Tropical Weather Discussion
Issued by NWS
AXNT20 KNHC 201731
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
131 PM EDT Thu Apr 20 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 1200 UTC surface analysis and satellite imagery through
Subtropical Depression ONE has become Tropical Depression One,
at 20/1500 UTC. The center of T.D. ONE, at 20/1500 UTC, is near
36.1N 40.0W, in the Atlantic Ocean. T.D. ONE is moving northwest,
or 320 degrees, 12 knots. The estimated minimum central pressure
is 996 mb. The maximum sustained wind speeds are 30 knots with
gusts to 40 knots. Please read the PUBLIC ADVISORIES about
Tropical Depression ONE, that are issued under the WMO header
WTNT31 KNHC and under the AWIPS header MIATCPAT1. FORECAST/
ADVISORIES about Tropical Depression ONE are issued under the
WMO header WTNT21 KNHC, and under the AWIPS header MIATCMAT1.
Convective precipitation: widely scattered moderate to isolated
strong is within 180 nm to 240 nm to the NE of the line that
runs from 32N30W to 35N34W 36N42W 37N48W 39N54W. Isolated to
widely scattered moderate from 34N to 38N between 47W and 56W.
The Monsoon Trough passes through the coastal sections of Sierra
Leone near 07N12W to 02N17W. The ITCZ is along 02N19W 03N32W
02N36W. Convective precipitation: widely scattered moderate to
isolated strong from 06N southward between 20W and 35W. Scattered to
numerous strong from 01N southward, to the coast of Brazil, between
46W and 50W.
...THE GULF OF MEXICO...
An upper level cyclonic circulation center is in the SW corner of
the Gulf of Mexico near 22N93W. Cyclonic wind flow covers the
Gulf of Mexico from 27N southward from 89W westward. Convective
precipitation: widely scattered moderate to isolated strong from
25N southward between 83W and 90W
Upper level anticyclonic wind flow covers the area that is from
29N southward from 89W eastward.
A surface ridge passes through SW Georgia, across the Florida
Panhandle, into SE Louisiana, into south Central Texas.
...LOW LEVEL CLOUD CEILINGS AND WEATHER FOR THE OFFSHORE OIL
PLATFORM SITES THAT ARE IN THE AREA WHOSE BOUNDARIES ARE FROM 27N
NORTHWARD AND FROM 88W WESTWARD...
MVFR: KHQI, KEIR, and KVOA.
LOW LEVEL CLOUD CEILINGS AND WEATHER...FOR THE COASTAL PLAINS OF
THE U.S.A. FROM THE DEEP SOUTH OF TEXAS TO FLORIDA...
TEXAS: MVFR in Hebbronville, at the Corpus Christi NAS, in Bay
City, and in Tomball. LOUISIANA: MVFR in Baton Rouge, at the NW
corner of Lake Pontchartrain, at the New Orleans NAS, and in
Galliano. MISSISSIPPI: MVFR in the Hattiesburg metropolitan area.
ALABAMA and FLORIDA: VFR.
...THE CARIBBEAN SEA...
Broad middle level-to-upper level anticyclonic wind flow spans the
Caribbean Sea, to the east of the line that runs from the southern
coast of Cuba that is along 80W, to the central coast of Honduras.
The anticyclonic wind flow is related to a Colombia-to-Eastern
Pacific Ocean ridge that extends beyond 08N/09N along 90W.
Upper level SW wind flow covers the NW corner of the Caribbean
Sea, related to the SW Gulf of Mexico upper level cyclonic
circulation center. Convective precipitation: scattered moderate
to isolated strong from 17N to 19N between 84W and 86W. Broken to
overcast multilayered clouds and other possible rainshowers are
from 16N northward from 80W westward.
Broad surface cyclonic wind flow, in the isobaric pattern, extends
from the Windward Passage into the SW corner of the Caribbean Sea.
Other areas of convective precipitation: widely scattered moderate
to isolated strong from 15N to 20N between 74W and 78W. Scattered
moderate to isolated strong from 10N to 12N between 73W and 78W.
Rainshowers are possible elsewhere, in scattered to broken low
level clouds, across much of the area.
24-hour rainfall totals that are listed for the period that ended
at 20/1200 UTC...according to the PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...0.01 in San Juan in
Puerto Rico, and in Nassau in the Bahamas.
Middle level-to-upper level westerly is moving across the island.
Hispaniola is on the eastern side of a ridge that extends from
Colombia to the Eastern Pacific Ocean near 08N/09N along 90W.
Convective precipitation: isolated moderate in the coastal waters,
and at some coastal observing sites.
SURFACE OBSERVATIONS...for Port-au-Prince in Haiti: VFR. for the
DOMINICAN REPUBLIC: Barahona: VFR. few cumulonimbus clouds. Santo
Domingo: MVFR. ceiling 1800 feet. La Romana: VFR. Punta Cana:
light rain. MVFR. ceiling 1800 feet. Santiago: VFR. earlier nearby
rainshowers have ended for the moment. Puerto Plata: MVFR. ceiling
The GFS MODEL forecast for 250 mb shows that SW wind flow will
cover the area from the start of the 48-hour forecast period,
until about 6 hours to 12 hours from the end of the period. A
ridge will extend from Colombia into the Eastern Pacific Ocean
along 08N90W. The wind flow will shift to the W and NW during the
last 6 hours to 12 hours. The GFS MODEL forecast for 500 mb shows
that NW wind flow will move across Hispaniola during the next
48-hour forecast period. A ridge will be to the west of
Hispaniola. The GFS MODEL forecast for 700 mb shows that broad
anticyclonic wind flow, with a ridge, will span the area.
...THE REST OF THE ATLANTIC OCEAN...
Upper level cyclonic wind flow covers the area from 20N northward
between 20W and 70W. This cyclonic wind flow is moving around the
upper level cyclonic circulation center that is close to T.D. ONE.
A cold front curves through 32N44W to 28N46W 25N53W 26N65W, and
29N74W. Convective precipitation: rainshowers are possible in
areas of scattered-to-broken low level clouds, that are to the
north of the line that passes through 32N39W 25N41W 21N50W 23N60W
A surface ridge extends from 32N22W, to a 1016 mb high pressure
center that is near 24N25W, 14N36W, and 06N53W.
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