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000 FXUS62 KMFL 141019 AFDMFL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 519 AM EST SAT FEB 14 2009 .DISCUSSION... NOCTURNAL VISIBLE SATELLITE ANIMATION CONTINUES TO SHOW A BANK OF DENSE SEA FOG OVER THE SOUTHEASTERN GULF OF MEXICO...WHICH CURRENTLY ENCOMPASSES ALL OF OUR LOCAL GULF WATERS...AND HAS SPREAD INLAND OVER COASTAL COLLIER/MAINLAND MONROE COUNTIES. DENSE FOG ADVISORY IS ALREADY IN EFFECT FOR THESE REGIONS...AND WILL MONITOR TRENDS IN THE EVENT THAT ADVISORY SHOULD NEED TO BE EXPANDED EASTWARD LATER THIS MORNING. OTHERWISE...AN AXIS OF WEAK LOW-LEVEL CONVERGENCE AND ASSOCIATED LINE OF CUMULUS WILL CONTINUE TO MOVE NORTHWARD OVER THE ATLANTIC WATERS THIS MORNING...AND MAY GENERATE A FEW SHOWERS. OVERALL...EXPECT SIMILAR CONDITIONS TO FRIDAY TO PREVAIL ACROSS THE AREA TODAY...WITH SOUTHWEST FLOW IN THE BOUNDARY LAYER REMAINING LIGHT ENOUGH TO ALLOW ATLANTIC COAST SEA BREEZE TO PENETRATE INLAND THIS AFTERNOON. WILL USE A PERSISTENCE TEMPERATURE FORECAST...WITH HIGHS ALONG THE ATLANTIC COAST REACHING THE LOWER/MID 80S AND STRUGGLING TO REACH THE MID 70S AS FOG GRADUALLY LIFTS ALONG THE GULF COAST. SHOWER THREAT WILL BE LIMITED BY PERSISTENT MID-LEVEL SUBSIDENCE INVERSION AND SLIGHT DRYING OF THE ATMOSPHERIC COLUMN...BUT WILL INCLUDE A 10 POP ALONG EAST COAST THIS AFTERNOON AND EARLY EVENING GIVEN PRESENCE OF WEST-SOUTHWESTERLY STEERING FLOW. SETUP WILL BE FAVORABLE FOR AREAS OF FOG...SOME LOCALLY DENSE...TO AFFECT MUCH OF THE AREA ONCE AGAIN ON SATURDAY NIGHT/SUNDAY MORNING. GLOBAL MODELS CONTINUE TO SUGGEST THAT THE LARGE MID/UPPER-LEVEL ANTICYCLONE...CURRENTLY ALIGNED FROM CENTRAL AMERICA NORTHWARD TO SOUTHERN FLORIDA...WILL WEAKEN FROM LATE SATURDAY NIGHT THROUGH SUNDAY...AS A SERIES OF MID-LEVEL WAVES IN THE SUBTROPICAL JET ERODE THE NORTHERN PERIPHERY OF THE RIDGE. THIS WILL ALLOW WESTERLY GRADIENT FLOW TO INCREASE IN THE LOWER/MID-LEVELS...WITH DIURNAL MIXING PROCESSES RESULTING IN STRONGER SOUTHWEST FLOW ACROSS THE AREA ON SUNDAY. THIS WILL IN ALL LIKELIHOOD BE SUFFICIENT TO KEEP EAST COAST SEA BREEZE OFF SHORE...WITH VERY WARM TEMPERATURES IN THE MID/UPPER 80S ANTICIPATED INTERIOR AND EAST COAST. RECORD HIGHS OF 86F AND 87F WILL BE IN JEOPARDY AT MIA/PBI RESPECTIVELY...WITH RECORD OF 89F AT FLL A BIT MORE UNLIKELY. MEANWHILE...A STRONGER UPPER TROUGH MOVING ACROSS THE TENNESSEE VALLEY WILL INDUCE SURFACE CYCLOGENESIS OFF THE CAROLINA COAST...WHICH SHOULD FORCE COLD FRONT SOUTHWARD ACROSS THE AREA SOMETIME EARLY MONDAY MORNING. UNFAVORABLE TIMING WILL LIMIT THREAT FOR MUCH NEEDED RAINFALL...WITH HIGHEST POPS FOR SHOWERS ACROSS NORTHWEST PORTION OF FORECAST AREA. A MUCH COOLER/DRIER AIRMASS WILL SPREAD OVER THE AREA ON MONDAY...AS CANADIAN SURFACE HIGH MOVES EASTWARD OVER OHIO VALLEY. NORTHWEST FLOW ALOFT WILL REMAIN IN PLACE FOR THE FIRST HALF OF THE EXTENDED PERIOD...WITH EASTERLY FLOW RETURNING BY LATE TUESDAY AS SURFACE HIGH SHIFTS EASTWARD OFF THE COAST OF THE CAROLINAS. A DRY/SUBSIDENT REGIME WILL LIMIT THREAT FOR ANY RAINFALL DURING THIS PERIOD...WITH MOISTURE NOT BEGINNING TO RETURN UNTIL LATE WEDNESDAY...AS FLOW GRADUALLY VEERS TO SOUTHEAST. MODELS CONTINUE TO SHOW THE POTENTIAL FOR PERHAPS A STRONGER COLD FRONT SOMETIME THURSDAY NIGHT OR FRIDAY MORNING... AND WILL MAINTAIN SLIGHT CHANCE SHOWER WORDING ASSOCIATED WITH THIS. EXPECT ANOTHER SURGE OF COOLER/DRIER AIR TO AFFECT SOUTH FLORIDA FROM LATE NEXT WEEK INTO THE WEEKEND. && .MARINE... DENSE SEA FOG OVER THE SOUTHEASTERN GULF OF MEXICO WILL BE THE PRIMARY MARINE WEATHER CONCERN IN THE SHORT TERM...WITH SOUTH/SOUTHWEST FLOW AROUND 10 KNOTS RESULTING IN SEAS GENERALLY RUNNING 1-2 FEET. A STRONG COLD FRONTAL PASSAGE WILL LEAD TO DETERIORATING CONDITIONS FROM LATE SUNDAY NIGHT THROUGH EARLY TUESDAY MORNING...WITH SCA FOR WINDS LIKELY TO BE REQUIRED FOR ALL WATERS WITH THE EXCEPTION OF BISCAYNE BAY. DUE TO SHORT DURATION OF STRONG NORTH FLOW...WILL CAP GULF STREAM SEAS AT 8 FEET. CONDITIONS WILL IMPROVE DURING THE MIDDLE OF NEXT WEEK...BEFORE ANOTHER FRONTAL PASSAGE BY THE END OF THE WEEK. && .FIRE WEATHER... AFTERNOON RH VALUES MAY FALL INTO THE 40-45 PERCENT RANGE ALONG THE ATLANTIC COAST TOMORROW AFTERNOON...AS TEMPERATURES RISE INTO THE MID/UPPER 80S. OTHERWISE...MORE SUBSTANTIAL FIRE WEATHER CONCERNS WILL OCCUR OVER THE NORTHWEST INTERIOR ON MONDAY AND TUESDAY AFTERNOONS...AND ACROSS THE ENTIRE AREA FOLLOWING PASSAGE OF A STRONGER COLD FRONT LATE IN THE WEEK. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 82 61 86 60 / 20 20 20 30 FORT LAUDERDALE 84 65 86 64 / 10 10 10 10 MIAMI 84 64 86 63 / 10 10 10 10 NAPLES 77 61 78 61 / - - 20 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR FLZ063-FLZ066- FLZ067-FLZ069-FLZ070-FLZ071-FLZ073-FLZ075. AM...NONE. GM...NONE. && $$ LONG TERM...70/DD SHORT TERM/AVIATION...65/GS
