793
FXUS62 KMLB 161531
AFDMLB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
1031 AM EST MON DEC 16 2024
..NEW UPDATE
KEY MESSAGES
ISSUED AT 209 AM EST MON DEC 16 2024
- INCREASING COVERAGE OF SHOWERS LATER TODAY THROUGH WEDNESDAY.
REPEAT RAIN BANDS MAY LEAD TO STANDING WATER IN URBAN AREAS
ALONG THE SPACE AND TREASURE COASTS ON TUESDAY AND WEDNESDAY.
- HAZARDOUS BEACH AND BOATING CONDITIONS PERSIST AS WE BEGIN THIS
WEEK, INCLUDING HIGH SURF AND A HIGH RIP CURRENT RISK. SLOW
IMPROVEMENTS ARE LIKELY BY MID-WEEK AS WINDS RELAX.
- ABOVE NORMAL TEMPERATURES THROUGH MID-WEEK, WITH SOME LOCALES
REACHING THE LOWER 80S. MUCH COOLER TEMPERATURES REMAIN ON THE
HORIZON BY THE WEEKEND.
UPDATE
ISSUED AT 1031 AM EST MON DEC 16 2024
STRONG HIGH PRESSURE OFFSHORE OF THE NORTHEAST U.S. WILL CONTINUE
TO PRODUCE AN ONSHORE BREEZE TODAY. SURFACE WINDS WILL BE OUT OF
THE EAST-NORTHEAST WITH SPEEDS AROUND 10 TO 15 MPH, AND GUSTS UP
TO 25 MPH. ONSHORE WINDS WILL INCREASE MOISTURE, LEADING TO
CONTINUED ISOLATED TO SCATTERED SHOWER DEVELOPMENT OVER THE
WATERS, WITH THIS ACTIVITY MOVING ONSHORE AND INLAND. GREATEST
RAIN CHANCES WILL FOCUS ALONG THE COAST, UP TO 30-50 PERCENT,
DECREASING TO 20-30 PERCENT INLAND TODAY. MODEL SOUNDINGS AND
GUIDANCE INDICATES A GRADUAL INCREASE IN INSTABILITY THROUGH THE
AFTERNOON, MAINLY SOUTHEAST OF THE I-4 CORRIDOR. SPC MESOSCALE
ANALYSIS ALREADY SHOWS MLCAPE UP TO 500-1000 J/KG FROM AROUND THE
CAPE SOUTHWARD ALONG THE COAST. NOT SEEING ANY LIGHTNING ACTIVITY
YET OVER THE WATERS, BUT ISOLATED STORM DEVELOPMENT WILL BE
POSSIBLE AS THE DAY PROGRESSES. HAVE THEREFORE ADDED A SLIGHT
CHANCE OF THUNDERSTORMS THIS AFTERNOON, MAINLY FROM NEAR MELBOURNE
AREA SOUTHWARD ALONG THE TREASURE COAST, WHERE GREATEST
INSTABILITY WILL RESIDE.
SKIES WILL BE PARTLY TO MOSTLY CLOUDY, AND HIGHS WILL REMAIN
WARMER THAN NORMAL IN THE MID TO UPPER 70S ALONG THE COAST AND
UPPER 70S TO AROUND 80 DEGREES INLAND.
LARGE BREAKING WAVES OF 5-8 FEET WILL CONTINUE ALONG THE COAST,
CONTINUING DANGEROUS SURF CONDITIONS AND THE POTENTIAL FOR MINOR
TO MODERATE BEACH EROSION AROUND THE TIMES OF HIGH TIDE. A HIGH
SURF ADVISORY CONTINUES THROUGH THIS EVENING AND A HIGH RISK FOR
LIFE-THREATENING RIP CURRENTS PERSISTS TODAY AS WELL. ENTERING THE
SURF IS HIGHLY DISCOURAGED!
PREVIOUS DISCUSSION
ISSUED AT 209 AM EST MON DEC 16 2024
----------SYNOPTIC OVERVIEW----------
QUASI-ZONAL FLOW PERSISTS ACROSS THE LOWER 48 THIS MORNING, WITH
MAINLY ABOVE-NORMAL HEIGHTS EXTENDING FROM FLORIDA TO THE GREAT
LAKES. AT THE SURFACE, GUIDANCE INITIALIZED A 1040 HPA HIGH-PRESSURE
CENTER OFFSHORE OF CAPE COD WITH TEXTBOOK COLD-AIR DAMMING (CAD)
EXTENDING TO N GA. FLORIDA RESIDES BETWEEN THIS SURFACE RIDGE AND
A TROUGH OF LOW PRESSURE OVER THE GREATER ANTILLES. THE RESULT IS
AN UNINTERRUPTED FETCH OF WARM, MOIST AIR OFF THE SW ATLANTIC &
GULF STREAM.
H5 HEIGHTS WILL REMAIN ABOVE NORMAL THROUGH MID-WEEK. HOWEVER, OUR
WEATHER WILL CONTINUE TO BE DOMINATED BY BOUNDARY LAYER FEATURES. AS
THE CARIBBEAN TROUGH MOVES WESTWARD, POSITIVE MOISTURE AND LOW-LEVEL
VORTICITY ADVECTION WILL PUSH ACROSS CENTRAL AND SOUTH FLORIDA
WITHIN THE MEAN EASTERLY FLOW. TOTAL MOISTURE (PW) VALUES ARE NOW
PREDICTED TO EXCEED 1.5" ON TUE/WED WHICH IS APPROACHING OR EVEN
EXCEEDING 175% OF NORMAL FOR MID-DECEMBER. UNSETTLED WEATHER APPEARS
TO BE IN THE CARDS DURING THIS TIMEFRAME.
OUR NEXT SYNOPTIC FEATURE, AN UPPER-LEVEL TROUGH, CURRENTLY SITS OFF
THE BRITISH COLUMBIA COAST. BY THURSDAY, THIS SHORTWAVE ENERGY WILL
PASS OVER THE N APPALACHIANS, DRIVING A COLD FRONT ACROSS THE STATE.
MUCH DRIER AIR WILL RETURN TO FLORIDA TO END THE WORK WEEK.
IMMEDIATELY BEHIND IT, THE GRAND ENSEMBLE REINFORCES A LONG WAVE
TROUGH OVER THE NORTHEAST U.S. BY THE WEEKEND. THIS SHOULD FORCE
ANOTHER COLD FRONT THROUGH THE STATE BY FRIDAY. HIGH PRESSURE, OF
CANADIAN ORIGIN, IS FORECAST TO PUSH OVER THE OHIO VALLEY BY
SUNDAY. 15/12Z ENSEMBLE CLUSTERS REVEALED STRONG AGREEMENT
REGARDING THE LONG WAVE PATTERN, BUT THERE REMAINS A SPLIT AS TO
THE DEPTH OF THE TROUGH. CURRENTLY, ENSEMBLE-AVERAGED 5 KFT
TEMPERATURES ARE EXPECTED TO DROP TO AROUND +5C BY LATE THIS
WEEKEND.
ENSEMBLE MEANS INDICATE THAT A PACIFIC JET EXTENSION SHOULD QUICKLY
FLATTEN THIS UPCOMING MERIDIONAL PATTERN. COMBINED WITH A DEVELOPING
POSITIVE EPO WITHIN MJO PHASE 6, A STEADY WARMING TREND SHOULD
COMMENCE AROUND THE CHRISTMAS HOLIDAY.
-------SENSIBLE WEATHER & IMPACTS-------
TODAY-TONIGHT...
BREEZY EAST WINDS CONTINUE TODAY WITH 20-40% SHOWER CHANCES, THE
HIGHEST ALONG THE TREASURE AND SPACE COASTS. LIGHTNING PROBABILITIES
LOOK TO REMAIN UNDER 20% AS WE ARE STILL FAIRLY STABLE ABOVE 10 KFT.
TEMPERATURES REMAIN ABOVE NORMAL WITH A MIX OF CLOUDS AND SUN.
SHOWER COVERAGE INCREASES TONIGHT TO 40-50% SOUTH OF CAPE CANAVERAL
AS DEEPER MOISTURE AND ASSOCIATED COASTAL CONVERGENCE RAMP UP.
NEIGHBORHOOD HREF PROBABILITIES FOR LOCALIZED 1"+ RAINFALL TOTALS
THROUGH DAYBREAK TOMORROW ARE 20-30% FOR OUR SPACE AND TREASURE
COAST COMMUNITIES. ON THE WHOLE, COASTAL RAINFALL TALLIES SHOULD
AVERAGE AROUND 0.2 TO 0.4" DURING THE NEXT 24 HR, LESSENING TO UNDER
0.2" ALONG THE I-4 CORRIDOR.
OUR PRIMARY HAZARDS WILL REMAIN AT THE BEACH WHERE A HIGH SURF
ADVISORY AND HIGH RISK FOR DEADLY RIP CURRENTS CONTINUE. RESIDENTS
AND VISITORS ALIKE SHOULD STAY OUT OF THE ATLANTIC!
TUESDAY-WEDNESDAY...
COURTESY OF THE WEAKENING TROUGH WELL TO OUR SOUTH, UNUSUALLY HIGH
MOISTURE CONTENT AND COINCIDENT DIURNAL INSTABILITY WILL BE PRESENT
ACROSS THE DISTRICT DURING THIS TIMEFRAME. RAIN CHANCES HAVE
INCREASED TO 60-70% EACH DAY ALONG THE COAST SOUTH OF CAPE
CANAVERAL, AND 30-50% ELSEWHERE. ISOLATED LIGHTNING REMAINS A LOW
(20-30%) THREAT.
THERE IS ALSO AT LEAST A NON-ZERO RISK FOR HEAVY RAIN ALONG THE
COAST WHERE FRICTIONAL CONVERGENCE INTERACTS WITH THIS MOISTURE-
LADEN ENVIRONMENT. STATISTICAL GUIDANCE HOLDS A 20% CHANCE OF
ADDITIONAL RAINFALL TALLIES EXCEEDING 2" ALONG THE SPACE AND
TREASURE COASTS, WITH REASONABLE HIGH-END TALLIES AS HIGH AS 3" OR
SO. WHILE ANY RAINFALL WILL BE BENEFICIAL, WE WILL MONITOR THE URBAN
COASTAL CORRIDOR FOR POSSIBLE DRAINAGE ISSUES, ESPECIALLY IF HEAVY
RAIN ACCUMULATES IN A SHORT PERIOD.
BREEZES WILL TEND TO RELAX SOMEWHAT AS THE PRESSURE GRADIENT EASES.
HOWEVER, TEMPERATURES WILL REMAIN BALMY AND ABOVE SEASONAL NORMS.
THURSDAY-WEEKEND...
A WEAKENING COLD FRONT IS LIKELY TO CROSS THE AREA ON THURSDAY,
PROVIDING A DOSE OF DRIER AIR TO THE STATE. WE WILL HANG ONTO 20-30%
SHOWER CHANCES THURSDAY, BUT DRY WEATHER IS FORECAST FROM FRIDAY
THROUGH THE WEEKEND.
AS MENTIONED IN THE OVERVIEW, A STRONGER (BUT DRY) COLD FRONT IS
FORECAST TO PASS BY SOMETIME ON FRIDAY, OPENING THE DOOR FOR MUCH
COOLER AIR TO DRAIN DOWN THE PENINSULA THIS WEEKEND. FLORIDA IS
LIKELY TO RESIDE BOTH SOUTH OF THE SOUTHERN FLANK OF THE UPPER JET
AND THE NEXT CONTINENTAL HIGH. THIS PATTERN ALSO LACKS THE HIGH-
LATITUDE BLOCKING TYPICALLY ASSOCIATED WITH HIGH-IMPACT COLD
INTRUSIONS INTO FLORIDA. UNSURPRISINGLY, STATISTICAL GUIDANCE HAS
TRENDED AWAY FROM SOME OF THE EXTREME COLD SCENARIOS THAT WERE
MODELED A COUPLE OF DAYS AGO.
NO QUESTION ABOUT IT: IT WILL BE COOLER NEXT WEEKEND! WE
CURRENTLY FORECAST HIGHS IN THE MID 60S NORTH TO NEAR 70F SOUTH,
BUT THE INTERQUARTILE (25-75TH PERCENTILE) TEMPERATURE SPREAD
INCREASES TO 6-10 DEG F, INDICATIVE OF SOME POTENTIAL FOR FUTURE
ADJUSTMENTS TO THESE VALUES. LIKE OUR RECENT COOL SNAPS,
WIDESPREAD 40S ARE FORECAST FRI-SUN NIGHTS OVER THE INTERIOR AND
I-4 LOCALES. MINIMUM WIND CHILLS IN THE MID/UPPER 30S LOOK
ATTAINABLE OVER THESE SAME AREAS. ENSEMBLE GUIDANCE AND
STATISTICAL AIDS CONTINUE TO LESSEN THE POTENTIAL FOR A FREEZE,
WITH PROBABILITIES BELOW 20% FOR ALL REGIONS EXCEPT WELL TO THE
NORTHWEST OF I-4 ON MONDAY.
LEADING UP TO CHRISTMAS...
A WARMING TREND IS LIKELY NEXT WEEK AS SURFACE EASTERLY FLOW
REDEVELOPS OFF THE ATLANTIC. WHILE THIS PATTERN MAY, YET AGAIN,
LEAD TO A FEW COASTAL SHOWERS, WE CURRENTLY LOOK TO BE VOID OF
ANY SIGNIFICANT WEATHER MAKERS. THERE IS A 50-80% (NORTH-SOUTH)
CHANCE OF HIGHS IN THE 70S ON CHRISTMAS EVE, INCREASING TO A
60-90% CHANCE BY CHRISTMAS DAY.
MARINE
ISSUED AT 209 AM EST MON DEC 16 2024
HAZARDOUS BOATING CONDITIONS ARE STICKING AROUND THROUGHOUT THE OPEN
ATLANTIC THROUGH AT LEAST TUESDAY MORNING BEFORE SOME STEADY
IMPROVEMENTS FOR THE MIDDLE OF THE WEEK. LENGTHY SWELL PERIODS TODAY
AND TOMORROW FURTHER INCREASE THESE HAZARDS NEAR OUR INLETS.
EASTERLY ONSHORE WINDS HAVE PEAKED, BUT THEY WILL REMAIN MODERATE
THROUGH AT LEAST WEDNESDAY. SEAS 7-12 FT TODAY, SUBSIDING TO 5-8 FT
ON TUESDAY AND 4-6 FT BY WEDNESDAY. INTRACOASTAL AND INSHORE BOATING
WILL BEGIN TO IMPROVE AS WELL, BUT AT LEAST A MODERATE CHOP WILL
PERSIST. SCATTERED TO NUMEROUS SHOWERS ARE LIKELY THROUGH WEDNESDAY
ALONG WITH A LOW CHANCE FOR LIGHTNING ACTIVITY.
HIGH PRESSURE MOVES OFF INTO THE ATLANTIC THIS WEEK, AND A PAIR OF
COLD FRONTS ARE FORECAST TO APPROACH THE LOCAL WATERS BY THURSDAY
AND FRIDAY. WINDS WILL TURN NORTH-NORTHWEST LATE THIS WEEK AS
SHOWERS BECOME MORE ISOLATED.
AVIATION
(12Z TAFS)
ISSUED AT 642 AM EST MON DEC 16 2024
WATCHING SOME STRATUS CREEPING SOUTH INTO LAKE COUNTY AND WILL
MONITOR IF IT IS ABLE TO MAKE IT TO KLEE. DEEP ONSHORE FLOW
CONTINUES ACROSS THE AREA. ISOLD-SCT RAIN SHOWERS WILL SPREAD ONTO
THE COAST AND FURTHER INTO THE INTERIOR LATER THIS
MORNING/AFTERNOON. MAIN IMPACTS WILL BE BRIEF DOWNPOURS AND GUSTY
WINDS. "VICINITY" WORDING REMAINS IN PLACE FOR COASTAL TAF SITES
WITH TEMPO GROUPS AS NECESSARY. GENERALLY VFR, EXCEPT LOCAL MVFR,
ESP INVOF SHOWERY PRECIP. NERLY WINDS 5-10 KTS ACROSS THE INTERIOR
AND 10-15 KTS AT THE COAST (FEW HIGHER GUSTS) WILL INCREASE TO
10-15 KTS INLAND AND 15 KTS NEAR THE COAST WITH FREQUENT HIGHER
GUSTS DURING THE DAY.
PRELIMINARY POINT TEMPS/POPS
DAB 78 64 77 65 / 30 30 40 20
MCO 80 65 81 66 / 20 20 50 20
MLB 79 67 79 67 / 50 40 60 40
VRB 80 69 81 68 / 50 50 60 50
LEE 80 63 81 65 / 20 10 30 20
SFB 79 64 80 66 / 30 20 50 20
ORL 80 64 81 66 / 20 20 50 20
FPR 79 69 80 68 / 50 50 60 50
MLB WATCHES/WARNINGS/ADVISORIES
FL...HIGH SURF ADVISORY UNTIL 7 PM EST THIS EVENING FOR FLZ141-154-
159-164-347-447-647-747.
AM...SMALL CRAFT ADVISORY UNTIL 10 AM EST TUESDAY FOR AMZ550-552-555.
SMALL CRAFT ADVISORY UNTIL 3 AM EST WEDNESDAY FOR AMZ570-572-575.
UPDATE...WEITLICH
AVIATION...SEDLOCK
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