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000
AGXX40 KNHC 280800
MIMATS

Marine Weather Discussion
NWS National Hurricane Center Miami FL
400 AM EDT Tue Mar 28 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...

Weak high ridging extending westward from the western Atlantic
to the north-central gulf, with a weak high center located near
27N84W. It is providing gentle to moderate east to southeast
winds throughout, except for light to gentle anticyclonic flow
around its immediate vicinity. The fresh to strong east winds
along the northern Yucatan Peninsula have diminished to moderate
winds.

Deepening low pressure is over the southern Plains. The ridge
currently in place over the north-central waters will begin to
shift eastward tonight and Wed as the low pressure advances
eastward. With high pressure then becoming situated across the
Bahamas, this will result in a tightening of the pressure
gradient across the western Gulf beginning tonight and through
Wednesday with fresh to strong southeast winds and seas building
to around 9 ft, or possibly briefly to 10 ft. The highest of
these seas will be in the northwest portion of the area. The low
will send a cold front into the northwest gulf early on Thursday,
and quickly move across the gulf while weakening as it reaches
the eastern waters on Friday night. Strong southerly winds will
precede the front over the far northern waters on Thursday
through Friday. Scattered to numerous showers and thunderstorms
are expected to spread east just ahead of this front. High
pressure behind the front will shift eastward allowing for fresh
to locally strong southeast flow to set up over the far western
gulf on Saturday.

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

A weak pressure pattern remains in control over the Caribbean
due to a break down of the gradient attributed to low pressure
east of the central Bahamas. Both Ascat and buoy data reveal
gentle to moderate winds prevailing over the Caribbean. High
pressure will become established across the Bahamas tonight as
the low moves northeast then east over the central Atlantic. This
pattern will help to increase the winds slightly across the
Caribbean basin. The high will expand across the SW N Atlantic by
Wednesday night which will cause fresh to strong winds to
develop across the Gulf of Honduras through Friday. The high will
then slide eastward by Friday night in response to a a cold
front expected to approach the southeast U.S. This will allow
for winds across the central Caribbean to increase to 15 to 20
kt during the Friday night through Saturday time period.

Mainly 5 to 7 ft seas will prevail over the tropical N Atlantic
forecast zones through the week along with moderate trade winds.
Late this week, winds are expected to diminish as the low
pressure passing north of the area brings a frontal trough near
the region north of 15N.

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

Broad and low pressure of 1005 mb near 27N67W has taken a more
definitive northeast track during the past several hours. A warm
front extends from the low to 29N64W to 28N58W. A trough trails
from the low to the southeast Bahamas. Relatively weak high
pressure of 1018 mb is present west of the low pressure, while
strong high pressure is to its north and northeast. The 0124Z
Ascat pass noted a swath of gale force winds northeast of the low
within about 30 nm of a line from 30N64W to 29N67W to 27N69W. The
Ascat pass also reveals that the gale force winds are embedded
within a swath of 20-30 kt winds between 60 nm and 240 nm of the
low in its northeast quadrant. Seas within the gale force wind
area are in the 12-18 ft, while seas elsewhere east of the
Bahamas are in the 8-11 ft range primarily due to a northeast
swell. Higher seas of 10-15 ft are associated with the 20-30 kt
winds.

The low is on track, as stated in previous discussions, to exit
the northeast zone AMZ115 this afternoon. North to northeast
gale force winds will mainly confined to the northwest quadrant
of the low over zone AMZ115, at a distance of 60 nm to 120 nm.
The gale force winds will then shift east of the that zone this
afternoon, but will remain over our high seas area. Strong to
near gale force north to northeast winds will remain over the
eastern part of zone AMZ115 tonight, before becoming northwest to
north winds of 15-20 kt early on Wednesday. Seas of 8-13 ft in
mixed will linger in the eastern part of the same zone tonight,
then slowly subside to 8-10 ft on Wednesday, to 6-8 ft by late
Wednesday afternoon, and to 5-6 ft on Thursday.

Models in good agreement in depicting weak high pressure over
the Bahamas to expand in coverage through Wednesday night. The
high will then slide eastward beginning Thursday afternoon as a
cold front approaches the northwest waters. Current forecast has
the cold front reaching the northwest waters Friday night, with
fresh to strong southerly winds developing on Friday over these
waters well ahead of the front. Seas are expected to build to
around 9 ft with these winds. The front is forecast to reach
from near 31N75W to South Florida by Saturday evening.

$$

.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...
.AMZ115...ATLANTIC FROM 27N TO 31N BETWEEN 65W AND 70W...
Gale Warning today.

$$

*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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