[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172349
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
749 PM EDT SAT SEP 17 2016

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 1800 UTC surface analysis and satellite imagery through
2330 UTC.

...SPECIAL FEATURES...

Tropical Depression Julia is centered near 30.5N 76.3W at 17/2100
UTC or about 235 nm southeast of Charleston, South Carolina.
Julia is slowly drifting toward the northwest. Estimated minimum
central pressure is 1010 mb. Maximum sustained wind speed is 25 kt
with gusts to 35 kt. Scattered moderate convection exists within
180 nm of the center in the eastern semicircle.  Please see the
latest NHC Forecast/Advisory under the AWIPS/WMO headers
MIATCMAT1/WTNT21KNHC for more details.

Tropical Storm Karl is centered near 18.1N 40.4W at 17/1500 UTC
or about 1225 nm east of the Leeward Islands moving west at 11
kt. Estimated minimum central pressure is 1005 mb. Maximum
sustained wind speed is 40 kt with gusts to 50 kt. Scattered
moderate and isolated strong convection exists within 240 nm of
the center in northeastern semicircle. Please see the latest
Forecast/Advisory under the AWIPS/WMO headers MIATCMAT2/WTNT22
KNHC for more details.

A surface low is located at 13N20W a couple hundred nm southeast
of the Cabo Verde Islands. The low is associated with a tropical
wave extending near the 20W longitude from roughly 09N to 17N.
Isolated moderate to strong convection is occurring from 09N-16N
from 24W eastward to the West Africa coast.  Environmental
conditions appear conducive for development, and a tropical
depression could form by early next week while this system moves
westward to west-northwestward across the eastern tropical
Atlantic. This system is likely to bring heavy rain and gusty
winds to portions of the Cabo Verde Islands during the next couple
of days. This system has a medium chance of tropical formation
within the next 48 hours.

...TROPICAL WAVES...

A tropical wave extends across the central Tropical Atlantic
with axis near the 58W longitude extending approximately from 11N
to 21N. The wave is moving toward the west at about 10 to 15 kt.
The wave coincides with a 700 mb inverted trough depicted by model
guidance and is identified by the SUNY-ALBANY trough diagnostics.
However, no convection or significant surface features are associated
to this feature at this time.

...ITCZ/MONSOON TROUGH...

The Monsoon Trough extends from the wave/low described above
centered near 13N20W to 14N34W. Aside from the convection related
to the tropical wave, scattered moderate convection is observed
within 300 nm south of the boundary between 22W-31W.

...DISCUSSION...

GULF OF MEXICO...

A mid-level trough extends near the Texas coastline from 27N97W
to 30N95W. Associated with this trough is a weak 1014 mb surface
low near 28N95W. As observed from satellite and radar, scattered
moderate convection exists north of 26N between 90W and 95W. The
remainder of the Gulf has no significant deep convection. To the
southwest, a thermal surface trough extends across the Bay of
Campeche from 23N93W to 19N95W. Winds are generally weak across
the Gulf veering from 5-10 kt east to southeast winds in the
eastern Gulf to 10-15 kt south to southwest winds in the western
Gulf. A similar weather pattern will prevail through the next 48
hours.

CARIBBEAN SEA...

A vigorous upper-level low is centered over the northeastern
Caribbean near 17N63W and it is associated with the surface
trough extending from 20N62W to 13N64W. Scattered moderate
convection is occurring on the east side of the upper low/surface
trough from 12N to 16N between 59W and 63W. Enhanced diurnal
convection has been occurring over the Greater Antilles and and
Central America during the late afternoon hours. Elsewhere no
significant deep convection is occurring over the Caribbean. The
easterly tradewinds are generally 10-20 kt, except 20 to 25 kt
just north of Colombia and in the Gulf of Venezuela. The upper-low
and trough should push westward and weaken during the next couple
of days. They will also be interacting with a tropical wave that
will be entering the Caribbean on Sunday, continuing the
likelihood of scattered moderate and isolated strong convection
in the Lesser Antilles, Puerto Rico, and Hispaniola for the next
couple of days.

...HISPANIOLA...

Only isolated moderate convection occurred over the island this
afternoon. However, the interaction of a tropical wave with an
upper low/surface trough will enhance the chances of scattered
moderate and isolated strong convection over Hispaniola during the
next couple of days.

ATLANTIC OCEAN...

Tropical Depression Julia and Tropical Storm Karl are occurring
over the Atlantic this evening. Please see the Special Features
section above for details. A surface trough extends across the
west-central Atlantic from 24N69W to 31N59W. Scattered moderate
convection is occurring with 240 nm southeast of the trough axis.
The trough should move westward without much change during the
next couple of days.  The east Atlantic is dominated by a surface
ridge anchored by a 1029 mb high centered near the Azores at
37N26W. Except near the tropical cyclones, the trade winds are
generally 10-20 kt across the tropical North Atlantic.

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

$$
LANDSEA
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