[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 162354
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sat Sep 17 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 1800UTC surface analysis and satellite imagery through
2300 UTC.

...SPECIAL FEATURES...

The center of Tropical Storm Fiona is very near Guadeloupe at
8pm AST. Tropical storm conditions and heavy rains are occurring
across parts of the Leeward Islands. The storm is centered near
16.5N 61.5W at 16/0000 UTC or 10 nm NNW of Guadeloupe moving W at
13 kt. Estimated minimum central pressure is 1002 mb. Maximum
sustained wind speed is 45 kt with gusts to 55 kt. Peak seas of
21 ft are near and northeast of the center. Seas 12 ft or greater
extend from the center of Fiona to 240 nm in the NE quadrant,
120 nm in the SE quadrant, 75 nm in the SW quadrant, and 270 nm
in the NW quadrant. Fiona remains sheared, with numerous moderate
to scattered strong convection within about 120 nm E semicircle.
Scattered moderate to isolated strong convection is noted
elsewhere from 12N to 15N between 55W and 61W. On the forecast
track, the center of Fiona is expected to move across the Leeward
Islands during the next few hours, near or just south of the
Virgin Islands and Puerto Rico Saturday into Sunday, and approach
the southern or eastern coast of the Dominican Republic Sunday
afternoon. Fiona is forecast to move across the Dominican
Republic Sunday night and Monday. Gradual strengthening is
forecast during the next 48 hours or so before the center of
Fiona reaches the Dominican Republic on Sunday. Tropical storm
conditions are beginning across portions of the Leeward Islands
within the warning area and will continue through Saturday.
Tropical storm conditions will spread westward to the U.S. and
British Virgin Islands Saturday morning, and across Puerto Rico
Saturday afternoon and Saturday night. Tropical storm conditions
are possible on Dominica this evening or tonight and across the
watch area in the Dominican Republic beginning Sunday afternoon.
Heavy rains from Fiona will reach the Leeward Islands by this
evening, spreading to the British and U.S. Virgin Islands and
Puerto Rico Saturday, reaching the Dominican Republic Sunday, and
the Turks and Caicos Monday night or Tuesday. These rains may
produce flash and urban flooding, along with mudslides in areas
of higher terrain, particularly southern and eastern Puerto Rico
and the eastern Dominican Republic. Swells generated by Fiona are
affecting the Leeward and northern Windward Islands, and are
beginning to reach the Virgin Islands and Puerto Rico. Swells
will then reach the northern coast of Hispaniola, the Turks and
Caicos Islands, and the southeastern Bahamas over the weekend.
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...

An eastern Atlantic tropical wave has its axis along 28W from
05N to 15N moving westward at 15-20 kt. Scattered moderate
convection is seen on either side of the wave axis, and mainly
from 07N to 12N between 23W and 32W.

A central Atlantic tropical wave has its axis along 42W from 08N
to 21N moving westward at 15 kt. An area of disorganized showers
and thunderstorms are near the northern end of the tropical
wave. Some slow development of this system is possible early next
week while it moves northwestward to northward 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 extends from the northern border of The
Gambia near 13.5N16W southwestward to 11N20W to 08N28W. Scattered
moderate to isolated strong convection is observed from 04N to
08N between 13W and 21W.

GULF OF MEXICO...

A surface trough is analyzed across the Gulf waters, and extends
from 27N85W to 22N91W. Convection continues to flare up over most
of Florida and the eastern Gulf. Upper diffluence is helping to
induce this convective activity. Another area of showers, with
embedded thunderstorms is over the SW Gulf. Gentle to moderate
winds prevail across the Gulf region with seas generally in the
1-3 ft range. Winds and seas may be locally higher in and near
thunderstorms.

For the forecast, high pressure over the southeastern U.S. is
maintaining gentle to moderate easterly breezes and slight seas,
and this will continue through early next week. A surface trough
over the eastern Gulf will support scattered showers and
thunderstorms over the southeastern Gulf into Sat.

CARIBBEAN SEA...

Please see the SPECIAL FEATURES section for information on
Tropical Storm Fiona, which is forecast to impact the NE
Caribbean.

Outside of Fiona, a band of showers and thunderstorms extends
from just S of Dominican Republic all the way to NE Nicaragua.
A belt of fresh to locally strong NE winds coincides with this
convective activity. Scattered showers and thunderstorms are
also noted over the SW Caribbean likely associated with the
eastern extent of the Eastern Pacific monsoon trough.

Satellite derived wind data also show gentle to moderate trades
across the remainder of the basin, with the exception of an area
of moderate to fresh winds over the Gulf of Honduras. Seas are
generally 3-5 ft, except 5-6 ft along the belt of fresh to locally
strong NE winds.

For the forecast, Tropical Storm Fiona will move to 16.8N 62.8W
Sat morning, 17.2N 64.9W Sat afternoon, 17.6N 66.6W Sun morning,
18.2N 68.2W Sun afternoon, 18.8N 69.2W Mon morning, and 19.6N
70.2W Mon afternoon. Fiona will change little in intensity as it
moves to near 21.6N 71.7W Tue afternoon.

ATLANTIC OCEAN...

Please see the SPECIAL FEATURES section for information on
Tropical Storm Fiona.

A cold front enters the forecast area near 31N71W, and continues
SW to near 29N77W. A surface trough runs from 29N78W to near SE
Florida. Numerous showers and thunderstorms are over Florida and
the NW Bahamas. Gentle to moderate winds are on either side of
the front with seas of 3-5 ft.

A frontal low over the western Atlantic Ocean a few hundred miles
west-northwest of Bermuda continues to produce disorganized
showers and thunderstorms. This low is expected to move eastward
to east-southeastward at about 10 kt, and development into a
tropical cyclone is not anticipated due to strong upper-level
winds.

The remainder of the Atlantic forecast waters is under the
influence of a ridge, with a 1021 mb high pressure located near
29N29W. Another high pressure center of 1020 mb is near 31N53W. A
frontal trough extends from 32N30W to 28N45W. Only a few showers
are noted near the trough axis. Under the influence of the ridge,
mainly light and variable winds are noted roughly N of 25N. Winds
increase between Fiona and the ridge to the N, with fresh to
strong winds reaching 20N-21N between 55W-63W based on scatterometer
data. An area of fresh to strong winds NE winds, with seas of
6-8 ft, is seen from 18N-22N between 18W-23W due to the pressure
gradient between the high pressure near 29N29W and lower
pressures over W Africa.

For the forecast west of 55W, Tropical Storm Fiona will move to
16.8N 62.8W Sat morning, 17.2N 64.9W Sat afternoon, 17.6N 66.6W
Sun morning, 18.2N 68.2W Sun afternoon, 18.8N 69.2W Mon morning,
and 19.6N 70.2W Mon afternoon. Fiona will change little in
intensity as it moves to near 21.6N 71.7W Tue afternoon. The
cold front will shift slowly eastward through the weekend.
Moderate northeast winds north of the frontal boundary will
continue through the most of the weekend. Scattered showers and
thunderstorms are expected near the frontal boundary.

$$
GR
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