[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 272338
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
638 PM EST Tue Feb 27 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...SPECIAL FEATURES...

A strong 973 mb low pressure system with storm force winds
centered over the Azores supports a cold front that crosses the
Madeira and the western Canary Islands from 32N17W to 25N24W to
20N46W then continues as stationary front to 25N53W. A tight
pressure gradient associated with the deep low pressure and cold
air advection associated with cold front are supporting gale force
winds N of 29N and west of the front to 38W. Gale conditions are
forecast to prevail through tonight then will gradually diminish
as the low pressure weakens and moves E and the front dissipates.
Altimeter satellite passes are showing seas of 15 to 30 ft in NW
to N swell north of 20N and east of 45W. For more details, refer
to the NHC High Seas Forecast under AWIPS/WMO Headers
MIAHSFAT2/FZNT02 KNHC.

Gale force winds are also observed per scatterometer data ahead of
the cold front over the Madeira and the Canary Islands. Meteo
France is including a forecast of gale force winds in the areas
called Irving, Madeira, and Casablanca, Agadir. The forecast
indicates SW to W gale force winds, with severe gusts. Please
refer to the Meteo- France High Seas Forecast for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the eastern Atlantic from the coast of
Liberia near 06N11W to 02N16W, where it transitions to the
intertropical convergence zone which continues to 00N20W to
01N30W to 04N36W to the coast of Brazil near 02S44W. Scattered
moderate and isolated strong convection is present from 05S to
02S between 17W and 24W and from 04S to 03N between 24W and 30W.

...DISCUSSION...

GULF OF MEXICO...

A weakening frontal boundary reaches from near Tampa Florida to
the Coastal Bend of Texas. Radar and satellite imagery from the
across the northern Gulf shows limited cloudiness and only a few
spotty showers along and up to 90 nm north of the frontal
boundary. Otherwise, weak ridging extends WSW from the Straits of
Florida over the central Gulf. Light to moderate east to southeast
winds are generally noted over the Gulf with 2 to 4 ft seas
prevailing.

For the forecast, the front will weaken and dissipate today and
tonight. High pressure already over the region will be strong
enough to suppress convection today through Wed night. Another,
stronger cold front will move into the NW Gulf Wed night. Gale
conditions will be possible over the SW Gulf near Tampico Thu
night and near Veracruz Fri morning following the passage of this
front.

CARIBBEAN SEA...

Weak high pressure centered approximately between Bermuda and the
northern Bahamas near 27N71W is supporting moderate to fresh to
trade winds over the basin, except for over the south central
Caribbean and to the lee of Cuba. Moderate to fresh trade winds
persist elsewhere. An upper-level low is centered NE of Puerto
Rico near 23N63W. A sharp trough extends SW from the low to Costa
Rica. This trough is triggering a few showers over Hispaniola and
over portions of the northeast Caribbean. Otherwise, convergent
upper- level winds on the NW side of the trough are suppressing
convection over the western half of the Caribbean.

Little change is expected during the next several days as
moderate to fresh winds persist over the basin. Strong winds will
continue pulsing along the N coast of Colombia during the late
night and early morning hours. Strong winds will also funnel
through the Windward Passage through Thu. Large long period swells
will reach the Atlantic passages in the Leeward and Windward
Islands on Thu.

ATLANTIC OCEAN...

A weak pressure gradient resides over the Atlantic waters west of
45W. Gentle to light winds north of 22N and moderate trade winds
south of 22N are generated by modest 1022 mb high pressure
centered near 26N71W. A weakening cold front crosses the waters NW
of the Bahamas from 32N68W to near Cape Canaveral Florida.
Cloudiness and scattered showers are occurring along and up to
90 nm SE of this boundary.

Looking ahead, the cold front will weaken and continue heading SE
to reach the central Bahamas Wed evening, as high pressure builds
north of the front. Strong low pres passing north of the area
will drag another cold front into the NW waters Thu night, with
deteriorating conditions expected for the waters north of 27N and
W of 65W. The system will support gales Fri night through Sat
night over the waters N of 27N between 50W and 70W. A significant
swell event will accompany this system, affecting all waters east
of north Florida and Bahamas at the end of the week.

East of 50W, fresh to strong northwest winds extend outward from the
areas of strong to gale force winds noted in the Special Features
sections to as far S as 20N and as far W as 45W. Because the
subtropical ridge is disrupted by the deep low pressure over the
north central Atlantic, only gentle to moderate trade winds are
currently occurring over the Tropical Atlc waters E of the Windward
Islands. Long period NW to N swell generated by the deep low near
the Azores are causing seas of 8 to 12 ft to reach as far south
as 15N to the E of 40W. Looking ahead for the waters east of 50W,
winds and seas will gradually subside north of 25N through mid
week, then another powerful low pressure system is expected to
approach from the western Atlantic and bring strong to near gale
force winds and large seas to the area north of 20N between 40W
and 50W once again by then end of the week.

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

$$
McElroy
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