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Show Area Forecast Discussion - Key West, FL (Florida Keys) Selection: |
| #505071 (Received by flhurricane at: 10:41 PM 14.Apr.2012) AFDKEY AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS NATIONAL WEATHER SERVICE KEY WEST FL 1033 PM EDT SAT APR 14 2012 .DISCUSSION... A HIGH PRESSURE CELL HAS BEEN BUILDING OVER THE WESTERN NORTH ATLANTIC DURING THE LAST 12-18 HOURS AS EXPECTED...WITH AN ASSOCIATED ABRUPT INCREASE IN GRADIENT FLOW LOCALLY. A CLOUD CLUSTER AT THE NOSE OF THE EASTERLY WIND SURGE PASSED THROUGH THE FLORIDA KEYS AND ADJOINING COASTAL WATERS TODAY. MUCH DRIER AIR ALOFT HAS WORKED INTO THE REGION FROM EAST TO WEST...AND SHOWERS ARE NOW ISOLATED IN COVERAGE MAINLY WELL SOUTH AND WEST OF KEY WEST. ALL FORECASTS HAVE BEEN UPDATED TO LOWER RAIN CHANCES...INCREASE WINDS...AND ADJUST TRANSITIONS IN THE FIRST PERIOD. && .MARINE... A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ALL ZONES. EASTERLY WINDS HAVE SURGED TO 25-30 KNOTS SUSTAINED IN SOME AREAS...WITH GUSTS OCCASIONALLY BREACHING GALE FORCE. WAVE MODELS INDICATE A LARGE AREA IN THE STRAITS OF FLORIDA WITH SEAS OF 8-12 FEET...AND THIS HAS BEEN CONFIRMED BY A FEW SHIPS OF OPPORTUNITY THIS EVENING. WINDS AND SEAS LIKELY ARE AT THEIR PEAK TONIGHT...WITH A SLOW DECREASE EXPECTED AFTER ABOUT 2-3AM. HOWEVER...SUSTAINED WINDS ARE NOT LIKELY TO LULL LESS THAN 20KT ON SUNDAY...BEFORE SURGING TO 20-25 KNOTS SUNDAY EVENING. && .AVIATION... MAINLY VFR CONDITIONS ARE EXPECTED AT KEY WEST INTERNATIONAL AND MARATHON AIRPORT THROUGHOUT THE FORECAST PERIOD. BRIEF MVFR CIGS ARE LIKELY IN PASSING SHOWERS THIS EVENING. EAST TO SOUTHEAST WINDS OF 20 TO 25 KNOTS WILL DECREASE TO 15 TO 20 KNOTS OVERNIGHT. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...NONE. GM...SMALL CRAFT ADVISORY IN EFFECT FOR GMZ031-GMZ032-GMZ033- GMZ034-GMZ042-GMZ043-GMZ044-GMZ052-GMZ053-GMZ054-GMZ055- GMZ072-GMZ073-GMZ074-GMZ075. && $$ |
| #505004 (Received by flhurricane at: 3:02 PM 14.Apr.2012) AFDKEY AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS NATIONAL WEATHER SERVICE KEY WEST FL 300 PM EDT SAT APR 14 2012 .DISCUSSION...LATEST AVAILABLE IR IMAGERY OVERLAID WITH MIDDLE AND UPPER LEVEL MODEL STREAMLINE ANALYSIS AND OBSERVATIONS AS OF 200 PM DEPICT A LARGE RIDGE SITUATED FROM MICHIGAN SOUTHWARD TO THE CENTRAL GULF OF MEXICO. ANOTHER LONGWAVE TROUGH IS UPSTREAM OF THAT FEATURE AND IT ENCOMPASSES THE WESTERN CONUS. CLOSER TO THE KEYS...WATER VAPOR IMAGERY AND STREAMLINE ANALYSIS DELINEATES A SMALLER SCALE NORTHEAST TO SOUTHWEST ORIENTED TROUGH AXIS FROM THE NORTHWESTERN BAHAMAS TO THE WESTERN TIP OF CUBA...BUT THIS FEATURE IS ALSO ENSCONCED IN QUITE A BIT OF DRY AIR. AT THE SURFACE...AS OF 200 PM...THE 1030 MB CENTER OF A BUILDING WESTERN ATLANTIC ANTICYCLONE IS LOCATED NEAR BUOY 41002 NEAR 32 NORTH 75 WEST. RADAR CONTINUES TO DETECT SCATTERED SHOWERS ACROSS THE KEYS ISLAND CHAIN AND ADJOINING WATERS. A FEW LOCATIONS SUCH AS MARATHON HAVE RECEIVED RAINFALL AMOUNTS AROUND ONE HALF OF AN INCH OF RAINFALL. .CURRENTLY...AS OF 200 PM...VISIBLE SATELLITE IMAGERY DETECTS SCATTERED SHOWERS CONCENTRATED ACROSS THE MIDDLE AND LOWER KEYS AND SURROUNDING GULF...HAWK CHANNEL...AND FLORIDA STRAITS WATERS. WINDS ARE BETWEEN 15 TO 20 KNOTS FROM SAND KEY WESTWARD...BUT SUSTAINED EAST TO SOUTHEAST 20 KNOTTERS WITH GUSTS BETWEEN 25 AND 30 KNOTS ARE BEING RECORDED FROM SAND KEY EASTWARD. TEMPERATURES OUTSIDE OF SHOWERS ARE GENERALLY IN THE LOWER 80S WITH DEWPOINTS IN THE UPPER 60S. .SHORT TERM FORECAST...LATEST (12Z) RUNS OF THE GFS...UKMET...AND ECMWF...ALL ARE SIMILAR WITH INDICATIONS OF RISING 500 MB HEIGHTS THROUGH THE REST OF THE WEEKEND AND INTO MONDAY. THE CENTER OF THE HIGHEST 500 MB HEIGHTS (IN THE UPPER 580S) IS PRESENTLY OVER THE CENTRAL GULF...BUT WILL TRANSLATE TO OVER THE FLORIDA PENINSULA BY SUNDAY NIGHT AND MONDAY...AND THEN MOVE INTO THE WESTERN ATLANTIC OCEAN BY TUESDAY. THE AFOREMENTIONED NEAR 1030 MB SURFACE RIDGING LOCATED OVER THE WESTERN ATLANTIC WILL REMAIN LOCKED IN PLACE FROM TONIGHT THROUGH MONDAY...BEFORE IT WEAKENS TO BETWEEN A 1020 AND 1025 MB ANTICYCLONIC RIDGE MONDAY NIGHT THROUGH TUESDAY NIGHT. SO THE SURFACE TROUGH CURRENTLY OVER THE KEYS THAT IS ASSOCIATED WITH SCATTERED SHOWERS IN PLACE WILL CONTINUE TO MOVE WESTWARD AND GRADUALLY DISSOLVE TO THE WEST OF THE KEYS THIS EVENING. THE VERY LATEST MIMIC TPW (TOTAL PRECIPITABLE WATER) SATELLITE IMAGERY SCANS AS OF 17Z SHOW THAT THE LEADING EDGE OF DRY AIR IS ALREADY REACHING THE UPPER KEYS AND EASTERN FLORIDA STRAITS. BUT NEVERTHELESS...GIVEN AVAILABLE LOW LEVEL CONVERGENCE IN ASSOCIATION WITH THE DEPARTING TROUGH...WILL CONTINUE TO MAINTAIN MIDDLE OF THE ROAD CHANCES FOR SHOWERS ACROSS THE MARINE DISTRICT THROUGH THE LATE AFTERNOON AND EVENING HOURS. THEREAFTER...12Z NAM AND GFS MODEL FORECAST SOUNDINGS ILLUSTRATE PWAT FALLING FROM NEAR 1.00 INCHES BY MIDNIGHT TO BETWEEN .75 TO 1.00 INCHES SUNDAY MORNING...BUT THEN REMAINING AT ONE INCH OR LESS THROUGH AT LEAST TUESDAY NIGHT. KEYS LANDLUBBERS WILL ENJOY COMFORTING BREEZY TO WINDY CONDITIONS FOR TONIGHT THROUGH MONDAY NIGHT...WITH THE EAST TO SOUTHEAST BREEZES SLACKENING APPRECIABLY TUESDAY AND TUESDAY NIGHT. BUT UNFORTUNATELY...WITH SOME EXCEPTIONS...SEA DWELLERS WILL EXPERIENCE UNFAVORABLE MARINE CONDITIONS THROUGH THE PERIOD. DAYTIME HIGH AND LOW TEMPERATURES WILL BE NEAR CLIMATOLOGICAL MAXIMA AND MINIMA FOR THIS TIME OF YEAR. IN TERMS OF THE SHOWER THREAT...WILL MAINTAIN ISOLATED SHOWERS IN THE FORECAST THROUGH THE PERIOD GIVEN THE SPEED CONVERGENCE ASSOCIATED WITH THE MAGNITUDE OF THIS EASTERLY FLOW IN THE BOUNDARY LAYER...BUT THIS ACTIVITY WILL BE VERY BRIEF AND USUALLY ONLY OCCUR LATE AT NIGHT OR EARLY MORNING EACH DAY. EXTENDED...WEDNESDAY THROUGH SATURDAY...500 MB FLOW BECOMES MORE ZONAL...WITH WEAK IMPULSES CONTINUING WITHIN THE FLOW THROUGH THE PERIOD. THE WESTERN ATLANTIC SURFACE RIDGING WILL CONTINUE TO WEAKEN...ALLOWING FOR JUST GENTLE TO MODERATE BREEZES THROUGH THE PERIOD. DAYTIME HIGH AND LOW TEMPERATURES WILL REACH A FEW DEGREES ABOVE AVERAGE...INTO THE MID 80S...WITH OVERNIGHT LOWS ONLY FALLING INTO THE LOWER 70S. WILL CONTINUE WITH DIME POPS GIVEN 12Z MODEL FORECAST INDICATING PWAT REMAINING NEAR 1.00 INCHES. && .MARINE...A SMALL CRAFT ADVISORY IS NOW IN PLACE ACROSS ALL WATERS FOR TONIGHT THROUGH MONDAY. SCATTERED SHOWERS HAVE BEEN AND WILL CONTINUE TO BE ACCOMPANIED BY WIND GUSTS BETWEEN 30 AND 35 KNOTS ACROSS THE ENTIRE MARINE DISTRICT THROUGH THIS EVENING...BUT DRIER AIR WILL GRADUALLY FILTER ACROSS THE WATERS FROM EAST TO WEST...WITH ONLY ISOLATED LOW TOPPED SHOWERS EXPECTED TO IMPACT THE WATERS SUNDAY THROUGH AT LEAST THURSDAY. SEAS WILL BUILD TO 6 TO 10 FEET ACROSS THE FLORIDA STRAITS TONIGHT THROUGH MONDAY...WITH SEAS BUILDING TO AROUND 7 FEET ACROSS THE EXTREME SOUTHEASTERN GULF OF MEXICO AROUND REBECCA SHOAL CHANNEL. SEAS INSIDE THE REEF (HAWK CHANNEL) WILL BECOME VERY ROUGH AND AVERAGE BETWEEN 3 TO 5 FEET. SMALL CRAFT ADVISORIES WILL REMAIN POSTED ACROSS THE FLORIDA STRAITS FOR SUSTAINED EAST TO SOUTHEAST WINDS NEAR 20 KNOTS...STILL GENERATING COMBINED SEAS AVERAGING BETWEEN 5 AND 8 FEET. SMALL CRAFT WILL STILL NEED TO EXERCISE CAUTION ACROSS ALL OTHER WATERS MONDAY NIGHT AND TUESDAY. A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS IS POSSIBLE ON TUESDAY NIGHT ACROSS THE FLORIDA STRAITS. && .AVIATION... INFREQUENT MVFR OR LOWER CONDITIONS ARE POSSIBLE AT EYW AND MTH THIS AFTERNOON. SINCE THESE CONDITIONS WILL BE SHORT-LIVED AND VERY DIFFICULT TO TIME...ONLY VFR CONDITIONS WILL BE ADVERTISED IN THE TERMINAL FORECASTS. ANY PROLONGED SUB-VFR EPISODES WILL BE HANDLED BY SENSIBLE FORECAST AMENDMENTS. VFR CONDITIONS WILL PREVAIL AT EYW AND MTH TONIGHT THROUGH AT LEAST SUNDAY MORNING. SUSTAINED EAST TO SOUTHEAST WINDS OF 20 TO 25 KNOTS ARE EXPECTED FROM JUST OFF THE SURFACE TO ABOUT 5000 FEET. && .CLIMATE... ON THIS DATE IN KEYS WEATHER HISTORY...IN 1940...THE HIGH TEMPERATURE IN KEY WEST WAS ONLY 68 DEGREES. THIS SET THE DAILY RECORD FOR COOLEST MAXIMUM TEMPERATURE MEASURED IN KEY WEST ON APRIL 14TH...A RECORD WHICH STILL STANDS 72 YEARS LATER. TEMPERATURE RECORDS AT KEY WEST DATE BACK TO 1872. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...NONE. GM...SMALL CRAFT ADVISORY...GMZ031-034>GMZ042-044>GMZ052-055>GMZ072-075. && $$ |
| #504980 (Received by flhurricane at: 12:20 PM 14.Apr.2012) AFDKEY AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS NATIONAL WEATHER SERVICE KEY WEST FL 1215 PM EDT SAT APR 14 2012 CORRECTED SPELLING 1ST PARAGRAPH .DISCUSSION...LATEST AVAILABLE IR IMAGERY OVERLAID WITH MIDDLE AND UPPER LEVEL MODEL STREAMLINE ANALYSIS AND OBSERVATIONS AS OF 900 AM DEPICT LOW AMPLITUDE RIDGING IN PLACE FROM THE GREAT LAKES STATES SOUTHWARD TO THE NORTHERN GULF COAST...BUT THERE IS A ANOTHER DEVELOPING LONGWAVE TROUGH OVER THE WESTERN CONUS. ON THE REGIONAL SCALE AND CLOSER TO THE KEYS...STREAMLINE ANALYSIS DOES HINT AT THE SEMBLANCE OF A SHORTWAVE TROUGH AXIS SITUATED FROM ACROSS SOUTHWEST FLORIDA TO THE SOUTH CENTRAL GULF OF MEXICO...BUT THE WATER VAPOR IMAGERY COLOR ENHANCEMENT SCHEMA THAT IS AM USING ALSO DELINEATES LOTS DRY AIR ASSOCIATED WITH THIS FEATURE. AT THE SURFACE...THE 1030 MB CENTER OF A BUILDING WESTERN ATLANTIC ANTICYCLONE IS POSITIONED JUST OFF OF NORTH CAROLINA. CLOSER TO THE KEYS...SCATTERED SHOWERS ARE ASSOCIATED WITH SEPARATE WIND SURGES THAT ARE LOCATED ACROSS THE KEYS WATERS AS WELL AREAS IN THE BAHAMAS FROM ANDROS ISLAND EASTWARD OUT TO CAT ISLAND. THE 12Z MORNING SOUNDING ILLUSTRATED GENTLE TO MODERATE MOSTLY EAST WINDS FROM THE SURFACE TO 10 KFT AND WAS STILL IN AN ENVIRONMENT AHEAD OF THE CURRENT WIND SURGE...WITH PWAT ONLY AT 1.14 INCHES. .CURRENTLY...AS OF 900 AM...LATEST AVAILABLE IR IMAGERY OVERLAID WITH RADAR RETURNS FROM KEY WEST SHOW PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE KEYS ISLAND CHAIN AND ADJOINING WATERS. TEMPERATURES OUTSIDE OF ANY RAINCOOLED SHOWERS ARE GENERALLY IN THE UPPER 70S TO NEAR 80 DEGREES WITH DEWPOINT TEMPERATURES IN THE MIDDLE TO UPPER 60S. RADAR DOES DETECTS SCATTERED SHOWERS CONCENTRATED OVER THE MIDDLE AND UPPER KEYS. THIS IS ASSOCIATED WITH ONE WIND SURGE MOVING ACROSS THE SEVEN MILE BRIDGE. AS SUCH...C-MAN STATIONS ALONG THE FLORIDA REEF ARE REGISTERING EAST TO SOUTHEAST WINDS BETWEEN 10 AND 15 KNOTS FROM SOMBRERO KEY WESTWARD...BUT ARE GENERALLY ALREADY NEAR 20 KNOTS FROM SOMBRERO KEY LIGHT EASTWARD UP TO MOLASSES REEF LIGHT. WINDS ARE GUSTING TO NEAR 30 KNOTS IN SOME OF THESE SHOWERS. .REST OF TODAY...WINDS WILL CONTINUE TO INCREASE TO NEAR 20 KNOTS AND GUSTY FROM EAST TO WEST FOR THE NEXT COUPLE OF HOURS...SO WE WILL BE HOISTING SMALL CRAFT ADVISORY CONDITIONS ACROSS ALL WATERS OUT TO THE DRY TORTUGAS. GIVEN THE AMOUNT OF DRY AIR IN THE MID LEVELS AND THE PRESENT COVERAGE OF SHOWERS OBSERVED UPSTREAM...I WILL BE LOWERING OUR RAIN CHANCES DOWN INTO THE CHANCE CATEGORY...50%...AS THE UPPER LEVEL SUPPORT REMAINS INSUFFICIENT TO GENERATE NUMEROUS COVERAGE. BUT ON THE FLIP SIDE OF THAT COIN...AM CONCERNED ABOUT SOME LOCAL WIND GUSTS BETWEEN 30 AND 35 KNOTS...SO HAVE INCLUDED THAT WORDING IN THE MARINE ZONES. THERE IS ALSO SECOND WIND SURGE IS NOW APPROACHING THE UPPER KEYS FROM ANDROS ISLAND...AND ONCE THIS BROKEN LINE OF SHOWERS MOVES ACROSS THE KEYS DURING THE MID TO LATE AFTERNOON HOURS...THINK THAT WINDS WILL INCREASE A FEW MORE KNOTS...BECOMING SUSTAINED BETWEEN 20 AND 25 KNOTS WITH OCCASIONAL GUSTS NEAR 30 KNOTS. && .MARINE...SMALL CRAFT ADVISORIES WILL BE HOISTED ACROSS ALL WATERS AT 1030 AM. SEAS BEYOND THE REEF WILL BUILD TO 5 TO 8 FEET BY LATE AFTERNOON...AS THE WIND SURGES AND ACCOMPANYING SHOWER ACTIVITY PROGRESSES WESTWARD ACROSS THE MARINE DISTRICT. THERE IS A POSSIBILITY OF MARINE WEATHER STATEMENTS OR EVEN A COUPLE OF SPECIAL MARINE WARNINGS AS KEY WEST RADAR MAY DETECT SOME WIND GUSTS EXCESS OF 34 KNOTS. SMALL CRAFT ADVISORIES WILL REMAIN POSTED THROUGHOUT THE KEYS COASTAL WATERS FROM TONIGHT THROUGH EARLY TUESDAY...DUE TO FRESH TO STRONG EAST TO SOUTHEAST WINDS...SUSTAINED AT 20 TO 25 KNOTS. AS ALWAYS...MARINERS ARE ADVISED TO MONITOR NOAA WEATHER RADIO. && .AVIATION... INFREQUENT MVFR CONDITIONS ARE EXPECTED AT EYW AND MTH TODAY. SINCE THESE MVFR CONDITIONS WILL BE SHORT-LIVED AND VERY DIFFICULT TO TIME...ONLY VFR CONDITIONS WILL BE ADVERTISED IN THE TERMINAL FORECASTS. ANY PROLONGED MVFR EPISODES WILL BE HANDLED BY SENSIBLE FORECAST AMENDMENTS. VFR CONDITIONS WILL PREVAIL AT EYW AND MTH TONIGHT. SUSTAINED EAST TO SOUTHEAST WINDS NEAR 10 KNOTS FROM JUST OFF THE SURFACE TO ABOUT 5000 FEET WILL INCREASE TO 20 TO 25 KNOTS THIS AFTERNOON. && .CLIMATE... ON THIS DATE IN KEYS WEATHER HISTORY...IN 1940...THE LOW TEMPERATURE IN KEY WEST WAS 58 DEGREES. THIS SET THE DAILY RECORD FOR MINIMUM TEMPERATURE MEASURED IN KEY WEST ON APRIL 14TH...A RECORD WHICH STILL STANDS 72 YEARS LATER. TEMPERATURE RECORDS AT KEY WEST DATE BACK TO 1872. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...NONE. GM...SMALL CRAFT ADVISORY IN EFFECT ACROSS ALL WATERS AS OF 15Z...GMZ031-034>GMZ042-044>GMZ052-055>GMZ072-075. && $$ |
| #504956 (Received by flhurricane at: 9:53 AM 14.Apr.2012) AFDKEY AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS NATIONAL WEATHER SERVICE KEY WEST FL 945 AM EDT SAT APR 14 2012 .DISCUSSION...LATEST AVAILABLE IR IMAGERY OVERLAID WITH MIDDLE AND UPPER LEVEL MODEL STREAMLINE ANALYSIS AND OBSERVATIONS AS OF 900 AM DEPICT LOW AMPLITUDE RIDGING IN PLACE FROM THE GRETA LAKES STATES SOUTHWARD TO THE NORTHERN GULF COURSE...BUT THERE IS A ANOTHER DEVELOPING LONGWAVE TROUGH OVER THE WESTERN CONUS. ON THE REGIONAL SCALE AND CLOSER TO THE KEYS...STREAMLINE ANALYSIS DOES HINT AT THE SEMBLANCE OF A SHORTWAVE TROUGH AXIS SITUATED FROM ACROSS SOUTHWEST FLORIDA TO THE SOUTH CENTRAL GULF OF MEXICO...BUT THE WATER VAPOR IMAGERY COLOR ENHANCEMENT SCHEMA THAT IS AM USING ALSO DELINEATES LOTS DRY AIR ASSOCIATED WITH THIS FEATURE. AT THE SURFACE...THE 1030 MB CENTER OF A BUILDING WESTERN ATLANTIC ANTICYCLONE IS POSITIONED JUST OFF OF NORTH CAROLINA. CLOSER TO THE KEYS...SCATTERED SHOWERS ARE ASSOCIATED WITH SEPARATE WIND SURGES THAT ARE LOCATED ACROSS THE KEYS WATERS AS WELL AREAS IN THE BAHAMAS FROM ANDROS ISLAND EASTWARD OUT TO CAT ISLAND. THE 12Z MORNING SOUNDING ILLUSTRATED GENTLE TO MODERATE MOSTLY EAST WINDS FROM THE SURFACE TO 10 KFT AND WAS STILL IN AN ENVIRONMENT AHEAD OF THE CURRENT WIND SURGE...WITH PWAT ONLY AT 1.14 INCHES. .CURRENTLY...AS OF 900 AM...LATEST AVAILABLE IR IMAGERY OVERLAID WITH RADAR RETURNS FROM KEY WEST SHOW PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE KEYS ISLAND CHAIN AND ADJOINING WATERS. TEMPERATURES OUTSIDE OF ANY RAINCOOLED SHOWERS ARE GENERALLY IN THE UPPER 70S TO NEAR 80 DEGREES WITH DEWPOINT TEMPERATURES IN THE MIDDLE TO UPPER 60S. RADAR DOES DETECTS SCATTERED SHOWERS CONCENTRATED OVER THE MIDDLE AND UPPER KEYS. THIS IS ASSOCIATED WITH ONE WIND SURGE MOVING ACROSS THE SEVEN MILE BRIDGE. AS SUCH...C-MAN STATIONS ALONG THE FLORIDA REEF ARE REGISTERING EAST TO SOUTHEAST WINDS BETWEEN 10 AND 15 KNOTS FROM SOMBRERO KEY WESTWARD...BUT ARE GENERALLY ALREADY NEAR 20 KNOTS FROM SOMBRERO KEY LIGHT EASTWARD UP TO MOLASSES REEF LIGHT. WINDS ARE GUSTING TO NEAR 30 KNOTS IN SOME OF THESE SHOWERS. .REST OF TODAY...WINDS WILL CONTINUE TO INCREASE TO NEAR 20 KNOTS AND GUSTY FROM EAST TO WEST FOR THE NEXT COUPLE OF HOURS...SO WE WILL BE HOISTING SMALL CRAFT ADVISORY CONDITIONS ACROSS ALL WATERS OUT TO THE DRY TORTUGAS. GIVEN THE AMOUNT OF DRY AIR IN THE MID LEVELS AND THE PRESENT COVERAGE OF SHOWERS OBSERVED UPSTREAM...I WILL BE LOWERING OUR RAIN CHANCES DOWN INTO THE CHANCE CATEGORY...50%...AS THE UPPER LEVEL SUPPORT REMAINS INSUFFICIENT TO GENERATE NUMEROUS COVERAGE. BUT ON THE FLIP SIDE OF THAT COIN...AM CONCERNED ABOUT SOME LOCAL WIND GUSTS BETWEEN 30 AND 35 KNOTS...SO HAVE INCLUDED THAT WORDING IN THE MARINE ZONES. THERE IS ALSO SECOND WIND SURGE IS NOW APPROACHING THE UPPER KEYS FROM ANDROS ISLAND...AND ONCE THIS BROKEN LINE OF SHOWERS MOVES ACROSS THE KEYS DURING THE MID TO LATE AFTERNOON HOURS...THINK THAT WINDS WILL INCREASE A FEW MORE KNOTS...BECOMING SUSTAINED BETWEEN 20 AND 25 KNOTS WITH OCCASIONAL GUSTS NEAR 30 KNOTS. && .MARINE...SMALL CRAFT ADVISORIES WILL BE HOISTED ACROSS ALL WATERS AT 1030 AM. SEAS BEYOND THE REEF WILL BUILD TO 5 TO 8 FEET BY LATE AFTERNOON...AS THE WIND SURGES AND ACCOMPANYING SHOWER ACTIVITY PROGRESSES WESTWARD ACROSS THE MARINE DISTRICT. THERE IS A POSSIBILITY OF MARINE WEATHER STATEMENTS OR EVEN A COUPLE OF SPECIAL MARINE WARNINGS AS KEY WEST RADAR MAY DETECT SOME WIND GUSTS EXCESS OF 34 KNOTS. SMALL CRAFT ADVISORIES WILL REMAIN POSTED THROUGHOUT THE KEYS COASTAL WATERS FROM TONIGHT THROUGH EARLY TUESDAY...DUE TO FRESH TO STRONG EAST TO SOUTHEAST WINDS...SUSTAINED AT 20 TO 25 KNOTS. AS ALWAYS...MARINERS ARE ADVISED TO MONITOR NOAA WEATHER RADIO. && .AVIATION... INFREQUENT MVFR CONDITIONS ARE EXPECTED AT EYW AND MTH TODAY. SINCE THESE MVFR CONDITIONS WILL BE SHORT-LIVED AND VERY DIFFICULT TO TIME...ONLY VFR CONDITIONS WILL BE ADVERTISED IN THE TERMINAL FORECASTS. ANY PROLONGED MVFR EPISODES WILL BE HANDLED BY SENSIBLE FORECAST AMENDMENTS. VFR CONDITIONS WILL PREVAIL AT EYW AND MTH TONIGHT. SUSTAINED EAST TO SOUTHEAST WINDS NEAR 10 KNOTS FROM JUST OFF THE SURFACE TO ABOUT 5000 FEET WILL INCREASE TO 20 TO 25 KNOTS THIS AFTERNOON. && .CLIMATE... ON THIS DATE IN KEYS WEATHER HISTORY...IN 1940...THE LOW TEMPERATURE IN KEY WEST WAS 58 DEGREES. THIS SET THE DAILY RECORD FOR MINIMUM TEMPERATURE MEASURED IN KEY WEST ON APRIL 14TH...A RECORD WHICH STILL STANDS 72 YEARS LATER. TEMPERATURE RECORDS AT KEY WEST DATE BACK TO 1872. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...NONE. GM...SMALL CRAFT ADVISORY IN EFFECT ACROSS ALL WATERS AS OF 15Z...GMZ031-034>GMZ042-044>GMZ052-055>GMZ072-075. && $$ |
| #504957 (Received by flhurricane at: 9:53 AM 14.Apr.2012) AFDKEY AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS NATIONAL WEATHER SERVICE KEY WEST FL 945 AM EDT FRI APR 13 2012 .DISCUSSION...LATEST AVAILABLE IR IMAGERY OVERLAID WITH MIDDLE AND UPPER LEVEL MODEL STREAMLINE ANALYSIS AND OBSERVATIONS AS OF 900 AM DEPICT LOW AMPLITUDE RIDGING IN PLACE FROM THE GRETA LAKES STATES SOUTHWARD TO THE NORTHERN GULF COURSE...BUT THERE IS A ANOTHER DEVELOPING LONGWAVE TROUGH OVER THE WESTERN CONUS. ON THE REGIONAL SCALE AND CLOSER TO THE KEYS...STREAMLINE ANALYSIS DOES HINT AT THE SEMBLANCE OF A SHORTWAVE TROUGH AXIS SITUATED FROM ACROSS SOUTHWEST FLORIDA TO THE SOUTH CENTRAL GULF OF MEXICO...BUT THE WATER VAPOR IMAGERY COLOR ENHANCEMENT SCHEMA THAT IS AM USING ALSO DELINEATES LOTS DRY AIR ASSOCIATED WITH THIS FEATURE. AT THE SURFACE...THE 1030 MB CENTER OF A BUILDING WESTERN ATLANTIC ANTICYCLONE IS POSITIONED JUST OFF OF NORTH CAROLINA. CLOSER TO THE KEYS...SCATTERED SHOWERS ARE ASSOCIATED WITH SEPARATE WIND SURGES THAT ARE LOCATED ACROSS THE KEYS WATERS AS WELL AREAS IN THE BAHAMAS FROM ANDROS ISLAND EASTWARD OUT TO CAT ISLAND. THE 12Z MORNING SOUNDING ILLUSTRATED GENTLE TO MODERATE MOSTLY EAST WINDS FROM THE SURFACE TO 10 KFT AND WAS STILL IN AN ENVIRONMENT AHEAD OF THE CURRENT WIND SURGE...WITH PWAT ONLY AT 1.14 INCHES. .CURRENTLY...AS OF 900 AM...LATEST AVAILABLE IR IMAGERY OVERLAID WITH RADAR RETURNS FROM KEY WEST SHOW PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE KEYS ISLAND CHAIN AND ADJOINING WATERS. TEMPERATURES OUTSIDE OF ANY RAINCOOLED SHOWERS ARE GENERALLY IN THE UPPER 70S TO NEAR 80 DEGREES WITH DEWPOINT TEMPERATURES IN THE MIDDLE TO UPPER 60S. RADAR DOES DETECTS SCATTERED SHOWERS CONCENTRATED OVER THE MIDDLE AND UPPER KEYS. THIS IS ASSOCIATED WITH ONE WIND SURGE MOVING ACROSS THE SEVEN MILE BRIDGE. AS SUCH...C-MAN STATIONS ALONG THE FLORIDA REEF ARE REGISTERING EAST TO SOUTHEAST WINDS BETWEEN 10 AND 15 KNOTS FROM SOMBRERO KEY WESTWARD...BUT ARE GENERALLY ALREADY NEAR 20 KNOTS FROM SOMBRERO KEY LIGHT EASTWARD UP TO MOLASSES REEF LIGHT. WINDS ARE GUSTING TO NEAR 30 KNOTS IN SOME OF THESE SHOWERS. .REST OF TODAY...WINDS WILL CONTINUE TO INCREASE TO NEAR 20 KNOTS AND GUSTY FROM EAST TO WEST FOR THE NEXT COUPLE OF HOURS...SO WE WILL BE HOISTING SMALL CRAFT ADVISORY CONDITIONS ACROSS ALL WATERS OUT TO THE DRY TORTUGAS. GIVEN THE AMOUNT OF DRY AIR IN THE MID LEVELS AND THE PRESENT COVERAGE OF SHOWERS OBSERVED UPSTREAM...I WILL BE LOWERING OUR RAIN CHANCES DOWN INTO THE CHANCE CATEGORY...50%...AS THE UPPER LEVEL SUPPORT REMAINS INSUFFICIENT TO GENERATE NUMEROUS COVERAGE. BUT ON THE FLIP SIDE OF THAT COIN...AM CONCERNED ABOUT SOME LOCAL WIND GUSTS BETWEEN 30 AND 35 KNOTS...SO HAVE INCLUDED THAT WORDING IN THE MARINE ZONES. THERE IS ALSO SECOND WIND SURGE IS NOW APPROACHING THE UPPER KEYS FROM ANDROS ISLAND...AND ONCE THIS BROKEN LINE OF SHOWERS MOVES ACROSS THE KEYS DURING THE MID TO LATE AFTERNOON HOURS...THINK THAT WINDS WILL INCREASE A FEW MORE KNOTS...BECOMING SUSTAINED BETWEEN 20 AND 25 KNOTS WITH OCCASIONAL GUSTS NEAR 30 KNOTS. && .MARINE...SMALL CRAFT ADVISORIES WILL BE HOISTED ACROSS ALL WATERS AT 1030 AM. SEAS BEYOND THE REEF WILL BUILD TO 5 TO 8 FEET BY LATE AFTERNOON...AS THE WIND SURGES AND ACCOMPANYING SHOWER ACTIVITY PROGRESSES WESTWARD ACROSS THE MARINE DISTRICT. THERE IS A POSSIBILITY OF MARINE WEATHER STATEMENTS OR EVEN A COUPLE OF SPECIAL MARINE WARNINGS AS KEY WEST RADAR MAY DETECT SOME WIND GUSTS EXCESS OF 34 KNOTS. SMALL CRAFT ADVISORIES WILL REMAIN POSTED THROUGHOUT THE KEYS COASTAL WATERS FROM TONIGHT THROUGH EARLY TUESDAY...DUE TO FRESH TO STRONG EAST TO SOUTHEAST WINDS...SUSTAINED AT 20 TO 25 KNOTS. AS ALWAYS...MARINERS ARE ADVISED TO MONITOR NOAA WEATHER RADIO. && .AVIATION... INFREQUENT MVFR CONDITIONS ARE EXPECTED AT EYW AND MTH TODAY. SINCE THESE MVFR CONDITIONS WILL BE SHORT-LIVED AND VERY DIFFICULT TO TIME...ONLY VFR CONDITIONS WILL BE ADVERTISED IN THE TERMINAL FORECASTS. ANY PROLONGED MVFR EPISODES WILL BE HANDLED BY SENSIBLE FORECAST AMENDMENTS. VFR CONDITIONS WILL PREVAIL AT EYW AND MTH TONIGHT. SUSTAINED EAST TO SOUTHEAST WINDS NEAR 10 KNOTS FROM JUST OFF THE SURFACE TO ABOUT 5000 FEET WILL INCREASE TO 20 TO 25 KNOTS THIS AFTERNOON. && .CLIMATE... ON THIS DATE IN KEYS WEATHER HISTORY...IN 1940...THE LOW TEMPERATURE IN KEY WEST WAS 58 DEGREES. THIS SET THE DAILY RECORD FOR MINIMUM TEMPERATURE MEASURED IN KEY WEST ON APRIL 14TH...A RECORD WHICH STILL STANDS 72 YEARS LATER. TEMPERATURE RECORDS AT KEY WEST DATE BACK TO 1872. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...NONE. GM...SMALL CRAFT ADVISORY IN EFFECT ACROSS ALL WATERS AS OF 15Z...GMZ031-034>GMZ042-044>GMZ052-055>GMZ072-075. && $$ |
| #504936 (Received by flhurricane at: 6:44 AM 14.Apr.2012) AFDKEY AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS...CORRECTED NATIONAL WEATHER SERVICE KEY WEST FL 639 AM EDT SAT APR 14 2012 ...EASTERLY WIND SURGE ACCOMPANIED BY NUMEROUS SHOWERS WILL OVERSPREAD THE FLORIDA KEYS AND ADJACENT COASTAL WATERS TODAY... .DISCUSSION... EARLY MORNING SURFACE ANALYSIS DEPICTS HIGH PRESSURE (1027 MILLIBARS) CENTERED ALONG THE CAROLINA COASTLINE...AND A TROUGH OF LOW PRESSURE POSITIONED IN A "BACKDOOR" CONFIGURATION FROM THE BAHAMAS NORTHWESTWARD TO LAKE OKEECHOBEE. ALOFT...A SUBTLE SHORTWAVE TROUGH IS DIVING SOUTHEASTWARD ACROSS OUR REGION...WHICH IS ASSISTING WITH SHOWER AND ISOLATED THUNDERSTORM DEVELOPMENT ALONG AND AHEAD OF THE SOUTHWESTWARD MOVING SURFACE TROUGH. THIS TROUGH IS DISPLAYED NICELY BY MIMIC TOTAL PRECIPITABLE WATER VAPOR (PWAT) IMAGERY...WHICH SHOWS AN AXIS OF PWATS IN THE 1.25 TO 1.5 INCH RANGE ADVECTING ACROSS THE BAHAMAS AND THE UPPER KEYS. OTHERWISE...RIDGING ALOFT IS BUILDING ACROSS THE CENTRAL PORTIONS OF THE GULF OF MEXICO...EXTENDING NORTHWARD TO THE TENNESSEE AND OHIO VALLEYS. AT 10Z...SKIES WERE CLOUDY ACROSS THE UPPER KEYS...PARTLY TO MOSTLY CLOUDY OVER THE MIDDLE KEYS...AND PARTLY CLOUDY FOR THE LOWER KEYS. SHOWERS ARE GRADUALLY INCREASING IN COVERAGE...WITH SCATTERED SHOWERS MOVING WESTWARD NEAR 15 MPH ACROSS PORTIONS OF THE MIDDLE AND UPPER KEYS AND ADJACENT COASTAL WATERS. TEMPERATURES WERE GENERALLY IN THE MIDDLE 70S...WITH DEWPOINTS IN THE MIDDLE 60S. WINDS AT ISLAND LOCATIONS IN THE UPPER KEYS WERE EASTERLY NEAR 15 MPH...WITH EAST TO SOUTHEAST WINDS AT 5 TO 10 MPH NOTED ELSEWHERE ALONG THE ISLAND CHAIN. ON THE COASTAL WATERS AT 10Z...WINDS ON THE ATLANTIC WATERS ADJACENT TO THE UPPER KEYS WERE EAST TO SOUTHEASTERLY NEAR 15 KNOTS...WITH GUSTS UP TO 25 KNOTS NEAR SHOWER ACTIVITY. WINDS ELSEWHERE WERE EAST TO SOUTHEASTERLY AT 10 TO 15 KNOTS. .SHORT TERM (TODAY THROUGH MONDAY)... AN EASTERLY WIND SURGE WILL PROGRESS FROM EAST TO WEST ACROSS OUR REGION TODAY. THIS WEATHER PATTERN WILL BE FORCED BY STRENGTHENING HIGH PRESSURE MOVING INTO THE ATLANTIC WATERS ADJACENT TO THE CAROLINAS...WHICH WILL PUSH THE AFOREMENTIONED SURFACE TROUGH SOUTHWESTWARD ACROSS OUR REGION. LOW-LEVEL CONVERGENCE ALONG THE TROUGH WILL BE ENHANCED ALOFT BY THE WEAK SHORTWAVE CURRENTLY OVERHEAD. WE THUS EXPECT NUMEROUS SHOWERS AND ISOLATED EMBEDDED THUNDERSTORMS TO DEVELOP AND MIGRATE WESTWARD ACROSS THE ISLAND CHAIN AND ADJACENT COASTAL WATERS THROUGHOUT THE DAY...IN CONCERT WITH THE WIND SURGE. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE AS EMBEDDED DOWNPOURS POTENTIALLY TRAIN OVER PORTIONS OF THE ISLAND CHAIN. WE HAVE THUS INCREASED RAIN CHANCES TO LIKELY (60%)...AND ADDED THUNDER ALONG WITH LOCALLY HEAVY RAIN TO THE FORECAST GRIDS. WITH INCREASING CLOUDS AND WIND SPEEDS...EXPECT HIGH TEMPERATURES TO TOP OUT NEAR 80 DEGREES...WITH DEWPOINTS RISING INTO THE UPPER 60S. THE SHORTWAVE ALOFT WILL DEPART OUR REGION LATE TODAY AND RIDGING ALOFT WILL BEGIN TO BUILD OVER OUR REGION TONIGHT. AS THE SURFACE TROUGH DEPARTS TO OUR WEST...EXPECT SHOWER COVERAGE TO DIMINISH DURING THE OVERNIGHT HOURS. A MUCH DRIER AND STABLE AIR MASS WILL QUICKLY OVERSPREAD OUR AREA BY THE PREDAWN HOURS...AS MODEL SOUNDINGS DEPICT PWATS RAPIDLY FALLING BELOW ONE INCH BEFORE SUNRISE. A BRIEF SPELL OF COOL AIR ADVECTION AND RAINS EARLY IN THE EVENING SHOULD ALLOW LOWS TO FALL TO NEAR MID-APRIL CLIMATOLOGY...OR THE LOWER 70S. MODEL SOUNDINGS INDICATE THAT STRONG EAST TO SOUTHEASTERLY WINDS WILL INCREASE IN DEPTH UP TO 800 MILLIBARS (6500 FEET) BY SUNDAY EVENING. WE HAVE LEFT ISOLATED SHOWERS IN THE FORECAST FOR THE REMAINDER OF THE WEEKEND THROUGH MONDAY...WE CANNOT RULE OUT STRAY...LOW-TOPPED SHOWERS CREATED BY SPEED CONVERGENCE OVER THE STRAITS CROSSING PORTIONS OF THE ISLAND CHAIN...AS WE CANNOT RULE OUT STRAY...LOW- TOPPED SHOWERS CREATED BY SPEED CONVERGENCE OVER THE STRAITS CROSSING PORTIONS OF THE ISLAND CHAIN. OTHERWISE...EXPECT NEAR AVERAGE TEMPERATURES AND SLIGHTLY BELOW AVERAGE DEWPOINTS FOR THE REMAINDER OF THE SHORT TERM PERIOD...WHICH WILL FEATURE PERSISTENT BREEZY TO WINDY CONDITIONS FOR ISLAND LOCATIONS AND HAZARDOUS CONDITIONS ON THE COASTAL WATERS. && .LONG TERM (MONDAY NIGHT THROUGH FRIDAY)... RIDGING ALOFT WILL REMAIN POSITIONED OVER OUR REGION ON MONDAY NIGHT AND TUESDAY...DOWNSTREAM OF A GRADUALLY DE-AMPLIFYING LONGWAVE TROUGH THAT WILL BE TRAVERSING THE CENTRAL UNITED STATES. A TIGHT PRESSURE GRADIENT WILL PERSIST THROUGH TUESDAY...AS HIGH PRESSURE OVER THE WESTERN ATLANTIC ONLY GRADUALLY WEAKENS. EXPECT BREEZY TO NEAR WINDY CONDITIONS TO PERSIST THROUGH EARLY TUESDAY. WINDS WILL GRADUALLY DIMINISH BY MIDWEEK AS OUR LOCAL PRESSURE GRADIENT FINALLY LOOSENS...COMPLIMENTS OF A DEVELOPING ZONAL FLOW REGIME ALOFT. WE HAVE CAPPED POPS AT 10% IN THE FORECAST GRIDS FOR THE UPCOMING WEEK...AS TIMING ANY PERIODS OF WEAK ISENTROPIC LIFT MIGRATING THROUGH OUR REGION IN THE PERSISTENT BUT WEAKENING EASTERLY FLOW REGIME WILL BE DIFFICULT. THE ECMWF MAINTAINS A MORE AMPLIFIED PATTERN...AND WE MAY NEED TO RAISE RAIN CHANCES LATE IN THE UPCOMING WEEK AS A BOUNDARY POTENTIALLY APPROACHES OUR REGION FROM THE NORTHWEST. OTHERWISE...EXPECT TEMPERATURES TO RUN SLIGHTLY ABOVE CLIMATOLOGY...BUT COMFORTABLE DEWPOINT TEMPERATURES...IN THE MIDDLE 60S...SHOULD PERSIST THROUGH AT LEAST MIDWEEK. && .MARINE... HIGH PRESSURE CENTERED ALONG THE CAROLINA COAST WILL PUSH A TROUGH OF LOW PRESSURE SOUTHWESTWARD ACROSS THE ISLAND CHAIN TODAY. OUR LOCAL PRESSURE GRADIENT WILL RAPIDLY TIGHTEN BY EARLY AFTERNOON...AND AN EASTERLY WIND SURGE WILL OVERSPREAD THE COASTAL WATERS FROM EAST TO WEST AS THE MORNING PROGRESSES. NUMEROUS SHOWERS AND ISOLATED EMBEDDED THUNDERSTORMS WILL ACCOMPANY THE WIND SURGE...WITH LOCALLY HIGHER WIND GUSTS POSSIBLE NEAR STRONGER SHOWER AND THUNDERSTORM ACTIVITY. EAST WINDS OF 20 TO 25 KNOTS ARE EXPECTED TO SPREAD ACROSS FLORIDA BAY AND THE ATLANTIC WATERS ADJACENT TO THE UPPER KEYS...INCLUDING HAWK CHANNEL...BY THE MID MORNING HOURS. SMALL CRAFT ADVISORIES HAVE BEEN HOISTED FOR THESE SECTIONS THIS MORNING...AND SEAS BEYOND THE REEF...ADJACENT TO THE UPPER KEYS...WILL RAPIDLY BUILD TO 5 TO 7 FEET BY EARLY AFTERNOON. SMALL CRAFT ADVISORIES WILL BE ISSUED LATER THIS MORNING FOR THE REMAINDER OF THE KEYS COASTAL WATERS...AS THE WIND SURGE AND ACCOMPANYING SHOWER AND EMBEDDED THUNDERSTORM ACTIVITY PROGRESSES WESTWARD. SEAS BEYOND THE REEF...ADJACENT TO THE LOWER AND MIDDLE KEYS...WILL BUILD TO 5 TO 8 FEET LATE THIS AFTERNOON. SMALL CRAFT ADVISORIES WILL REMAIN POSTED THROUGHOUT THE KEYS COASTAL WATERS FROM TONIGHT THROUGH EARLY TUESDAY...DUE TO FRESH TO STRONG EAST TO SOUTHEAST WINDS...SUSTAINED AT 20 TO 25 KNOTS. WINDS AND SEAS WILL DIMINISH BY LATE TUESDAY AS HIGH PRESSURE OVER THE WESTERN ATLANTIC WEAKENS...BUT A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS IS POSSIBLE ON TUESDAY NIGHT ACROSS THE FLORIDA STRAITS. && .AVIATION... THROUGH 00Z...15TH...VFR CONDITIONS WILL PREDOMINATE EARLY THIS MORNING...BEFORE OCCASIONAL MVFR AND POSSIBLE IFR CONDITIONS OVERSPREAD THE ISLAND TERMINALS FROM EAST TO WEST THIS MORNING AND AFTERNOON. MOSTLY EAST WINDS OF 5 TO 10 KNOTS WILL GRADUALLY INCREASE TO BETWEEN 10 AND 15 KNOTS WITH GUSTS OF 20 TO 25 KNOTS BY LATE THIS MORNING AND AFTERNOON. && .CLIMATE... ON THIS DATE IN KEYS WEATHER HISTORY...IN 1940...THE LOW TEMPERATURE AT KEY WEST DROPPED TO 58 DEGREES...AND THE HIGH TEMPERATURE ONLY REACHED 68 DEGREES. THESE VALUES SET DAILY RECORDS FOR THE LOW AND COOL MAXIMUM TEMPERATURES AT KEY WEST FOR APRIL 14TH...RECORDS THAT REMAIN STANDING 72 YEARS LATER. TEMPERATURE RECORDS AT KEY WEST DATE BACK TO 1872. && .PRELIMINARY POINT TEMPS/POPS... KEY WEST 80 71 80 72 / 60 60 10 10 MARATHON 80 71 82 72 / 60 60 10 10 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...NONE. GM...SMALL CRAFT ADVISORY FOR GMZ031-034>GMZ042-044>GMZ052-055>GMZ072-075. && $$ |
| #504937 (Received by flhurricane at: 6:44 AM 14.Apr.2012) AFDKEY AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS NATIONAL WEATHER SERVICE KEY WEST FL 634 AM EDT SAT APR 14 2012 ...EASTERLY WIND SURGE ACCOMPANIED BY NUMEROUS SHOWERS WILL OVERSPREAD THE FLORIDA KEYS AND ADJACENT COASTAL WATERS TODAY... .DISCUSSION... EARLY MORNING SURFACE ANALYSIS DEPICTS HIGH PRESSURE (1027 MILLIBARS) CENTERED ALONG THE CAROLINA COASTLINE...AND A TROUGH OF LOW PRESSURE POSITIONED IN A "BACKDOOR" CONFIGURATION FROM THE BAHAMAS NORTHWESTWARD TO LAKE OKEECHOBEE. ALOFT...A SUBTLE SHORTWAVE TROUGH IS DIVING SOUTHEASTWARD ACROSS OUR REGION...WHICH IS ASSISTING WITH SHOWER AND ISOLATED THUNDERSTORM DEVELOPMENT ALONG AND AHEAD OF THE SOUTHWESTWARD MOVING SURFACE TROUGH. THIS TROUGH IS DISPLAYED NICELY BY MIMIC TOTAL PRECIPITABLE WATER VAPOR (PWAT) IMAGERY...WHICH SHOWS AN AXIS OF PWATS IN THE 1.25 TO 1.5 INCH RANGE ADVECTING ACROSS THE BAHAMAS AND THE UPPER KEYS. OTHERWISE...RIDGING ALOFT IS BUILDING ACROSS THE CENTRAL PORTIONS OF THE GULF OF MEXICO...EXTENDING NORTHWARD TO THE TENNESSEE AND OHIO VALLEYS. AT 10Z...SKIES WERE CLOUDY ACROSS THE UPPER KEYS...PARTLY TO MOSTLY CLOUDY OVER THE MIDDLE KEYS...AND PARTLY CLOUDY FOR THE LOWER KEYS. ACROSS THE ISLAND CHAIN WERE MOSTLY CLEAR. SHOWERS ARE GRADUALLY INCREASING IN COVERAGE...WITH SCATTERED SHOWERS MOVING WESTWARD NEAR 15 MPH ACROSS PORTIONS OF THE MIDDLE AND UPPER KEYS AND ADJACENT COASTAL WATERS. TEMPERATURES WERE GENERALLY IN THE MIDDLE 70S...WITH DEWPOINTS IN THE MIDDLE 60S. WINDS AT ISLAND LOCATIONS IN THE UPPER KEYS WERE EASTERLY NEAR 15 MPH...WITH EAST TO SOUTHEAST WINDS AT 5 TO 10 MPH NOTED ELSEWHERE ALONG THE ISLAND CHAIN. ON THE COASTAL WATERS AT 10Z...WINDS ON THE ATLANTIC WATERS ADJACENT TO THE UPPER KEYS WERE EAST TO SOUTHEASTERLY NEAR 15 KNOTS...WITH GUSTS UP TO 25 KNOTS NEAR SHOWER ACTIVITY. WINDS ELSEWHERE WERE EAST TO SOUTHEASTERLY AT 10 TO 15 KNOTS. .SHORT TERM (TODAY THROUGH MONDAY)... AN EASTERLY WIND SURGE WILL PROGRESS FROM EAST TO WEST ACROSS OUR REGION TODAY. THIS WEATHER PATTERN WILL BE FORCED BY STRENGTHENING HIGH PRESSURE MOVING INTO THE ATLANTIC WATERS ADJACENT TO THE CAROLINAS...WHICH WILL PUSH THE AFOREMENTIONED SURFACE TROUGH SOUTHWESTWARD ACROSS OUR REGION. LOW-LEVEL CONVERGENCE ALONG THE TROUGH WILL BE ENHANCED ALOFT BY THE WEAK SHORTWAVE CURRENTLY OVERHEAD. WE THUS EXPECT NUMEROUS SHOWERS AND ISOLATED EMBEDDED THUNDERSTORMS TO DEVELOP AND MIGRATE WESTWARD ACROSS THE ISLAND CHAIN AND ADJACENT COASTAL WATERS THROUGHOUT THE DAY...IN CONCERT WITH THE WIND SURGE. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE AS EMBEDDED DOWNPOURS POTENTIALLY TRAIN OVER PORTIONS OF THE ISLAND CHAIN. WE HAVE THUS INCREASED RAIN CHANCES TO LIKELY (60%)...AND ADDED THUNDER ALONG WITH LOCALLY HEAVY RAIN TO THE FORECAST GRIDS. WITH INCREASING CLOUDS AND WIND SPEEDS...EXPECT HIGH TEMPERATURES TO TOP OUT NEAR 80 DEGREES...WITH DEWPOINTS RISING INTO THE UPPER 60S. THE SHORTWAVE ALOFT WILL DEPART OUR REGION LATE TODAY AND RIDGING ALOFT WILL BEGIN TO BUILD OVER OUR REGION TONIGHT. AS THE SURFACE TROUGH DEPARTS TO OUR WEST...EXPECT SHOWER COVERAGE TO DIMINISH DURING THE OVERNIGHT HOURS. A MUCH DRIER AND STABLE AIR MASS WILL QUICKLY OVERSPREAD OUR AREA BY THE PREDAWN HOURS...AS MODEL SOUNDINGS DEPICT PWATS RAPIDLY FALLING BELOW ONE INCH BEFORE SUNRISE. A BRIEF SPELL OF COOL AIR ADVECTION AND RAINS EARLY IN THE EVENING SHOULD ALLOW LOWS TO FALL TO NEAR MID-APRIL CLIMATOLOGY...OR THE LOWER 70S. MODEL SOUNDINGS INDICATE THAT STRONG EAST TO SOUTHEASTERLY WINDS WILL INCREASE IN DEPTH UP TO 800 MILLIBARS (6500 FEET) BY SUNDAY EVENING. WE HAVE LEFT ISOLATED SHOWERS IN THE FORECAST FOR THE REMAINDER OF THE WEEKEND THROUGH MONDAY...WE CANNOT RULE OUT STRAY...LOW-TOPPED SHOWERS CREATED BY SPEED CONVERGENCE OVER THE STRAITS CROSSING PORTIONS OF THE ISLAND CHAIN...AS WE CANNOT RULE OUT STRAY...LOW- TOPPED SHOWERS CREATED BY SPEED CONVERGENCE OVER THE STRAITS CROSSING PORTIONS OF THE ISLAND CHAIN. OTHERWISE...EXPECT NEAR AVERAGE TEMPERATURES AND SLIGHTLY BELOW AVERAGE DEWPOINTS FOR THE REMAINDER OF THE SHORT TERM PERIOD...WHICH WILL FEATURE PERSISTENT BREEZY TO WINDY CONDITIONS FOR ISLAND LOCATIONS AND HAZARDOUS CONDITIONS ON THE COASTAL WATERS. && .LONG TERM (MONDAY NIGHT THROUGH FRIDAY)... RIDGING ALOFT WILL REMAIN POSITIONED OVER OUR REGION ON MONDAY NIGHT AND TUESDAY...DOWNSTREAM OF A GRADUALLY DE-AMPLIFYING LONGWAVE TROUGH THAT WILL BE TRAVERSING THE CENTRAL UNITED STATES. A TIGHT PRESSURE GRADIENT WILL PERSIST THROUGH TUESDAY...AS HIGH PRESSURE OVER THE WESTERN ATLANTIC ONLY GRADUALLY WEAKENS. EXPECT BREEZY TO NEAR WINDY CONDITIONS TO PERSIST THROUGH EARLY TUESDAY. WINDS WILL GRADUALLY DIMINISH BY MIDWEEK AS OUR LOCAL PRESSURE GRADIENT FINALLY LOOSENS...COMPLIMENTS OF A DEVELOPING ZONAL FLOW REGIME ALOFT. WE HAVE CAPPED POPS AT 10% IN THE FORECAST GRIDS FOR THE UPCOMING WEEK...AS TIMING ANY PERIODS OF WEAK ISENTROPIC LIFT MIGRATING THROUGH OUR REGION IN THE PERSISTENT BUT WEAKENING EASTERLY FLOW REGIME WILL BE DIFFICULT. THE ECMWF MAINTAINS A MORE AMPLIFIED PATTERN...AND WE MAY NEED TO RAISE RAIN CHANCES LATE IN THE UPCOMING WEEK AS A BOUNDARY POTENTIALLY APPROACHES OUR REGION FROM THE NORTHWEST. OTHERWISE...EXPECT TEMPERATURES TO RUN SLIGHTLY ABOVE CLIMATOLOGY...BUT COMFORTABLE DEWPOINT TEMPERATURES...IN THE MIDDLE 60S...SHOULD PERSIST THROUGH AT LEAST MIDWEEK. && .MARINE... HIGH PRESSURE CENTERED ALONG THE CAROLINA COAST WILL PUSH A TROUGH OF LOW PRESSURE SOUTHWESTWARD ACROSS THE ISLAND CHAIN TODAY. OUR LOCAL PRESSURE GRADIENT WILL RAPIDLY TIGHTEN BY EARLY AFTERNOON...AND AN EASTERLY WIND SURGE WILL OVERSPREAD THE COASTAL WATERS FROM EAST TO WEST AS THE MORNING PROGRESSES. NUMEROUS SHOWERS AND ISOLATED EMBEDDED THUNDERSTORMS WILL ACCOMPANY THE WIND SURGE...WITH LOCALLY HIGHER WIND GUSTS POSSIBLE NEAR STRONGER SHOWER AND THUNDERSTORM ACTIVITY. EAST WINDS OF 20 TO 25 KNOTS ARE EXPECTED TO SPREAD ACROSS FLORIDA BAY AND THE ATLANTIC WATERS ADJACENT TO THE UPPER KEYS...INCLUDING HAWK CHANNEL...BY THE MID MORNING HOURS. SMALL CRAFT ADVISORIES HAVE BEEN HOISTED FOR THESE SECTIONS THIS MORNING...AND SEAS BEYOND THE REEF...ADJACENT TO THE UPPER KEYS...WILL RAPIDLY BUILD TO 5 TO 7 FEET BY EARLY AFTERNOON. SMALL CRAFT ADVISORIES WILL BE ISSUED LATER THIS MORNING FOR THE REMAINDER OF THE KEYS COASTAL WATERS...AS THE WIND SURGE AND ACCOMPANYING SHOWER AND EMBEDDED THUNDERSTORM ACTIVITY PROGRESSES WESTWARD. SEAS BEYOND THE REEF...ADJACENT TO THE LOWER AND MIDDLE KEYS...WILL BUILD TO 5 TO 8 FEET LATE THIS AFTERNOON. SMALL CRAFT ADVISORIES WILL REMAIN POSTED THROUGHOUT THE KEYS COASTAL WATERS FROM TONIGHT THROUGH EARLY TUESDAY...DUE TO FRESH TO STRONG EAST TO SOUTHEAST WINDS...SUSTAINED AT 20 TO 25 KNOTS. WINDS AND SEAS WILL DIMINISH BY LATE TUESDAY AS HIGH PRESSURE OVER THE WESTERN ATLANTIC WEAKENS...BUT A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS IS POSSIBLE ON TUESDAY NIGHT ACROSS THE FLORIDA STRAITS. && .AVIATION... THROUGH 00Z...15TH...VFR CONDITIONS WILL PREDOMINATE EARLY THIS MORNING...BEFORE OCCASIONAL MVFR AND POSSIBLE IFR CONDITIONS OVERSPREAD THE ISLAND TERMINALS FROM EAST TO WEST THIS MORNING AND AFTERNOON. MOSTLY EAST WINDS OF 5 TO 10 KNOTS WILL GRADUALLY INCREASE TO BETWEEN 10 AND 15 KNOTS WITH GUSTS OF 20 TO 25 KNOTS BY LATE THIS MORNING AND AFTERNOON. && .CLIMATE... ON THIS DATE IN KEYS WEATHER HISTORY...IN 1940...THE LOW TEMPERATURE AT KEY WEST DROPPED TO 58 DEGREES...AND THE HIGH TEMPERATURE ONLY REACHED 68 DEGREES. THESE VALUES SET DAILY RECORDS FOR THE LOW AND COOL MAXIMUM TEMPERATURES AT KEY WEST FOR APRIL 14TH...RECORDS THAT REMAIN STANDING 72 YEARS LATER. TEMPERATURE RECORDS AT KEY WEST DATE BACK TO 1872. && .PRELIMINARY POINT TEMPS/POPS... KEY WEST 80 71 80 72 / 60 60 10 10 MARATHON 80 71 82 72 / 60 60 10 10 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...NONE. GM...SMALL CRAFT ADVISORY FOR GMZ031-034>GMZ042-044>GMZ052-055>GMZ072-075. && $$ |
