[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 081142
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Thu Jul 8 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
1130 UTC.

...SPECIAL FEATURES...

Tropical Storm Elsa is located over southern South Carolina
near 32.4N 81.3W at 08/0900 UTC or about 90 mi WNW of Charleston,
South Carolina and about 210 mi WSW of Wilmington, North Carolina,
moving NNE at 14 kt. Maximum sustained wind speed is 35 kt with
gusts to 45 kt. The estimated minimum central pressure is 1007
mb. Satellite imagery shows that the cyclone is sheared, with
a large area of scattered moderate to strong convection displaced
far to the northeast of its center. This convection is noted
from 31N to 36N between 76W-82W, which includes the northern
portion of South Carolina and most of the eastern half of North
Carolina. On the current forecast track, Elsa will move over South
Carolina and North Carolina today, pass near the eastern Mid-
Atlantic states by tonight, and move near or over the northeastern
United States on Fri and Fri night. The system should move over
Atlantic Canada by Fri night and Sat. Elsa is forecast to become a
post-tropical cyclone Fri night or Sat.

Elsa is expected to produce storm totals of 3 to 5 inches with
isolated maximum amounts up to 8 inches are likely today across
portions of South Carolina, which may result in limited flash and
urban flooding. Elsa is also expected to produce 2 to 4 inches of
rain with isolated totals up to 6 inches possible across central
and eastern North Carolina into southeastern Virginia and from the
Mid-Atlantic into New England through Fri.

Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT5.shtml, Forecast/Advisory
at https://www.nhc.noaa.gov/text/MIATCMAT5.shtml, and the High
Seas Forecast issued by the NWS Ocean Prediction Center at
https://ocean.weather.gov/shtml/NFDHSFAT1.php for more details.
For marine information within 60 nm of the coast, please see
products from your local NWS Weather Forecast Office at
www.weather.gov.

Gale warning E of 35W: The pressure gradient between high
pressure of 1029 mb located about 400 nm east-northeast of the
Azores and lower pressures over Africa is resulting in strong
to gale-force north to northeast winds north of 20N and east of
25W, including the Canary Islands. Meteo-France has issued a Gale
Warning for Agadir from 08/12 UTC to 09/00 UTC. The forecast calls
for north winds Force 8 in the Beaufort Wind scale with gusts.
For more details, refer to the Meteo-France High Seas Forecast
listed in their website:
www.meteofrance.com /previsions- meteo- marine/
bulletin/grandlarge/metarea2.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 23W south
of 11N southward, moving westward at 10-15 kt. This wave is
surrounded by a moist atmospheric environment. Scattered moderate
convection is within 300 nm W of the wave axis from 04N-11N.

Another eastern Atlantic tropical wave, with a larger amplitude,
has its axis extending from 23N34W to 15N35W and to 04N36W. It is
moving westward near 15 kt. A small area of scattered moderate
convective is ahead of the wave primarily associated to the ITCZ
within 30 nm of line from 06N36W to 05N39W.

A central Atlantic tropical wave has its axis along 56W south of
14N, moving westward at 15-20 kt. Scattered moderate convection
is increasing within 180 nm W of the wave from 08N-10N and
within 120 nm E of the wave from 09N to 10N. The leading edge
of this convection is reach the coast of Brazil near the French
Guiana border.

A tropical wave over the Caribbean has its axis along 70W south of
13N. It is moving westward near 15 kt. Isolated showers are
possible near this wave over the Caribbean. Scattered moderate
convection is over sections of central Venezuela.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the coast of Guinea-Bissau
near 11N15W to 09N21W and to 08N32W. A segment of the ITCZ is
analyzed from 06N39W to 34N51W. Scattered moderate convection
is within 60 nm south of the trough between 15W-20W and within
60 nm S of the ITCZ between 39W-45W. Similar convection is well
S of the monsoon trough from 02N to 06N E of 16W to just inland
the coast of Africa.

GULF OF MEXICO...

An upper-level low is over southern Texas. A trough extends from
the low to over northern Mexico. At the surface, a 1008 mb low
is analyzed over southern Texas. A trough is just inland the
Texas coast. The combination of divergence east of the upper-level
trough along with the aforementioned surface features is leading
to large clusters of scattered moderate to convection over the NW
Gulf from 23N to 30N and W of 92W. Some of this activity may
produce gusty winds. It will continue throughout and into the
evening. Latest surface observations and overnight ASCAT data
indicate moderate to fresh southeast winds in this area of
convection. A diurnal surface trough moved off the Yucatan
Peninsula during the overnight hours and into the eastern part of
the SW Gulf to a position from 24N90W to 19N92W. Scattered
moderate convection is west of the trough to 96W and from 19N to
21N. Gentle to moderate southeast winds continue across most of
the Gulf, except in the northeast section of the basin where
gentle southwest to west winds remain in the wake of Tropical
Storm Elsa. Seas are generally 3-6 ft throughout the Gulf.

For the forecast: High pressure from the Atlantic will build
westward across the area through the next few days, with
relatively quiet conditions expected. The Yucatan Peninsula trough
will shift westward to the SW Gulf during the mornings through
the weekend followed by fresh to strong southeast winds. Scattered
to numerous showers and thunderstorms over the NW Gulf are
expected to continue through this evening.

CARIBBEAN SEA...

Near-gale force east winds were detected by an overnight ASCAT
pass over the Gulf of Venezuela. Strong trades continue in the
south central Caribbean within 120 nm of the coast of Colombia,
with resulting wave heights of 8-11 ft as was suggest by overnight
altimeter data over that area of the Caribbean and by NOAA buoy
42058 at 15N75W. Strong trades are also occurring in the Gulf of
Honduras with wave heights of 6-8 ft. Moderate to fresh trades
prevail over the remainder of the Caribbean. Wave heights range
from 5-8 ft in the eastern Caribbean, 6-9 ft in the north central
Caribbean, 7-10 ft in a northeast swell in SW Caribbean, and 4-6
ft in the NW Caribbean and Windward Passage.

For the forecast: Widespread strong trades will continue in the
south-central Caribbean into Fri night. These winds may reach
near gale force Thu through Fri night. Fresh to strong winds will
pulse at night in the Gulf of Honduras through Sun.

ATLANTIC OCEAN...

The Bermuda-Azores high dominates the Atlantic forecast waters.
Of note, during the summer, the Gulf of Mexico and the Caribbean
Sea are dominated by the Bermuda-Azores high, when it is at its
westernmost position. Circulation around the high results in
southerly winds over the Gulf of Mexico and easterly winds over
the Caribbean Sea. These winds bring warm, moist air from the
ocean over land. For us in South Florida, this pattern brings with
it the rainy season and high dewpoints. The latest surface
analysis valid at 0600 UTC depicts a 1029 mb Azores high near
36N35W, with its associated ridge stretching westward to near 75W,
then west-southwest to South Florida. An upper trough extends
from 31N66W to 28N70W. Scattered moderate convection is
within 60 nm of the trough. Isolated showers and thunderstorms
are north of 26N W of 70W.

An overnight ASCAT pass picked up on fresh strong east winds
between the southeastern Bahamas and Hispaniola, where
wave heights are 5-7 ft. These winds will continue to pulse
through early next week. An area of fresh trades due to a tight
pressure gradient between the high pressure ridge over the
northern part of the are and relatively lower pressure in the
tropics is over the area defined from 10N to 22N east of 52W.
Gentle to moderate trades are present elsewhere, except for light
winds near and along the high pressure ridge between 55W-67W. Wave
heights are in the range of 4-6 ft W of 70W, and 5-7 ft over the
remainder of the basin except for higher wave heights of 6-8 ft
due to a northeast swell east of the Lesser Antilles from 11N to
20N between 57W-61W. This swell will subside by early this
evening.

For the forecast W of 65W: Fresh to strong south to southwest
winds over the far northwest part of the area will lift north of
the area this morning as Tropical Storm Elsa, currently over South
Carolina, continues to pull away from the region. High pressure
will then build westward across the area through Sun night. East
winds will pulse to fresh to strong speeds at night between the
southeastern Bahamas and Hispaniola through the period.

$$
Aguirre
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