[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 082106 AAA
TWDAT

Tropical Weather Discussion...Updated
NWS National Hurricane Center Miami FL
0005 UTC Fri Jul 9 2021

Updated for the latest information on Tropical Storm Elsa

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 1800 UTC surface analysis and satellite imagery through
1940 UTC.

...SPECIAL FEATURES...

Tropical Storm Elsa is centered near 36.3N 78.3W at 08/2100 UTC
or 110 nm WSW of Norfolk Virginia moving NE at 18 kt. Estimated
minimum central pressure is 1006 mb. Maximum sustained wind
speed is 45 kt with gusts to 55 kt. Numerous moderate convection
is noted within 240 nm in the northeast semicircle of Elsa with
a band of scattered moderate convection within 150 nm southeast
of a line from 35N77W to 29N84W. Heavy rainfall is forecast
across central and eastern North Carolina into southeastern
Virginia, and from the Mid-Atlantic into New England through
Friday are possible, which could result in limited-to-
considerable flash and urban flooding, as well as isolated minor
river flooding. Elsa will move to 38.7N 75.1W Fri morning,
becoming extratropical near 47.0N 63.0W Sat morning, and will
dissipate by Sun afternoon.

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.

Caribbean Sea Gale Warning: Gale force winds over the south-
central Caribbean near the coast of Colombia are continuing due
to the combination of high pressure north of the area and lower
pressures over northern Colombia. Gales will pulse tonight through
Fri with seas building to 12 to 14 ft. Please read the latest NWS
High Seas Forecast issued by the National Hurricane Center at the
website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml.

Gale warning east of 35W: The pressure gradient between high
pressure of 1031 mb located across the Azores near 38N28W and
lower pressure over Africa is supporting gale force winds in the
Agadir area of the Meteo-France High Seas Forecast waters. The
Gale Warning for Agadir continues to 09/00 UTC. The forecast
calls for N 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...

An eastern Atlantic tropical wave has its axis near 27W south of
11N, moving quickly W at 20 to 25 kt. This wave is surrounded by
a moist atmospheric environment. Scattered moderate convection is
noted from 02N to 06N between 27W and 33W.

A central Atlantic tropical wave with a large amplitude has its
axis near 37W/38W south of 23N, moving quickly W at around 20 kt.
Isolated to scattered moderate convection is noted near the
southern portion of the wave axis from 03N to 06N between 33W and
41W.

A tropical N Atlantic tropical wave has its axis near 60W south of
12N to across northern South America, moving W at around 15 to 20
kt. Scattered moderate and isolated strong convection is noted
from 08N to 11N between 54W and 68W with additional convection
over portions of northern South America.

A Caribbean Sea tropical wave has its axis near 78W/79W south of
14N to across eastern Panama and into the eastern Pacific Ocean,
moving quickly W at around 20 kt. Scattered moderate and isolated
strong convection is noted south of 10N between 79W and 82W.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the coast of Africa near
12N16W to 08N23W to 10N30W to 08N35W. The ITCZ extends from 07N40W
to 10N58W. Convection is described in the tropical waves section
above.

GULF OF MEXICO...

A middle to upper-level low is over southern Texas. A trough
extends from the low to over northern Mexico. At the surface, a
1009 mb low is analyzed over southern Texas near 28N98W. A trough
is just inland over eastern Mexico from 26N98W to near Tampico,
Mexico continuing along the coast of Mexico to 18N95W. The
combination of divergence east of the upper-level trough along
with the aforementioned surface features is leading to a large
complex of scattered moderate and isolated strong convection
within 240 nm southeast of a line from 31N93W to 23N99W. Heavy
rainfall and flash flooding will be possible along the Texas Gulf
coast over the next few days. See products issued by your local
National Weather Service Forecast Office for additional
information. Isolated thunderstorms are noted over the central
Gulf between 85W and 90W.

Moderate to fresh SE-S winds are noted in the NW Gulf, with
moderate SE-S winds elsewhere west of 90W along with seas in the 4
to 6 ft range, with gentle to moderate SE-S winds east of 90W
along with seas in the 2 to 4 ft range.

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. A broad
low pressure remains nearly stationary over South Texas enhancing
scattered to numerous strong thunderstorms over the western Gulf.
These storms will continue to produce frequent lighting and fresh
to strong southeast winds in the northwest Gulf. This activity
will continue through tonight.

CARIBBEAN SEA...

Please see the Special Features above for details on the Gale
Warning in effect for the south-central Caribbean near the coast
of Colombia.

Elsewhere in the central Caribbean, fresh to strong trades
prevail. Moderate to fresh trades prevail across the remainder of
the Caribbean basin except light to gentle south of 10N in the SW
Caribbean. Seas are in the 8 to 12 ft range in the central
Caribbean, and 4 to 7 ft elsewhere. Isolated to scattered showers
and thunderstorms extend from 10N to 14N west of 82W to across
eastern Nicaragua, and from 14N to 18N west of 85W including
across eastern and central Honduras.

For the forecast, a ridge north of the area combined with the
Colombian low will enhance strong to gale force winds north of
Colombia through Fri. Widespread fresh to strong trades will
continue in the south-central Caribbean and the Gulf of Honduras
through Fri night. Fresh to strong winds will pulse at night in
the Gulf of Honduras through early next week.

ATLANTIC OCEAN...

Please see the Special Features above for details on the Gale
Warning in effect for the Agadir area of the Meteo-France High
Seas Forecast waters.

A band of scattered moderate convection is noted from the far NW
Bahamas and north of 27N and west of 77W with additional activity
across the Florida Peninsula. The Bermuda-Azores high dominates
the Atlantic forecast waters. The 1032 mb high is centered near
36N38W. Gentle to moderate anticyclonic winds prevail around the
high across the waters north of the ITCZ and west of 30W, except
moderate to fresh offshore of northern Florida, fresh to strong
south of 22N offshore of northern Hispaniola, and moderate to
fresh across the tropical N Atlantic west of 55W. Seas of 4 to 7
ft dominate the waters west of 30W. Fresh to strong N-NE winds are
located from 19N to 31N east of 22W to the coast of Africa due to
a locally tight pressure gradient, with moderate to fresh N-NE
winds elsewhere north of 15N and east of 30W. Seas are in the 7 to
11 ft range in the area of fresh to strong winds.

For the forecast west of 65W, outer bands of Tropical Storm Elsa
extend southwest into the western Atlantic enhancing showers and
thunderstorms over the region. Fresh to strong southwest winds
over the far northwest part of the area will lift north as
Tropical Storm Elsa, currently over North 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.

$$
Lewitsky
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