376
FXCA20 KWBC 031513
PMDCA

Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
1113 AM EDT Fri Oct 03 2025

Forecast Bulletin 3 October 2025 at 1515 UTC:

On Friday, Central America and portions of Colombia are expected
to see effects of an amplified circulation that is occurring due
to the entrance of an Easterly Wave over Costa Rica, interacting
with the monsoon trough. With the available moisture in the
region, long fetch onshore flow are expected to bring moderate
precipitation from El Salvador, through Costa Rica, and into the
western coasts of Colombia. Expect maxima of 30-60mm in Colombia,
and maxima of 20-45mm from Costa Rica to the Azuero Peninsula. On
Saturday, the Easterly Wave progresses eastward to Honduras and
into Nicaragua and west Costa Rica. The wave will continue to
favor onshore flow into the Pacific basins of the Gulf of Fonseca
region into Costa Rica and Panama. The monsoon trough is acting as
a moisture transport for the system, as the long fetch onshore
flow favors the entrance of moist flow interacting with the
terrain of Central America. On Saturday, expect maxima of 30-60mm
from south Nicaragua to the Azuero Peninsula in Panama. From
Chiapas to the Gulf of Fonseca region, expect maxima of 20-35mm.
Similar amounts of are expected in east Panama and the Darien
region. Southwest Colombia can see maxima of 25-50mm.On Sunday,
the Easterly Wave is just entering Belize and along the Gulf of
Fonseca Region. The conditions from Saturday are continuing and as
the wave propagates west, while in the upper levels a trough
extends in to Central America, with its base over Chiapas and
Guatemala by Sunday evening. The extent of the moist onshore flow
has moved into southern Chiapas and along the coastal regions of
Central America, reaching Costa Rica and Panama, assisted by the
monsoon trough in the region. In the western Caribbean, the
circulation is favoring onshore flow from Belize through Honduras
and Nicaragua. Expect maxima of 35-70mm in Costa Rica and west
Panama, as well as in western Colombia. Higher localized amounts
are expected. From southern Chiapas through west Nicaragua, expect
maxima of 30-60mm. From east Honduras through Nicaragua, expect
maxima of 25-50mm.

Mexico expected to see an increase in precipitation over the next
several days. On Friday, a low level cyclonic circulation is
present in the Bay of Campeche, favoring onshore flow from the
northeast into central Veracruz. This circulation is enhanced by
the base of a weak upper level trough, quasi-stationary over the
region from Friday through the weekend. To the south, another
circulation from the monsoon trough is meandering just south of
Jalisco and Colima. This region is an area of interest by the
National Hurricane Center, with a potential for tropical cyclone
development within the next several days. The extent of this
circulation reaches portions of Guerrero, extending into Colima
and Jalisco by Saturday morning. The moist onshore flow is
interacting with the coastal terrain of the region, favoring
orographic lift and precipitation steadily increasing every day
from Friday through early Monday morning. The heaviest
precipitation in the forecast period is expected on Sunday, when
the circulation has amplified. On Friday and Saturday expect
generalized maxima of 20-45mm from Jalisco to west Oaxaca. On
Sunday, expect maxima of 50-100mm in Colima and southwest
Guerrero, with localized higher amounts possible. East Guerrero
and Oaxaca can expect maxima of 20-45mm.

In the Bahamas and the Caribbean, the presence of a weak
stationary boundary is expected to meander over the north Bahamas,
extending from the Central Atlantic Ocean into Florida and just
north of west Cuba. The presence of this boundary is favoring
moisture convergence along it, particularly over the north
Bahamas. The Greater Antilles are expected to see moisture
convergence associated with troughing just south of the boundary,
influenced by the moisture advection from the trade winds.
Elsewhere to the east, lower amounts of available moisture are
favoring drier conditions, and significant precipitation is not
expected in the eastern Caribbean over the forecast period. The
Bahamas will see the presence of a shortwave trough in the upper
levels, enhancing precipitation and the potential for a slight
risk of severe weather on Friday and Saturday. Expect maxima of
30-60mm of precipitation on Friday, and a decrease on Saturday
with maxima of 20-35mm. By Sunday the chances of severe weather
are minimal, however expect maxima of 15-30mm.

In Tropical South America, the region is seeing primarily a zonal
flow in the upper levels, while in the lower levels, moisture is
expected to remain over the western Amazon Basin on Friday. areas
of moisture convergence along troughs in the region will see the
effects of diurnal heating and maxima of 20-35mm are expected
along the east Colombia and west Venezuela. Generalized maxima of
15-25mm are expected in the central regions of Colombia and into
Ecuador and Peru. On Saturday, similar conditions are expected and
much of the region can expect generalized maxima of 15-25mm due to
diurnal processes. By Sunday, a region of moisture convergence
develops over Venezuela and into north Amazonas-Brasil. This
region can expect maxima of 20-35mm that extend into
Roraima-Brasil and the northern Amazon Basin.

Positions of Tropical/Easterly Waves Initialized at 12 UTC
TYP SOF INIT 04/00 04/12 05/00 05/12 06/00 06/12 07/00 07/12
TW  17N  53W   54W  55W   56W   57W  58W   ---
EW  17N  81W   82W  83W   84W   85W  87W   89W   91W   92W

For the latest available charts please visit:
https://www.wpc.ncep.noaa.gov/international/crb_day1-3.shtml

Castellanos...(WPC)
$$