AXNT20 KNHC 201804
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
204 PM EDT THU OCT 20 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 1200 UTC surface analysis and satellite imagery through
An elongated area of surface low pressure is about 200 nm to the
NE of the Central Bahamas, moving northwestward about 10 mph.
This system has become slightly better organized since yesterday.
It is possible, still, that it may become a subtropical or
tropical cyclone before it merges with a cold front that is
forecast to be in the western Atlantic Ocean on Friday night. A
NOAA reconnaissance aircraft is scheduled to investigate the area
this afternoon. It is possible that locally heavy rainfall may
reach parts of Hispaniola today. The chance of formation into
a tropical cyclone is medium. An upper level trough extends from
the Atlantic Ocean near 31N71W to 25N73W, into the NW corner of
the Caribbean Sea, to the coast of Mexico and Belize. Convective
precipitation: scattered strong from 16N to 19N between 68W and
74W around Hispaniola. Widely scattered moderate to isolated
strong in the Atlantic Ocean from 20N to 30N between 63W and 70W,
and from 27N to 30N between 70W and 75W, and from 24N to 32N
between 55W and 62W. Surface low pressure covers the Atlantic
Ocean from 20N northward from 60W westward.
An Atlantic Ocean tropical wave is along 40W from 16N southward,
moving westward 10 to 15 knots. Convective precipitation:
widely scattered moderate to isolated strong, and mixed with
Monsoon Trough precipitation, from 08N to 13N between 33W and
The Monsoon Trough passes through the coastal sections of Guinea-
Bissau near 12N16W, to 09N23W 09N37W 08N43W. Convective
precipitation: scattered strong from 09N to 10N between 41W and
43W, and from 11N to 12N between 44W and 45W. Rainshowers are
possible elsewhere from 18N southward between 10W and 46W.
...THE GULF OF MEXICO...
Upper level anticyclonic wind flow spans the Gulf of Mexico.
Comparatively drier air in subsidence is apparent in water vapor
imagery from 93W eastward. Broad surface anticyclonic wind flow
covers the area from 93W eastward.
Upper level cyclonic wind flow extends from the Atlantic Ocean,
across Florida, into the SE corner of the Gulf of Mexico. This
cyclonic wind flow is a result of an upper level trough that
extends from 31N71W to 25N73W, into the NW corner of the Caribbean
Sea, near the coast of Mexico and Belize.
A surface trough is in the Texas coastal plains, in advance of a
cold front that is moving through central Texas at this moment.
Convective precipitation: scattered moderate to isolated strong
within 90 nm of the Texas coast. A second surface trough is in the
SW corner of the Gulf of Mexico, from the deep south of Texas to
the northern part of the Isthmus of Tehuantepec of southern
Mexico. Convective precipitation: isolated moderate within 60 nm
to 90 nm of the coast from Texas to 20N91W.
...FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE IN THE AREA WHOSE
BOUNDARIES ARE FROM 27N NORTHWARD AND FROM 88W WESTWARD...
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 Port Isabel. light rain in Harlingen. rainshowers
and thunder in Huntsville. light rain at the Houston Hobby
Airport. MVFR at the Houston Intercontinental Airport. LOUISIANA:
MVFR in Lake Charles and Lafayette. MISSISSIPPI/ALABAMA/FLORIDA:
...THE CARIBBEAN SEA...
Upper level cyclonic wind flow covers the area to the W and NW
of the line from 20N70W and the Dominican Republic, to 16N73W,
to eastern sections of Honduras. This cyclonic wind flow is
related to the upper level trough that is described in the Special
Features section that is at the beginning of this bulletin. Some
of this cyclonic wind flow also is spilling over into the SE
corner of the Gulf of Mexico.
Upper level cyclonic wind flow is reaching parts of the eastern
Caribbean Sea, at the edge of the cyclonic wind flow that is
moving around an Atlantic Ocean 10N53W cyclonic circulation
center. Comparatively drier air in subsidence is apparent in water
vapor imagery in the area of the cyclonic wind flow.
24-HOUR RAINFALL TOTAL IN INCHES FOR THE PERIOD ENDING AT
20/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...1.89 in Tegucigalpa
in Honduras; 0.25 in Guadeloupe; 0.03 in Nassau in the Bahamas and
in St. Thomas in the Virgin Islands; and 0.01 in Merida in
Please refer to the Special Features section, that is at the
beginning of this bulletin, for more information about an Atlantic
Ocean low pressure center and related rainfall. It is possible
that locally heavy rainfall may reach parts of Hispaniola today.
An upper level trough extends from the Atlantic Ocean near 31N71W
to 25N73W, into the NW corner of the Caribbean Sea, to the coast
of Mexico and Belize. Convective precipitation: scattered strong
from 16N to 19N between 68W and 74W around Hispaniola. Upper level
SW wind flow is moving across Hispaniola.
SURFACE OBSERVATIONS...FOR PORT-AU-PRINCE IN HAITI: rain for the
last several observations. FOR THE DOMINICAN REPUBLIC...Barahona:
VFR/no ceilings; few cumulonimbus clouds. Santo Domingo:
rainshowers and thunder. La Romana: rainshowers and thunder...
temporarily MVFR for the last observation. Punta Cana:
rainshowers. Santiago: MVFR. Puerto Plata: VFR/no ceilings;
few cumulonimbus clouds.
The GFS MODEL forecast for 250 MB shows that SW wind flow for most
of day one eventually will become W wind flow, with a Caribbean
Sea ridge. Anticyclonic wind flow will cover the entire area
during day two. The GFS MODEL forecast for 500 MB shows that SW
wind flow will move across the area for the next 48 hours.
The GFS MODEL forecast for 700 MB show that S to SW wind flow will
move across the area during day one, eventually become purely SW
wind flow. Day two will consist of more SW wind flow, becoming
anticyclonic with a ridge by the end of day two.
...THE ATLANTIC OCEAN...
An upper level cyclonic circulation center is near 10N53W. Upper
level cyclonic wind flow covers the Atlantic Ocean from 03N to 20N
between 45W and 63W. A surface trough is along 22N47W 20N50W
18N51W 14N52W. Convective precipitation: isolated moderate to
locally strong is in the Atlantic Ocean from 05N to 14N between
46W and 54W.
An upper level trough extends from 35N27W to a 29N40W cyclonic
circulation center. Upper level cyclonic wind flow covers the
Atlantic Ocean from 22N northward between 20W and 44W. A surface
trough is along 32N29W 27N38W 25N47W. Convective precipitation:
rainshowers are possible to the N and NW of the line that passes
through 32N23W 21N38W 23N53W.
For additional information please visit