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Atlantic Tropical Weather Discussion



410 
AXNT20 KNHC 191039
TWDAT 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Sun Sep 19 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 
1030 UTC. 

...SPECIAL FEATURES...

Recently upgraded Tropical Storm Peter is centered near 18.0N 53.5W at 19/0900 UTC
or 550 nm E of the Northern Leeward Islands moving NW at 13 kt. Estimated
minimum central pressure is 1005 mb. Maximum sustained wind speed
is 35 kt with gusts to 45 kt. Numerous moderate to isolated strong
convection is observed within 150 nm in the northeast semicircle
of the center of Peter. An earlier Sentinel altimeter pass 
indicate seas were already reaching 12 ft on the north side of the
storm. The center of Peter will pass to the northeast of the 
Leeward Islands Mon, then continue to move northward toward 
Bermuda through the latter part of the week. Heavy rain and large 
swells are expected to impact the N Leeward Islands, Virgin 
Islands and Puerto Rico. Interests across these areas should 
monitor this system closely. Please read the latest NHC Public 
Advisory at https://www.nhc.noaa.gov/text/MIATCPAT1.shtml and 
Offshore Waters Forecasts at 
www.nhc.noaa.gov/marine/offshores.php for more details.

Newly formed Tropical Depression Seventeen is centered near 11.8N 28.2W at
19/0900 UTC or 290 nm SW of the Southernmost Cabo Verde Islands
moving NNW at 12 kt. Estimated minimum central pressure is 1007
mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt.
Scattered moderate to isolated strong convection is noted within
180 nm on the western semicircle of the center of T.D. Seventeen.
The depression is expected to move NW over the next several days,
and cross west of 35W by late Tue as a minimal tropical storm. 
Refer to the latest NHC Tropical Weather Outlook at 
www.hurricanes.gov for more details. For sea conditions near this 
system, please read the Meteo-France High Seas Forecast at: 
http://weather.gmdss.org/II.html

...TROPICAL WAVES...

An Atlantic tropical wave extends from 19N26W southward through 
Tropical Depression Seventeen near 11.8N 28.2W, to 04N29W, and is
moving W near 10 kt. Scattered moderate to isolated strong convection is noted within
180 nm on the western semicircle of the center of T.D. Seventeen.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends across the Mauritania coast at 17N16W 
through T.D. Seventeen, and another low near 08N35W. The ITCZ 
then continues from 08N35W to 07N45W. Numerous moderate to strong
convection is occurring S of the monsoon trough along the coast 
of Senegal, Gambia, Guinea-Bissau and Guinea. Scattered moderate 
convection is present near the second low from 05N to 07N between
36W and 39W.

The E end of the E Pacific monsoon trough is triggering a cluster
of showers and scattered thunderstorms near Portobelo, Panama.

...GULF OF MEXICO...

A persistent surface trough meanders east-northeastward from the 
Crystal River, Florida to just off the mouth of the Mississippi
River, to near 26N95W. Scattered showers and thunderstorms are 
noted along another trough extending just off the coast of the
state of Veracruz, Mexico. Gentle to moderate winds and slight
seas are evident across the Gulf this morning. 

For the forecast, weak high pressure will extend across the E and
central Gulf of Mexico through the early part of the week. This 
pattern will support continued gentle to moderate winds and mostly
slight seas across the Gulf through the next several days. 
Looking ahead, a weak cold front may move into the NW and N 
central Gulf by mid week.

...CARIBBEAN SEA...

In addition to the showers and thunderstorms off Panama, another
cluster is ongoing off the southern Peninsula of Haiti again this
morning. A ship reported strong to near gale force winds in this
area of thunderstorm, likely due to strong downdrafts. Elsewhere
trade winds are well below average with mostly gentle to moderate
breezes and slight to moderate seas noted in all areas. This
relatively relaxed period is courtesy of fairly weak high pressure
centered north of the area off the northern Bahamas. 

For the forecast, Peter will move to 18.8N 55.3W this afternoon, 
then continue to move to the northeast of the Leeward Islands and 
reach 19.8N 57.8W Mon morning and 20.8N 60.1W Mon afternoon. 
Expect large swell off the Leeward Islands into mid week. Peter 
will continue to move northward and away from the Leewards 
thereafter through mid week. Peter will displace the weakening 
Atlantic ridge currently north of the region, allowing trades 
winds over the south-central Caribbean to diminish over the next 
several days. 

...ATLANTIC OCEAN...

Please read the Special Features section above for details on 
newly formed Tropical Storm Peter E of the Leeward Islands and a 
newly formed Tropical Depression Seventeen SW of the Cabo Verde 
Islands.

Convergent trade winds are coupling with divergent flow aloft to
generate scattered moderate to isolated strong convection ahead of
Peter and northeast of the Leeward Islands from 21N to 24N 
between 51W and 60W. A modest surface trough is producing 
scattered moderate convection from 29N to 31N between 55W and 
61W. Refer to the Tropical Waves and Monsoon Trough/ITCZ sections
for additional convection across the Atlantic Basin.

The Atlantic ridge extends southwestward from a 1029 mb Azores
high, passing S of Bermuda to another high 1018 mb N of the 
Bahamas. These features are providing light to gentle winds with 
seas at 2 to 4 ft N of 24N between 40W and the Georgia-N Florida 
coast. Other than the areas within 180 nm of Peter and T.D.
Seventeen, generally moderate winds and seas persist elsewhere
across the Atlantic Basin. 

For the forecast west of 60W, Peter will move to 18.8N 55.3W this
afternoon, 19.8N 57.8W Mon morning, 20.8N 60.1W Mon afternoon, 
21.7N 62.2W Tue morning, 22.7N 63.9W Tue afternoon, and 23.7N 
64.9W Wed morning. Peter will change little in intensity as it 
moves to the southeast of Bermuda by late Wed. Elsewhere west of 
70W, gentle to moderate winds and slight to moderate seas will 
persist over open waters through the early part of the week, with 
swell to 8 ft associated with the tropical storm reaching the 
waters east of 72W by Wed. 

$$
Christensen