238 FXUS64 KMOB 190455 AAB AFDMOB AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MOBILE AL 1155 PM CDT MON MAR 18 2013 .AVIATION...[06Z ISSUANCE]...IFR TO MVFR CONDITIONS GENERALLY FROM 06Z THROUGH 12Z TUES DUE IN LOW CLOUDS...WITH BASES AROUND 400 FT...AND POSSIBLE LIGHT RAIN AND FOG. SKIES GRADUALLY CLEAR TUES MORNING BECOMING PARTLY CLOUDY BY TUES AFTERNOON. WINDS WILL BE SOUTH TO SOUTHWEST AT 12 TO 15 KNOTS WITH GUSTS TO 20 KNOTS THROUGH 08Z FOLLOWED BY NORTHWEST WINDS AT 10 TO 15 KNOTS WITH GUSTS TO 18 KNOTS THROUGH 00Z WED. 32/EE && .UPDATE...PLAN TO LET THE SEVERE THUNDERSTORM WATCH EXPIRE AT 10 PM. STRONG STORMS WILL MOVE INTO OUR SE MS ZONES OVER THE NEXT HOUR OR TWO BUT RADAR SHOWS THESE STORMS GRADUALLY WEAKENING. THIS TREND SHOULD CONTINUE AS INSTABILITY DECREASES FURTHER. STILL CANNOT RULE OUT AN ISOLATED SEVERE OVER THE NEXT COUPLE OF HOURS WITH THIS CLUSTER OF STORMS...BUT THE THREAT IS NOT WIDESPREAD ENOUGH TO CONTINUE WITH A WATCH. WILL ALSO UPDATE NEAR TERM GRIDS BASED ON RADAR TRENDS. 34/JFB && .PREVIOUS DISCUSSION (ISSUED 630 PM CDT)... .AVIATION...[06Z ISSUANCE]...MOSTLY VFR TO MVFR CONDITIONS THROUGH 15Z TUE FOLLOWED VFR CONDITIONS THROUGH 00Z WED. IFR TO MVFR CONDITIONS ALSO POSSIBLE AT TIMES MAINLY IN AND AROUND SHOWERS AND THUNDERSTORMS GENERALLY FROM 03Z AND 08Z TUES AHEAD AND ALONG AN APPROACHING COLD FRONT...FOLLOWED BY IFR TO MVFR CONDITIONS IN LOW CLOUDS AND LIGHT RAIN IN THE WAKE OF THE FRONT MOVING ACROSS THE REGION AFTER 06Z TONIGHT. SKIES GRADUALLY CLEAR LATE TUES MORNING THROUGH TUES AFTERNOON. WINDS WILL BE SOUTH TO SOUTHWEST AT 12 TO 15 KNOTS WITH GUSTS TO 20 KNOTS THROUGH 08Z FOLLOWED BY NORTHWEST WINDS AT 10 TO 15 KNOTS WITH GUSTS TO 18 KNOTS THROUGH 00Z WED. 32/EE .UPDATE...A SEVERE THUNDERSTORM WATCH IS NOW IN EFFECT UNTIL 10 PM CDT FOR MOST INLAND COUNTIES OF SOUTHWEST AL AND SOUTHEAST MS. A LARGE AREA OF STRONG TO SEVERE THUNDERSTORMS OVER EAST CENTRAL MISSISSIPPI AND WEST CENTRAL ALABAMA WILL CONTINUE TO MOVE SOUTHEAST OVER THE WATCH AREA THROUGH MID TO LATE EVENING. MANY REPORTS OF LARGE HAIL AND DAMAGING WINDS HAVE BEEN REPORTED WITH THE STRONGER THUNDERSTORMS OVER MS DURING THE LAST 2 TO 3 HOURS. CONDITIONS REMAIN FAVORABLE FURTHER DOWNSTREAM FOR THE SAME TYPE OF CONDITIONS...ESPECIALLY OVER THE WATCH AREA THROUGH THIS EVENING. WITH VERY STEEP MID LEVEL LAPSE RATES AROUND 8C STILL IN PLACE COMBINED WITH MIXED LAYERED CAPES EVEN UP TO 2500 J/KG THE THREAT FOR LARGE HAIL AND DAMAGING WINDS WILL REMAIN HIGHER THAN NORMAL THROUGH MID TO LATE EVENING. FREQUENT CLOUD TO GROUND LIGHTNING AND VERY HEAVY RAIN WILL ALSO ACCOMPANY THUNDERSTORMS THROUGH THIS EVENING. MOST OF THE THUNDERSTORMS WERE MOVING EAST SOUTHEAST AT 40 MPH. 32/EE .PREV DISCUSSION... /ISSUED 245 PM CDT MON MAR 18 2013/ SHORT TERM [TONIGHT AND TUESDAY]...A WARM MOIST AIRMASS WILL BE IN PLACE THIS EVENING ACROSS THE FORECAST AREA AHEAD OF A COLD FRONT APPROACHING FROM THE NORTHWEST. SCATTERED SHOWERS AND A FEW THUNDERSTORMS HAVE BEEN TRYING TO DEVELOP THIS AFTERNOON UNDER A VERY STRONG CAPPING INVERSION IN THE MID LEVELS. THIS CAP IS EXPECTED TO ERODE BY LATE THIS AFTERNOON...FOLLOWED BY SCATTERED TO NUMEROUS THUNDERSTORMS THROUGH THE EVENING HOURS. SEVERE WEATHER PARAMETERS CONTINUE TO INDICATE THE MAIN THREATS WITH THE STRONGER SUPERCELLS TO BE LARGE HAIL UP TO 2" IN DIAMETER AND DAMAGING MICROBURST WINDS UP TO 60 MPH. DEEP LAYER SHEAR (0-3KM) WILL BE NEAR 200 M^2/S^2...SUFFICIENT ENOUGH FOR A FEW TORNADO PRODUCING SUPERCELLS. STAY TUNED TO FURTHER DEVELOPMENTS AND INFORMATION AS THEY BECOME AVAILABLE. THE COLD FRONT WILL ENTER INTO OUR INLAND SOUTHEAST MISSISSIPPI ZONES SHORTLY BEFORE MIDNIGHT...AND THEN SWEEP THROUGH THE ENTIRE FORECAST AREA BY DAYBREAK TUESDAY. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL PERSIST SOUTHEAST OF I-65 AFTER MIDNIGHT...BUT THE SEVERE WEATHER THREAT SHOULD NO LONGER EXIST. THE PRECIPITATION AHEAD OF THE FRONT WILL ALSO MOVE EAST OF THE AREA BY DAYBREAK. MOSTLY SUNNY SKIES AND DRY CONDITIONS WILL RETURN ON TUESDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTH. LOWS TEMPERATURES TONIGHT WILL RANGE BETWEEN 48 AND 56 DEGREES NORTHWEST OF I-65...AND RANGE BETWEEN 56 AND 61 DEGREES SOUTHEAST OF I-65. HIGHS TUESDAY WILL BE IN THE 70S. /22 [TUESDAY NIGHT THROUGH THURSDAY]...DUE TO THE DRIER AIRMASS...LOWS TUESDAY NIGHT WILL DROP BACK TO MORE NORMAL LEVELS...IN THE MID/UPPER 30S INLAND TO LOW 50S NEAR THE COAST. AN UPPER LEVEL DISTURBANCE WILL PASS WEST AND SOUTH OF THE FORECAST AREA ON WEDNESDAY BUT MAY BE ENOUGH TO GENERATE A FEW ISOLATED SHOWERS ACROSS THE SOUTHWEST PORTIONS OF THE AREA AND ACROSS THE MARINE AREA. ANOTHER SURGE OF COOL AND DRY AIR WILL MOVE INTO THE AREA WEDNESDAY NIGHT INTO THURSDAY IN THE WAKE OF THIS DISTURBANCE. CLOUDS WILL BEGIN TO INCREASE ON THURSDAY AS LOW PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS AND MOVES EAST. THIS WILL ALLOW A STALLED FRONT OVER THE MARINE AREA TO LIFT NORTHWARD AS A WARM FRONT...CAUSING WINDS TO BECOME SOUTHERLY AND MOISTURE LEVELS TO GRADUALLY INCREASE. /13 LONG TERM [THURSDAY NIGHT THROUGH NEXT MONDAY]...THE EXTENDED REMAINS UNCERTAIN AND ONLY MINOR CHANGES WERE MADE. AS SOUTHERN PLAINS SURFACE LOW MOVES EASTWARD THURSDAY NIGHT...A SFC WARM FRONT LIFTS NORTHEASTWARD GRADUALLY AND WILL FORCE SOME LIGHT OVERRUNNING PCPN ALONG AND TO ITS NORTH. GIVEN UPPER LEVEL FLOW PATTERN'S ORIENTATION...SFC LOW SHOULD TAKE A MORE SOUTHERLY TRACK THAN FORECAST BY LATEST GFS AND AREAS ALONG AND SOUTH OF HIGHWAY 84 THUS STAND TO RECEIVE THE BEST CHANCE OF RAIN WITH SCATTERED THUNDERSTORMS ON FRIDAY (DEPENDING ON INSTABILITY AND VERTICAL WIND SHEAR) A FEW STRONG STORMS COULD DEVELOP. THIS IS TO BE DETERMINED ONCE WE HAVE A BETTER HANDLE ON LARGE SCALE FEATURE EVOLUTION. AS SFC LOW MOVES QUICKLY OVER REGION FRIDAY EVENING...SFC WINDS SHIFT TO NW AND COOLER AIR ADVECTS INTO OUR AREA. HOWEVER...REGION DOES NOT DRY OUT COMPLETELY. A SERIES OF MINOR IMPULSES CONTINUE STREAMING ALONG IN A THEN SOUTHWESTERLY MID- AND UPPER-LEVEL FLOW PATTERN WHICH MAY ACT TO FORCE ADDITIONAL LARGE SCALE LIFT AND SUBSEQUENT LIGHT RAIN BEHIND THE SFC FRONT. LOOKS LIKE ONE WAVE MOVING NORTHEASTWARD OUT OF THE SWRN GULF OF MEXICO AND ANOTHER DIGGING IN THE SOUTHERN PLAINS WILL COMBINE TO RAISE RAIN CHANCES AGAIN BY SAT NIGHT AND INTO EARLY SUNDAY. THE SYSTEM MOVES QUICKLY AND SUBSIDENT AIR RETURNS IN THAT SYSTEM'S WAKE ON MONDAY. AT THIS POINT AM FORECASTING WELL BELOW SEASONAL NORMS FOR HIGH AND LOW TEMPERATURES FOR PERIOD SATURDAY THROUGH MONDAY WITH A SLOW MODERATION WITH AN NORTHERLY WIND COMPONENT FROM EARLY SATURDAY THROUGH MONDAY. /13 MARINE...A MODERATE SOUTHERLY WIND FLOW WILL PERSIST OVER THE MARINE AREA THROUGH THIS EVENING AHEAD OF A COLD FRONT. SHOWERS AND THUNDERSTORMS CAN BE EXPECTED WITH THE BEST CHANCE OCCURRING THIS EVENING THROUGH THE OVERNIGHT HOURS. THE COLD FRONT WILL MOVE ACROSS THE REGION LATE TONIGHT LEADING TO A MODERATE TO STRONG OFFSHORE FLOW THROUGH MID WEEK. A LIGHT TO MODERATE EASTERLY WIND FLOW WILL REDEVELOP LATE IN THE WEEK AS A SURFACE RIDGE OF HIGH PRESSURE OVER THE NATIONS MID SECTION SHIFTS EAST. /22 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...NONE. FL...NONE. MS...NONE. GM...NONE. && $$