008 AFDMEG AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 508 AM CDT SUN MAY 24 2009 .DISCUSSION... THE BIGGEST CHALLENGES INCLUDE FLASH FLOODING/HEAVY RAINFALL POTENTIAL THIS MORNING AS WELL AS RAIN CHANCES TODAY THROUGH THURSDAY. LATEST MODELS WERE IN FAIR AGREEMENT. SLIGHTLY PREFERRED THE 00Z ECMWF MODEL AS THIS MODEL APPEARED TO BE HANDLING MOISTURE AND RAINFALL FIELDS BEST. THE BIGGEST CHANGE TO THE PREVIOUS FORECAST WAS TO SCALE BACK THE FLASH FLOOD WATCH AND SHORTEN IT TO 10 AM CDT. BASED ON RADAR TRENDS...MAY BE ABLE TO CANCEL THE ENTIRE WATCH BY 8 AM CDT AS THE HEAVIEST RAIN MAY BE NORTH AND WEST OF THE WATCH AREA BY THEN. DOPPLER RADAR ESTIMATES OF 1 TO 3 INCHES OF RAINFALL OCCURRED IN THE WATCH AREA SINCE 7 PM CDT SATURDAY. AN ADDITIONAL INCH OR TWO MAY OCCUR BEFORE THE RAIN ENDS. AT 5 AM CDT ACROSS THE MIDSOUTH AND FORECAST AREA...RAIN/SHOWERS WERE OCCURRING OVER MUCH OF WEST TN AND EAST CENTRAL AR WITH DRIER CONDITIONS OVER NORTH MS AND NEAR THE MO AND KY BORDERS. SURFACE TEMPERATURES WERE IN THE 66 TO 71 DEGREE RANGE WITH SURFACE DEWPOINTS IN THE 60S...NEAR 70 AT ABERDEEN MS. A SURFACE LOW WAS JUST NORTHWEST OF GREENWOOD MS...SLOWLY MOVING NORTHWEST. TODAY...KEPT VERY HIGH RAIN CHANCES EVERYWHERE...80 TO 100 PERCENT...AS MOST AREAS SHOULD GET AT LEAST 0.01 INCH OF RAINFALL. APPEARS THE HEAVIEST RAIN WILL OCCUR EARLY THIS MORNING OVER EAST CENTRAL AR WHERE 1 TO 2 INCHES MAY OCCUR. THINK MANY DRY HOURS WILL OCCUR...ESPECIALLY SOUTH OF I-40 WHERE EVEN SOME PEEKS OF SUN ARE POSSIBLE THIS AFTERNOON. MAY BE TOO PESSIMISTIC WITH RAIN CHANCES TODAY AS SINKING AIR BEHIND THE LOW MAY ACTUALLY DRY THINGS OUT ACROSS PARTS OF THE AREA...PARTICULARLY SOUTHWEST OF A FORREST CITY AR TO TUPELO MS LINE. AS THE SURFACE LOW MOVES WEST OF THE AREA...THE BULK OF THE RAIN WILL MOVE WEST AS WELL. PREFERRED THE WARMER SIDE OF GUIDANCE NUMBERS FOR LOCATIONS ALONG AND SOUTH OF I-40 WITH HIGHS RANGING FROM THE MID 70S OVER NE AR TO LOWER 80S OVER NORTH MS. THERE IS A VERY LOW CHANCE THAT AN ISOLATED TORNADO MAY OCCUR SOUTH OF I-40 AND EAST OF I-55 BETWEEN 9 AM AND 2 PM CDT AS THE COMBINATION OF ADEQUATE SHEAR AND INSTABILITY MAY ALLOW FOR A BRIEF SPINUP IN A BAND OF SHOWERS/STORMS. THE LATEST RUC MODEL SUGGEST THAT WINDS WILL WEAKEN CONSIDERABLY THROUGH THE MORNING WITH DECREASING HELICITY VALUES. BELIEVE THIS TORNADO POTENTIAL REMAINS TOO LOW TO MENTION IN HWO AT THIS TIME...BUT WOULD INCREASE IF WINDS DO NOT WEAKEN AS QUICKLY AS THE RUC MODEL SUGGESTS AND IF BETTER DESTABILIZATION/HEATING OCCURS THIS MORNING. WILL MONITOR. SOME REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS CAN BE EXPECTED OVER THE AREA AS THE AIR WILL DESTABILIZE THIS AFTERNOON IN A MOIST AIRMASS. WITH FORECAST LIFTED INDICES -3 TO -7...ADDED MENTION OF STRONG STORMS IN THE HWO AS THESE MAY PRODUCE GUSTY WINDS AND HEAVY DOWNPOURS. WITH PRECIPITABLE WATER VALUES ABOVE 1.7 INCHES AND SURFACE DEWPOINTS IN THE UPPER 60S TO NEAR 70...LOCALLY HEAVY RAINFALL OF 1 TO 2 INCHES MAY OCCUR WHICH MAY CAUSE LOCALIZED FLOODING. TONIGHT...KEPT RATHER HIGH RAIN CHANCES 40 TO 70 PERCENT FOR SHOWERS AND THUNDERSTORMS AS MODELS CONTINUE TO SHOW ABUNDANT MOISTURE AND SOME LIFT OVER THE AREA. THE BULK OF ACTIVITY SHOULD DIMINISH BY 10 PM CDT WITH THE LOSS OF DAYTIME HEATING. MUGGY AND MOSTLY CLOUDY CONDITIONS WILL PREVAIL WITH LOWS MAINLY IN THE UPPER 60S. MEMORIAL DAY...MOIST AND UNSTABLE CONDITIONS WILL ALLOW FOR SCATTERED TO NUMEROUS MAINLY AFTERNOON SHOWERS AND THUNDERSTORMS TO DEVELOP OVER THE AREA. KEPT HIGH RAIN CHANCES IN THE 60 TO 70 PERCENT RANGE AS MOST AREAS SHOULD GET WET. HOWEVER...MOST HOURS WILL BE DRY AND ANY RAIN SHOULD BE BRIEF IN DURATION...MAINLY LESS THAN 30 MINUTES. A FEW STORMS MAY BE STRONG WITH GUSTY WINDS AND HEAVY RAINFALL. MOSTLY CLOUDY SKIES WITH HIGHS IN THE LOWER 80S CAN BE EXPECTED. MONDAY NIGHT THROUGH THURSDAY...MOIST AND UNSTABLE CONDITIONS ARE EXPECTED TO CONTINUE WITH SCATTERED MAINLY AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS. WENT WITH DECREASING RAIN CHANCES EACH DAY...BUT NOT SURE IF THIS WILL HAPPEN. APPEARS A COLD FRONT MAY MOVE THROUGH THE AREA ON THURSDAY...WHICH MAY ENHANCE RAIN CHANCES THEN. KEPT STRONG THUNDERSTORM MENTION IN HWO AS THE AIR WILL BE UNSTABLE. MUGGY CONDITIONS WITH HIGHS IN THE 80S AND LOWS IN THE MID TO UPPER 60S CAN BE EXPECTED. THURSDAY NIGHT THROUGH SATURDAY...DRIER CONDITIONS ARE FORECAST BY LATEST MODELS...SO WENT WITH AN OPTIMISTICALLY DRY FORECAST DURING THIS TIME FRAME. TEMPERATURES ARE EXPECTED TO BE NEAR OR SLIGHTLY BELOW NORMAL. FORECAST CONFIDENCE DURING THIS TIME FRAME REMAINS RATHER LOW. MBS && .AVIATION... 06Z TAF CYCLE WORSENING CONDITIONS AFTER SUNRISE AS CEILINGS AND VSBY EXPECTED IN IFR RANGE. PERHAPS A FEW BREAKS IN IFR CONDITIONS IN THE AFTERNOON...BUT WILL NOT LAST LONG. AC/ARS && .PRELIMINARY POINT TEMPS/POPS... MEM 80 69 82 69 / 100 60 70 40 MKL 78 69 81 68 / 100 50 70 40 JBR 76 68 80 68 / 100 80 70 60 TUP 82 69 82 68 / 90 50 70 30 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR LEE AR- PHILLIPS. MO...NONE. MS...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR COAHOMA- PANOLA-QUITMAN-TATE-TUNICA. TN...NONE. && $$