[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 260605
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 AM EDT Wed Sep 26 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...

The remnant of Kirk is analyzed as a 1006 mb low near 12N50W or
about 565 nm east of the Windward Islands. A tropical wave
extends from the low to near 17N, and south of the low to near
04N. This system is moving westward at about 22 kt. The associated
shower and thunderstorm activity continues to become better
organized. Scattered moderate to strong convection is within 60
nm of the low in the W quadrant. Scattered moderate convection is
elsewhere within 90 nm of the low, except 120 nm in the N
quadrant. Scattered moderate isolated strong convection is
elsewhere within 150 nm east of the low and wave from 09N to 14N
and within 90 nm east of the wave from 14N to 17N. Similar
convection is elsewhere within 240 nm west of the wave from 08N to
14N, and within 120 nm west of the wave from 14N to 17N. Recent
satellite-derived wind data also indicate that the circulation has
become better defined and that the winds have increased. If this
development trend continues, then advisories will be re-initiated
on this system later this morning. Interests in the Windward and
Leeward Islands should monitor the progress of this disturbance.
An Air Force Reserve reconnaissance aircraft is schedule to
investigate this disturbance later today. There is a high chance
of redevelopment of this system within the next 48 hours. For more
information on this system, see High Seas Forecasts issued by the
National Weather Service.

Post-Tropical Cyclone Leslie is currently centered about 740 nm
west-southwest of the Azores Islands. It is producing gale force
winds. Scattered moderate isolated strong convection is seen from
28N to 33N between 37W and 41W. Scattered moderate convection is
from 33N to 38N between 38W and 42W. Leslie is expected to
reacquire subtropical or tropical characteristics on Thu or Fri
while the cyclone meanders over the north-central Atlantic. There
is a medium chance of of this system becoming a tropical 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 22W from
03N to 17N, moving westward at 10 to 15 kt. Model guidance depicts
a broad 700 mb trough over and near this wave. The satellite-
derived low to mid-level nicely display a NE to SE wind shift
across the wave. Satellite imagery shows  Isolated showers and
thunderstorms are within 150 nm west and 120 nm east of the wave
axis from 11N to 14N.

A tropical wave has is its axis along 50W, with a 1006 mb low on
it near 12n60w. This system is described under the Special
Features section above.

A tropical wave has its axis along 60W south of 19N, moving
westward at 15 kt. This wave is shrouded in a very moist and
unstable environment as observed in satellite imagery and in the
Total Precipitable Water (TPW) satellite animation where it shows
a broad pool of moisture. The moisture is noted to be in the form
of multilayer clouds, with scattered showers and thunderstorms
along the wave, and within 240 nm west of the wave south of 15N.
are underneath these clouds from 08N to 15N between 57W and 62W,
including the Windward Islands. This activity will continue
through at least early this afternoon as a very moist upper
southerly flow remains in place across the eastern Caribbean.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends off the coast of Africa over
Senegal at 13N17W and continues to 10N22W to 08N26W, where latest
scatterometer data indicated the ITCZ begins and continues to
07N31W to near 07N42W. Outside of the convection mentioned with
the two tropical waves and the remnants of Kirk, scattered
moderate convection is within 90 nm north of the ITCZ between
28W-34W. Scattered moderate isolated strong convection is within
90 nm north of the ITCZ between 35W-38W and within 60 nm north
of the ITCZ between 26W-28W. Scattered moderate convection is
within 60 nm south of the ITCZ between 31W-33W.

...DISCUSSION...

GULF OF MEXICO...

A very moist and unstable air mass along with upper-level
diffluence over the north-central Gulf Coast resulted in
scattered showers and isolated thunderstorms north of 27N between
84W-90W last night. This activity has since dissipated.
Scattered showers and thunderstorms moving westward are  over the
eastern Gulf from 26N to 29N east of 84W to the Florida coast.
This activity fired up yesterday evening along the Florida west
coast sea breeze boundary, and has pushed into the eastern Gulf.

A thermal trough over the east- central Bay of Campeche is
weakening and is no longer producing any significant shower
activity. A surface trough will develop over the Yucatan peninsula
each evening, shift W over the SW Gulf each night, then dissipate
each morning. Elsewhere across the Gulf, gentle to moderate winds
will increase to between moderate and fresh during the second
half of this week as high pressure builds N of the region.

CARIBBEAN SEA...

Scattered showers and thunderstorms ahead of a tropical wave that
is approaching the Windward Islands have moved into the far
eastern Caribbean, and are south of 17N east of 64W to across
the Windward Islands. Isolated showers and thunderstorms are
elsewhere over the eastern Caribbean. The eastern Pacific
monsoon trough combined with diffluence aloft earlier enhanced
scattered moderate to isolated strong convection in the SW
Caribbean. Over the past few hours, this activity has diminished
to scattered showers and isolated thunderstorms. Scattered
moderate convection over the interior sections of Honduras and
Nicaragua are gradually diminishing, with the heaviest of this
activity now having shifted to the western sections of those
countries. Expect fresh to strong winds over the central
Caribbean through midweek, with moderate to fresh winds thereafter
through Friday.

ATLANTIC OCEAN...

Currently, there are three tropical waves in the tropical Atlantic
between Africa and the Lesser Antilles. There is also a low with
possible tropical cyclone development potential associated with
along the wave along 50W. For information on those features,
please read the Special Features and Tropical Waves sections
above.

A surface trough is analyzed from just south of a developing
hurricane force wind warning 1000 mb low pressure at 33N43W, south
to 26N45W to 24N50W and to 20N60W. Scattered moderate isolated
strong convection is within 90 to 120 nm east of the trough north
of 25N.

A surface trough extends from 28N29W to 22N30W. Only isolated
showers are within 60 nm of the trough. Otherwise, ridging over
the northeast Atlantic is helping to maintain generally stable
and create fair weather north of 20N and east of 30W.

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

$$
Aguirre
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