[Printable]
Links in the discussion text will open a (small) new browser window with more information inside.
A more complete Weather Glossary is Available Here
000 FXUS62 KMFL 231404 AFDMFL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 1004 AM EDT TUE SEP 23 2008 .UPDATE... LATEST WATER VAPOR IMAGERY AND RUC ANALYSIS SHOWS MID/UPPER TROUGH AXIS ACROSS NORTH CENTRAL FLORIDA...WITH PERHAPS A WEAK SFC TROUGH IN VICINITY OF LAKE OKEECHOBEE. A WELL-DEFINED MOISTURE AXIS LIES ACROSS SOUTH FLORIDA AHEAD OF THESE FEATURES. AS A RESULT...WIDESPREAD MID/HIGH CLOUDS COVER THE NORTHERN HALF OF THE CWA. THE OVERNIGHT LAND BREEZE HAS FINALLY GIVEN WAY TO A LIGHT ONSHORE FLOW ALONG EAST COAST AREAS. AS THIS NE FLOW STRENGTHENS SOME TODAY...OFFSHORE SHOWERS AS WELL AS A SEA BREEZE OR OTHER WEAK COASTAL CONVERGENCE BOUNDARY SHOULD MOVE SLOWLY INLAND AND LEAD TO AN INCREASE IN SHOWER/THUNDERSTORM DEVELOPMENT. ACTIVITY COULD BECOME FAIRLY WIDESPREAD ESPECIALLY ACROSS THE SOUTHERN HALF OF THE CWA AS AREAS SOUTH OF ALLIGATOR ALLEY SEE THE MOST HEATING. THE 12Z MIAMI SOUNDING SUGGESTS DECENT INSTABILITY...BUT SHOWS ONLY A SLIGHT CHANCE FOR MICROBURSTS GIVEN THE MOSTLY MOIST ENVIRONMENT. CURRENT FORECAST HAS THIS SCENARIO HANDLED WELL AND WILL NOT MAKE ANY CHANGES AT THIS TIME. && .MARINE... ONLY CHANGE TO THE MARINE FORECAST TODAY WAS TO SLIGHTLY INCREASE THE WINDS OVER THE NORTHERN ATLANTIC WATERS AND LAKE OKEECHOBEE. GUIDANCE SEEMS TO BE UNDER DOING THE WINDS SLIGHTLY RIGHT NOW...AS SOME OF THE LAKE TOWERS HAVE BEEN SUSTAINED AROUND 15KTS. GFS SHOWS AN INCREASE IN WINDS FROM JUST ABOVE THE SFC THROUGH 850MB THROUGH THE DAY TODAY...SO A SLIGHT INCREASE IN MARINE WINDS SEEMS PLAUSIBLE. WILL RE-EVALUATE SWELL FORECAST WITH 12Z MODEL CYCLE AND CURRENT TRENDS...BUT IF CURRENT FORECAST VERIFIES THEN A SMALL CRAFT ADVISORY MAY BE NEEDED AFTER MIDNIGHT TONIGHT. UPDATE/MARINE: STRASSBERG && .PREV DISCUSSION... /ISSUED 722 AM EDT TUE SEP 23 2008/ AVIATION...A NW LAND BREEZE WILL GIVE WAY TO THE PREVAILING NE FLOW AT THE EAST COAST TERMINALS BY 14Z THIS MORNING. NE FLOW WILL PREVAIL AT KAPF...WITH A POSSIBLE SEA BREEZE THIS AFTERNOON...THOUGH THIS IS SOMEWHAT UNCERTAIN. TSRA IS A BETTER BET TODAY AT ALL TERMINALS...BUT STILL...DUE TO THE TIMING UNCERTAINTIES AND THE UNCERTAINTY IN EXACTLY WHEN A STORM WILL AFFECT A GIVEN TERMINAL...DECIDED TO KEEP WITH VCTS AND WILL AMEND WITH CONVECTIVE TRENDS. VFR WILL PREVAIL....BUT IFR WILL BE BRIEFLY POSSIBLE IN TSRA TODAY. /DG DISCUSSION...AS THE UPPER RIDGE...EXTENDING FROM THE W GULF OF MEX THROUGH THE S AND CENTRAL GREAT PLAINS AND OVER THE GREAT LAKES... BUILDS NE INTO NEW ENGLAND...THE TROUGH OVER THE EASTERN SEA BOARD AND EXTENDING SW INTO THE S APPALACHIANS...DEEPENS AND MOVES OFF -SHORE INTO THE ATLC. BY WED...A CLOSED LOW DEVELOPS OFF OF THE COASTAL CAROLINAS...REMAINING NEARLY STATIONARY THU...THEN RETRO GRADING W AND OVER THE CAROLINAS THU THROUGH SAT BEFORE THE LOW WEAKENS AND LIFTS NE SUN INTO MON THOUGH TROUGHINESS REMAINS OVER THE EASTERN U.S. WITH SOUTHWESTERLY FLOW ALOFT REMAINS OVER S FLA WITHE ATLC RIDGE PERSISTING TO THE SE OF THE AREAS. CIRCULATION ABOUT THIS UPPER LOW WILL PULL THE SYSTEM DEVELOPING N OF HISPANIOLA NORTHWARD...KEEPING THIS SYSTEM WELL E OF S FLA. AT THE SURFACE...AN INVERTED TROUGH OFF OF THE SE U.S. COAST PRE -CEDES THE DEVELOPING UPPER TROUGH TO THE NW. THIS TROUGH EXTENDS SW OVER S FLA AND AS A SURFACE LOW DEVELOPS OVER THE ATLC...THE TROUGH MOVES THROUGH S FLA TODAY. THIS SURFACE LOW...AS PER LATEST GFS...PERSISTS OFFSHORE OFF THE CAROLINAS INTO THE EARLY PART OF THE WEEKEND...THEN GETS ABSORBED INTO THE DEEP SURFACE LOW THAT DEVELOPS N OF HISPANIOLA TUE WHICH WILL MOVE N TOWARD NEW ENGLAND. AFTER TODAY...DRIER AND MORE STALE AIR MOVES OVER S FLA WHICH WILL PERSIST INTO SAT. CHANCES OF RAIN POSSIBLY INCREASE SUN AND MON AS MOISTURE THAT HAS BEEN SHUNTED TO THE S OF THE AREA BEGINS TO CREEP NORTHWARD AGAIN. FOR THE SHORT TERM...TODAY THROUGH THU...HIGH POPS AND SLIGHTLY COOLER TODAY AS THE SURFACE TROUGH AND E/W COAST SEA BREEZES INCREASE RAINFALL POTENTIAL AND ENOUGH CLOUDS TO LIMIT HEATING A LITTLE. TONIGHT DIMINISHING POPS FROM NW TO SE AS TROUGH SLIDES THROUGH WITH LOWER POPS WED BUT POSSIBLY HIGHER E COAST AS STEERING WINDS WILL BE WESTERLY. CHANCES FOR RAIN WED NIGHT AND THU MINIMAL IF AT ALL. WITH SOME MOISTURE TODAY AND WITH SLIGHTLY COOLER TEMPS...INTERIOR AREAS MAY SEE A LITTLE FOG WED AND THU MORNING. EXTENDED PERIOD...FRI THROUGH MON...STILL RELATIVELY DRY FRI AND SAT WITH A GRADUAL INCREASE IN THE CHANCES OF RAIN SUN AND INTO EARLY NEXT WEEK AS THE CARIBBEAN MOISTURE PULLED N OVER S FLA. LITTLE CHANGE TO EXTENDED AS LONG RANGE MODELS HAVE WAFFLED A LITTLE AND HOW SOON AND HOW MUCH THE MOISTURE RETURNS. MARINE...WINDS SHIFTING NE AS TROUGH SLIDES THROUGH BUT STAYING 10 KTS OR LESS TODAY. WINDS INCREASE TONIGHT AS SURFACE LOW FORMS TO THE NE BUT ALSO A NE SWELL BEGINS TO IMPACT TLC WATERS. N/NE WINDS INCREASE TONIGHT INTO WED...POSSIBLY 15 TO 18 KTS BEFORE DECREASING. SWELLS CONTINUE TO INCREASE AS WELL...UP TO 3 TO 5 FEET. THOUGH WINDS DECREASE THU AND INTO THE WEEKEND...THE N/NE SWELLS TO PERSIST ..POSSIBLY BECOMING 6 TO 8 FEET IN THE PALM BEACH WATERS WED NIGHT AND 3 TO 5 FEET CONTINUING TO THE BROWARD/DADE WATERS. SWELLS DECREASE THU AFTERNOON INTO THE WEEKEND. A SMALL CRAFT ADVISORY WILL MOST LIKELY BE NEEDED LATE TONIGHT IN THE ATLC FOR SEAS 7 TO 8 FEET...INCREASING TO 9 TO 11 FEET BY EARLY THU BEFORE SEAS SLOWLY BEGIN TO SUBSIDE TO BELOW ADVISORY CRITERIA SAT. A HIGH SURF ADVISORY WILL BE NEEDED WED NIGHT AND THU AS THE SURF...ESPECIALLY PALM BEACH COUNTY...WILL BECOME QUITE ROUGH AS LARGE BREAKERS CAN BE EXPECTED. THESE HIGHLIGHTS WILL BE HOISTED AS CONDITIONS DEVELOP. FIRE WEATHER...NO CONCERNS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 87 74 86 73 / 60 30 20 20 FORT LAUDERDALE 89 75 86 75 / 60 40 20 20 MIAMI 89 76 87 74 / 60 40 30 20 NAPLES 88 72 88 72 / 60 20 10 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...15/JR SHORT TERM/AVIATION...04/AT