NWS Area Forecast Discussion
000 FXUS64 KMOB 111055 AFDMOB AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOBILE AL 455 AM CST THU MAR 11 2010 .SHORT TERM...(TODAY AND TONIGHT) MOST OF THE HEAVIER CONVECTION HAS REMAINED OFFSHORE OVERNIGHT...APPEARING TO BE ROOTED IN A SECONDARY SFC BOUNDARY AS INDICATED BY RUC AND MSAS ANALYSIS. TO THE NORTH OF THIS BOUNDARY...STRATIFORM LIGHT TO MODERATE RAIN DEVELOPED ACROSS THE AREA WHICH EFFECTIVELY SERVED TO ELIMINATE ANY REMAINING SFC BASED CAPE...PREVENTING DEEPER CONVECTION FROM MOVING ONSHORE. WHILE THE MODELS WERE/AND STILL ARE INSISTENT THAT 2-4 INCHES WOULD OCCUR ALONG AND EAST OF I-65 FROM 06-12Z...THAT SIMPLY DOES NOT LOOK LIKE IT IS GOING TO HAPPEN. WATER VAPOR IMAGERY INDICATES SIGNIFICANTLY DRIER AIR ENCROACHING UPON THE AREA FROM THE WEST AND THIS IS BRINGING AN END TO THE LARGE AREA OF RAIN FROM WEST TO EAST. MORE ISOLATED SHOWERS AND A FEW RUMBLES OF THUNDER ARE OCCURRING FURTHER WEST OVER SE MS...LIKELY ENHANCED THE STEEPENING MID LEVEL LAPSE RATES ASSOCIATED WITH THE DRIER AIR. HOWEVER...THE DRIER AIR WILL SOON BE TOO MUCH TO OVERCOME AND MUCH OF THE CONVECTION SHOULD COME TO AN END BY MID MORNING ACROSS THE FORECAST AREA. WITH THE LACK OF MORE SIGNIFICANT CONVECTION...RAIN RATES WILL NOT BE HIGH ENOUGH TO SUPPORT A HIGH THREAT OF FLASH FLOODING...THEREFORE THE FLASH FLOOD WATCH HAS BEEN CANCELLED. A LARGE SPREAD IN THE MAV/MET HIGH TEMP FORECAST FOR TODAY. THE NAM MAINTAINS THE LOW LEVEL STRATUS FOR MUCH OF THE DAY...SERVING TO LIMIT DAYTIME HEATING AND IS 5-9 DEGREES COOLER THAN THE MAV. GIVEN HOW MUCH DRY AIR IS MOVING IN ABOVE 850 MB COMBINED WITH THE HIGHER MARCH SUN ANGLE...THINK THAT THE STRATUS DECK SHOULD SCATTER OUT BY LATE MORNING. THEREFORE...WILL LEAN CLOSER TO THE MAV AND GO WITH HIGHS IN THE MID TO UPPER 70S. A SECONDARY SHORTWAVE CURRENTLY SEEN ON WATER VAPOR OVER ARIZONA AND NEW MEXICO IS FORECAST TO ROUND THE BASE OF THE LARGE CYCLONE OVER THE CENTRAL PLAINS...BECOMING NEGATIVELY TILTED AS IT ENTERS THE LOWER MS VALLEY TONIGHT. THERE IS STARK DISAGREEMENT IN THE GUIDANCE WITH THE AMERICAN MODELS VERY DRY THROUGH 12Z FRI WITH THE ECMWF/CANADIAN PAINTING A QUARTER TO HALF INCH OF PRECIP ACROSS THE EASTERN HALF OF THE CWA. DYNAMICS WILL BE VERY ROBUST WITH THIS SYSTEM...IN THE FORM OF STRONG UPPER LEVEL DIVERGENCE AND HEIGHT FALLS. THE MAIN INHIBITING FACTOR IS THE DEGREE OF DRY AIR IN THE MID LEVELS. CURRENTLY LEANING TOWARD THE CONSISTENT ECMWF IN BELIEVING THE OVERALL DYNAMICS COMBINED WITH RESIDUAL LOW LEVEL MOISTURE AND INSTABILITY WILL BE ENOUGH TO PRODUCE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. WET BULB ZEROS WILL BE QUITE LOW (7-9 KFT)...SO HAIL MAY BE A CONCERN WITH ANY STRONGER CONVECTION THAT CAN MATERIALIZE. 34/JFB && .LONG TERM...FOR FRI EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...WITH THE BEST COVERAGE OCCURRING OVER THE EASTERN CWFA GENERALLY EAST OF THE I-65 CORRIDOR DURING THE MORNING HOURS. HAVE LEANED TOWARDS THE WETTER ECMWF SOLUTION WHICH DEPICTS MAIN SHORT WAVE TROUGH WITH ATTENDANT LOW NEAR THE SFC TO MOVE ACROSS THE LOWER MS RIVER VALLEY AND CENTRAL GULF STATES LATE FRI MORNING. MAIN CONCERN WITH THIS PATTERN ON FRI WILL BE THE IMPRESSIVE HEIGHTS FALLS IN THE MID LEVELS LEADING TO WETBULB 0 VALUES FALLING BELOW 10K FT FOR MOST AREAS COUPLED WITH A LEFT FRONT EXIT REGION OF 130 KT MID TO UPPER LEVEL JET SHIFTING NE FROM THE NORTH CENTRAL GULF TO LOWER GA AND NORTHERN SECTIONS OF FL. WITH MOSTLY UNIDIRECTIONAL SHEAR AT ALL LEVELS MAIN CONCERN WITH SOME OF THE STRONGER THUNDERSTORMS WILL BE LARGE HAIL AND ISOLATED CASES OF DAMAGING WINDS. AGAIN MOST OF THE HEAVIER SHOWERS AND THUNDERSTORMS WILL BE EAST OF THE I-65 CORRIDOR FRI MORNING. BY LATE FRI INTO SAT GOOD DRYING IS NOTED AT ALL LEVELS FOR THE MOST PART WITH SOME WRAP AROUND MOISTURE...LOW STRATUS...FROM MAIN UPPER SYSTEM TO THE NORTH ADVECTING SOUTHWARD TO THE CENTRAL GULF COAST STATES FRI NIGHT INTO SAT. CONDITIONS WILL ALSO BE RATHER BREEZY ESPECIALLY DURING THE DAYLIGHT HOURS BOTH FRI AFT AND SAT AS A STRONG WESTERLY FLOW ALOFT MIXES CLOSER TO THE SFC. WITH THIS...HAVE KEPT A SLIGHT CHANCE FOR LIGHT RAIN OR LIGHT SHOWERS FOR SAT GENERALLY FOR WRAP AROUND MOISTURE COMBINED WITH SHEAR ZONE ALOFT. FOR SUN THROUGH MIDWEEK WEAK HIGH PRES TAKES CONTROL NEAR THE SFC WITH MAIN UPPER LOW TO THE N OPENING UP AND SLOWLY SHIFTING EAST. BY WED NEXT SYSTEM LOOKS TO BE MOSTLY OVER THE OPEN GULF WITH THE GFS SOLUTION FURTHER TO THE SOUTH AND MOVING FASTER TO THE EAST THAN THE ECMWF. AS FOR TEMPS WILL CONTINUE TO LEAN TOWARDS THE CURRENT 00Z MEX GUIDANCE MAKING MINOR TWEAKS TO DAYTIME HIGHS JUST ALONG THE IMMEDIATE COAST. 32/EE && .AVIATION...12Z TAF CYCLE. MODERATE RAIN GENERALLY CONFINED TO EAST OF INTERSTATE 65 AND WILL CONTINUE TO PUSH EAST THROUGH THE EARLY MORNING. SCATTERED SHOWERS ARE NOTED FURTHER WEST. MOST OF THE PRECIPITATION SHOULD END ACROSS THE REGION BY MID MORNING. MVFR TO IFR CIGS WILL PERSIST THROUGH THAT TIME...BUT AS SIGNIFICANTLY DRIER LOW AND MID LEVEL AIR SPREADS IN FROM THE WEST COMBINED WITH THE MARCH SUN ANGLE...CIGS SHOULD SCATTER OUT BY LATE MORNING. LINGERING LOW LEVEL MOISTURE AND LIGHT SOUTHERLY FLOW MAY RESULT IN SOME MVFR TO IFR CIGS/VSBYS OVERNIGHT. THERE IS ALSO A CHANCE OF SHOWERS AND THUNDERSTORMS... ESPECIALLY EAST OF I-65 TOWARD DAYBREAK FRIDAY AS ANOTHER POTENT UPPER LEVEL DISTURBANCE APPROACHES ALONG WITH A COLD FRONT. && .MARINE...WHILE THE SYNOPTIC SCALE FLOW SUPPORTS SOUTHERLY WINDS OF AROUND 15 KTS WITH HIGHER GUSTS...WIDESPREAD SHOWERS AND THUNDERSTORMS OVER THE OPEN GULF WATERS IS RESULTING IN LOCALLY HIGHER WINDS AND SEAS. SEVERAL SPECIAL MARINE WARNINGS HAVE BEEN ISSUED OVERNIGHT AND MARINERS SHOULD PAY CLOSE ATTENTION TO FURTHER WARNINGS/STATEMENTS. THE THUNDERSTORM ACTIVITY WILL BEGIN TO END BY MID MORNING AND THE GRADIENT WINDS WILL WEAKEN TO AROUND 10 KT OUT OF THE SOUTHWEST. ONSHORE FLOW INCREASES AGAIN OVERNIGHT WITH THE APPROACH OF A COLD FRONT WITH ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS POSSIBLE THROUGH FRIDAY MORNING. A STRONG WEST TO NORTHWEST WIND IS EXPECTED IN THE WAKE OF THE FRONT LATE FRIDAY THROUGH SATURDAY. SMALL CRAFT ADVISORIES MAY BECOME NECESSARY. OFFSHORE FLOW IS EXPECTED TO DIMINISH BY SUNDAY/MONDAY. 34/JFB && .FIRE WEATHER...DRIER CONDITIONS ARE EXPECTED FRI THROUGH EARLY NEXT WEEK WITH AFTERNOON RELATIVE HUMIDITIES RANGING FROM THE MID 30 PERCENTILE INLAND AND THE LOWER 40 PERCENTILE CLOSER TO THE COAST. HIGHER THAN NORMAL DISPERSIONS WILL ALSO BE LIKELY FRI THROUGH SUN DUE TO A MODERATE TO STRONG WESTERLY FLOW IN THE MID TO UPPER LEVELS SOUTH OF THE MAIN UPPER VORTEX TO NORTH. 32/EE && .PRELIMINARY POINT TEMPS/POPS... MOBILE 76 56 74 45 / 30 50 40 10 PENSACOLA 73 58 74 48 / 60 60 60 10 DESTIN 70 60 71 51 / 80 60 60 10 EVERGREEN 75 55 74 44 / 70 60 60 10 WAYNESBORO 78 52 72 43 / 20 40 40 10 CAMDEN 75 54 73 45 / 70 50 50 10 CRESTVIEW 75 58 76 45 / 80 60 60 10 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...NONE. FL...NONE. MS...NONE. GM...NONE. && $$
NWS MOB Office Area Forecast Discussion