Area Forecast Discussion
Issued by NWS Melbourne, FL

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000
FXUS62 KMLB 190025
AFDMLB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
725 PM EST THU DEC 18 2014

.DISCUSSION...

CURRENT-OVERNIGHT...INFRARED SATELLITE IMAGERY LOOP SHOWING JET
STREAM CIRRUS/CIRROSTRATUS STREAMING WEST TO EAST ACROSS THE GULF OF
MEXICO AND FLORIDA. THE SKY CONDITIONS WILL VARY BETWEEN PARTLY
CLOUDY TO CONSIDERABLE CLOUDINESS AS THE CIRRUS/CIRROSTRATUS THINS
THEN THICKENS AGAIN THROUGHOUT THE OVERNIGHT HOURS. LIGHT TO CALM
WINDS MUCH OF THE FORECAST AREA AS THE LOWEST LAYERS OF THE
ATMOSPHERE DECOUPLE. LIGHT NORTHWEST TO WEST DRAINAGE WIND FLOW
TOWARD SUNRISE. TEMPERATURES LOOK REASONABLE.

UPDATING THE ZONES TO BRING WEATHER ELEMENT TRENDS CURRENT.


PREVIOUS ZONES DISCUSSION
CURRENT-TONIGHT...MOSTLY SUNNY CONDITIONS OVER EAST CENTRAL FLORIDA
THIS AFTERNOON WITH OCCASIONAL/FEW TO SCATTERED MID-HIGH LEVEL
CLOUDS. CONDITIONS WILL REMAIN DRY. CANNOT RULE OUT SOME
SHALLOW/LOCALIZED PATCHY GROUND FOG IN PRONE LOCATIONS LATE
OVERNIGHT BUT DO NOT THINK IT WILL BECOME WIDESPREAD AND WILL LEAVE
MENTION ABSENT FROM THE GRIDS/ZONES. OVERNIGHT LOWS AGAIN IN THE 40S
AREAWIDE. WINDS WILL BECOME LIGHT TO CALM IN THE EVENING THROUGH THE
OVERNIGHT.

FRI...THE FLAT MID LEVEL RIDGING WILL REMAIN IN PLACE OVER THE
REGION WITH ZONAL FLOW ALOFT. AT THE SURFACE WEAK HIGH PRESSURE WILL
HANG ON FOR ONE MORE DAY. AN AREA OF LOW PRESSURE WILL CONTINUE TO
DEVELOP ALONG THE NORTHEAST TEXAS/LOUISIANA COAST ON THIS DAY. WINDS
WILL RESPOND BY VEERING TO NORTHEAST OR EAST THROUGH THE AFTERNOON
WITH SPEEDS LESS THAN 10 MPH THANKS TO A WEAK PRESSURE GRADIENT.
CONTINUED DRY CONDITIONS FORECAST WITH TEMPERATURES NEAR NORMAL
AFTER A COOL START TO THE MORNING.

FRIDAY NIGHT-SATURDAY NIGHT...ZONAL FLOW PREVAILS ALOFT WHILE A WEAK
SHORTWAVE PASSES NORTH OF THE REGION EARLY SATURDAY. MOISTURE BEGINS
TO INCREASE SLIGHTLY SATURDAY NIGHT AND WEAK CONVERGENCE ASSOCIATED
WITH STATIONARY BOUNDARY TO THE NORTH MAY PROMOTE ISOLATED SHOWERS
ACROSS NORTHERN CWA LATE.

SUNDAY-CHRISTMAS EVE DAY...AN UNSETTLED PATTERN IN STORE THROUGH THE
MIDDLE OF NEXT WEEK AS A BROAD SHORT WAVE TROUGH OVER THE WESTERN
STATES WORKS ITS WAY ACROSS THE NATION. EXTENDED MODEL SOLUTIONS
INDICATE THAT A 160KT H30-H20 JET STREAK OVER THE PACIFIC WILL PUSH
INTO THE PACIFIC NW AND FEED ITS ENERGY DOWN STREAM TO THE LIFTING
JET OVER THE SE CONUS. HOWEVER...BOTH GFS/ECMWF MODELS MAINTAIN A
LIFTING ORIENTATION WITH THE SOUTHERN JET WHILE HOLDING THE RIDGE
OVER THE SW ATLANTIC FIRMLY IN PLACE. BOTH OF THESE FEATURES WILL
PREVENT THE FRONT FROM MAKING A CLEAN/RAPID PASS THROUGH CENTRAL
FL...RESULTING IN AN EXTENDED PERIOD OF PRECIPITATION AS DEEP
MOISTURE POOLS WITHIN THE FRONTAL TROUGH.

INTERACTION BETWEEN THE ATLANTIC RIDGE AND THE STALLED FRONTAL
TROUGH WILL GENERATE A DEEP SW FLOW THROUGH THE COLUMN...RESULTING
IN STRONG ISENTROPIC LIFT THAT USUALLY GENERATES MORE STRATIFORM
THAN CONVECTIVE RAIN. HOWEVER...AS THE FRONTAL TROUGH DRIFTS INTO
THE CENTRAL PENINSULA...IT WILL ERODE THE WESTERN FLANK OF THE
ATLANTIC RIDGE AND BREAK UP THE STRONG SUBSIDENCE INVERSION THAT
CURRENTLY DOMINATES THE H100-H70 LYR ACRS CENTRAL/NORTH FL. THE
STEEPENING LAPSE RATES WILL COMBINE WITH H50 TEMPERATURES BETWEEN
-10C/-12C THAT COULD TRIGGER ISOLATED LIGHTNING STORMS.

WILL KEEP POPS MENTIONED THROUGH THE PERIOD BUT AOB 50 PCT. A
PROLONGED PERIOD OF S/SWRLY FLOW AHEAD OF THE FRONT WILL KEEP
TEMPERATURES ABOVE AVERAGE...THOUGH CLOUDS AND RAIN COOLED AIR WILL
HELP OFFSET THIS EFFECT DURING THE DAYTIME. AFTERNOON MAXES IN THE
L/M70S N OF I-4...M/U70S TO THE SOUTH. MIN TEMPS U50S/L6S0 INTERIOR
AND L/M60S ALONG THE COAST.

AT THIS TIME...CONSENSUS MODEL SOLUTIONS SUGGEST AXIS OF LONG-WAVE
TROUGH CROSSES CWA BETWEEN MID DAY AND SUNSET CHRISTMAS EVE DAY.
ASSOCIATED SURFACE COLD FRONT SHOULD CROSS THE CWA AND BRING AN END
TO THE PRECIPITATION DURING THE DAY. ONSET OF GUSTY NW
WINDS...CAUSING ADVECTION OF DRIER/COOLER AIR BY LATE DAY/SUNSET.

&&

.AVIATION...SCATTERED TO BROKEN AOA FL120. VFR. SHALLOW PATCHY
GROUND FOG POSSIBLE ACROSS A FEW OF THE TERMINALS BEFORE SUNRISE BUT
NOT CONFIDENT ENOUGH TO INCLUDE IN TAFS AT THIS TIME. REVIEW OF THE
1AM/06Z TO 7AM/12Z WEATHER ROUNDUPS DID NOT INDICATE SHALLOW GROUND
FOG AT ANY OF THE REPORTING SITES. THERE MAY HAVE BEEN SOME MESONET
SITES THAT EXPERIENCE SHALLOW GROUND FOG.

&&

.MARINE...



CURRENT-OVERNIGHT...THE NOAA BUOYS WERE RECORDING NORTHWEST WINDS
AROUND 10 KNOTS AND 2 FOOT LONG PERIOD SEAS. THE TWO SCRIPPS BUOYS
JUST OFF PORT CANAVERAL AND FORT PIERCE INLET WERE RECORDING 1 TO 2
FOOT LONG PERIOD SEAS. THE CMAN REPORTING SITES AT TRIDENT PIER IN
PORT CANAVERAL AND AT SEBASTIAN INLET WERE RECORDING LIGHT ONSHORE
WINDS. THESE WINDS SHOULD SHIFT BACK TO THE WEST AS ANY LOCAL MESO
SCALE CIRCULATIONS DIMINISH AND SYNOPTIC SCALE WINDFLOW RE
ESTABLISHES ITSELF.

THE EVENING MARINE UPDATE LOOKS AT MARINE WEATHER/SEAS TREND WORDING
CHANGES.

PREVIOUS MARINE DISCUSSION
TODAY/FRI...WEAK HIGH PRESSURE OVER THE AREA. FAVORABLE
BOATING CONDITIONS FOR SMALL CRAFT. LIGHT NW FLOW WITH WIND SPEEDS
MAINLY 5-10 KTS. WINDS ARE FORECAST TO VEER TO THE N/NNE/NE LATER IN
THE AFTERNOON ON FRI. SEAS GENERALLY AOB 2FT...POTENTIALLY UP TO 3FT
IN THE GULF STREAM.

FRIDAY NIGHT...HIGH PRESSURE RIDGE EXTENDING FROM THE NORTHERN GULF
TO THE GREAT LAKES WILL WEAKEN AS IT DRIFTS TOWARD THE EASTERN
SEABOARD. AS IT DOES...THE PREVAILING LIGHT FLOW WILL BECOME
EASTERLY BY MIDNIGHT...THEN S/SE BY DAYBREAK SATURDAY. FAVORABLE
BOATING CONDITIONS TO CONTINUE WITH SUSTAINED WIND SPEEDS AOB 10
KT...SEAS GENERALLY AOB 2 FT...UP TO 3 FT IN THE GULF STREAM.

SATURDAY-TUESDAY...A WEAK H100-H70 SHORTWAVE WILL PINCH OFF OF THE
BASE OF THE TROUGH OVER THE WESTERN U.S. AND PUSH ACROSS THE DEEP
SOUTH SATURDAY...DRAGGING A WEAK COLD FRONT INTO THE FL PANHANDLE
WHERE IT IS EXPECTED TO STALL BY LATE SATURDAY NIGHT. THIS WILL
RESULT IN A PERSISTENT LIGHT TO GENTLE SOUTHERLY BREEZE THROUGH THE
WEEKEND...BECOMING S/SW GENTLE TO MODERATE MONDAY AS A REINFORCING
TROUGH PUSHES INTO THE GULF AND NUDGES THE FRONT INTO THE
NORTHERN/CENTRAL PENINSULA EARLY NEXT WEEK. SEAS AOB 2 FT NEARSHORE
AND 2-4 FT OFFSHORE.

&&

.FIRE WEATHER...REMAINDER OF AFTERNOON/FRIDAY...MINIMUM RH VALUES
DROPPING INTO THE 30S ONCE AGAIN ACROSS A GOOD PORTION OF THE CWA.
WINDS AND ERC VALUES REMAIN BELOW CRITICAL THRESHOLDS...ALTHOUGH
LIGHT WINDS WILL LIMIT DISPERSION TO POOR-FAIR THRU FRI.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  46  69  54  74 /   0   0  10  10
MCO  47  72  54  76 /   0   0  10  10
MLB  45  72  56  75 /   0   0  10  10
VRB  45  73  55  76 /   0   0  10  10
LEE  46  69  53  74 /   0   0  10  10
SFB  47  72  55  75 /   0   0  10  10
ORL  50  71  56  75 /   0   0  10  10
FPR  46  72  53  75 /   0   0  10  10

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&

$$

VOLKMER/WIMMER




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