[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 081737
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0205 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 1200 UTC surface analysis and satellite imagery through
1645 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 05N12.5W and
continues to 01.5N40W to 00N45W to the coast of northern Brazil
near 01N51W. Scattered moderate to strong convection is noted
from 00N to 04N between 15W and coastal Brazil.

...DISCUSSION

GULF OF MEXICO...

A very broad mid-latitude trough continues to move slowly
eastward across the eastern U.S. today, and extends SW across
much of the northern half of the Gulf to 25N89W. Sinking
vertical motion within the trough is aiding in producing mostly
clear skies across most of the N half of the basin. To the SE, a
stalled and dying frontal boundary extends from the NW Bahamas
southwestward across the Florida Keys and then into the SE gulf.
A 1020 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 is producing
high clouds across the SW Gulf, however no significant shower
activity is observed.

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. Moderate to
fresh trade winds are noted across the tropical north Atlantic
waters west of 50W, south of the main ridge. Seas are 6 to 8 ft
in decaying NE to E swell. Regional radar mosaics indicate
scattered warm topped showers with isolated tstorms 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 reaches from weak 1014
mb low pressure centered north of the area near 32N73W
southwestward across the NW Bahamas then across the Florida
Keys. Moderate N to NE winds prevail across the Atlantic the W
of the front. Moderat 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 supper scattered moderate to strong convection within
200 nm SE of the front, from the central Bahamas NNE to beyond
31N. 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.

Farther east, a mid/upper trough reaches from just S of the
Azores to a deep layered upper cyclone near 24N39W, then extends
W and SW and a very broad cyclonic circulation to 65W. Despite
upper support on the east side of the mid/upper trough, no
significant moisture is noted north of the ITCZ as deep layer
moisture remains limited, and dry stable air continues to exit
westward off of W Africa. 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

$$
Stripling
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