[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 270557
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
157 AM EDT Thu Sep 27 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
0545 UTC.

...Special Features...

Tropical Storm Kirk is centered near 13.0N 57.0W at 27/0300 UTC,
or about 150 nm E of Barbados or 255 nm ESE of Martinique, moving
west-northwestward or 285 degrees at 14 kt. The estimated minimum
central pressure has risen to 1002 mb. The maximum sustained wind
speed is 45 kt with gusts to 55 kt. Kirk is under vertical shear
as noted by its low-level center displaced from its deep
convection. This convection consists of the scattered moderate to
strong type intensity within 120 nm north of the center, and
within 90 nm NW and 60 nm NE of the center. Scattered moderate
isolated strong convection is elsewhere from 11N to 15N between
52W and 55W, and within 30 nm of a line from 15N57W to 16N57W to
17N55W. The latest NHC advisory keeps Kirk moving in its current
motion over the over the next few days. On the forecast track,
the center of Kirk will move across the Lesser Antilles within the
tropical storm warning area Thu or Thu evening. Kirk is expected
to produce very heavy rain across the northern Windward and
southern Leeward Islands Thu through much of Fri. These rains may
produce life-threatening flash floods and mudslides. See latest
NHC Forecast/Advisory under AWIPS/WMO Headers MIATCMAT2/WTNT22
KNHC for more details.

Post-Tropical Cyclone Leslie, located over the central Atlantic
Ocean several hundred miles west-southwest of the Azores remains a
powerful non-tropical low with hurricane-force winds. The
associated shower activity is gradually becoming more organized,
and Leslie is expected to again become a subtropical storm, or
possibly a tropical storm, later today or on Fri while it moves
west-southwestward at about 8 kt over the north-central Atlantic.
Latest satellite imagery shows a large shield rain with embedded
scattered to numerous showers to southwest of the low from 32N to
35N between 45W and 50W, and d also within 30 nm either side of a
line from 37N40W to 35N42W to 34N43W. There is a high chance of
this system becoming a tropical or subtropical cyclone during the
next 48 hours. For more information on this system, see High Seas
Forecasts issued by the National Weather Service.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 27W from
03N to 19N, moving westward at 10 to 15 kt. Total precipitable
water (TPW) imagery clearly indicates a maximum in low-level
moisture to the east of this wave. 700 mb guidance from the GFS
has a sharp 700 mb inverted trough over the wave. Isolated
showers and thunderstorms are seen within 180 nm east of the wave
from 06N to 09N, and also from 14N to 19N.

A rather ill-defined central Atlantic tropical wave has its axis
near 38W from 03N to 19N, moving westward at 15 kt. 700 mb
guidance from the GFS depicts a broad 700 mb trough over the
environment of this wave. Recent mid-level satellite winds reveal
a broad inverted trough over the wave, with winds shifting from
northeast to southeast across the wave axis. Scattered showers and
isolated thunderstorms are east of the wave from 08N to 11N
between 33W and 37W. Isolated showers and thunderstorms are in the
vicinity of where the wave axis intersects the ITCZ, roughly from
05N to 08N between 37W and 40W.

A tropical wave has its axis along 75W south of 19N, moving
westward at 15 kt. Scattered showers and isolated thunderstorms
are noted within 120 nm west of the wave south of 13N. Isolated
showers and thunderstorms are within 120 nm either side of the
wave north of 13N.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis briefly extends off the coast of Africa
over Guinea Bissau to near 11N12W. It resumes at 11N24W to 08N30W,
where it transitions to the ITCZ to just west of the tropical
wave near 38W, and resumes west of the same wave at 07N39W
to 06N47W. Outside of the convection mentioned with the two
tropical waves, scattered moderate convection is within 120 nm
south of the ITCZ between 43W and 45W and within 60 nm north of
of the ITCZ between 39W and 41W.

...DISCUSSION...

GULF OF MEXICO...

Earlier scattered moderate convection that was over the much of
the northwestern Gulf has diminished, except recent radar data
shows new scattered new scattered moderate isolated strong
convection developing ahead of a cold front that is over eastern
Texas. This activity is expected to push further into the
northwestern Gulf waters through early this morning. Some of the
activity may produce strong gusty winds and frequent lightning.
The cold front will become stationary along the Texas coast this
morning. Scattered showers and thunderstorms are elsewhere west of
89W, while isolated showers and thunderstorms are east of 89W.

A thermal trough is analyzed over the central Bay of Campeche.
Scattered showers and thunderstorms are near the coast of Mexico
between Veracruz and Tuxpan and over the Gulf south of 21N and
west of 95W.

High pressure to the northeast of the region will support gentle
to moderate east to southeast winds and seas less than 4 ft across
most of the region through Sun. The only exception is locally
fresh winds each night associated with a trough moving over the
eastern Bay of Campeche.

CARIBBEAN SEA...

Instability generated by the eastern Pacific monsoon trough that
protrudes into the far southwestern Caribbean, along with pretty
decent upper-level ventilation continues to allow for scattered
showers and thunderstorms to continue over much of the
southwestern Caribbean south of 14N and west of 77W. Scattered
showers and isolated thunderstorms are over much of the
northwestern Caribbean, and also south of 16N east of 70W,
including the vicinity of Trinidad and Tobago.

Expect fresh to strong trade winds to continue over the south-
central Caribbean through Thu.

ATLANTIC OCEAN...

Tropical Storm Kirk and two tropical waves between Africa and the
Lesser Antilles are described above in the Special Features and
Tropical Waves sections.

A strong cold front and an associated area of gale force winds
extend southward from Post-Tropical Cyclone Leslie, which is
centered well north of the area near 36N39W with a pressure of 978
mb. It is producing hurricane force winds. The cold front enters
the forecast area near 31N33W, and extends southwestward to 25N40W
to 23N50W to 25N59W, then is weakening northwestward to 27N66W. A
pre-frontal trough extends from near 25N36W to 20N43W. Satellite
imagery shows scattered moderate convection along and within 75 nm
east of the front north of 28N, and within 60 nm to the south of
the front between 56W and 66W. Similar convection is along and
within 60 nm north of the front between 44W and 52W. Isolated
showers are along and near the pre-frontal trough. The cold front
is forecast to become stationary from near 29N35W to 23N44W and to
near 21N51W by this afternoon and dissipate by early Fri
afternoon. Large swell generated by the Post-Tropical Cyclone
Leslie low are expected to spread east of 75W by Fri night, and
continue through the weekend. Post-Tropical Cyclone Leslie low is
forecast to again become a tropical or subtropical storm during
the next couple of days. More details are described above under
the Special Features section.

Elsewhere, an upper-level anticyclone, in combination with a very
moist low-level easterly flow, is enhancing isolated showers and
thunderstorms over the southeastern and central Bahamas, northern
Cuba and the Florida Straits. A high pressure ridge extends over
the northwest Bahamas and the waters east of Florida, creating
fair weather north of 25N west of 75W.

For additional information please visit
http://www.hurricanes.gov/marine

$$
Aguirre
This weather bulletin was brought to you by:
www.nashvilleweather.net