[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 102305
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sun Sep 11 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 1800 UTC surface analysis and satellite imagery through
2245 UTC.

...TROPICAL WAVES...

An eastern Atlantic tropical wave has its axis extending from
21N31W to 10N34W to 04N34W. It is moving westward at 15-20 kt.
Scattered moderate convection is within 180 east of the wave from
12N to 14N, within 120 nm west of the wave from 10N to 14N and
also west of the wave from 05N to 07N between 35W-40W.

A central Atlantic tropical wave has its axis extending from
23N52W to 16N53W and to 10N54W. It is moving westward at
about 15 kt. No convection is noted at this time with this
tropical wave as it moving through a very dry and stable
surrounding environment.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coastal plains of
Mauritania near 17N16W and extends southwestward to 09N30W
and to 08N39W, where latest scatterometer data indicates that
it transitions to the ITCZ to 09N50W and to 11N59W. Outside of
any convection referenced in the tropical wave section above,
numerous moderate to isolated strong convection is from 08N
to 15N between 15W-18W. Scattered moderate convection is
within 180 nm south of the ITCZ between 48W-52W and within 60
south of the ITCZ between 52W-55W.

GULF OF MEXICO...

A mid to upper-level trough extends from the central U.S.
southward to mid to upper-level level near 28N93W and continues
south to inland Mexico near 18N93W. This features supports a
surface trough that extends from just south of southeastern
Louisiana to 25N90W and to 23N93W. Upper-level divergence to the
east of the mid to upper-level trough combined with high amounts
of atmospheric precipitable water is resulting in numerous
moderate to isolated strong convection over just about the entire
eastern Gulf as well as over the eastern part of the central
Gulf. This convective activity has moved inland most of central
and northern Florida. Similar convection lifting north-northeastward
is over the Yucatan Channel and waters just northeast of the
northeast tip of the Yucatan Peninsula. No precipitation is
occurring in the western Gulf and in the west-section of the
central Gulf where skies are generally fair under dry sinking
air.

The gradient between the aforementioned surface trough over the
central Gulf and higher pressure over the western Atlantic is
leading to fresh to locally strong southerly winds and seas of
3-6 ft over the eastern Gulf, mainly east of 87W. Gusts to
25-30 kt were recently reported by a couple of east Gulf
buoys. Over the western half of the Gulf, light to gentle and
variable winds prevail along with seas around 1 ft.

For the forecast, the surface trough that extends from just
south of southeastern Louisiana to 25N90W and to 23N93W will
linger through the middle of next week before dissipating. Fresh
to near gale force SW winds ahead of the trough and in deep
convection will continue to affect mainly the east-central and
southeastern part of the Gulf through the remainder of the
weekend. Areas of scattered to numerous showers and thunderstorms
are expected to continue east of the trough. Otherwise, light to
gentle variable winds are forecast Mon and Tue, increasing to
moderate speeds west of 90W Wed through Thu night.

CARIBBEAN SEA...

Upper-level divergence is ahead of the Gulf of Mexico mid to
upper-level trough, and is combining with enhanced moisture that
is present over the far western Caribbean Sea. As a result,
scattered moderate and isolated strong convection is occurring
west of 86W in the NW Caribbean, including over the western
portion of the Yucatan Channel. Clusters of scattered moderate to
strong convection are noted in the southwestern Caribbean mainly
enhanced by the eastern Pacific monsoon trough that extends into
the far southwestern Caribbean Sea. Low pressure of 1010 mb is
along the trough near 10N79W. Scattered showers and thunderstorms
are elsewehre west of 79W. Elsewhere, patches of low clouds
moving westward with the trade wind flow are evident, particularly
from 14N to 18N. Isolated to scattered showers are possible with
these clouds. Scattered showers and thunderstorms are over the
interior sections of Hispaniola, Puerto Rico and Cuba.

High pressure ridging is north of the Greater Antilles. Latest
ASCAT data passed show generally moderate to fresh east winds
over the south-central Caribbean. Moderate to locally fresh
southeast winds are over the northwestern Caribbean. Moderate
trade winds are elsewhere, except for light to gentle in the far
SW Caribbean. Seas are 4-6 ft in the south-central Caribbean,
and 2-4 ft elsewhere.

For the forecast, mainly moderate east to southeast winds will
continue across the basin through Sun night, except for fresh to
locally strong winds in the south-central Caribbean and Gulf of
Honduras where winds will be fresh to strong at night. Trade
winds are forecast to increase to fresh speeds in the eastern and
central Caribbean Tue through Thu as a tropical wave moves
across the area. Northerly swell will propagate through the
Atlantic passages early on Tue, and will gradually subside late
Wed.

ATLANTIC OCEAN...

What was earlier Hurricane Earl well north of the discussion
area is now a large extra-tropical cyclone near 44N53W.

A cold front is analyzed from near 31N58W to 30N65W and northwest
to 31N72W. The cold front is supported by a broad upper-level
trough that is digging east-southeastward. Moderate to fresh
north winds and seas of 6-8 are north of the front per latest
ASCAT and altimeter data passes. Fresh southwest winds are
within 300 nm east of the front north of 29N. Scattered moderate
convection is along and within 150 nm southeast of the front. An
area of rain with embedded scattered showers and possible
isolated thunderstorms is southeast of the scattered moderate
convection from 24N to 29N between 54W-57W.

Relatively weak high pressure of 1019 mb analyzed near 23N59W
has a ridge extending from it west-northwestward to the NW
Bahamas and east-northeastward to 25N52W. A surface trough
extends from 28N50W to 24N52W. The trough is moving north-
northward. An area of scattered showers and isolated thunderstorms
lifting northward is noted to the northeast of the trough from
28N to 31N between 44W-49W. Farther east, a 1023 mb high is
located near 28N34W. A ridge extends from the high eastward to
28N24W, and northeastward to a weak high of 1017 mb north of the
area at 33N33W. A ridge extends west-northwest from the high to
near 34N46W.

The highest seas in the area are in the 8-11 ft range from
29N-31N between 53W-60W, and from 23N-31N between 45W-53W. These
seas are the result of swell that was generated from former
tropical cyclone Earl, and the surface trough along that extends
from 28N50W to 24N52W. An area of fresh trade winds with 7-8 ft
seas is from 15N-25N between 23W-40W.

For the forecast west of 55W, the weak high pressure that
extends from a 1019 mb high near 23N59W west-northwestward
to the NW Bahamas will change little through Sun. The
aforementioned cold front is will reach from near 27N55W to
25N66W Sun afternoon, and dissipate on Mon. Northeasterly swell
will follow the front, and spread across the area waters Sun
through Tue, then decay on Wed.

$$
Aguirre
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