000
AGXX40 KNHC 210550
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
150 AM EDT THU AUG 21 2014

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN
SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND
64W...AND THE SW N ATLANTIC INCLUDING THE BAHAMAS.

...GULF OF MEXICO...

MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS OFFICIAL
WHICH WAS HEAVY GFS. NWPS USED FOR WAVE PARAMETERS. HIGH
CONFIDENCE TILL SUN...THEN LOW CONFIDENCE ON MON.

A RIDGE EXTENDS FROM FL BAY TO THE MS DELTA WITH A HIGH PRES
CENTER ALONG THE RIDGE NEAR 28N87W. THE HIGH WILL GRADUALLY
SHIFT NW ALONG THE RIDGE TO THE N-CENTRAL GULF TODAY AND
TONIGHT...THEN SHIFT FURTHER NW OVER INTERIOR LA ON FRI...WITH A
RIDGE EXTENDING SE TO THE SE GULF WATERS. THE HIGH WILL SHIFT SE
ALONG THE RIDGE AND BACK OVER THE NE GULF OVER THE WEEKEND AND
CONTINUE EARLY NEXT WEEK AS THE RIDGE BECOMES ORIENTATED FROM SW
LA TO FL BAY.

VARIABLE 5-10 KT WINDS EXPECTED OVER THE NE GULF WATERS TILL FRI
WHEN THEY BECOME NE AT 5-10 KT. THE LIGHT AND VARIABLE CONDITIONS
WILL DEVELOP AGAIN ON FRI NIGHT AND SAT...THEN BECOME NE ACROSS
THE NE GULF WATERS AGAIN EARLY MON. BY THEN THE GRADIENT MAY BE
TIGHTENING AS A TROPICAL LOW...POSSIBLY A TROPICAL CYCLONE...
CONTINUES NW THROUGH THE BAHAMAS. EXPECT SE-S 15-20 KT RETURN
FLOW ACROSS THE W-CENTRAL AND NW WATERS AROUND THE W PERIPHERY
OF THE RIDGE THIS MORNING...DIMINISHING TO 10-15 KT LATER TODAY
AND THEN BECOMING 5-10 KT DURING THE DAYLIGHT HOURS...AND 10-15
KT DURING THE OVER NIGHT HOURS THROUGH THE REMAINDER OF THE
PERIOD.

S OF 23N...EXPECT AN EVENING ENHANCEMENT OF 15-20 KT NE WINDS
ALONG THE W COAST OF THE YUCATAN PENINSULA EACH EVENING SETTING
UP AN INVERTED TROUGH OVER THE EASTERN BAY OF CAMPECHE DURING
THE LATE NIGHT HOURS. THE TROUGH WILL SHIFT W ACROSS THE CENTRAL
BAY OF CAMPECHE DURING EACH MORNING...AND LOSE IDENTITY DURING
THE EARLY AFTERNOON HOURS ACROSS THE CENTRAL BAY OF CAMPECHE.

...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN
55W AND 64W...

MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS OFFICIAL
WHICH WAS HEAVY GFS. NWPS USED FOR WAVE PARAMETERS. MED
CONFIDENCE W PORTION...LOW CONFIDENCE E PORTION.

FRESH TO LOCALLY STRONG EASTERLY TRADES WILL CONTINUE ACROSS THE
S-CENTRAL CARIBBEAN THROUGH EARLY FRI. THE TROPICAL LOW PRES
NEAR 12.5N54.5W HAS BECOME BETTER ORGANIZED...PARTIALLY DUE TO
AN EASTERLY WAVE MERGING WITH THE CIRCULATION. NHC GUIDANCE
FAVORS THE LOW TRACKING NORTHWESTERLY...WITH GOOD POTENTIAL FOR
TROPICAL CYCLONE FORMATION. EVEN IF THE LOW DOES NOT DEVELOP
SIGNIFICANTLY...THERE IS STRONG GRADIENT NE OF THE LOW LEVEL
CIRCULATION...ROUGHLY FROM 14-23N BETWEEN 50-60W...WHERE E 20-25
KT WINDS ARE CURRENTLY SUPPORTED. EXPECT THE GRADIENT TO
GRADUALLY TIGHTEN TONIGHT INTO FRI SUPPORTING AN INCREASE TO AT
LEAST 20-30 KT BY LATE FRI. RECON WILL INVESTIGATE THE AREA
TODAY AND GET A BETTER HANDLE OF THE AFFECTED AREA. THERE IS
SOME POSSIBILITY OF A MINIMUM GALE BEING POSTED OVER THE N...OR
NE...SEMICIRCLE EVEN IF TROPICAL CYCLONE FORMATION DOES NOT
OCCUR.

FOR NOW...A WEAK SURFACE LOW CENTER WILL BE OVER THE TROPICAL
ATLC WATERS NEAR 14N55W AT SUNRISE THIS MORNING...NEAR 15N61W AT
SUNSET TODAY...NEAR 16N65W AT SUNRISE FRI...NEAR THE MONA
PASSAGE AT SUNSET FRI...OVER HISPANIOLA AT SUNRISE SAT...NEAR
THE WINDWARD PASSAGE AT SUNSET SAT...WITH THE LOW THEN MOVING NW
THROUGH THE BAHAMA CHAIN THROUGH MON NIGHT. EXACT TRACK AND
INTERACTION WITH THE LARGER ISLANDS WILL OF COURSE PLAY A MAJOR
PART IN THE ORGANIZATION OR WEAKENING OF THIS TROPICAL LOW...AND
MARINERS SHOULD EXPECT FREQUENT ADJUSTMENTS TO THE NDFD GRIDS...
TEXT AND MARINE GRAPHICS OVER THE NEXT WEEK. IN ANY EVENT EXPECT
AT LEAST FRESH TO STRONG WINDS WITHIN 540 NM N AND NE OF THESE
ESTIMATED POSITIONS.

...SW N ATLANTIC INCLUDING THE BAHAMAS...

MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS OFFICIAL
WHICH WAS MOSTLY GFS. NWPS USED FOR WAVE PARAMETERS. LOW-MED
CONFIDENCE DUE TO TROPICAL LOW.

PLEASE ALSO REFER TO CARIBBEAN AND TROPICAL ATLC SECTION FOR
DETAILS ON THE TROPICAL LOW. A RIDGE WILL MEANDER FROM 30N55W TO
CENTRAL FL THROUGH SAT THEN BEGIN TO RETRACT E AS A TROPICAL LOW
MOVES OUT OF THE N-CENTRAL CARIBBEAN INTO THE S-CENTRAL PORTION
OF THE DISCUSSION AREA. EXPECTING SW 10-15 KT CONDITIONS N OF
THE RIDGE TODAY...THEN DIMINISHING TO 5-10 KT ON FRI. EASTERLY
TRADES FROM THE RIDGE AXIS S TO ALONG 25N ARE EXPECTED TO
CONTINUE INITIALLY AT 5-10 KT. TO THE S OF 25N MODERATE 10-15 KT
TRADES ARE EXPECTED W OF 65W...EXCEPT FOR 15-20 KT CONDITIONS
ALONG THE N COAST OF HISPANIOLA. EXPECT EASTERLY 20-25 KT WINDS
ACROSS THE WATERS S OF 23N E OF 65W THIS MORNING...INCREASING TO
20-30 KT LATE FRI. MUCH UNCERTAINTY...BUT EXPECT AT A MINIMUM A
LARGE AREA OF ENHANCED 20-25 KT WINDS TO SHIFT W ACROSS THE
WATERS S OF 24N E OF THE BAHAMAS TODAY THROUGH FRI...THEN MOVE
THROUGH THE SOUTHERN BAHAMAS ON SAT...THE CENTRAL BAHAMAS ON
SUN...AND THE NORTHERN BAHAMAS ON SUN WITH POSSIBLE TROPICAL
CYCLONE FORMATION THROUGHOUT THE ENTIRE PERIOD. THERE WILL BE
SIGNIFICANT CHANGES TO THE NDFD GRIDS...TEXT AND MARINE GRAPHICS
OVER THE NEXT WEEK.

$$

.WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE
COORDINATED THROUGH AWIPS 12 PLANET 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.HURRICANE WARNINGS.GOV/MARINE

$$

.FORECASTER NELSON. NATIONAL HURRICANE CENTER.