[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281804
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
103 PM EST Wed Feb 28 2018

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1745 UTC.

...SPECIAL FEATURES...

A 978 mb low pressure located well to the northeast of the area
just east of the Azores Islands near 37N22W. A cold front
associated with this low enters the discussion area at 32N10W, and
continues to 25N17W to 21N33W and to 19N30W, where it transitions
to a weakening stationary front to 19N37W and to 19.5N45W where it
becomes a weak trough to 24N52W. As a result, a very tight
pressure gradient is analyzed over the far eastern portion of the
area to the north of 25N. The Ascat pass from near 1100 UTC this
morning confirmed the ongoing gale westerly gale force winds
north of about 26N. Please refer to the METEO- FRANCE High Seas
Forecast link at WWW.METEOFRANCE.COM/PREVISIONS-METEO-MARINE/BULLETIN/
GRANDLARGE/METAREA2. Gale force winds are forecast for the areas
IRVING, MADEIRA, CASABLANCA AND AGADIR. Near gale force S to SW
winds over Cadiz are forecast to increase to gale force tonight
into early on Thu. The OUTLOOK, for the 24 hours that follow the
forecast that is valid until 01/1200 UTC, consists of: the
persistence of a cyclonic near gale or gale north of 25N.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends off the coast of Africa through
the coastal sections of Liberia near 06N11W and continues
southwestward to 02N16W. The ITCZ continues then continues from
02N16W to below the Equator near 190W, and continuing along 01S to
29W where it briefly ends. It resumes at the Equator along 34W
and to 02S42W. Scattered moderate isolated strong convection is
within 150 nm S of the monsoon trough axis between 10W-15W, and
also within 90 nm n of the monsoon trough axis between 12W-14W.
Scattered moderate convection is within 30 nm of 01N18W and within
30 nm of 01N21W. Similar activity is S of the ITCZ within 60 nm
of line from 04S18W to 04S23W.

...DISCUSSION...

GULF OF MEXICO...

Isolated showers are seen moving west-northwest across the Straits
of Florida spun of from moisture related to the tail-end of a
stationary front that is just east of the central Bahamas. The
fresh to strong winds observed this morning off the northern
coast of the Yucatan Peninsula have diminished to mainly fresh
winds as of early this afternoon. Elsewhere, weak ridging from the
western Atlantic extends westward over the northern waters. The
gradient associated with this ridging is maintaining gentle to
moderate east to southeast winds over most of the Gulf with seas
in the 1 to 3 ft range. The exception is in the NW Gulf, where
fresh southeast winds are noted along with seas of 3 to 5 ft seas.

The fresh southeast winds over the NW Gulf will diminish tonight
ahead of a cold front moving into the northern Gulf early Thu.
Strong northerly winds will follow the front over mainly the
western Gulf into Fri. The front will stall from the Straits of
Florida to near Veracruz Mexico by late Fri before dissipating
Sat. A ridge will build across the Gulf through Sun.

CARIBBEAN SEA...

Weakening high pressure north of the area is supporting generally
moderate to fresh trade winds across the basin this afternoon.
The fresh to strong NE winds earlier noted through the Windward
Passage have diminished to mainly moderate winds per the Ascat
pass from 1416 UTC this morning. Upper level diffluence on the
southeastern side of a broad upper trough that extends from just
east of Puerto Rico to the along the NW coast of Colombia and to
just south of Panama is supporting patches of low-level moisture
with isolated showers moving quickly in the trade wind flow over
the southeastern and Caribbean and much of the central Caribbean.
Elsewhere across the central and western Caribbean, fairly dry
conditions are present due to dry sinking air in the wake of
the aforementioned upper trough.

Reinforcing high pressure to the north of the area will continue
to support moderate to fresh trade winds across the basin, with
strong winds pulsing at night off Colombia through late week.
These winds will diminish by Sat as the high pressure weakens and
shifts east ahead of a deep low pressure moving into the western
Atlantic. Large swell will impact the tropical Atlantic waters
through Sat, with a more significant swell event penetrating the
NE Caribbean starting early on Sun.

ATLANTIC OCEAN...

A cold front extends from a 1002 mb low just north of the area at
33N41W southwestward through 32N44W to 27N60W and to 25N67W,
where it transitions to stationary front to 26N70W to just east of
the Bahamas near 25N75W. Scattered showers and possible weak
isolated thunderstorms are noted from 26N to 29N between 53W-59W
aided mainly by an upper short-wave trough that extends from
32N56W to just east of Puerto Rico that is acting upon deep layer
moisture present along the front east of 60W. Drier conditions
persist elsewhere, but low level clouds persist within 120 nm of
the front. Current buoy and recent altimeter data indicate seas of
10 to 15 ft N of the front east of 57W, and 9 to 12 ft N of the
front between 57W and 66W. Latest satellite imagery shows cyclonic
swirls of broken to mid level clouds with scattered showers along
the stationary frontal boundary, with similar clouds over the NW
Bahamas. Farther to the south, gentle to moderate winds prevail.
Looking ahead, the cold front will stall east of the Bahamas and
dissipate through late Thu. Fresh southerly flow will increase
late Thu off NE Florida ahead of another cold front moving off the
coast Thu night. The front will reach from Bermuda to the Straits
of Florida by late Fri, just ahead of a reinforcing front with
strong to possibly gale force winds north of 24N related to deep
low pressure moving off the Virginia coast. The fronts will merge
Sat and reach from 22N65W to the Windward Passage by Sun. A
significant swell event and likely the largest of this winter
winter season will accompany this system, affecting all waters to
the east of north Florida and the Bahamas by the end of the week.

Over the far eastern Atlantic, strong to near gale force winds
persist north of 20N into the area of gales described in the
special features. Recent altimeter satellite data continue to
highlight very large seas to the north of about and east of 40W.

For additional information please visit
http://www.hurricanes.gov/marine

$$
Aguirre
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