[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 062359
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
759 PM EDT Wed Sep 6 2017

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
2300 UTC.

...SPECIAL FEATURES...

The center of Hurricane Irma, at 07/0000 UTC is near 18.8N 65.4W,
or about 30 nm NW of St. Thomas, and about 45 nm ENE of San Juan
Puerto Rico. Irma is moving WNW or 295 degrees, at 14 knots. The
estimated minimum central pressure is 914 mb. The maximum
sustained wind speeds remain 160 kt with gusts to 195 kt. Irma is
the strongest hurricane to be in the Atlantic basin outside of the
Caribbean Sea and the Gulf of Mexico. Irma has a well defined eye
about 25 NM in diameter. Numerous moderate and scattered strong
convection is observed in the eastern semicircle within 150 nm and
in the western semicircle within 90 nm. Scattered moderate and
isolated strong convection is seen elsewhere in the eastern
semicircle within 240 nm and in the western semicircle within 150
nm. Please read the latest NHC Intermediate Public Advisory under
AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC and, the Forecast/
Advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more
details.

The center of newly upgraded Hurricane Jose, at 07/2100 UTC is
near 13.9N 45.8W, or about 905 NM E of the Lesser Antilles. Jose
is moving WNW, 285 degrees, at 15 knots. The estimated minimum
central pressure is 994 mb. The maximum sustained wind speeds are
now 65 kt with gusts to 80 kt. Numerous moderate and isolated
strong convection is present within 60 nm of the center and within
30 nm of 12.5N47.5W. Scattered moderate convection is present
elsewhere from 12N to 17N between 44W and 48W. Please read the
latest Forecast/Advisory under AWIPS/WMO headers MIATCMAT2/WTNT22
KNHC for more details.

The center of newly upgraded Hurricane Katia, at 07/0000 UTC, is
in the SW Gulf of Mexico near 21.7N 94.9W, or about 170 nm E of
Tampico, Mexico, moving SE or 135 degrees, at 3 knots. The
estimated minimum central pressure is 992 mb. The maximum
sustained wind speeds are 65 kt with gusts to 80 kt. Numerous
moderate and scattered strong convection is found within 30 nm of
the center. Scattered moderate and isolated strong convection is
taking place elsewhere from 20N to 24N between 90W and 98W. Please
read the latest NHC Forecast/Advisory under AWIPS/WMO headers
MIATCMAT3/WTNT23 KNHC for more details.

...TROPICAL WAVES...

A tropical wave is off the coast of W Africa. Its axis extends
from 15N27W to low pres 1012 mb centered near 08N28W to 03N28W,
moving W around 15 kt. SSMI TPW imagery shows the wave is embedded
in an area of deep layer moisture. The wave is also coincides
with well defined troughing at 700 mb. Moderate convection is
present from 04N to 06N between 31W and 34W and from 10N to 12N
between 32W and 34W.

A tropical wave over the western Caribbean has an axis extending
from near the western tip of Cuba at 23N84W to just SW of Costa
Rica near 09N84W, moving W around 15 kt. TPW satellite imagery
indicates this wave has limited moisture to work with, probably as
a result of interaction with an upper-level low centered near
15N81W. The wave is collocated with modest troughing at 700 mb in
initial model wind fields. There is no significant convection
currently associated with this wave.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from Mauritania on the African coast
near 19N16W to 17N20W to low pres 1012 mb near 08N28W to 06N32W.
Aside from the convection associated with the Atlantic tropical
wave, widely scattered moderate convection is present from 05N to
07N between 17W and 21W.

...DISCUSSION...

GULF OF MEXICO...

Newly upgraded Hurricane Katia is drifting SE over the SW Gulf of
Mexico. See the special features section above. Farther N, a cold
front extends SW from the Florida Panhandle near 30N85W to
28N91W. Scattered moderate convection is seen along and up to 150
nm SE of the front. In the upper levels, an upper level trough
touches the northern Gulf coast from Louisiana to the Florida
Panhandle. Otherwise, high pressure dominates the Gulf. Upper
level divergence SE of the trough is enhancing diurnal convection
Florida and the NE Gulf. Expect Katia to intensify gradually and
slowly meander over the SW Gulf for the next two to three days.
Also expect increased convection over S Florida and the Straits of
Florida over the next 24 hours.

CARIBBEAN SEA...

Hurricane Irma remains a formidable major hurricane just to the
ENE of San Juan Puerto Rico. See Above. A tropical wave is also
over the W Caribbean. See above. In addition, the eastern portion
of the E Pacific monsoon trough traverses Costa Rica and Panama
and intersects the tropical wave. Convection associated with the
tropical wave is confined to latitudes over or south of Panama and
Costa Rica. In the upper levels, an upper-level trough crosses
the Caribbean from eastern Honduras to eastern Cuba. Winds
converging in the vicinity of the trough are inhibiting convection
over virtually all of the basin.

...HISPANIOLA...

Cloudiness and convection associated with Hurricane Irma is
rapidly approaching with Hurricane warnings already in effect for
N Hispaniola. The core of Irma is expected to miss Hispaniola, but
expect windy and rainy weather to affect the island through
Friday morning. See Special Features for more details.

ATLANTIC OCEAN...

Major Hurricane Irma and Hurricane Jose are both over the
Atlantic. A tropical wave is also passing over the eastern
Atlantic. See above. Scattered moderate and isolated strong
convection is occurring over the W Atlantic N of 30N between 69W
and 73W due to the cold front approaching the coastlines of
Georgia and South Carolina. A 1033 mb high is centered over the
eastern Atlantic just N of the Azores near 42N26W. A slightly
weaker 1031 mb high is centered over the central Atlantic near
39N46W. The enhanced pressure gradient between ridging on the
south side of these highs and low pressure associated with Irma
and Jose is generating fresh to locally strong trades from 15N to
23N between 35W and 55W and from 18N to 26N between 55W and 65W.

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

$$
McElroy
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