376
FXCA20 KWBC 021854
PMDCA

Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
154 PM EST Tue Dec 02 2025

Forecast Bulletin 02 December 2025 at 1800 UTC:

In the Caribbean, an upper level trough, which is reflected in the
mid and low levels, has its axis located between Hispaniola and
Puerto Rico. The upper level trough will continue propagating
southeastward towards the Lesser Antilles on Wednesday, and will
begin to lose definition after Thursday afternoon. The upper-level
trough will help to enhance upper-level divergence over the Lesser
Antilles from today through Wednesday night. A plume of moisture
with precipitable water exceeding 50mm is forecast to reach the
Lesser Antilles later today and remain in the region until
Thursday night. The combination of the instability associated with
the upper-level trough and the moisture advection will cause
rainfall and thunderstorms over the Lesser Antilles from today
through Thursday. Rainfall totals are forecasted to be around
20-35mm from today through Wednesday. Additional 20-35mm of
rainfall are forecasted for the Windward Islands from Wednesday
through Thursday. After Thursday night, calmer conditions are
anticipated as upper-level divergence decreases and dry air
intrudes.

A cold front extends from Florida through the Gulf and into
Mexico. Part of this cold front is forecast to continue moving
east towards the Bahamas on Thursday. Over the western Caribbean,
however, a low-level high will prevent the cold front from
propagating towards Central America, and it will likely transition
into a decaying stationary front over the Gulf on Wednesday. With
the low-level winds becoming southerly on Thursday, the front is
projected to become a warm front and move towards the US. Most of
the precipitation associated with this system is expected today,
as low-level moisture convergence increases. On Friday, a shear
line in front of the cold front is forecasted to develop over
Turks and Caicos, extending over Jamaica, which will increase
low-level convergence in Jamaica and rainfall in the region.
Accumulations, however, are not forecasted to exceed 15mm. Another
cold front is forecast to reach northeastern Mexico on Friday,
causing some precipitation over the region.

Over Sinaloa, precipitation is expected from Wednesday through
Friday with the presence of a shortwave mid-level trough
supporting convection. More precipitation is expected from
Thursday through Friday in that area as  a strong upper-level
trough, propagating east and reflected at mid- and low-levels,
reaches Mexico, enhancing upper-level divergence. Additional
accumulations around 15-30mm are likely.

Mostly calm conditions are anticipated throughout the forecast
period over most of Central America, with an upper-level high,
reflected at mid-levels, dominating the region. Some precipitation
can be expected each day due to local effects, diurnal heating and
moisture advection. Most of the rainfall in Central America can be
expected to happen over Costa Rica and Panama today, with the
presence of the monsoon trough enhancing moisture advection from
the Caribbean and the Pacific. After that, dry air will limit
rainfall over the area.

Over South America, the main drivers of precipitation will be
moisture advection, low-level convergence, local effects, diurnal
heating and convectively induced troughs. From today through
Wednesday an area of interest is western Colombia, where enhanced
low-level convergence and orographic lifting will support high
rainfall totals. Precipitation will be further enhanced over
western Colombia, particularly over the Pacific coast as low-level
winds will become more favorable for moisture advection from the
Pacific Ocean. The highest totals are expected from Thursday
through Friday with accumulations reaching 25-50mm. Another area
of interest is Brazil, where upper level speed divergence will
support deep convection in the area of the next three days.



Positions of Tropical/Easterly Waves Initialized at 12 UTC
TYP SOF  INIT  03/00  03/12  04/00  04/12  05/00  05/12  06/00
--  --    --    ---    ---    ---    ---    ---    ---    ---

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

Rivera-Torres...(WPC)
$$