FXUS62 KMLB 170740 AFDMLB AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 340 AM EDT TUE SEP 17 2013 .DISCUSSION... TODAY...AN INVERTED TROUGH IN THE MID LVLS IN THE H7-H5 LYR OFF THE SE FL COAST WILL DRIFT NORTHWARD TODAY AS HIGH PRESSURE BUILDS DOWN THE MID ATLC COAST AND INCREASES THE ONSHORE E-ENE LOW LVL FLOW IN THE SFC TO 850 MB LYR. DEEPER MOISTURE SOUTH OF A LINE FROM LAKE KISSIMMEE TO MELBOURNE ALONG WITH THE PROXIMITY TO THE MID LVL TROUGH AXIS AND THE INCREASING ONSHORE FLOW WILL SPELL THE HIGHEST SHOWER/TSTM CHANCES ACROSS THE TREASURE COAST INTO OKEECHOBEE COUNTY WITH 60 PCT. WILL KEEP 50 POPS FOR BREVARD/OSCEOLA AND 30/40 PCT RAIN CHANCES ACROSS NRN SECTIONS...WHICH SHOULD HAVE SLIGHTLY LOWER PWATS...BUT STILL RATHER MOIST ONSHORE FLOW TODAY. CONSIDERABLE CLOUDINESS SHOULD RETURN TO MUCH OF THE AREA BY AFTERNOON. HIGHS IN THE UPPER 80S COAST TO LOWER 90S INTERIOR. AN EAST SWELL WILL PRODUCE A MODERATE RISK OF RIP CURRENTS AT THE BEACHES. TONIGHT...LOW LVL ONSHORE FLOW TO 15-20 KNOTS ACROSS THE ATLANTIC AND CONTINUED DEEP MOISTURE SHOULD ALLOW FOR THE DEVELOPMENT OF CONVERGENT BAND SHOWERS ACROSS THE ATLC WATERS MOVING ONSHORE ALONG THE COAST THROUGH THE NIGHT. HIGHER THAN NORMAL COASTAL RAIN CHANCES OF 30-40 PCT ARE FORECAST WITH ISOLATED ACTIVITY MAKING IT INTO THE INTERIOR. EXPECT BREEZY CONDITIONS ALONG THE IMMEDIATE COAST AND BEACHES NORTH OF CAPE CANAVERAL. WED-THU...DEEP AND MOIST ONSHORE FLOW WILL CONTINUE TO BE THE RULE THROUGH MID WEEK AS THE FLORIDA PENINSULA IS PLACED BETWEEN HIGH PRESSURE MOVING OFF THE EASTERN SEABOARD AND A BROAD AND WEAK LOW OVER THE SOUTHERN GULF OF MEXICO/BAY OF CAMPECHE/NW CARIBBEAN. DEEPEST MOISTURE AND HIGHEST COVERAGE REMAIN ACROSS THE SOUTHERN THIRD OF THE STATE...WITH BOTH THE GFS AND ECMWF SHOWING A WEAK SURFACE TROUGH DEVELOPING OVER THE BAHAMAS UNDER THE UPPER LEVEL SHORTWAVE AS IT PUSHES AWAY FROM FL INTO THURSDAY. THIS FEATURE LOOKS TO HELP ENHANCE MOISTURE CONVERGENCE AND PUSH BACK THE ONSET OF ANY DRYING THAT MODELS WERE PREVIOUSLY INDICATING. HAVE BUMPED UP POPS ON BOTH WEDS AND THURS...TO REFLECT THIS. EAST COAST SEA BREEZE WILL BE DIFFUSE AND FAST MOVING....THUS EXPECT MUCH ACTIVITY WILL BE FROM MID MORNING THROUGH MID AFTERNOON. BREEZY CONDITIONS WILL CONTINUE...ESPECIALLY ALONG THE COAST...WHICH WILL CONTINUE TO BRING ONSHORE MOVING ACTIVITY THROUGH THE PERIOD. FRI...THE LOCAL PRESSURE GRADIENT SLACKENS AND ONSHORE FLOW WEAKENS IN RESPONSE TO THE HIGH TO THE NORTH WEAKENING AND MOVING FARTHER INTO THE ATLANTIC. FRI APPEARS TO BE THE DRIEST DAY OF THE WEEK AS BOTH MODELS STILL SHOW A PUSH OF DRIER AIR AS A SHORTWAVE RIDGE MOVES ACROSS THE SOUTHEAST. SAT-TUES...THE 00Z GFS HAS CHANGED ITS TUNE DRAMATICALLY IN THE EVOLUTION OF THE BROAD AREA OF LOW PRESSURE OVER THE GULF OF MEXICO OVER THE WEEKEND INTO EARLY NEXT WEEK. IT NOW DEPICTS A CONSIDERABLY STRONGER UPPER LEVEL TROUGH/LOW SWINGING THROUGH THE MISSISSIPPI AND TENNESSEE VALLEYS...ALONG WITH STRONG BAROCLINIC CYCLOGENESIS ALONG THE NORTHERN GULF AND EAST COAST. THIS SWINGS THROUGH A DECENT COLD FRONT THROUGH MOST OF THE STATE LEAVING BEHIND A VERY UNORGANIZED AREA OF LOWER PRESSURE ALONG THE FRONT IN THE BAY OF CAMPECHE. THE 00Z ECMWF REMAINS CLOSE TO THE PREVIOUS MODEL SOLUTIONS WITH A WEAKER TROUGH AND BROADER DOUBLE BARRELED (BAROCLINIC NORTH/TROPICAL SOUTH) AREA OF LOW PRESSURE OVER THE GULF ON SUN WHICH THEN LIFTS OUT IN THE GENERAL VICINITY OF FLORIDA AND THE BAHAMAS INTO MID NEXT WEEK. BOTH SCENARIOS LOOK COMPLEX...AND THE UNCERTAINTIES IN INTENSITY AND STRUCTURE OF ANY LOW THAT WOULD POTENTIALLY IMPACT THE AREA ARE QUITE LARGE. BUT REGARDLESS OF HOW THIS FEATURE DEVELOPS...IT APPEARS WE ARE HEADED TOWARD WETTER PERIOD FOR AT LEAST THE FIRST HALF OF NEXT WEEK. && .AVIATION...EXPECT SHOWERS/TSTMS TO DEVELOP AND PUSH SLOWLY INLAND FROM THE TREASURE COAST FROM MID DAY INTO THE AFTERNOON HOURS. HAVE INCLUDED SHORT TSRA WINDOWS THIS AFTERNOON FOR KVRB-KSUA. FURTHER NORTH...INLAND MOVING SHOWERS/ISOLATED TSTMS EXPECTED TODAY FROM FROM KDAB-KMLB TOWARD KSFB-KMCO AND KLEE. FOR NOW HAVE VCTS FOR NRN INTERIOR TERMINALS. VCSH PSBL COASTAL TERMINALS LATER TUE TONIGHT. && .MARINE... INCREASING ONSHORE WINDS TO 15 TO 18 KNOTS ACROSS THE NRN WATERS THIS AFTERNOON INTO TONIGHT WILL NECESSITATE SMALL CRAFT EXERCISE CAUTION HEADLINES WITH SEAS BUILDING TO 4-6 FT ACROSS THE NORTHERN AND CENTRAL OFFSHORE WATERS TONIGHT. WED-THURS...MODERATE ONSHORE FLOW CONTINUES INTO WEDNESDAY... ESPECIALLY NORTH OF SEBASTIAN INLET WITH EAST-NORTHEAST WINDS AROUND 15KTS...OCCASIONALLY 15-20KTS WELL OFFSHORE. WINDS SOUTH OF THE INLET WILL BE AROUND 10-15KTS UNDER A WEAKER GRADIENT. THERE WILL BE A SLOW DECLINE OF WINDS INTO THURSDAY AS THE HIGH TO THE NORTH WEAKENS WITH WINDS BECOMING 10-15KTS BY LATE IN THE DAY. THE LONG EAST-NORTHEAST FETCH WILL KEEP SEAS ELEVATED BOTH DAYS WITH 4-6FT NEARSHORE AND UP TO 7 FEET WELL OFFSHORE NORTH OF THE CAPE. THIS IS THE FIRST MODEL RUN SHOWING SEAS MAKING IT UP THAT HIGH...AND IF IT PERSISTS AN SCA FOR SEAS MAY BE NEEDED. DOMINANT WAVE PERIODS WILL LIKELY BE MIXED BETWEEN THE 5-6SEC WIND WAVE AND 12-14 SEC SWELL. FRI-SUN...ONSHORE FLOW SLOWLY WEAKENS ON FRI AND SAT AS HIGH TO THE NORTH ALSO WEAKENS AND MOVES FURTHER INTO THE ATLANTIC. EAST-SOUTHEAST WINDS AROUND 10KTS. SEAS SLOWLY SUBSIDE TO 4-5FT ON FRI AND 3-4FT SAT. BEYOND SAT...FORECAST BECOME UNCERTAIN AS MODEL SOLUTIONS DIFFER IN HANDLING A BROAD LOW FORECAST TO MOVE ACROSS THE GULF AND FLORIDA EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... DAB 89 76 88 75 / 30 30 40 30 MCO 91 74 91 73 / 40 20 40 10 MLB 89 76 89 76 / 50 30 50 30 VRB 88 74 89 74 / 60 30 60 40 LEE 91 73 90 73 / 30 20 40 10 SFB 91 74 91 74 / 40 20 40 10 ORL 91 75 90 75 / 40 20 40 10 FPR 88 74 89 73 / 60 30 60 40 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...VOLKMER LONG TERM....MOSES PALMBAYWEATHER.info
Posted on: Tue, 17 Sep 2013 07:40:56 +0000