464  
FXUS62 KMLB 210220  
AFDMLB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MELBOURNE FL  
920 PM EST MON NOV 20 2017  
   
DISCUSSION
 
 
RELATIVELY QUIET WX PATTERN OVERNIGHT AS HI PRES OVER THE ERN  
SEABOARD PUSHES INTO THE W ATLC AND MAINTAINS A STEADY EASTERLY FLOW  
ACRS CENTRAL FL. FRONTAL BOUNDARY EXTENDING FROM THE SRN GOMEX ACRS  
THE FL STRAITS WILL DISSIPATE, THOUGH ITS REMNANT H100-H70 MOISTURE  
BAND/H85-H70 THETA-E RIDGE WILL BEGIN TO DRIFT BACK TO THE NORTH AS  
MID LVL WINDS VEER TO THE SE.  
 
EVNG KXMR/KTBW RAOBS CONTINUE TO SHOW A VERY DRY/STABLE AIRMASS OVER  
CENTRAL FL WITH PWAT VALUES ARND 0.75", AVG H85-H50 DEWPOINT  
DEPRESSIONS BTWN 20-30C OVER THE TREASURE COAST/LAKE-O REGION, AND A  
SHARP SUBSIDENCE INVERSION IN THE H85-H70 LYR. PWAT INCREASES TO  
ARND 1.50" AT KMFL/KEYW, MUCH OF WHICH IS TRAPPED BLO THE SAME MID  
LVL SUBSIDENCE INVERSION, ALBEIT IN A MUCH WEAKER STATE. LATEST  
RADAR IMAGES FROM KMFL DO SHOW BANDING PRECIP MOVING ONSHORE, BUT  
LIMITED TO POINTS SOUTH OF BROWARD CO AND SHOWING NO SIGN OF ANY  
NORTHWARD DRIFT.  
 
WHILE H100-H70 MOISTURE IS EXPECTED TO INCREASE AS HI PRES BUILDS  
OVER THE W ATLC, THE DRY/STABLE AIR OVER CENTRAL FL WILL REQUIRE  
SIGNIFICANT MODIFICATION BEFORE IT CAN SUPPORT ANY PRECIP. INDEED,  
THE HRRR AND LCL WRF MODELS ARE QUITE BEARISH ON PRECIP DVLPG OVER  
THE TREASURE COAST OVERNIGHT, AND EVEN THEN, MORE IN THE PREDAWN HRS  
THAN OVERNIGHT. AS SUCH, WILL CULL POPS BACK TO 20PCT AFT 09Z WITH  
THE EVNG UPDATE. ONSHORE FLOW WILL KEEP OVERNIGHT MIN TEMPS ABV  
AVG...L/M60S INLAND AND M/U60S ALONG THE COAST.  
 

 
   
AVIATION
 
THRU 22/00Z.  
SFC WINDS: THRU 21/06Z...COASTAL SITES E/NE 8-12KTS...INTERIOR SITES  
4-8KTS. BTWN 21/06Z-21/12Z...E/NE 4-8KTS. BTWN 21/13Z-21/16Z...BCMG  
E/SE 7-11KTS. BTWN 21/21Z-21/24Z...N OF KMLB-KISM BCMG E/NE 5-  
9KTS...S OF KMLB-KISM BCMG SE 4-8KTS.  
 
VSBYS/WX/CIGS...THRU 21/13Z PREVAILING VFR SCT-BKN040-050...AFT  
21/06Z BCMG MULTILAYERED BKN-OVC BTWN FL080-120. BTWN 21/13Z-  
21/16Z...S OF KMLB-KISM AREAS MVFR CIGS/VSBYS IN -RA/RA/BR...N OF  
KMLB LCL MVFR CIGS/VSBYS IN -RA/BR. AFT 21/16Z...PREVAILING CIGS  
BTWN FL060-080...AREAS MVFR CIGS/VSBYS AND LCL IFR CIGS/VSBYS IN +RA  
ALL SITES...SLGT CHC TSRA.  
 

 
   
MARINE
 
 
THE CENTER OF A LARGE HI PRES RIDGE BLANKETING THE ERN CONUS WILL  
DRIFT OFF THE CAROLINA COAST OVERNIGHT, MAINTAINING A GENTLE TO  
MODERATE EASTERLY BREEZE WHILE DOING SO...OCNL G20KTS. LATEST BUOY  
OBS ARE INDICATING 4-6FT SEAS IN THE SHELF WATERS, 5-7FT IN THE GULF  
STREAM...DOMINANT PDS BTWN 6-7SEC RESULTING IN ROUGH CONDITIONS WITH  
STEEP WAVE FACES. WHILE WINDS ARE EXPECTED TO DIMINISH SLIGHTLY  
OVERNIGHT AS THE RIDGE PUSHES INTO W ATLC, OVERALL CONDITIONS WILL  
REMAIN POOR ENOUGH TO CONTINUE LATEST ADVISORY/CAUTIONARY STATEMENTS  
OVERNIGHT.  
 

 
   
MLB WATCHES/WARNINGS/ADVISORIES
 
 
FL...NONE.  
AM...SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR SEBASTIAN INLET  
TO JUPITER INLET 20-60 NM-VOLUSIA-BREVARD COUNTY LINE TO  
SEBASTIAN INLET 20-60 NM.  
 
SMALL CRAFT ADVISORY UNTIL 10 AM EST TUESDAY FOR SEBASTIAN INLET  
TO JUPITER INLET 0-20 NM.  
 

 
 

 
 
SHORT TERM/AVIATION...BRAGAW  
IMPACT WX/RADAR.......SEDLOCK  
 
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