Tropical Weather Discussion

axnt20 knhc 230555

Tropical weather discussion
NWS National Hurricane Center Miami FL
155 am EDT sun Sep 23 2018

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 0000 UTC surface analysis and satellite imagery through 
0515 UTC.

...Special features...

Tropical Storm Kirk centered near 9.0n 26.4w at 23/0300 UTC, or
370 nm SSW of the southernmost Cabo Verde islands, moving WNW at
14 kt. Estimated minimum central pressure is 1006 mb. Maximum
sustained wind speed is 35 kt with gusts to 45 kt. Some
strengthening is forecast through Sunday, with little change in 
intensity expected on Monday and Tuesday. Scattered moderate to
strong convection is observed from 08n-11n between 24w-31w. See 
the latest NHC forecast/advisory under AWIPS/WMO headers 
miatcpat2/wtnt32 knhc for more details.

Tropical Depression Eleven centered near 13.8n 54.5w at 23/0300 
UTC, or 380 nm E of the Windward Islands, moving NW at 3 kt. 
Estimated minimum central pressure is 1008 mb. Maximum sustained 
wind speed is 25 kt with gusts to 35 kt. The depression is expected 
to weaken to a remnant low on Sunday and dissipate by Sunday 
night east of the Lesser Antilles. Scattered moderate convection 
is noted from 12n-15n between 51w-55w. See the latest NHC 
forecast/advisory under AWIPS/WMO headers miatcpat1/wtnt31 knhc 
for more details.

Satellite imagery indicates that a frontal non-tropical low 
pressure system is located about 1000 nm west-southwest of the 
Azores. Conditions are expected to become conducive for this low 
to acquire subtropical or tropical characteristics during the next
day or so, and a subtropical or tropical cyclone is likely to 
form by early next week while the low meanders over the central 
Atlantic Ocean. The system has a medium chance of tropical cyclone
formation within the next 48 hours. Please refer to the latest 
tropical weather outlook under AWIPS/WMO headers miatwoat/abnt20 
knhc for more information.

A cold front extends from a 1004 mb low pressure located N of the
area near 34n44w to 31n41w to 25n50w to 28n59w. The most recent 
scatterometer data provide observations of minimal gale-force 
winds N of 29n and within 60 nm south of the front. Seas of 11 to
13 ft are within the area of these winds. These conditions are 
expected through Sunday morning.

...Tropical waves...

A tropical wave has its axis along 44w from 03n-16n and is moving
west at 10-15 kt. The wave corresponds nicely with a maximum in 
tpw imagery. Model analyses depict an associated 700 mb trough 
along 44w. Scattered showers are located near and east of the 
wave axis from 10n-13n between 38w-44w. 

A western Caribbean tropical wave has its axis along 87w from 
09n-21n, moving west around 10 kt. The 700 mb trough associated 
with this wave is well depicted in model guidance, and tpw imagery
shows abundant moisture in its environment. Scattered moderate 
convection is noted south of 20n between 85w-90w. Moisture 
associated with this wave will continue to spread inland across 
Central America through the weekend, enhancing similar convection
across this area.

...Monsoon trough/ITCZ...

The monsoon trough extends from the African coast near 18n16w to 
17n21w. It continues west of T.S. Kirk near 06n28w to 05n33w. The
ITCZ begins near 05n33w to 05n43w, then resumes near 06n46w to
11n53w. Aside from the convection associated with the tropical 
wave and cyclones across the area, scattered showers are located 
along and within 75 nm on either side of the monsoon trough 
between 30w-36w.


Gulf of Mexico...

An upper-level cyclonic circulation is centered near 28n87w. This
feature is enhancing convection across the eastern Gulf waters
mainly along 84w. To the west, a surface trough is analyzed along
91w from 24n-29n. Scattered showers are noted along the trough. A
cold front is entering the northwest Gulf enhancing convection 
north of 25n and west of 95w. This front is likely to stall and 
dissipate today. Gentle to moderate E to se winds and seas 3 ft or
less will prevail across most of the Gulf of Mexico through the 
middle of next week. A surface trough will develop over the 
Yucatan Peninsula each evening, shift W over the SW Gulf each 
night, then dissipate by morning. Moderate to fresh winds will 
accompany this trough. 

Caribbean Sea...

A tropical wave is moving across the far western Caribbean, and a
portion of this wave is entering Central America. Please see the 
tropical waves section for more details.

The eastern Pacific monsoon trough combined with diffluence aloft
continues to enhance convection over portions of Panama and the
waters of the southwest Caribbean from the coasts of Panama and
Costa Rica northward to 13n and eastward to 78w. Plenty of 
moisture will persist over the extreme southwest Caribbean, Panama
and Costa Rica through the weekend. Elsewhere, fresh to strong 
winds prevail over the central Caribbean. These winds will 
diminish across most of the basin by tonight. 

Atlantic Ocean...

Currently, there are two tropical cyclones and a tropical wave
between the West Coast of Africa and the Lesser Antilles. Please 
see the special features and tropical waves sections for more 

A broad 1010 mb low is centered 200 nm south of Bermuda. A 
surface trough runs through the low from 30n62w to the low near 
29n64w to 26n70w. Scattered showers are noted along the trough and
near the low. Unfavorable upper-level winds and dry air are expected 
to limit development tonight and Sunday, but conditions could 
become more conducive for some development of this system on 
Monday or Tuesday while it moves westward and west-northwestward 
over the southwestern Atlantic Ocean. By the middle of next week, 
strong upper-level winds are likely to limit additional 
development as the system turns northward and moves closer to the 
southeastern coast of the United States. This feature has a low 
chance of tropical cyclone formation during the next 48 hours.

The remainder of the basin is under the influence of a surface 
ridge, anchored by a 1027 mb high centered near 39n20w. 

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