[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 011034
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Wed Sep 1 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
1000 UTC.

...SPECIAL FEATURES...

Tropical Depression Ida is centered near 37.3N 82.5W at 01/0900
UTC or 120 nm W of Roanoke Virginia moving NE at 21 kt. Estimated
minimum central pressure is 1000 mb. Maximum sustained wind speed
is 25 kt with gusts to 35 kt. Ida is moving into the central
Appalachians and should become a remnant low today. Widespread
heavy rain and areas of life threatening flash flooding are
likely today and tonight near the track of Ida. Enhanced risk for
several tornados is expected across parts of the Mid-Atlantic
today. Please read the latest WPC Public Advisory at:
https://www.wpc.ncep.noaa.gov/tropical/tropical_advisories.php?storm=IDA
and the Storm Summary Message at:
https://www.wpc.ncep.noaa.gov/discussions/nfdscc4.html, for more
details.

Tropical Depression Kate is centered near 25.7N 51.7W at 01/0900
UTC or 780 nm NE of the Northern Leeward Islands moving NNW at 8
kt. This general motion is expected to continue through this
morning, followed by a turn toward the northwest by this afternoon.
A turn toward the north and north-northeast is forecast late
Thursday and early Friday. Estimated minimum central pressure is
1007 mb. Maximum sustained wind speed is 30 kt with gusts to 40
kt. Little change in strength is forecast during the next day or so,
followed by gradual weakening thereafter. Kate is forecast to become
a remnant low on Thursday, with the remnant low dissipating on
Friday. During the overnight hours, convection has developed near
the center. Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT5.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT5.shtml for more
details.

Tropical Depression Twelve strengthens into Tropical Storm Larry
over the eastern Tropical Atlantic. At 01/0900 UTC, Tropical Storm
Larry is centered near 12.3N 24.8W or 150 nm S of the Southernmost
Cabo Verde Islands moving W at 17 kt. Estimated minimum central
pressure is 1003 mb. Maximum sustained wind speed is 40 kt with
gusts to 50 kt. On the forecast track, a westward to west-
northwestward motion is expected during the next couple of days,
followed by a turn to the northwest over the weekend. Additional
strengthening is forecast during the next few days and Larry is
expected to become a hurricane by late Thursday or Friday. Please
read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT2.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT2.shtml for more
details.

...TROPICAL WAVES...

An Atlantic tropical wave is along 45W from 20N southward, moving
W at about 15 kt. Scattered moderate convection is noted where the
wave meets the monsoon trough from 07N to 10N between 45W and
50W.

A weak Atlantic tropical wave is near 54W from 17N southward into
French Guiana, moving W at 10 to 15 kt. Scattered showers are near
the southern end of the wave axis.

A Caribbean tropical wave is along 72W/73W and extends from Haiti
to near the Venezuela/Colombia border, moving W at 10 to 15 kt.
Scattered moderate convection is over western Venezuela and Lake
Maracaibo, and in the south-central Caribbean from 13N-15N between
73W-77W.

...MONSOON TROUGH/ITCZ...

The monsoon trough exits the Senegal coast near 14N17W to 13N21W,
then continues W of Larry from 11N27W to 09N40W to 08N48W. The
ITCZ extends from 08N48W to 08N53W. Scattered moderate to isolated
strong convection is found within about 150 nm S of the monsoon
trough between 37W-42W.

...GULF OF MEXICO...

Weak high pressure of 1015 mb located over the SE Gulf dominates
the region. Fresh to strong SW winds are noted over the NE Gulf
mainly N of 28N E of 90W ahead of a frontal trough over the SE
CONUS. Moderate to locally fresh easterly winds are just N of the
Yucatan Peninsula in association with a thermal trough that
usually develops over the Yucatan peninsula during the evening
hours, then shifts westward into the SW Gulf at night and
dissipates over the SW Gulf in the morning. Seas are 5-7 ft over
the NE Gulf and 3-5 ft elsewhere, except 1-3 ft over the SE, Bay
of Campeche and NW Gulf.

For the forecast, fresh to strong southwest to west winds over
the NE Gulf will persist through tonight ahead of a frontal
trough. Then, light and variable winds will prevail over the NE
Gulf during the upcoming weekend. Elsewhere, a ridge will dominate
the Gulf region producing mainly gentle to moderate southerly
winds through Fri. Pulsing fresh winds are expected northwest of
the Yucatan Peninsula at night through Fri due to local effects
associated with a thermal trough.

...CARIBBEAN SEA...

An upper-level low spinning over the Bahamas and central Cuba is
triggering scattered showers and a few thunderstorms near the S
coast of W Cuba, but particularly over the Gulf of Batabano and
the Isle of Youth. Scattered showers with embedded thunderstorms
also noted over the SW Caribbean in association with a broad area
of low pressure.

Gentle to moderate trades are noted over much of the basin except
fresh to strong winds in the Gulf of Honduras and just N of the
broad area of low pressure previously located near 12N78W. Seas
are 6-8 ft in the Gulf of Honduras, 3-5 ft over the NW and SW
parts of the basin, with 1-3 ft seas elsewhere.

For the forecast, the pressure gradient between a ridge east of
Florida and lower pressure over northern Colombia will support
moderate to fresh trade winds over the S central and NW Caribbean.
Similar wind speeds are expected in the Gulf of Honduras at night
through the weekend. A broad area of low pressure is producing
disorganized shower activity over the southwestern Caribbean Sea.
Some slow development of this system is possible over the next
couple of days while it moves westward or west- northwestward at 5
to 10 kt toward Central America. Thereafter, land interaction
with Central America and the Yucatan Peninsula of Mexico will
likely limit further development of this system. Regardless of
development, heavy rains are possible across portions of Central
America and the Yucatan Peninsula late this week and this weekend.

...ATLANTIC OCEAN...

Please see the Special Features section above for more information
on Tropical Depression Kate and recently upgraded Tropical Storm
Larry.

Recent scatterometer data show light and variable winds over most
of the waters N of 20N and W of 60W, with the exception of moderate
to fresh southerly winds just off NE Florida. A surface trough is
analyzed N of Hispaniola. A few showers are near the trough axis
that extends from 26N67W to 20N71W. E of Kate, a high pressure
center of 1018 mb persists, and it is centered near 31N30W. The
pressure gradient between the high pressure and T.S. Larry is
producing a belt of moderate to fresh trade winds from 16N-26N E
of 30N to the W coast of Africa. Mainly gentle to moderate winds
prevail elsewhere, with light and variable winds near the high
pressure center. Aside from conditions associated to Kate and
Larry, seas are generally in the 3-6 ft range over the open waters
and 2 ft or less west of the Bahamas.

For the forecast west of 65W, fresh to strong southwest winds are
expected just off northeastern Florida today ahead of a frontal
trough forecast to move southward over northern Florida and the
northwestern waters through Fri night. Then, the trough will
weaken as it moves across the northern waters W of 70W Sat through
Sun night. Swells generated by tropical cyclone Larry are expected
to propagate over the waters NE and E of the Leeward Islands on
Sun, likely reaching 65W on Mon.

$$
GR
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