324  
AGXX40 KNHC 211627  
MIMATS  
 
MARINE WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL  
1227 PM EDT FRI JUL 21 2017  
 
MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO, CARIBBEAN SEA,  
AND TROPICAL NORTH ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W  
AND THE SOUTHWEST NORTH ATLANTIC INCLUDING THE BAHAMAS  
   
..GULF OF MEXICO
 
 
 
CONVECTION IS INCREASING ACROSS MUCH OF THE N HALF OF BASIN LATE  
THIS MORNING AS AN UPPER LOW IS SHIFTING SLOWLY WWD ACROSS THE  
NE GULF AND INTERACTING WITH AMPLE LLVL MOISTURE ABOUT BOTH SIDES  
OF LINGERING SFC TROUGH. THIS ACTIVITY EXPECTED TO CONTINUE  
THROUGH TONIGHT. W ATLC RIDGE EXTENDS WWD ALONG 28N AND VERY  
WEAKLY ACROSS FL AND WEAKLY ACROSS THE GULF ALONG ABOUT 27N, WITH  
A SYMPATHETIC HIGH HAVING FORMED NEAR 26N86N. 12Z OBS SUGGESTED  
SEAS 1-2 FT ACROSS ENTIRE BASIN EXCEPT 3-4 FT ACROSS SW PORTIONS  
IN RESPONSE TO YUCATAN THERMAL TROUGH SHIFTING W OVERNIGHT. WITH  
WEAK PRES PATTERN TO PREVAIL ACROSS THE BASIN NEXT SEVERAL DAYS,  
THIS THERMAL TROUGH WILL DOMINATE THE YUCATAN AND SW GULF DURING  
THE PERIOD. A VERY ENERGETIC TROPICAL WAVE MOVING ACROSS HONDURAS  
AND NICARAGUA THIS MORNING WILL ENHANCE YUCATAN CNVTN THIS  
AFTERNOON THROUGH TONIGHT AND THEN ACROSS W BAY OF CAMPECHE AND  
ADJACENT MEXICAN AREAS THROUGH SAT NIGHT.  
 
OTHERWISE, THE WEAK RIDGE WILL DOMINATE THROUGH SATURDAY  
PRODUCING GENTLE TO MODERATE WINDS AND SEAS OF 1 TO 3 FT, WITH  
THE EXCEPTION OF THE EASTERN GULF, WHERE VARIABLE WINDS AND SEAS  
OF 2 FT OR LESS WILL PREVAIL. ON SUNDAY, AS THE RIDGE BUILDS  
WESTWARD, EXPECT MODERATE TO LOCALLY FRESH SE TO S WINDS, AND  
SEAS OF 3 TO 5 FT ACROSS MUCH OF THE W AND SW GULF THROUGH  
TUESDAY NIGHT, WHERE THE PRESSURE GRADIENT WILL BE TIGHTER.  
 
...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN  
55W AND 64W...  
 
VERY ENERGETIC TROPICAL WAVE, FORMER TS DON, HAS MOVED INTO  
NICARAGUA AND HONDURAS WITH ACCOMPANYING WIND SURGE SLOWLY  
DIMINISHING IMPACTS ACROSS THE W CARIB WATERS AND GULF OF  
HONDURAS. SQUALLS AND TSTORMS HAVE MOVED WILL INLAND AND  
WEAKENED PAST SEVERAL HOURS. SEAS WERE 6-9 FT ACROSS WATERS OFF  
OF NICARAGUA AND 5-7 FT OFF OF HONDURAS AT 12Z AND ARE SLOWLY  
SUBSIDING. THIS WIND SURGE SHIFTED AREA OF MAX WIND AND SEAS FROM  
TYPICAL LOCATION OFF OF COLOMBIA TO THIS AREA OVERNIGHT AND THIS  
MORNING. MEANWHILE FARTHER E, TRAILING STRONG ENE EXTEND TO S OF  
HISPANIOLA AND THE S MONA PASSAGE WHERE SEAS WERE 6-7 FT WITH  
LIKELY AREAS TO 8 FT. PR BUOYS SHOWING SEAS AT 5 FT AT 12Z AND  
DOWN SLIGHTLY FROM OVERNIGHT. LARGE AEW COMPLEX COVERS FROM ABOUT  
72W TO THE WATERS E THROUGH NE OF THE ISLANDS AS SECONDARY VORT  
IS RIDING WNW UP THE BACK SIDE OF LEADING BROAD WAVE ALONG 71W  
AND WILL TRANSPORT THIS MOISTURE ACROSS THE NE CARIB THROUGH  
TONIGHT. AS THIS AEW COMPLEX MOVES ACROSS THE REMAINDER OF BASIN  
THROUGH THE WEEKEND, PEAK WINDS WILL PERSIST ACROSS THE S CENTRAL  
PORTIONS OF THE BASIN, IN NORMAL LOCATION WHERE SEAS WILL  
FLUCTUATE 7-9 FT. DIURNAL PROCESSES TO ENHANCE FRESH E TRADES S  
OF HISPANIOLA THROUGH THE WEEKEND. MODELS SHOW ATLC RIDGE  
SHIFTING SLIGHTLY W BY MON AND STRENGTHENING PRES GRAD JUST  
ENOUGH TO HINT AT 30 KT EARLY MORNING PEAK WINDS OFF OF COLOMBIA,  
WITH SEAS TO 10 FT.  
   
..SW N ATLANTIC INCLUDING THE BAHAMAS
 
 
HIGH PRESSURE RIDGES ACROSS THE W ATLC ALONG 28-29N TO CENTRAL  
FL YIELDING MODERATE TO FRESH TRADES S OF 23N E OF TURKS AND  
CAICOS BECOMING SE TO S WINDS THROUGH THE BAHAMAS. WIND SURGE  
ASSOCIATED WITH THE BROAD TROPICAL WAVE COMPLEX ACROSS THE E AND  
NE CARIB KICKED UP SEAS 6-7 FT WITH ISOLATED SPOTS TO 8 ACROSS  
THE FAR SE WATERS FROM N OF PR TO N OF LEEWARDS. ELSEWHERE SEAS  
RELATIVELY TRANQUIL AT 4-5 FT EXCEPT # FT OR LESS THROUGH BAHAMAS  
AND 2-3 FT ACROSS FL AND GA COASTAL WATERS. TUTT LOW ACROSS AND  
JUST E OF CENTRAL BAHAMAS INDUCING INCREASING CNVTN ATTM AND  
LOOKS TO BE AN ACTIVE DAY. SQUALLS AND TSTORM ASSOCIATED WITH  
WAVE ENERGY MOVING WNW ACROSS THE WATERS NE OF THE LEEWARDS WILL  
SHIFT ACROSS THESE WATERS LATE THIS AFTERNOON THROUGH TONIGHT.  
MODELS IN GOOD AGREEMENT THAT RIDGE WILL REMAIN GENERALLY INTACT  
INTO EARLY NEXT WEEK WITH LITTLE CHANGE TO CONDITIONS, AND  
MODIFIED MAINLY BY PASSING AEWS.  
 

 
   
WARNINGS
 
ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE  
COORDINATED THROUGH AWIPS II COLLABORATION CHAT, OR BY  
TELEPHONE:  
   
GULF OF MEXICO
 
 
NONE.  
 
.CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN  
55W AND 64W...  
NONE.  
   
SW N ATLANTIC INCLUDING THE BAHAMAS
 
 
NONE.  
 

 
 
*FOR DETAILED ZONE DESCRIPTIONS, PLEASE VISIT:  
HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF  
 
NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL  
DIGITAL FORECAST DATABASE (NDFD) AT:  
HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP  
 
FOR ADDITIONAL INFORMATION, PLEASE VISIT:  
HTTP://WWW.NHC.NOAA.GOV/MARINE  
 

 
 
.FORECASTER STRIPLING. NATIONAL HURRICANE CENTER.  
 
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