[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281741
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
141 PM EDT Fri Sep 28 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 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...SPECIAL FEATURES...

T.S. Kirk is weakening over the eastern Caribbean Sea. At 28/1500
UTC, Tropical Storm Kirk is centered near 13.8N 63.6W or about 160
nm (295 km) WSW of Martinique. It is moving toward the west-
northwest or 285 degrees at 11 knots. Estimated minimum central
pressure is 1007 mb. Maximum sustained wind speed is 40 knots
with gusts to 50 knots. Kirk is forecast to weaken to a
tropical depression tonight, and then degenerate into a trough of
low pressure on Saturday. On the forecast track, the center of
Kirk or its remnants will move across the eastern and central
Caribbean Sea over the next day or two. Kirk is expected to
produce total rainfall of 4 to 6 inches across the northern
Windward and southern Leeward Islands with isolated maximum totals
up to 10 inches across Martinique and Dominica. These rains may
produce life-threatening flash floods and mudslides. Across Saint
Croix and eastern Puerto Rico, Kirk is expected to bring 2 to 4
inches with isolated maximum totals of 6 inches today and
Saturday. Scattered moderate and isolated strong convection is
observed within 180 nm in the eastern semicircle. Please read the
latest NHC Forecast/Advisory under AWIPS/WMO Headers
MIATCMAT2/WTNT22 KNHC for more details.

Post-Tropical Cyclone Leslie is located over the central Atlantic
Ocean, several hundred miles west of the Azores.  Shower activity
has gradually increased near the center of the cyclone since last
night and Leslie is expected to once again become a subtropical
storm later today or tomorrow.  Earlier satellite data indicated
that the powerful low is producing storm-force winds that extend
several hundred miles from the center, and Leslie will likely
continue producing strong winds and high seas over a large portion
of the central Atlantic for the next few days regardless of when it
completes its transition to a subtropical storm. Scattered
moderate convection is observed within 180 nm of the center. For
more information on this system, see High Seas Forecasts issued by
the National Weather Service under AWIPS header NFDHSFAT1, and
WMO header FZNT01 KWBC.

...TROPICAL WAVES...

A tropical wave is near 19W from 03N-19N. Scattered moderate
convection is within 180 nm east of the wave axis south of 07N. This
system shows up well in the Total Precipitable Water animation,
and also has a sharp trough at the surface as seen by the ASCAT
scatterometer pass.

A second tropical wave near 45W extends from 02N-17N moving W at
10-15 kt. The TPW imagery shows a maximum E of the wave axis and
there is a trough in the GFS 700 mb analyses, but little signature
is seen at the surface. No significant convection is currently
associated with the wave.

A tropical wave is moving across the Caribbean Sea, near 81W from
21N southward. A pronounced 700 mb trough in the GFS analysis is
noted with the wave, but little signature of the wave is seen at
the surface. The wave, along with the monsoon trough, is helping
to induce scattered moderate and isolated strong convection within
180 nm of the wave axis south of 14N.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean near 14N17W and
continues SW to near 05N30W. The ITCZ extends from 05N30W to
07N52W and becomes indistinct farther west. Scattered moderate
and isolated strong convection is observed from 04N to 07N
between 18W and 28W.

...DISCUSSION...

GULF OF MEXICO...

A stationary front is located in the extreme NW Gulf waters from
the just offshore the Texas-Mexico border to Louisiana. A trough
extends southward from the end of the front near the Texas-Mexico
border to 19N95W. Scattered moderate convection is occurring
within 120 nm of these boundaries. Currents winds across the Gulf
are moderate breeze or weaker out of the east, as a weak ridge is
in place over the SE United States. The frontal boundary should
dissipate by Saturday with little change to the winds during the
next couple of days. Seas will remain below 8 ft through Sunday.

CARIBBEAN SEA...

Tropical Storm Kirk will bring strong winds and heavy rain over
portions of the Lesser Antilles during the day. Please, see
Special Features section for details. A tropical wave is moving
across the western Caribbean Sea. See Tropical Wave section for
details. Recent scatterometer data indicate generally easterly
moderate breeze or weaker winds ahead of Kirk, except for an
outflow boundary enhancement of winds to 25 kt in the southwestern
Caribbean Sea.  As tropical cyclone Kirk weakens over the
Caribbean Sea, expect mainly moderate to fresh winds through early
next week. Large northerly swell associated with Post-Tropical
Cyclone Leslie will affect the tropical Atlantic waters today
through Sunday, building seas to 10 or 11 ft.

ATLANTIC OCEAN...

Two tropical waves are currently between the coast of Africa and
the Lesser Antilles. A stationary front enters the forecast region
near 31N40W then continues SW to 22N59W. From there the feature is
a dissipating stationary front to 25N72W. The front is associated
with Post-Tropical Cyclone Leslie, which is centered N of area
near 37N46W with a central pressure of 992 mb. This system is
moving W at 9 kt. Please, see Special Features Section for more
details.

Large swell generated by Post-Tropical Cyclone Leslie, currently
a very large non-tropical low pressure system with gale-force
winds, is expected to propagate across the waters east of 75W by
tonight, reaching the Bahamas, the waters N of Hispaniola and the
Atlantic Passages E of la Mona Passage by early Saturday, and the
north and central coast of Florida later on Saturday.

A ridge extends from a 1023 mb high pressure located near 33N64W
across the western Atlantic reaching Florida. Another ridge
dominates the remainder of the Atlantic E of the aforementioned
cold front.

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

$$
CL
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