[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210005
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM EDT Wed May 20 2020

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
2345 UTC.

...TROPICAL WAVES...

A tropical wave with axis along 66W from 10N-21N is moving westward
at 15 kt. Latest visible imagery suggest a weak signature in the
low-level cloud pattern associated with this wave. Only isolated
showers are along and near the wave at the present time. The wave
axis is about 300 nm west of an area of scattered showers and
isolated thunderstorms that lies to the east of the Leeward Islands
from 10N to 15N and between 55W-60W. This activity is mainly attributed
to a sharp upper-level trough in that vicinity. Expect for low-level
moisture and resultant scattered showers to move across most of the
Lesser Antilles through Thu.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through Guinea near 10N14W and
continues to 05N23W, where latest scatterometer data indicates
it transitions to the ITCZ and continues to 04N31W to 05N42W and
to the coast of Brazil at 04N52W. Scattered moderate convection
is seen within 120 nm north of the ITCZ between 23W-28W and between
33W-39W. Similar activity is within 60 nm north of the ITCZ between
39W-42W.

GULF OF MEXICO...

Weak high pressure is across the basin. A stationary front is
analyzed over the western Florida panhandle extending to near
Gulfport, Mississippi. This front, with the aid of upper-level
support from an upper trough, is serving as the focus for
numerous showers and thunderstorms over most of the Florida
panhandle and adjacent coastal waters. Some of this activity has
reached the strong to severe range. To the southeast, a surface
trough extends from southeastern Florida to just west of the
lower Florida Keys as of 21 UTC. Scattered showers and
thunderstorms are noted to the southeast of this trough over
lower Straits of Florida. This activity is moving to the
northeast and is capable of producing strong gusty winds.
Another surface trough is analyzed from just northwest of the
Yucatan Peninsula southwest from there to just inland the coast
at 18N92W. The trough is not producing convection at the present
time.

As for the forecast, the high pressure will dominate much of the
Gulf waters through Sun, with the associated gradient producing
an east to southeast mainly moderate wind flow. A surface trough
will develop over the Yucatan Peninsula during the evening
hours, drift westward across the SW Gulf at night, and dissipate
in the morning. Fresh to locally strong winds will be associated
with this trough. The aforementioned stationary front over the
Florida panhandle will lift back to the north as a warm front on
Thu.

CARIBBEAN SEA...

Refer to the tropical waves section above for details on the
tropical wave currently moving across the eastern Caribbean.

Broad upper-level cyclonic wind flow, related to the Atlantic to
Yucatan Peninsula trough, continues to cover the far northwest
part of the Caribbean. Scattered showers and thunderstorms
moving eastward are observed from 10N-15N and west of 77W to
inland the coast of central America. This activity is being
aided by upper-level divergence present over that part of the
Caribbean. Isolated showers are seen over the northwest
Caribbean. Broad upper-level anticyclonic wind flow covers the
remainder of the basin, mainly to the east of 83W. Latest
scatterometer data depicts gentle to moderate trade winds across
the basin, except south of 14N between 66W-73W and near the Gulf
of Honduras, where moderate to fresh trade winds are noted.

As for the forecast, little change to be expected with the trade
winds, except over the Gulf of Honduras where they will increase
to strong speeds Fri and Fri night. The aforementioned tropical
wave will move across the rest of the eastern Caribbean through
Thu and over the eastern half of the central Caribbean Thu night
and Fri.

ATLANTIC OCEAN...

Upper-level diffluence related to the eastern part of an upper-
level trough over the western Atlantic in combination with a
surface trough that extends from near 29N75W southwestward to
southeastern Florida, is helping to sustain scattered showers
and thunderstorms south of about 30N and between 65W and the 78W
and also south of 25N from 78W to the Straits of Florida. This
activity is quickly moving to the east, except in the Straits of
Florida where it is moving to the northeast. A cold front
extends from a triple point at 34N63W southwestward to 31N71W,
where it becomes a stationary front to 31N75W. It continues
northwestward from there to inland the South Carolina coast at
33N80W. Isolated showers are possible along the cold front,
while scattered showers and thunderstorms are quickly tracking
northeastward just to the north of the stationary front west of
75W. Otherwise, surface high pressure, anchored by a 1022 mb
high center at 27N33W and a 1023 mb high center at 31N23W,
covers the remainder of the discussion Atlantic waters.

As for the forecast, former Tropical Cyclone Arthur located
north of the area near 34N65W will track south-southeastward
over the discussion area on Thu and weaken. Large long-period
northeast swell from former Arthur will affect the waters northeast
of the Bahamas through Fri, then subside Fri night and Sat. The
surface trough that extends from near 29N75W to southeastern Florida
will weaken through Thu. High pressure will build modestly across
the northern waters Fri through Sat night.

$$

Aguirre
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