[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 090004
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Tue May 8 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
2300 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough meanders westward across tropical western
Africa and terminates along the coast of Guinea-Bissau near
12N16W. The ITCZ begins offshore of Liberia near 05N12W and
continues to 01N30W to 00N45W to the coast of northern Brazil near
01S47W. Scattered moderate and isolated strong convection are
from 02N to 06N between 11W and 24W. Widely scattered moderate
convection is from 00N to 04N between 24W and 50W.

...DISCUSSION

GULF OF MEXICO...

Dry air and subsidence continues to support dry conditions over
the northern half of the Gulf basin. Over the SE Gulf, a stalled
and dying frontal boundary extends from the NW Bahamas
southwestward across the Florida Keys and then into the SE gulf. A
1019 mb high pressure is centered over the northwest Gulf behind
the front near 26.5N95W, maintaining generally gentle to light
winds and slight seas. Moderate to locally fresh NE winds are
noted over the far eastern Gulf between the high pressure and the
tail of the front, supporting 3 to 5 ft seas. An upper level
disturbance sinking SE into central Mexico, combined with a
surface trough extending from 22N98W to 18N96W is producing high
clouds and scattered showers across the SW Gulf.

The high pressure will shift east toward the northeast Gulf
through Fri, then into the Atlantic on Sat. This will maintain
moderate NE to E winds and 3 to 4 ft seas across the eastern
Gulf through the period. High daily temperatures over the
Yucatan peninsula will set up a weak thermal trough each
evening, which will move westward over the eastern Bay of
Campeche overnight then dissipate by afternoon each day
beginning Wed.

CARIBBEAN SEA...

A sharp elongated trough reaches from the Cayman Islands SSE to
offshore of Colombia, while troughing also lingers SE of the old
front across the NW Bahamas, extending SW across central Cuba to
a dying low pressure center near 20N83W. Broad ridging over the
central Atlantic is supporting moderate to fresh E to SE winds
across the basin east of the trough off Colombia, where seas are
running 5 to 7 ft. Generally gentle to light northerly winds are
noted across the Caribbean W of the trough. Regional radar
mosaics continue to indicate scattered warm topped showers with
isolated thunderstorms south of central Cuba and Jamaica to 15N
occurring along and E of the trough, and to the immediate N and NW
of the dying low center near 20N83W. Widely scattered passing
trade wind showers are observed moving W to NW off the Atlantic
into the Windward and Leeward Islands and across the NE Caribbean.
Otherwise, no significant weather is noted.

The trough is expected to drift westward and weaken through mid
week, but will remain the focus for showers and a few
thunderstorms through late today as the supporting mid/upper
trough lifts northeast and dampens out. Trade wind flow will
increase over the south central Caribbean by Fri night as
ridging builds north of the region. Little change otherwise in
the forecast.

ATLANTIC OCEAN...

The aforementioned old frontal boundary stretches from low
pressure N of the area to 31N74W to the NW Bahamas to 25N80W,and
across the Florida Keys. Moderate N to NE winds prevail across the
Atlantic the W of the front. Moderate to fresh SE to S winds
occurring the the SW of the Atlantic ridge are producing
converging moisture along and to the E of the front and a weak pre
frontal trough just SE of it across the Bahamas. A mid to upper
level jet entering the area from the Yucatan Peninsula to just E
of the front becomes divergent eastward to 70W and is providing
unstable conditions aloft to support scattered moderate
convection from 21N to 25N between 73W and 81W, and N of 25N
between 69W and 74W. The front is meandering today and is not
expected to move much through Wednesday before the ridge to the E
begins to nudge the old boundary WNW by Wednesday night or
Thursday.

The winds to the E of the front will diminish to moderate by Wed
as the low pressure lifts north. High pressure ridging extending
east to west along 31N Fri through Sat night will generate
gentle to moderate E to SE winds over the forecast waters,
except that fresh to locally strong winds will pulse between the
southeast Bahamas and the coast of Hispaniola.

The Atlantic ridge is centered on a pair of high pressure
centers along about 35N and between 30W and 50W. This alignment
is producing moderate to fresh tradewinds across the basin to
the south of 28N from the Cabo Verdes to the Caribbean, where
winds begin to veer SE into the Turks and Caicos and then SSE
further N, ahead of the front. Moderate to fresh trade winds are
noted across the tropical north Atlantic waters west of 50W,
south of the ridge. Seas are 6 to 8 ft in decaying NE to E swell.

Farther east, a mid/upper trough reaches from just S of the
Azores to a deep layered upper cyclone near 25N39W. No
significant moisture is noted with this feature. The surface
ridge will shift slowly NE through the end of the week and
maintain moderate to fresh tradewinds across the Tropical
Atlantic.

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

$$
Latto
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