AXNT20 KNHC 151045
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
645 AM EDT Thu Aug 15 2019
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
Potential for Heavy to Extreme Rain/Flooding from southern Mexico
to Central America:
Currently: scattered strong rainshowers cover the areas that are
from 05N to 13N between 76W and 86W. This area encompasses
Colombia near its border with Panama, across Panama, to
Nicaragua, and the adjacent coastal waters in the SW Caribbean
Sea and in the eastern Pacific Ocean. A large surge of moisture
will continue across Colombia, Panama, Costa Rica, and southern
Nicaragua during the next 24 to 36 hours. Environmental conditions
remain highly favorable for heavy rains to continue to accumulate,
with higher localized totals near strong topographical forcing.
Earlier rainfall totals: Costa Rica measured nearly 7 inches of
rainfall during the last 24 hours, with 2-4″ of additional rain
in the last 6 hours mostly on the north Caribbean side of the
country. By Friday: the focus of the heavy rainfall will shift
toward the north and northwest, to Nicaragua, El Salvador,
southern Honduras/Guatemala and southern Chiapas in Mexico. Flash
floods and mudslides will be the biggest hazard during this event.
An Atlantic Ocean tropical wave is along 43W/44W, from 19N
southward, is moving westward 10 to 15 knots. This wave is well
depicted in model guidance. Monsoon trough-related precipitation
is nearby, from 10N southward.
A Caribbean Sea tropical wave is along 71W/72W, from central
Hispaniola southward to Lake Maracaibo in Venezuela, is moving
westward 15 to 20 knots. The position of the wave was moved more
to the west, based on the upper air sounding data. Dry Saharan
air prevails in the wave’s environment, inhibiting significant
precipitation at this time.
A Caribbean Sea tropical wave is along 88W, from 19N in the
Yucatan Peninsula, passing through Belize, Honduras, and beyond
El Salvador, into the eastern Pacific Ocean, moving westward 10
knots. Isolated moderate to locally strong rainshowers are in the
Gulf of Honduras. This feature was helping to enhance the
precipitation that has been near the monsoon trough, during the
last 24 hours, in parts of Central America and adjacent waters S
of 15N between 80W and 90W. The SPECIAL FEATURES section gives
more details about a heavy rain event that is happening now and
for the next day or two, from Colombia, across Central America, to
The monsoon trough passes through the coastal sections of Senegal,
just to the north of its border with The Gambia, near 14N17W, to
11N24W 11N30W and 09N47W. Isolated moderate to locally strong
rainshowers are within 60 nm to 120 nm on either side of the line
that extends from 08N14W to 07N27W 08N48W 10N60W. Other isolated
moderate rainshowers are elsewhere from 12N southward from 60W
GULF OF MEXICO…
Upper level anticyclonic wind flow spans the area. The GFS model
shows a 700 mb trough that passes through the Florida Panhandle
toward the SW corner of the Gulf of Mexico. The GFS 500 mb pattern
consists of broad anticyclonic wind flow from 90W westward, and a
trough from the western coast of Florida along 26N northward.
A surface trough extends from the Florida Panhandle to the north
central Gulf of Mexico. A cold front is inland, from central
Georgia to southern Alabama and southern Mississippi. Widely
scattered moderate to isolated strong rainshowers are in the Gulf
of Mexico from 24N northward between Florida and 93W.
The weak cold front, that is in the southeastern U.S.A., will
reach the northern waters of the Gulf of Mexico later this
morning. The front should stall on Friday, before moving to the
north of the area on Saturday morning. Scattered moderate
rainshowers and thunderstorms will continue in the northern half
of the basin through Saturday. Moderate to fresh SW winds are
expected in the NE waters from Thursday through Saturday,
associated with the front. The wind speeds will pulse to fresh in
the western Yucatan Peninsula adjacent waters each evening,
associated with the diurnal surface trough. Surface high pressure
will establish itself elsewhere in the region on Friday, and
prevail through Monday. No tropical cyclone activity is expected
during the next several days.
An upper level trough extends from a cyclonic circulation center,
that is just to the north of the SE Bahamas, toward northern
coastal areas of Colombia. Isolated moderate rainshowers cover the
areas that are from 16N northward from the NE coast of the
Dominican Republic near 69W westward.
The monsoon trough is along 10N73W in northern Colombia, beyond
08N81W in the western half of Panama, and into the eastern
Pacific Ocean. Scattered strong rainshowers cover the areas that
are from 05N to 13N between 76W and 86W. This area encompasses
Colombia near its border with Panama, across Panama, to Nicaragua,
and the adjacent coastal waters in the SW Caribbean Sea and in
the eastern Pacific Ocean.
Broken to overcast multilayered clouds and isolated moderate
rainshowers are from 17N southward between 60W and 70W.
The tropical wave that currently is along 72W, will move across
the western Caribbean Sea on Friday and Saturday. The passage of
the second wave, along with high pressure to the north of the
area, will continue to support fresh to strong winds in the
central and southwest Caribbean Sea through Friday night, and in
the NW Caribbean Sea on Saturday and Sunday. Fresh to strong winds
will resume in the south central basin on Monday evening,
supported by a new tropical wave that will move across the region.
No tropical cyclone activity is expected during the next several
An upper level trough extends from an upper level cyclonic
circulation center that is between the Canary Islands and the
Madeira Archipelago, to a 27N39W cyclonic circulation center,
to a 22N51W cyclonic circulation center, to a third cyclonic
circulation center that is just to the north of the SE Bahamas.
The comparatively greatest concentration of isolated moderate to
locally strong rainshowers is from 23N to 29N between 44W and
54W, and from 24N northward between 70W and 80W. Other
rainshowers are possible, from 20N northward from Florida
eastward, and mostly on the northern side of the trough.
A surface ridge extends from a 1026 mb high pressure center that
is near 34N47W, to 31N55W, to 27N70W, across the Bahamas, to
24N85W in the Gulf of Mexico, and to 25N94W a bit more to the
A surface ridge, extending from the Bermuda High, will persist
across the forecast waters through Monday. This pattern will
maintain mainly gentle to moderate winds north of 22N, and
moderate to fresh winds south of 22N, through most of the period.
Strong winds are expected between the Turks and Caicos Islands
and Hispaniola, at night, through Friday night. No tropical
cyclone activity is expected for the next several days.