[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 092350
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM Wed Sep 09 2020

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 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2345 UTC.

...SPECIAL FEATURES...

Tropical Storm Paulette is centered near 20.5N 47.4W at 09/2100
UTC or about 900 nm east of the northern Leeward Islands moving
west-northwest at 8 kt. Estimated minimum central pressure is
996 mb. Maximum sustained wind speed is 50 kt with gusts to 60
kt. Paulette remains a sheared system, with its center exposed to
just to the south of its deepest convection. The convection
consists of the numerous moderate to strong type intensity within
150 nm of the center in the NE quadrant and of the numerous type
intensity elsewhere within 180 nm of the center in the NE
quadrant and within 150 nm of the center in the NW quadrant.
Paulette is expected to remain on its current motion through Fri,
then a northwestward motion should begin Fri night and continue
into the weekend. Paulette is forecast to weaken during the next
day or two but could restrengthen early next week. 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 Storm Rene is centered near 18.0N 32.7W at 09/2100 UTC,
or 510 nm west-northwest of the Cabo Verde Islands, moving west-
northwest at 11 kt. Estimated minimum central pressure is 1003
mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt.
The easterly shear over Rene has diminished some during the day
and upper-level outflow has become more evident. Satellite
imagery shows numerous moderate to strong convection within 150
nm of the center over the the western semicircle. Rene is
expected to remain on its current motion through the next couple
of days followed by a turn to the northwest, thereafter .Gradual
strengthening is forecast during the next 48 hours, and Rene is
expected to be near hurricane strength by Fri night. Please read
the latest NHC Public Advisory at:
https://www.nhc.noaa.gov/text/MIATCPAT3.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml for
more details.

...TROPICAL WAVE OVER WEST AFRICA...

A tropical wave over west Africa has its axis roughly along
13W from 06N to 19N. It is expected to emerge off the coast of
west Africa on Thu. Large clusters of scattered moderate to
strong convection that are preceding the are increasing over
west Africa from 08N to 18N between 13W-18W. This activity
contains frequent lightning and strong gusty winds. Gradual
development is expected once the system moves over water, and a
tropical depression is likely to form late this week or over the
weekend while the system moves westward across the eastern
tropical Atlantic. There is a medium chance of tropical cyclone
formation within the next 48 hours.

...TROPICAL WAVES...

A western Caribbean Sea tropical wave has its axis 81W south of
18N. It is moving westward at  W at 15 kt. Isolated showers and
thunderstorms are ahead of the wave and behind it to near 76W.

...MONSOON TROUGH/ITCZ...

No monsoon trough is noted in the eastern and central Atlantic
due to the circulations of Paulette and Rene. The ITCZ axis
extends from 12N49W to 11N61W. Isolated showers and thunderstorms
are along and near the ITCZ 57W-61W.

GULF OF MEXICO...

A surface trough extends from near Tampa Bay, Florida
southwestward to 26N85W and to near 23N89W as of 21Z. An
afternoon ASCAT pass detected the northeast to southeast wind
shift across the trough axis. This trough exists in this
location from the surface to 700 mb. The GOES-16 mid-level water
vapor channel and TPW imagery animation depict abundant moisture
over the far eastern Gulf and over the Florida peninsula.
Scattered to numerous showers and thunderstorms are occurring
over the far southeastern Gulf waters, while numerous strong
thunderstorms are along and just inland the central Florida coast
from Tampa to vicinity of Cross City. Scattered showers and
thunderstorms are elsewhere over much of central and northern
Florida, over some sections of South Florida and over just about
the entire range of the Straits of Florida. Similar convection
is over western Cuba and along and just offshore the northwest
coast of Cuba. Farther west, a cold front is over central Texas
as of 21Z. Isolated showers and thunderstorms are moving to
the northwest out ahead of the front to areas along the coast of
Texas. Gentle wind speeds prevail across the southeastern and
south-central Gulf areas, with moderate winds over the northeast
Gulf and the western Gulf.

As for the forecast, the aforementioned surface trough will
slowly move westward through the rest of the week. High pressure
to the north-northeast of the area will extend across the Gulf
leading to fairly tranquil marine conditions through the upcoming
weekend.

CARIBBEAN SEA...

Shower and thunderstorm activity associated with the tropical
wave along 81W is described in the above section under Tropical
Waves. Upper-level diffluence over the northwestern Caribbean
Sea between an upper-level inverted trough that is along 85W and
upper southerly flow present to its north and northeast is
enhancing scattered moderate isolated strong convection north of
20N between 81W- 85W, including similar activity that is over
western Cuba. Farther east, an upper-level NE to SW oriented
trough stretches from the eastern part of the Dominican Republic
to 14N75W and to 10N77W. The resultant instability is helping to
induce isolated to scattered showers and thunderstorms between
Puerto Rico and Jamaica, from 16N-20N, including near the
Windward and Mona passages. Scattered moderate to strong
convection is moving west- southwest over eastern and central
Cuba. A partial afternoon ASCAT pass revealed gentle to moderate
trade winds between 68W- 76W. Gentle trades prevail west of 76W.

As for the forecast, large swells associated with Paulette may
spread through Atlantic passages by the end of the week into the
weekend from the Leeward Islands to the Mona Passage. Paulette
is forecast to pass more than 450 nm NE of the Caribbean on
Sat when the center moves near 24N57W on a northwest course.
Elsewhere, the tropical wave along 81W will decelerate as it
continues across the remainder of the western Caribbean for the
remainder of the week.

ATLANTIC OCEAN...

Refer to the Special Features section for details on Tropical
Storm Paulette and on Tropical Storm Rene.

A small 1013 mb low is analyzed near 31N75W. Scattered moderate
convection is within 60 nm of the low in the SW quadrant and
within 30 nm of 30N76W. The low is forecast to move NW. This low
has a low chance of developing into a tropical cyclone before it
moves inland over eastern North Carolina on Thu afternoon. A
dissipating stationary front extends from the Mid-Atlantic coast
southwestward to inland southeastern Georgia. Very deep atmospheric
moisture in place along with plenty of instability is allowing
for scattered moderate to isolated strong convection to exist
from 22N to 30N and between 64W-75W. In addition, an upper-level
trough axis stretches from near 32N46W to an elongated upper-
level low near 25N53W and to 24N60W, where it transitions to a
shear axis that curves northwestward to 27N65W and to 32N72W. It
is helping to enhance the aforementioned convection. An afternoon
ASCAT pass highlighted fresh east winds to the northeast of a
line from 20N57W to 30N71W, with moderate winds southwest of
the same line, and gentle winds west of 74W.

As for the forecast, Tropical Storm Paulette located near 20.5N
47.4W 996 mb at 5 PM EDT moving WNW at 9 kt. Maximum sustained
winds 50 kt gusts 60 kt. Paulette will move to 20.9N 48.9W Thu
morning, 21.4N 50.9W Thu afternoon, 21.6N 52.7W Fri morning,
22.3N 54.1W Fri afternoon, 23.3N 55.4W Sat morning, and 24.8N
56.6W Sat afternoon. Paulette will change little in intensity as
it moves to 28.0N 60.5W by Sun afternoon. Large swells associated
with Paulette may spread into the waters east of the Bahamas by
the end of the week through the weekend. Elsewhere, a surface
trough from near Jacksonville, Florida to the Tampa Bay area
will slowly moved westward through the rest of the week.

$$
Aguirre
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