[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021018
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Thu Sep 2 2021

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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
1000 UTC.

...SPECIAL FEATURES...

Larry is upgraded to hurricane status at 02/0900 UTC. At this
time, it is centered near 13.0N 32.3W or 470 nm WSW of the
Southernmost Cabo Verde Islands moving W at 17 kt. Estimated
minimum central pressure is 987 mb. Maximum sustained wind speed
is 65 kt with gusts to 80 kt. On the forecast track, a gradual
turn toward the west-northwest and a decrease in forward speed are
expected Friday and Friday night. A slightly slower west-
northwestward motion is expected on Saturday. Steady to rapid
strengthening is forecast during the next couple of days, and
Larry is expected to become a a major hurricane by Friday night.
Numerous moderate to scattered strong convection is within 60 nm
N and 75 nm S semicircles of center. Similar convection is also
noted just to the west of Larry covering the waters from 10N-15N
between 32W-37W. Hurricane Larry will be accompanied by an
expanding wave height field that will send large swells toward the
Leeward Islands on Sun. This swell event is forecast to propagate
farther west likely reaching the Atlantic waters of Puerto Rico
and Hispaniola on Mon. Please read the latest NHC Public Advisory
at https://www.nhc.noaa.gov/text/MIATCPAT2.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT2.shtml for more
details.

...TROPICAL WAVES...

A tropical wave was added to the surface analysis near the coast
of Africa at 0O00 UTC. The wave is now along 18W from 19N southward,
moving W at around 15 kt. A cluster of moderate to isolated strong
convection is along the wave axis from 12N-15N E of 20W to the
coast of W Africa.

The axis of a tropical wave is near 52W from 20N southward, moving
westward at about 20 kt. A cluster of moderate to isolated strong
convection is noted where the wave meets the ITCZ near 07N53W.
The wave axis extends into French Guiana.

A low amplitude tropical wave is moving westward across the
Caribbean Sea with axis along 72W, south of 15N. The wave appears
to enhance some convective activity over northern Colombia.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Mauritania near 18N16W
to 14N26W, then resumes west of Larry near 12N35W to 08N51W. The
ITCZ extends from 08N51W to the coast of Guyana near 07N58W.
Aside from convection noted above, another cluster of moderate to
isolated strong convection is observed from 09.5N-12.5N between
43W-47W.

GULF OF MEXICO...

A 1014 mb surface high pressure is analyzed over the Florida Keys.
The latest ASCAT data show fresh to locally strong west winds in
the NE Gulf to the north of the weak high pressure. Mainly gentle
to moderate E to SE winds dominate the remainder of the Gulf,
with the exception of light and variable winds over the SE waters
thanks to the high pressure center. Seas are 2 to 4 ft across
most of the basin, except 4 to 6 ft in the NE Gulf. To the NW of
the Yucatan Peninsula, fresh NE to E winds, with 3 to 5 ft seas
are occurring due to local effects related to a thermal trough.
Scattered showers and thunderstorms are noted over the western Bay
of Campeche, and near the Veracruz region.

For the forecast, the fresh to strong west winds over the NE Gulf
will persist through early this morning ahead of a cold front
extending over the SE of United States. Then, light and variable
winds will prevail over the NE Gulf during the upcoming weekend.
Elsewhere, a ridge will dominate the Gulf region producing mainly
gentle to moderate southerly winds through Fri. Pulsing fresh
winds are expected northwest of the Yucatan Peninsula at night
through Fri. Looking ahead, an area of low pressure that is
currently located near the coast of Nicaragua could move over the
southwestern Gulf of Mexico during the weekend and early next
week, but by then strong upper-level winds would likely limit
significant development.

CARIBBEAN SEA...

Recent satellite derived winds data show gentle to moderate trade
winds across the Caribbean Sea, except for fresh to strong winds
in the Gulf of Honduras, and fresh E to SE winds near Cabo Gracias
a Dios, Nicaragua. Seas are 2 to 4 ft, except 4 to 6 ft in the
Gulf of Honduras. A small are of showers with embedded thunderstorms
is from 15N-17N between 80W-83W. This convective activity is
likely associated with a small area of low pressure located over
the coast of NE Nicaragua.

For the forecast, a ridge N of the Caribbean Sea combined with
lower pressure over northern Colombia will support moderate to
fresh trade winds over the south-central Caribbean through Sun.
Fresh to locally strong E to SE winds are expected in the Gulf of
Honduras at night through the weekend. A small area of low pressure
located near the coast of Nicaragua is producing disorganized
shower and thunderstorm activity. This low is expected to move
inland over Nicaragua this morning, but a portion of the low's
circulation could move over the Gulf of Honduras on Friday where
development, if any, is expected to be slow to occur. Regardless
of development, heavy rains are possible across portions of
Central America and the Yucatan Peninsula through the weekend.
There is a low chance for tropical cyclone development over the
next 48 hours. Please see the latest Atlantic Tropical Weather
Outlook at hurricanes.gov for more information on this feature.

ATLANTIC OCEAN...

Fresh to locally strong SW to W winds are noted just off NE
Florida. These winds are occurring ahead of a cold front that
extends over the SE of United States. An upper-level low is
spinning just NE of the central Bahamas generating scattered
showers and isolated thunderstorms from 22N-30N between 62W-73W.
A surface trough, the remnants of Kate, extends from 31N53W to
27N57W. Scattered showers and isolated thunderstorms are near the
trough axis. Fresh S winds are noted on the east side of the
trough, where seas are in the 5-7 ft range based on an altimeter
pass.

A 1024 mb surface high pressure is near 34N39W and dominates most
of the Atlantic forecast waters W of 30W. A belt of moderate to
fresh trades are noted from 16N to 23N between the coast of Africa
and 45W due to the pressure gradient between the aforementioned
high pressure to the N and Hurricane Larry. An occluded low
pressure is near the Azores.

For the forecast west of 65W, fresh to strong southwest winds off
NE Florida will shift northeast of the area by late Thu. These
winds are ahead of a cold front forecast to weaken as it moves
across the northern waters W of 70W Sat through Sun night. Looking
ahead, large swells generated by Hurricane Larry are expected to
propagate across the waters NE and E of the Leeward on Sun, likely
spreading beyond 65W Mon and Mon night.

For the forecast east of 65W, please see the Special Features
section for more information on Hurricane Larry forecast to
strengthen into a major hurricane Fri night, with seas up to 38
ft.

$$
GR
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