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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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