AXNT20 KNHC 150605
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 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 0000 UTC surface analysis and satellite imagery through
A large surge of moisture will continue across 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. Costa Rica has received 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 northward, 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 42W/43W, from 12N
southward, is moving westward 10 to 15 knots. This wave is well
depicted in model guidance. Monsoon trough-related precipitation
A Caribbean Sea tropical wave is along 67W/68W, from the Mona
Passage southward to Venezuela, is moving westward 15 to 20 knots.
Dry Saharan air prevails in the wave’s environment inhibiting
significant precipitation at this time.
A Caribbean Sea tropical wave is along 86W/87W, from 19N in the NW
corner of the Caribbean Sea, across Honduras and beyond Nicaragua,
moving westward 10 knots. This feature is helping to enhance the
precipitation that is near the monsoon trough, in parts of Central
America and adjacent waters S of 15N between 80W and 90W. Isolated
moderate rainshowers are in NE Nicaragua. 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 to
Nicaragua, in Central America.
The monsoon trough passes through the coastal sections of
Mauritania near 19N16W, to 12N25W and 08N45W. The ITCZ continues
from 08N45W, to NW French Guiana near 05N54W. Isolated moderate to
locally strong rainshowers are within 60 nm to 120 nm on either
side of the line that extends from 08N14W to 07N26W 09N31W 07N42W
08N47W 10N60W. Other isolated moderate rainshowers are from 12N
southward from 60W eastward.
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 is in the Florida Panhandle. A stationary front
is inland, passing through South Carolina to southern Mississippi
and central Louisiana. Widely scattered moderate to isolated
strong rainshowers are in the Gulf of Mexico from 26N northward
between Florida and 90W. Isolated moderate rainshowers are in
Mexico, from 20N southward between 90W and 100W.
The frontal boundary that is in the south and southeast U.S.A.
will reach the northern waters of the Gulf of Mexico on Thursday
morning. The front will 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 Saturday, and
prevail through Monday.
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 15N northward from Haiti westward.
The monsoon trough is along 09N/10N from 74W in Colombia, beyond
86W in the eastern Pacific Ocean. Numerous strong rainshowers from
04N to 10N between 75W and 80W, in Colombia and Panama, in
adjacent coastal waters of the SW Caribbean Sea, and in the
eastern Pacific Ocean, and in the Caribbean Sea from 10N to 12N
between 78W and 82W.
Broken to overcast multilayered clouds and isolated moderate
rainshowers are from 17N southward between 60W and 70W.
The 87W tropical wave will move out of the western Caribbean Sea
tonight. The second tropical wave, currently along 67W, will move
across the central Caribbean Sea on Thursday, and 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 Fri 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 32N between 42W and 51W,
and from 23N to 26N between 74W and 76W. Other rainshowers
possible, from 20N northward from Florida eastward, and mostly on
the northern side of the trough.
A surface ridge extends from a 1027 mb high pressure center that
is near 34N47W, to 30N57W, to SE Cuba.
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. No tropical cyclone
activity is expected for the next several days.