[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 030543
TWDAT

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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...SPECIAL FEATURES...

Hurricane Sam is centered near 36.4N 57.1W at 03/0300 UTC or 450
nm NE of Bermuda, moving NE at 14 kt. Estimated minimum central
pressure is 955 mb. Maximum sustained wind speed is 100 kt with
gusts to 120 kt. Numerous moderate and isolated strong
convection extends outward from the center 180 nm in the N
semicircle, 60 nm SE quadrant and 120 nm SW quadrant. Maximum
significant wave height is estimated at 42 ft, with seas 12 ft
and greater extending outward as far as 340 nm from the center.
A general track to the NE with an increase in forward speed is
expected for the next few days. Slow weakening is anticipated
during the next few days, and Sam could transition into a
powerful post-tropical cyclone on Monday night. Please read the
latest High Seas Forecast issued by the Ocean Prediction Center
at website
https://ocean.weather.gov/mobile/mobile_product.php?id=NFDHSFAT1
and the latest NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Tropical Depression Victor is centered near 14.8N 38.9W at
03/0300 UTC or 865 nm W of the Cabo Verde Islands, moving NW at
12 kt. Estimated minimum central pressure is 1005 mb. Maximum
sustained wind speed is 30 kt with gusts to 40 kt. Scattered
moderate to strong convection extends outward from the center
360 nm in the NE quadrant. Scattered moderate convection is
within 330 nm SE quadrant and 120 nm NW quadrant. Maximum
significant wave height near the center is estimated to be near
14 ft, and the seas should gradually subside during the next
couple days. A general NW motion is expected to continue over
the next few days. Gradual weakening is forecast over the next
couple of days, and Victor could become a remnant low during
that time. The system is then forecast to dissipate by Tuesday.
Please read the latest High Seas Forecast issued by the National
Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest NHC
Forecast/Advisory and Public Advisory at www.hurricanes.gov for
more details.

...TROPICAL WAVES...

A new tropical wave along the coast of west Africa is along 16W
from 03N-19N, moving W at 10-15 kt. Scattered moderate
convection is within 150 nm either side of the wave axis from
12N-18N.

An eastern Caribbean tropical wave has its axis along 65W from
19N southward to Venezuela, moving W at 15-20 kt. Isolated
moderate to strong convection is within 120 nm either side of
the wave axis from 11.5N to 14N. Isolated moderate convection is
west of the wave axis from 16N to 17.5N.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Senegal near 14N17W
to 07N20W. The ITCZ is from 07N20W to 05N32W, where there is a
break in the ITCZ. The ITCZ resumes from 08N42W to 06N50W to
08N59W. Aside from convection mentioned in the sections above,
scattered moderate convection is noted from 01N-08N between
21W-33W, and from 07N-10N between 57W-61W.

GULF OF MEXICO...

Mid to upper-level ridging is present over the Gulf of Mexico.
While the mid-level ridging is causing some subsidence over the
southern Gulf, ample moisture is present over the northern Gulf.
Scattered moderate convection is noted over the north-central
Gulf of Mexico, north of 26.5N between  86.5W and 90.5W. A
cluster of strong tstorms is along the southern Bay of Campeche
coast of Mexico, near Ciudad del Carmen. ASCAT data show fresh E
winds in the Florida Straits and SE Gulf of Mexico, where seas
are 4 to 5 ft. Gentle to moderate E to SE winds are noted
elsewhere across the basin, with 2 to 3 ft seas.

For the forecast, a weak ridge of high pressure will persist
north of the Gulf through early this morning, supporting
tranquil conditions across the western half of the basin.
Stronger high pressure will build across the region later today,
allowing winds and seas to increase over the SE Gulf. A weak
cold front will move across the Gulf on Mon and Tue, with little
enhancement of the winds
and seas.

CARIBBEAN SEA...

An upper-level trough extends from the NW Bahamas to eastern
Cuba to Nicaragua. Showers and tstorms are being enhanced along
and to the east of the upper-level trough axis. Scattered
moderate and isolated strong thunderstorms cover the
north-central Caribbean, north of 15.5N between 69W-81W. Similar
convection is seen in the south-central to SW Caribbean south of
13N between 70W-80W, partially enhanced by the extension of the
east Pacific monsoon trough. Recent ASCAT data show fresh trades
in the eastern and central Caribbean, mainly south of 17.5N and
east of 77W, where seas are 4 to 6 ft. Moderate trades prevail
across most other areas, where seas are 2 to 4 ft. NOAA buoy
42060, located near 16.4N 63.3W has recently reported 21 kt
winds and 6 ft seas. Earlier altimeter data from Saturday
afternoon showed seas of about 5 feet from 14N-17N between
67W-69W.

For the forecast, high pressure will build north of the area
today. This will bring an increase in trade winds and seas
across the central and E Caribbean through the middle of this
week. A large area of fresh, with some strong trade winds, with
building seas of 6 to 9 ft can be expected over the central
Caribbean early this week.

ATLANTIC OCEAN...

Refer to the Special Features section above for details on
Hurricane Sam and Tropical Depression Victor.

The Cumbre Vieja volcano on the island of La Palma in the Canary
Islands near 28.6N 17.8W has been erupting since September 19th.
High concentration of volcanic ash is found near the volcano.
Marine and aviation interests should monitor this ongoing
situation by reading the latest Volcanic Ash Advisory issued by
Meteo-France at http://vaac.meteo.fr/volcanoes/la-palma/ for
details.

West of 60W: A north-south oriented upper-level trough axis
extends over the west Atlantic along 76W. A surface trough
extends from 27N62W to 22N67W. Scattered moderate showers and
tstorms cover the area south of 26N between 63W-80W, with more
numerous moderate convection near the surface trough from
21N-26N between 63W-69W. Farther north, a 1022 mb high pressure
is centered near Cape Hatteras, North Carolina. Recent ASCAT
data show fresh trade winds south of 27N and west of 72W,
including in the Florida Straits. Moderate trade winds are
elsewhere south of 31N and west of 65W. Seas are 5 to 8 ft west
of 65W, in NE swell from Hurricane Sam. Between 60W-65W, 8-12 ft
seas are still occurring north of 27N, but these seas will
gradually subside as Sam pulls farther away. Buoy 41049 near
27.5N 62.9W is reporting 9 ft seas, mostly in N swell.

East of 60W: An upper-level low is near 27N46W. The positioning
of Hurricane Sam relative to this upper-low is enhancing
upper-level divergence in between the two features, leading to
an area of numerous moderate and isolated strong thunderstorms
north of 27N between 47W-56W. Surface ridging covers the
remainder of the eastern subtropical Atlantic, anchored by a
1025 mb high pressure near 37N36W. Fresh winds cover most of the
area from 10N-22N between 30W-60W, except winds up to 30 kt are
near T.D. Victor. Seas of 7 to 9 ft prevail across this area,
except higher near Victor. Winds near the Windward Islands are
fresh to strong. ASCAT also shows fresh to locally strong NE
winds near the Canary Islands. From 25N-31N between 25W-60W,
mainly moderate or weaker wind speeds prevail, but seas are in
the 6 to 8 ft range in mixed swell from Sam and Victor. The
exception is north of 29N and west of 55W, where larger seas
still prevail from swell due to Sam.

For the forecast west of 65W, swells generated from Hurricane
Sam, centered NE of the area, will continue to impact the area
waters through Mon. High pressure will build across the area in
the wake of Sam, which will bring moderate to fresh winds Mon
through mid week. Active weather is expected to develop across
the waters E of 75W and NE of the Bahamas Mon night through Tue.

$$
Hagen
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