Tropical Weather Discussion
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000
AXNT20 KNHC 171121
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
721 AM EDT Sat Jun 17 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 0600 UTC surface analysis and satellite imagery through
1045 UTC.

...SPECIAL FEATURE...

A tropical wave is along 37W/38W from 11N southward. The wave is
moving westward 10 to 15 knots. A 1009 mb low pressure is along
the tropical wave near 05N. The precipitation has become better
organized during the last 24 hours or so. The chance of formation
into a tropical cyclone during the next two days is medium. Widely
scattered moderate to isolated strong rainshowers cover the area
that is from 04N to 08N between 35W and 44W.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 24W/25W from 11N
southward, moving westward 10 to 15 knots. Widely scattered
moderate to isolated from 10N southward between 20W and 34W.

An Atlantic Ocean tropical wave is along 44W/45W from 15N
southward moving westward 10 knots. A 1011 mb low pressure center
is along the wave near 08N. Scattered moderate to isolated strong
rainshowers are from 09N to 11N between 46W and 50W.

A Caribbean Sea tropical wave is along 75W/76W, from 19N
southward, between Haiti and Jamaica. Scattered to numerous strong
rainshowers are from 15N to 18N, in the SE coastal waters of
Jamaica. Widely scattered moderate to isolated strong rainshowers
cover the are from the Caribbean Sea to the Bahamas, elsewhere,
from 15N to 25N between 70W and 80W, including across Cuba.
The precipitation that covers the area from 15N northward is part
of a larger-scale area of rainshowers with thunder, that is going
to remain in the NW corner of the Caribbean Sea, with a large-
scale area of broad surface low pressure. This weather system
will affect the waters and land areas of the NW corner of the
Caribbean Sea during the next several days.

...MONSOON TROUGH/ITCZ...

The Monsoon Trough passes through the coastal sections of Senegal
near 14N17W, to 09N20W, 07N26W, and 06N37W. The ITCZ is along
04N39W 02N49W. Convective precipitation: scattered to numerous
strong from 07N to 12N between 15W and 17W, possibly with the
next tropical wave. Isolated to widely scattered moderate
elsewhere from 05N to 12N between 10W and 18W. Rainshowers are
possible elsewhere from 10N southward from 60W eastward.

...DISCUSSION...

...THE GULF OF MEXICO...

An upper level trough is along 84W/85W in the Gulf of Mexico.
Upper level cyclonic wind flow covers the Gulf of Mexico.
Upper level anticyclonic wind flow covers Mexico from 100W
westward. Comparatively drier air in subsidence is apparent in
water vapor imagery across the Gulf of Mexico.

A surface ridge extends from a 1015 mb high pressure center that
is near 27N87W, into the SW corner of the Gulf of Mexico, near
the coast of Mexico along 20N. Surface anticyclonic wind flow
spans the entire area.

...CURRENT CONDITIONS AND WEATHER, FOR THE OFFSHORE OIL
PLATFORM SITES, FROM 27N NORTHWARD AND FROM 88W WESTWARD...

LIFR: none.

IFR: none.

MVFR: KVBS, KVAF, and KEMK.

CURRENT CONDITIONS AND WEATHER, FOR THE COASTAL PLAINS OF THE
U.S.A., FROM THE DEEP SOUTH OF TEXAS TO FLORIDA...

Texas: IFR in Hebbronville. MVFR, in patches, from Rockport to Bay
City, and from Tomball to Conroe to Huntsville. LOUISIANA:
MVFR in parts of the SW corner of the state, and from Baton Rouge
to the areas that surround Lake Pontchartrain. ALABAMA: LIFR in
parts of the Mobile metropolitan area. FLORIDA: LIFR in
Tallahassee. MVFR in Perry, with some earlier nearby rainshowers.

...THE CARIBBEAN SEA...

A tropical wave is along 75W/76W, from 19N southward, between
Haiti and Jamaica. Scattered to numerous strong rainshowers are
from 15N to 18N, in the SE coastal waters of Jamaica. Widely
scattered moderate to isolated strong rainshowers cover the are
from the Caribbean Sea to the Bahamas, elsewhere, from 15N to 25N
between 70W and 80W, including across Cuba. The precipitation that
covers the area from 15N northward is part of a larger-scale area
of rainshowers with thunder, that is going to remain in the NW
corner of the Caribbean Sea, with a large-scale area of broad
surface low pressure. This weather system will affect the waters
and land areas of the NW corner of the Caribbean Sea during the
next several days. A surface trough is along 85W/86W from the
coast of Honduras into the Yucatan Channel. Upper level
anticyclonic wind flow covers the Caribbean Sea from 70W westward.
A broad area of low pressure is expected to form in this area
during the next day or two. Scatterometer data have been showing
moderate-to-fresh winds in the wake of a tropical wave that
already has moved inland in Central America. Mainly gentle to
moderate winds are in the NW Caribbean Sea. Wind speeds are
expected to increase, and sea heights will build, across the
central and western Caribbean Sea, during the upcoming weekend.
A tight pressure gradient will exist between the developing low
pressure area and the Atlantic Ocean ridge. Plenty of moisture
and very active weather also are expected with this low pressure
center. It is likely that this weather will be affecting the
western and central Caribbean Sea, Central America, and most of
Cuba during the weekend. It is possible that locally heavy rain
and gusty winds may occur in parts of Cuba, the Yucatan Peninsula
and Central America.

24-hour rainfall totals that are listed for the period that ended
at 17/0000 UTC...according to the PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...are 0.01 in
Tegucigalpa in Honduras.

...HISPANIOLA...

Upper level NW wind flow is moving across Hispaniola.

SURFACE OBSERVATIONS...for Port-au-Prince in Haiti: VFR.
for the DOMINICAN REPUBLIC: Santo Domingo: VFR. La Romana:
VFR. few cumulonimbus clouds. Punta Cana: VFR. Santiago:
VFR. Puerto Plata: VFR.

The GFS MODEL forecast for 250 mb shows that NW wind flow will
move across the area during the next 48 hours. N wind flow is
possible, also, at the end of the 48-hour forecast period. A
Nicaragua-to-Cuba ridge will be to the west of Hispaniola. The
GFS MODEL forecast for 500 mb shows that anticyclonic wind flow
will span the entire area, either with an anticyclonic circulation
center, or with a ridge, during the first 24 to 30 hours. Expect
cyclonic wind flow with an inverted trough for the rest of the
time period. The GFS MODEL forecast for 700 mb shows that SE wind
flow will move across the area during the next 48 hours, with
Hispaniola being on the southern side of an Atlantic Ocean-to-
northern Caribbean Sea ridge.

...THE ATLANTIC OCEAN...

An upper level central Atlantic Ocean trough is anchored by a
cyclonic circulation center that is about 770 nm to the NE of
Puerto Rico, and that ends near NE coastal Venezuela. A NE-to-
SW oriented surface trough is within 180 nm to the south of
stationary front. Isolated moderate rainshowers cover the
Atlantic Ocean from 10N northward between 50W and 70W. Isolated
moderate to locally strong from 07N to 11N between 53W and 61W.

An upper level trough is within 420 nm to 750 nm to the west of
Africa. No significant deep convective precipitation is apparent
in satellite imagery.

A NE-to-SW oriented surface ridge is within 400 nm to 500 nm
to the SE of the 32N/33N stationary front and nearby surface
trough.

A 1020 mb high pressure center is near 27N63W. Surface
anticyclonic wind flow covers the area from 20N northward between
60W and 80W.

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

$$
MT



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