719 FXUS64 KMOB 281657 AAA AFDMOB AREA FORECAST DISCUSSION...MESOSCALE AND AVIATION UPDATE NATIONAL WEATHER SERVICE MOBILE AL 1159 AM CDT FRI MAR 28 2014 .MESOSCALE UPDATE...CURRENT PERIOD BEING DEFINED BY ISENTROPIC UPGLIDE SHOWERS NORTH OF A COMBINATION OUTFLOW/SQUALL LINE. THE EASTERN EDGE HAS MOVED OUT OF THE FA...WITH SOUTHERN EXTENTS APPROACHING SOUTHERN EDGES OF THE MARINE FA. AM EXPECTING THIS MORE STABLE PRECIP TO LAST WELL INTO MID AFTERNOON...BRINGING ANOTHER HALF OF AN INCH TO INCH OF RAIN TO THE FA. RADAR ESTIMATES SHOW A BAND OF 4"+ OVER NORTHERN PERRY AND GREENE TO CHOCTAW AND WILCOX COUNTIES...AND ALSO ALONG THE AL/FL GULF COAST. A FFW IS BEING CONSIDERED...ESPECIALLY WITH ANOTHER ROUND OF RAIN EXPECTED LATER TONIGHT INTO SATURDAY. /16 && .AVIATION... (18Z ISSUANCE)...IFR OR LOWER CIGS IN A BAND OF THUNDERSTORMS HAS MOVED EAST AND SOUTH OF THE FA...WITH MVFR TO VFR CIGS BEING REPORTED AT FORECAST POINTS. AM EXPECTING THE HIGHER CIGS TO LAST INTO TONIGHT...WITH ANOTHER LINE OF TSRA MOVING OVER THE FA IN THE LATTER PART OF THE FORECAST BRINGING DROPS IN CIGS/VISBYS TO IFR OR LOWER LEVELS. /16 && .SHORT TERM (TODAY AND TONIGHT)...THE COMBINATION OF INCREASED UPPER LEVEL DIVERGENCE...LOW LEVEL WARM AIR ADVECTION...AND ELEVATED INSTABILITY...HAS RESULTED IN A LARGE COVERAGE OF SHOWERS AND THUNDERSTORMS EARLY THIS MORNING. IN ADDITION...A LARGE AREA OF CONVECTION IS ALSO NOTED OVER CENTRAL AL SOUTHWEST INTO SOUTHWEST MS. SEVERAL RUNS OF THE HRRR AND THE 00Z NSSL WRF SHOW THIS CONVECTION ORGANIZING INTO A COMPLEX OF STORMS THAT MOVES SOUTHEAST THROUGH OUR AREA LATER THIS MORNING HOURS. IN FACT...THESE HI-RES MODELS ARE INDICATING ENOUGH OF A COLD POOL DEVELOPING TO RESULT IN BOWING STRUCTURES ALONG THE LEADING EDGE OF THE COMPLEX. WHILE REGIONAL RADAR DOES NOT YET SHOW THIS CONSOLIDATION...THE GLOBAL MODELS INDICATE THE BEST UPPER LEVEL DIVERGENCE (INITIALIZED WHERE THE CONVECTION IS) WILL SHIFT SOUTH AND EAST AS THE MORNING PROGRESSES. THEREFORE...WE WILL MAINTAIN CATEGORICAL RAIN CHANCES (80-90%) FROM AFTER SUNRISE THROUGH MIDDAY. WHILE THE BOWING STRUCTURES DO INDICATE THE POTENTIAL FOR STRONG WINDS...MLCAPES OF LESS THAN 500 J/KG COMBINED WITH DECREASING DEEP LAYER WIND PROFILES AS THE PARENT SHORTWAVE OVER THE MIDWEST QUICKLY MOVES TO THE NORTHEAST...SUGGESTS THE SEVERE THREAT WILL REMAIN ISOLATED AT BEST. THE PERSISTENT W-SW MID TO UPPER FLOW CONTINUES TO BRING IN STEEPER MID LEVEL LAPSE RATES (6.5-7.0 C/KM) FROM THE MEXICAN PLATEAU. THESE LAPSE RATES HAVE RESULTED IN PERIODS OF FREQUENT LIGHTNING AND A FEW SMALL HAIL SIGNATURES ON RADAR. SMALL HAIL WILL REMAIN POSSIBLE THROUGH THE MORNING ON AN ISOLATED BASIS. THE FORECAST FOR THIS AFTERNOON AND EVENING HINGES ON THE EVOLUTION OF THE CONVECTION THIS MORNING. BASED ON THE ANTICIPATION OF A COMPLEX OF STORMS MOVING SE THROUGH THE AREA THIS MORNING...A LARGE STRATIFORM SHIELD OF RAIN COULD AFFECT THE SOUTHERN AND EASTERN PORTIONS OF THE AREA THIS AFTERNOON...WITH CONDITIONS DRYING OUT FROM NW-SE THROUGH THE LATE AFTERNOON EARLY EVENING. WE COULD SEE A LULL IN PRECIP THROUGH THIS TIME FRAME AS WE WAIT FOR THE COLD FRONT AND NEXT STRONG SHORTWAVE TO MOVE IN FROM THE WEST. DEEP LAYER FORCING IS FORECAST TO INCREASE LATE THIS EVENING OVER INLAND SE MS AND SPREAD EASTWARD AFTER MIDNIGHT. GUIDANCE SHOWS MID LEVEL LAPSE RATES STEEPENING FURTHER...ON THE ORDER OF 7.0-8.0 C/KM. MLCAPES POTENTIALLY APPROACH 1000 J/KG TOMORROW NIGHT...HOWEVER THE AMOUNT OF SFC BASED INSTABILITY WILL BE DEPENDENT ON EARLIER CONVECTION. IN EITHER CASE...A GOOD DEGREE OF ELEVATED INSTABILITY WILL BE PRESENT. THEREFORE...THE COMPLEX OF STORMS THAT MOVES THROUGH LATE TONIGHT/EARLY SATURDAY MORNING WILL CARRY THE POTENTIAL OF LARGE HAIL. AN ISOLATED OCCURRENCE OF DAMAGING WINDS IS ALSO POSSIBLE...BUT AGAIN WILL DEPEND ON THE AMOUNT OF SFC BASED INSTABILITY. PRECIPITABLE WATERS AROUND 1.5 INCHES COMBINED WITH PERIODS OF DEEP CONVECTION WILL CERTAINLY PRODUCE LOCALLY HEAVY RAINFALL. GIVEN THE UNCERTAINTIES IN CONVECTIVE EVOLUTION TODAY...CONFIDENCE IS TOO LOW TO ISSUE ANY SORT OF FLOOD WATCH. MINOR FLOODING IN URBAN AND LOW LYING AREAS IS POSSIBLE ALONG WITH ISOLATED INSTANCES OF FLASH FLOODING. WENT LOWER THAN MAV GUIDANCE FOR HIGHS TODAY BASED ON THE ABUNDANT PRECIP AND CLOUDS. ON THE FLIP SIDE...WENT SLIGHTLY WARMER FOR LOWS. WILL MAINTAIN THE HIGH RIP CURRENT RISK AND HIGH SURF ADVISORY THROUGH THIS EVENING AS SURF HEIGHTS OF 4 TO 5 FEET WILL CONTINUE TO AFFECT THE BEACHES. 34/JFB .SHORT TERM (SATURDAY THROUGH SUNDAY)...SURFACE HIGH MOVING INTO THE WESTERN ATLANTIC OCEAN CONTINUES TO BRING A MODERATE TO STRONG ONSHORE FLOW DUE TO A SURFACE LOW DEEPENING AND MOVING RAPIDLY FROM EAST TEXAS TO THE CENTRAL OHIO/TENNESSEE VALLEY BY 12Z SATURDAY. A COLD FRONT WHICH WILL BE ASSOCIATED WITH THAT DEEPENING LOW WILL STRENGTHEN WHILE PASSING THROUGH OUR REGION SATURDAY MORNING. THESE FEATURES WILL ACT AS A CONVEYOR BELT BRINGING WATER VAPOR FROM THE CENTRAL GULF. WINDS ALOFT WILL GENERALLY BE SOUTHWEST ACROSS THE FORECAST AREA. AS AN UPPER TROUGH MOVES THROUGH OUR REGION FROM THE PLAINS...IT WILL DEEPEN TO AN EXTREMELY DEEP TROUGH THAT SHOWS A PROPENSITY TO CLOSE OFF IN THE GFS OUTPUT...AND AS COMPUTED BY THE EURO...IT ACTUALLY DOES CLOSE OFF BY LATE SATURDAY NIGHT AS IT CROSSES THE PIEDMONT REGION. THAT WOULD BRING A MORE CERTAIN PROSPECT OF A CLEAN SWEEP OF CLOUD COVER AND RAIN CHANCES BY SATURDAY AFTERNOON. EXPECTING BAND OF CONVECTION TO PASS EAST OF THE REGION CLOSE TO OR BY SUNRISE OR SHORTLY THEREAFTER. BOTH THE EURO AND GFS SHOW THE 850 MB TROUGH PASSING OUR REGION SO ANY POST-FRONTAL STRATIFORM RAIN WOULD END WITH CLEARING SKIES AROUND NOON OR SHORTLY THEREAFTER. MODEL SOUNDINGS SHOW INSTABILITY ELEVATED MOSTLY INLAND. WET BULB ZEROES WILL PLUMMET FROM AROUND 10000 FEET AROUND SUNRISE TO ABOUT 8000 FEET OVER THE WEST FLORIDA PANHANDLE AND SOUTHERN PORTIONS OF SOUTH CENTRAL ALABAMA. AT THE SAME TIME THE MODELS COMPUTE LI INCREASING FROM -4 TO 0 BETWEEN 12 AND 18Z OVER THE SAME REGION. THIS MEANS A HAIL THREAT FOR OUR REGION IS LINGERING AS A NARROW WINDOW AS THE MOIST STATIC ENERGY DECREASES AND WET BULB ZERO DECREASES ALONG WITH THE CONVECTION WITH THE PASSING LINE. SO ALONG THE SOUTHEAST PORTION OF THE REGION AND POINTS SOUTH...SURFACE BASED SEVERE CONVECTION IS UNCERTAIN...BUT AGAIN IN THE PRESENCE OF COUNTERACTING TERMS IN THE EQUATION AND THEIR RESPECTIVE TIMING...WE CANNOT BE THAT CERTAIN IN THE CLOSING STAGES OF THIS EVENT. THE RISK OF LOCALIZED FLOODING WILL HAVE ENDED BY SATURDAY MORNING. AFTER THE RAIN MOVES OUT SATURDAY...A COOL NORTH TO NORTHWEST WIND WILL SWEEP IN BUT IT IS NOT ASSOCIATED WITH A DEEP TRAJECTORY FROM ALBERTA. THE TRAJECTORY WOULD BE ORIGINATING MORE FROM THE PLAINS SO WE WOULD SEE LOWS DROPPING INTO UPPER 30S TO LOWER 40S SATURDAY AND SUNDAY NIGHTS. A RELATIVELY CLEAR DAY WOULD ENSUE ON SATURDAY WITH HIGHS IN THE LOWER AND MID 70S...AND HIGHS IN THE LOWER 70S SUNDAY. 77/BD .LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)...THE OCCLUDING BAROCLINIC SYSTEM OVER THE EASTERN UNITED STATES WILL MOVE OFFSHORE AND DEEPEN OVER THE WESTERN ATLANTIC SUNDAY NIGHT. WHILE ANOTHER TROUGH DEEPENS OVER THE WESTERN GREAT PLAINS AS A RIDGE BUILDS OVER OUR REGION AND THE EASTERN UNITED STATES. MONDAY EVENING...THE SURFACE RIDGE WILL HAVE MOVED SUFFICIENTLY EAST OF OUR AREA TO OPEN THE GULF UP. AS THE PLAINS SYSTEM GETS DEFLECTED NORTHEAST OVER THE GREAT LAKES TUESDAY. THE SURFACE RIDGE WILL MOVE JUST OFF THE GEORGIA COAST BECOMING QUASISTATIONARY AND MAINTAINING ELEVATED RH THROUGH MIDWEEK KEEPING TEMPS ABOVE SEASONAL. AS THE WEEK PROGRESSES...ZONAL POTENTIAL ENERGY GETS A CHANCE TO BUILD UP AND CONVERT TO EDDY KINETIC ENERGY FORMING ANOTHER TROUGH OVER THE PLAINS AROUND EARLY THURSDAY. EVIDENCE OF A WEAK COLD FRONT MOVING TOWARDS THE FA IS SHOWN IN THE GFS CALCULATIONS. THIS FRONT IS PROJECTED TO CROSS THE REGION LATE THURSDAY INTO FRIDAY. THE GFS COMPUTES THE FRONT SWEEPING THROUGH OUR REGION...UNLIKE THE 12Z RUN WHICH STALLED IT AND DEVELOPED AN OFFSHORE SURFACE LOW. THE NEW OUTPUT PUTS THE GFS MORE IN LINE WITH THE ECMWF AND INCREASING OUR CONFIDENCE IN RAIN CHANCES THURSDAY. GUIDANCE IS IN PRETTY CLOSE PHASE UNTIL THEN...BUT DISPERSES FURTHER OUT INTO THE EXTENDED PERIODS. 77/BD && .MARINE...A MODERATE TO STRONG ONSHORE FLOW PERSISTS THIS MORNING. WINDS HAVE GENERALLY BEEN BELOW ADVISORY LEVELS AND MORE IN THE 15-20 KT RANGE. THEREFORE...HAVE DROPPED THE ADVISORY FOR INSHORE BAYS/SOUNDS. WILL MAINTAIN THE SMALL CRAFT ADVISORY FOR THE AL/NW FL GULF WATERS THROUGH MIDDAY AS SEAS UP TO 7 FT WILL PERSIST. SIGNIFICANT WAVE HEIGHTS TO RANGE FROM 5-6 FT THIS AFTERNOON INTO TONIGHT. A COLD FRONT WILL MOVE THROUGH THE AREA SATURDAY MORNING WITH A MODERATE TO STRONG OFFSHORE FLOW DEVELOPING SATURDAY AFTERNOON AND NIGHT. A SMALL CRAFT ADVISORY MAY BECOME NECESSARY FOR THIS TIME FRAME. WINDS DIMINISH SUN-MON AS A SFC HIGH MOVES OVER THE REGION. A MORE PREDOMINATE LIGHT TO MODERATE ONSHORE FLOW DEVELOPS BY TUESDAY AS THE SFC HIGH MOVES EAST. PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH TONIGHT. GUSTY WINDS...FREQUENT LIGHTNING...AND TORRENTIAL DOWNPOURS CAN BE EXPECTED THE STRONGER STORMS. THERE IS A POTENTIAL FOR A FEW STORMS TO PRODUCE LARGE HAIL LATE TONIGHT. 34/JFB && .PRELIMINARY POINT TEMPS/POPS... MOBILE 73 63 75 44 70 / 90 80 30 00 00 PENSACOLA 71 64 76 48 69 / 90 80 40 05 00 DESTIN 68 66 75 50 68 / 90 70 50 05 00 EVERGREEN 72 62 73 41 71 / 90 80 40 00 00 WAYNESBORO 77 61 72 38 72 / 90 80 20 00 00 CAMDEN 74 60 71 42 70 / 90 80 40 00 00 CRESTVIEW 71 63 76 41 73 / 90 70 50 05 00 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...HIGH RIP CURRENT RISK UNTIL MIDNIGHT SATURDAY FOR THE FOLLOWING ZONES: LOWER BALDWIN...LOWER MOBILE... HIGH SURF ADVISORY UNTIL MIDNIGHT SATURDAY FOR THE FOLLOWING ZONES: LOWER BALDWIN...LOWER MOBILE... FL...HIGH RIP CURRENT RISK UNTIL MIDNIGHT SATURDAY FOR THE FOLLOWING ZONES: COASTAL ESCAMBIA...COASTAL OKALOOSA...COASTAL SANTA ROSA... HIGH SURF ADVISORY UNTIL MIDNIGHT SATURDAY FOR THE FOLLOWING ZONES: COASTAL ESCAMBIA...COASTAL OKALOOSA...COASTAL SANTA ROSA... MS...NONE. GM...SMALL CRAFT ADVISORY UNTIL 1 PM FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM DESTIN TO PENSACOLA FL OUT 20 NM... COASTAL WATERS FROM PENSACOLA FL TO PASCAGOULA MS OUT 20 NM...WATERS FROM DESTIN TO PENSACOLA FL FROM 20 TO 60 NM... WATERS FROM PENSACOLA FL TO PASCAGOULA MS FROM 20 TO 60 NM... && $$