Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
122 PM EST Tue Feb 25 2025

Forecast Bulletin 25 February 2025 at 1820 UTC:

In the larger scale, the presence of upper level divergence from a
disorganized divergent phase of the Madden-Julian Oscillation
(MJO) continues on Tuesday and it is expected for the rest of the
week.

In the Caribbean Basin...Central America...Mexico...

An upper level trough extends over Cuba and The Bahamas on Tuesday
and an associated cold frontal boundary is expected over southeast
Bahamas/Turks and Caicos, extending into central Cuba and becoming
stationary as it enters east Honduras and northward along the
mountain regions in Guatemala and Chiapas by Tuesday evening. A
weak secondary frontal boundary has developed over northwest
Bahamas and west Cuba but effects from this system are to remain
minimal. Upper level divergence from the left exit region of the
upper level jet will enhance convection over the Bahamas favoring
heavy precipitation in the region. Instability remains high and a
chance of severe weather remains over The Bahamas, Turks and
Caicos and Cuba on Tuesday. Increased moist onshore flow
associated with the front are expect in Honduras. Expect maxima of
20-45mm with a slight risk of severe weather in central Bahamas,
while elsewhere in the Bahamas, expect generalized maxima of
15-25mm. Cuba can expect similar amounts with a marginal risk of
severe weather. Northern Honduras can expect maxima of 15-30mm.
Similar maxima are expected in Puerto Rico.

On Wednesday,  the upper trough weakens over the west Caribbean
and, in turn, the frontal boundaries over the region begin to
weaken as well over the same aforementioned regions. The amount of
available moisture is expected to decrease over the Bahamas and
Cuba, as well as in Honduras. A weak prefrontal shear line
develops over Hispaniola, where the higher amounts of
precipitation in the region are expected on Wednesday. These
amounts are of 15-20mm. East Nicaragua, east Cuba, Jamaica, east
Dominican Republic, Puerto Rico and the Lesser Antilles can expect
generalized maxima of 15-20mm.

On Thursday, the upper level trough continues to propagate
eastward and weaken over Hispaniola and Puerto Rico. The frontal
boundary has weakened over the Bahamas, Cuba, and the Gulf of
Honduras while weak troughs remain to the east of the remains of
the front. As such, precipitation totals are expected to decrease
in the Caribbean Basin and Central America. To the north, a new
upper level trough is propagating over the southern United States,
as well as a frontal boundary that extends over the southern US
into Tamaulipas, Nuevo Leon, Coahuila. An increase in available
moisture is expected along the eastern coast of Mexico, and
interact with the Sierra Madre Occidental, where expect maxima of
15-25mm. Similar amounts are expected in Hispaniola. Elsewhere in
Honduras/Nicaragua and the Caribbean Basin expect generalized
maxima of 15-20mm.

In Tropical South America...

The western regions of Colombia and Ecuador are expected to see
heavy precipitation due to moist onshore flow interacting with the
terrain and enhanced by upper level diffluence. Tuesday seems to
be the day with the most favorable upper level conditions that
will help ventilate deep convection over the region. On Wednesday,
the flow of the upper levels is expected to shift to a more
southward direction, decreasing ventilation in the region. By
Thursday, the upper level flow is expected from the south and
west, favoring drier air to advect over the region, unfavorable
for deeper convection. In the mid levels however, the flow
continues to from the east, promoting moisture over Colombia and
Ecuador over the next three days. In the lower levels, expect
moisture entering the region from the west, in some instances
directly from the west. On Tuesday, expect maxima of 50-100mm in
the Gulf of Guayaquil region, while from northwest Ecuador to
southwest Colombia can expect maxima of 35-70mm. On Wednesday, the
aforementioned regions can expect maxima of 30-60mm. On Thursday,
expect maxima of 30-60mm along west Colombia and maxima of 40-80mm
in west Ecuador.

To the east, the presence of available moisture continues to
interact with the ITCZ and troughs that continue to propagate
along the ITCZ and develop diurnal convection over the region.
Drier conditions are expected from Venezuela to the Guianas as dry
air is advected in the region. On Wednesday and Thursday, the
presence of the nocturnal LLJ indicate that a pressure gradient is
enhancing over the southern Caribbean basin and north South
America, favoring a dry trend by Thursday. On Tuesday, expect
maxima of 25-50mm from south Colombia to west Ecuador and north
Peru, and from east Amazonas-Brasil to Para. West Amazonas-Brasil
can expect maxima of 20-35mm. On Wednesday, expect maxima of
20-45mm from south Colombia to west Ecuador, north Peru, and west
Amazonas. From east Colombia to north Brasil expect maxima of
15-25mm.  On Thursday, maxima of 20-45mm are expected in from
south Colombia to north Peru and west Amazonas-Brasil. Elsewhere
in Brasil, west Ecuador and central Peru expect maxima of 15-25mm.

For graphical information:
https://www.wpc.ncep.noaa.gov/international/crb_day1-3.shtml

Castellanos...(WPC)