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AGXX40 KNHC 250747
MIMATS

Marine Weather Discussion
NWS National Hurricane Center Miami FL
347 AM EDT Sat Mar 25 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...

Strong high pressure extending from the Mid-Atlantic U.S. coast
southwestward over the northern waters will slide eastward
through Sunday as a cold front approaches the far northwest gulf.
The tight gradient currently inducing fresh to strong southerly
winds over the northwest and north-central waters will relax
today allowing for these winds to diminish to mainly moderate
winds through the tonight, and moderate to locally fresh winds
Sunday through early next week. Seas of 7-9 ft in the northwest
gulf will subside to around 4-7 ft today. The front will stall
along the Texas coast this afternoon.

The 0226Z Ascat pass revealed a swath of strong east winds over
the southeast gulf waters south of 25N and east of 86W, including
the Straits of Florida. Seas associated with these winds are in
the 6-8 ft range. These winds are forecast to diminish to 15-20
kt this afternoon, with seas lowering to 4-6 ft.

Deep layer moisture associated with the upper trough currently
moving over eastern Texas, and that supports the cold front that
will approach the far northwest gulf this weekend, is streaming
eastward across portions of the north-central and northeast
gulf. This moisture and upper level energy with the trough
is expected to bring scattered shower and thunderstorm activity
over those portions of the gulf through Sunday morning. Some
of this activity may contain brief gusty winds. A thermal trough
will move off the Yucatan and over the eastern Bay of Campeche
each night the next several nights. Fresh to strong winds will be
possible with the trough each night, then mainly fresh winds
thereafter.

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

The fresh to strong northeast to east winds across the northwest
and north-central Caribbean waters have diminished to mainly
moderate to locally fresh winds per the 0226Z Ascat pass and
recent buoy observations there. These winds are forecast to
remain in the moderate range through Tuesday, then become east to
southeast moderate to locally strong winds on Wednesday. A
narrow swath of north to northeast strong winds is noted in the
Ascat pass just south of the eastern part of Hispaniola from
18.5N to 17N and between 69.5W and 71W. A weaker than normal
pressure pattern will persist over the central and eastern
Caribbean the next several days, as low pressure begins to
develop north of Hispaniola and slowly tracks north to northeast.
This pressure pattern will result in mainly gentle to moderate
trades over the Caribbean. A new set of large northerly swell
with seas of 8-10 ft has just recently started to propagate
across the northwest portion of zone AMZ127. This swell is
forecast to reach into zone AMZ027 by late tonight, however the
swell will be decaying at that time with seas down to 8 ft, and
to less than 8 ft by late on Sunday afternoon. A very well
pronounced upper trough in water vapor imagery stretches from the
southeastern Bahamas to Jamaica, and continues further southwest
to Costa Rica. Divergence aloft associated with a northeast to
southwest oriented jet stream branch east of the trough in
combination with a moist and unstable atmospheric environment in
place over much of the eastern Caribbean is triggering off
scattered showers and isolated thunderstorms east of about 71W.
This pattern will change little through early next week. Expect
pockets of heavy rain with some of the showers and thunderstorms
to affect the waters around Puerto Rico, the northern Leeward
Islands, and eastern Hispaniola.

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

The stationary front earlier analyzed 24N has weakened, and as
of 06Z is analyzed as a dissipating boundary east of 68W, and
as a shear line west of 68W. Strong high pressure is present
north of the front and shear line. The main marine issues over
the next few days will be related to the near future development
of surface low pressure, and the impacts to the winds and
combined seas due to the tight pressure gradient between it and
the strong high pressure. Global models have been consistently
suggesting that low pressure will form over the far southeast
waters in the general area of just north of the Mona Passage and
the eastern part of the Dominican Republic. As a matter of fact,
latest satellite imagery and surface observations from "MDPC" on
the eastern tip of the Dominican Republic indicate that weak low
pressure may forming near 19N68W along a surface trough situated
to the southeast of the aforementioned stationary front, and
southeast of an upper low located just north of eastern Cuba. The
ensuing result of the tight gradient is observed as strong to
near gale northeast to east winds over a large swath of area east
of the Bahamas from near 22N to 29N as depicted in the latest
Ascat data. Seas with these winds are in the range of 10-15 ft.

Model guidance all point to the low attaining momentum through
the next 24 to 36 hours as it drifts from just north of
Hispaniola to our northeastern waters. The strong to near gale
force winds are forecast to increase to gale force within a
portion of the aforementioned swath this afternoon. This swath of
winds will gradually shift translate over the eastern portion of
the basin through Monday with northeast to east winds of 30-40
kt gale force. These winds will then shift northeast of zone
AMZ115 early on Tuesday, with strong to near gale force north to
northeast winds lingering in the northeast portion of that zone,
with large seas of 10-15 ft. These winds then shift east of that
zone Tuesday night as the low accelerates eastward leaving fresh
to strong northerly winds in the far northeast portion.
Relatively weak high pressure is forecast to move south to over
the western half of the basin on Tuesday. The associated gradient
will bring light to gentle anticyclonic flow over the western
portion through Wednesday, while the central section of the basin
will see moderate northerly flow, and the eastern half north of
22N will be under moderate to fresh northerly flow except in the
northeast portion as mentioned above for Tuesday night. On
Wednesday, the northeast portion will see winds diminishing to
the moderate range. Northerly winds will be lighter south of 22N
Tuesday through Wednesday, with gentle to moderate flow northwest
to north flow expected there. Aside from the 10-15 ft seas in
the northeast portion of zone AMZ115 on Tuesday as stated
earlier, north to northeast swell will be slow in decaying over
the eastern half of the basin Tuesday through Wednesday, with
seas of 8-12 ft.

$$

.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...
.AMZ113...ATLANTIC FROM 27N TO 31N BETWEEN 70W AND 77W...
Gale Warning Sun.
GALE CONDITIONS POSSIBLE Sun night.
.AMZ115...ATLANTIC FROM 27N TO 31N BETWEEN 65W AND 70W...
Gale Warning Sun.
GALE CONDITIONS POSSIBLE Sun night into Mon night.
.AMZ119...ATLANTIC FROM 22N TO 27N E OF BAHAMAS TO 70W...
Gale Warning Sun.
GALE CONDITIONS POSSIBLE Sun night.
.AMZ121...ATLANTIC FROM 22N TO 27N BETWEEN 65W AND 70W...
Gale Warning today through Sun.
GALE CONDITIONS POSSIBLE Sun night.

$$

*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 Aguirre. National Hurricane Center.

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