[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281153
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
752 AM 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 0600 UTC surface analysis and satellite imagery through
1115 UTC.

...SPECIAL FEATURES...

T.S. Kirk has moved into the eastern Caribbean Sea, but associated
weather is still spreading across portions of the Lesser Antilles. At
28/0900 UTC, Tropical Storm Kirk is centered near 13.2N 62.5W or
about 85 nm (175 km) WSW of St. Lucia. It is moving toward the
west or 270 degrees at 10 knots. Estimated minimum central
pressure is 1005 mb. Maximum sustained wind speed is 45 knots with
gusts to 55 knots. Kirk is forecast to weaken to a tropical
depression later today or Saturday, and then degenerate into a
trough of low pressure. On the forecast track, Kirk's center, or
its remnants, will move across the eastern and central Caribbean
Sea over the next two or three days. This tropical cyclone 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 240 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. 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 has been added to the 0600 UTC analysis/surface
map near 17W from 04N-17N. Scattered moderate convection is along
the wave axis from 05N-12N between 14W-18W. This system shows up
well in the Total Precipitable Water animation, and coincides
with a 700 mb trough in the GFS analysis. In addition, the
Hovmoller Diagram indicates the westward propagation of the wave.

A second tropical wave near 31W extends from 03N-17N moving W at
10 kt. The wave remains embedded within an area of moisture as
depicted in the TPW animation. No significant convection is
currently associated with the wave.

A third tropical wave near 41W extends from 04N-17N moving W at
10 kt. The TPW imagery shows a maximum E of the wave axis. No
significant convection is currently associated with the wave.

A tropical wave is moving across the Caribbean Sea. Its axis is
near 80W from 20N southward. A pronounced 700 mb trough in the
GFS analysis is noted with the wave, which also coincides with a
north-south moisture maximum. 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 12N15W and
continues SW to near 07N20W, then W to near 06N33W. The ITCZ
extends from 06N33W to 07N40W to 06N50W to near the coast of
Guyana at 06N58W. Scattered moderate and isolated strong
convection is observed from 03N to 07N between 20W and 30W.

...DISCUSSION...

GULF OF MEXICO...

Isolated moderate convection is noted across the Gulf waters
ahead of a stationary front extending from SE Louisiana to NE
Mexico near 25N97W. Scattered moderate convection is also
occurring within 60 nm of the Mexican coast from 18N94W to 25N97W.
Recent scatterometer data provide observations of mainly gentle
easterly winds on either side of the front, forecast to weaken on
Friday as high pressure builds across the Gulf. The high pressure
located NE of the region will support gentle to moderate E to SE
winds and seas less than 4 ft across most of the Gulf waters
through Sunday.

A surface trough is analyzed just west of the Yucatan Peninsula.
Scattered showers are occurring within 120 nm of the trough. A
new surface trough is forecast to develop each evening over the
Yucatan Peninsula before pushing offshore into the SW Gulf each
night. A surge of moderate to fresh winds will accompany the
trough.

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 increasing winds of
20-30 kt over the eastern Caribbean ahead of Kirk, and mainly
moderate to fresh winds across the remainder of the eastern and
central Caribbean while gentle to moderate winds are noted over
the NW Caribbean. 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 Friday
through Sunday, building seas to 10 or 11 ft.

ATLANTIC OCEAN...

Three tropical waves are currently between the coast of Africa and
the Lesser Antilles. A stationary front enters the forecast
region near 31N33W then continues SW to 22N50W to 25N70W. The
front is associated with Post-Tropical Cyclone Leslie, which is
centered N of area near 37N45W with a central pressure of 985 mb.
This system is moving W at 10 kt. Please, see Special Features
Section for more details.

Large swell generated by Post-Tropical Cyclone Leslie, currently
a powerful non-tropical low pressure system with storm-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 1022 mb high pressure located near 36N59W
across the western Atlantic, reaching Florida and the Bahamas.
Another ridge dominates the remainder of the Atlantic E of the
aforementioned cold front.

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

$$
GR/CL
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