[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181130
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Sun Sep 18 2022

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...

Tropical Storm Fiona is centered near 17.1N 65.8W at 18/0900 UTC
or 70 nm WSW of St. Croix moving WNW at 7 kt. Estimated minimum
central pressure is 994 mb. Maximum sustained wind speed is 55 kt
with gusts to 65 kt. Peak wave heights are reaching 21 ft near
the center of Fiona. Wave heights of 12 ft or greater are within
90 nm of the center in the E semicircle, and within 60 nm of the
center in the W semicircle. Satellite imagery shows that banding
features have become pronounced as they wrap around the center
from the W semicircle. The imagery also shows numerous moderate
to isolated strong convection within 180 nm of the center in the
NE quadrant, within 240 of the center in the SE and quadrant and
within 90 nm of the center in the SW quadrant. Scattered moderate
convection is within 150 nm of the center in the NW quadrant.
Fiona is forecast to begin a northwestward motion later today and
continue through Mon, followed by a turn toward the north-
northwest on Tue. On the forecast track, the center of Fiona will
approach Puerto Rico this morning, and move near or over Puerto
Rico this afternoon or evening. Fiona will then move near the
northern coast of the Dominican Republic tonight and Mon, and
near or to the east of the Turks and Caicos Islands on Tue.
Strengthening is forecast, and Fiona is expected to become a
hurricane before reaching the southern or southwestern coast of
Puerto Rico later today. Additional strengthening is expected on
Mon and Tue while Fiona moves near the Dominican Republic and over
the southwestern Atlantic. Swell generated by Fiona is affecting
the Leeward Islands, the northern Windward Islands, the Virgin
Islands, Puerto Rico, the northern coast of the Dominican
Republic, the Turks and Caicos Islands, and the southeastern
Bahamas. These conditions could cause life-threatening surf and
rip current conditions. Please consult products from your local
weather office.

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
T.S. Fiona NHC Forecast/Advisory and NHC Public Advisory at
www.hurricanes.gov for more details.

...TROPICAL WAVES...

A central Atlantic tropical wave has its axis along 38W from
03N to 16N moving westward at about 15 kt. Scattered showers and
and a few thunderstorms are within 180 nm east of the wave
axis from 10N to 12N.

Another central Atlantic tropical wave has its axis extending from
near 26N46W to 19N50W to 11N51W. It has an estimated westward
motion of 15 kt. An area of scattered moderate convection is
displaced to its north and northeast due to strong upper-level
southeast to south winds. This activity is present from 24N
to 30N and between 43W-48W. A small area of scattered showers
and thunderstorms is along and within 150 nm east of the wave
from 19N to 21N. Overnight ASCAT data captured moderate to fresh
northeast to east winds across the wave axis. Wave heights with
these winds are 5-7 ft. Some slow development of this system is
possible during the early or middle part of this week, while it
moves generally northward, remaining over the central Subtropical
Atlantic. The latest Tropical Weather Outlook gives this system a
low chance of tropical cyclone formation through five days.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis enters the Atlantic through the coast of
Senegal near 14N17W and continues southwestward to 10N24W, to
10N34W and to 08N40W, where overnight scatterometer data indicates
that it transitions to the ITCZ to 07N43W and to 06N48W. Scattered
moderate to isolated strong convection is seen off the coast of
Africa from 07N to 14N between 13W-20W. Scattered moderate
convection is within 60 nm south of the trough axis between
23W-27W.

GULF OF MEXICO...

A ridge over the eastern United States extends southwestward
into the Gulf of Mexico, with the associated gradient supporting
mainly gentle to locally moderate easterly winds across the basin.
The exception are the nightly pulses of fresh northeast to east
winds off the northwest section of the Yucatan Peninsula.
Altimeter and buoy data indicate wave heights of 1-3 ft, except
for 3-4 ft wave heights offshore the northwest section of the
Yucatan Peninsula. An area of numerous showers and thunderstorms
is confined to the western Bay of Campeche. Isolated showers and
thunderstorms are elsewhere south of 22N west of 90W, and from
22N to 26N west of 94W. A surface trough extends from central
Florida south-southwest to the western part of the Straits of
Florida. No significant convection is being produced by this
trough, only isolated showers to east over the Straits of
Florida. The rest of the Gulf remains under fairly tranquil
weather conditions.

For the forecast, high pressure over the southeastern U.S. will
maintain gentle to moderate easterly breezes and slight seas the
next few days.

CARIBBEAN SEA...

Please see the Special Features section for information on
Tropical Storm Fiona currently located over the northeastern
Caribbean Sea as it approaches Puerto Rico.

Outside of convection associated to Fiona, scattered showers and
thunderstorms are noted from 14N to 18N between 79W-85W, and
from 11N to 14N west of 80W to inland Nicaragua. Similar activity
is from 12N to 14N between 70W-75W. Isolated showers and
thunderstorms are over the remainder of the basin and near
Jamaica. Overnight ASCAT data passes indicate fresh to strong
trade winds are off the southern coast of Hispaniola, especially
N of 15N and between 68W-72W, and also at the entrance of the
Windward Passage. Wave heights over these waters are 4-7 ft.
Elsewhere, moderate or lighter winds along with lower wave heights
of 2-4 ft prevail.

For the forecast, Tropical Storm Fiona about 70 nm southeast of
Puerto Rico at 5 AM EDT moving WNW at 7 kt has maximum sustained
winds 55 kt gusts 65 kt. Fiona is forecast to strengthen to a
hurricane near 17.8N 66.9W this afternoon with maximum sustained
winds 65 kt gusts 80 kt, move to near 18.7N 68.0W late tonight,
then gradually strengthen as it moves to near the northeast coast
of the Dominican Republic near 19.8N 69.0W Mon afternoon with
maximum sustained winds 70 kt gusts 85 kt, moves to the Atlantic
waters north of Hispaniola near 21.2N 69.8W late Mon night and
continue to strengthen as is tracks farther north and away from
the Caribbean Sea. Residual swell over the eastern Caribbean from
Fiona will slowly subside over the eastern Caribbean Mon into Tue.

ATLANTIC OCEAN...

Please see the Special Features section for information on
Tropical Storm Fiona, which is forecast to be in the vicinity of
the Turks and Caicos early on Tue.

A surface trough extends from near 31N80W to west-central Florida
and to western part of the Straits of Florida. A trough is aloft
over the surface trough. These features are sustaining an area of
scattered moderate convection over the waters from north of the
NW Bahamas to 32N and between 74W-80W. Moderate to fresh easterly
winds are north of 29N and west 77W, along with wave heights of
3-5 ft. Fresh to strong trades are between the southeastern
Bahamas and Haiti.

Weak low pressure of 1014 mb is just north of the area near
32N61W, with cold front southwest to near 28N65W. Isolated showers
and thunderstorms are east of the front from 28N to 31N between
59W and the front. Similar activity is west of the front within
30 nm of 29.5N68W. Otherwise, relatively weak high pressure is
present over the remainder of the tropical Atlantic.

In the eastern Atlantic, fresh to strong north to northeast winds
are offshore SW Western Sahara and Mauritania, primarily from 18N
to 22N and west of 20W. Wave heights over these waters are 6-8
ft. Elsewhere, moderate or lighter winds along with wave heights
of 3-6 ft are present.

For the forecast west of 55W, Tropical Storm Fiona is over the
far northeastern Caribbean Sea approaching Puerto Rico, with
maximum sustained winds 55 kt gusts 65 kt and moving WNW at 7 kt
with a pressure of 994 mb is forecast to strengthen to a hurricane
near 17.8N 66.9W this afternoon with maximum sustained winds 65
kt gusts 80 kt. Fiona is forecast to move to near 18.7N 68.0W late
tonight, then gradually strengthen as it moves to near 19.8N
69.0W Mon afternoon with maximum sustained winds 70 kt gusts 85
kt, to near 21.2N 69.8W late Mon night, to near 22.6N 70.5W Tue
afternoon, to near 23.9N 70.7W late Tue night with maximum
sustained winds 90 kt gusts 110 kt, to near 27.5N 70.0W late Wed
night with maximum sustained winds 95 kt gusts 115 kt and to north
of the area near 33.0N 66.0W late Thu night. High pressure will
build in the wake of Fiona.

$$
Aguirre
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