Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
121 PM EST Fri Dec 05 2025

Forecast Bulletin 05 December 2025 at 1820 UTC:

Mexico and Central America:

A positively tilted upper- to mid-level trough is currently
located over the southwest United States and northwest Mexico,
including the Baja Peninsula and the region of Sonora. As the
trough progresses eastward into the weekend, a remnant trough,
potentially in the form of a cutoff low per the GFS, will remain
in place over the weekend and early next week. This setup will
support strong upper-level divergence today into early in the
morning on Saturday. Steep lapse rates will also be present, with
mid-level temperatures to reach as low as -12 degrees Celsius,
which will be conducive for the generation of strong and
potentially severe thunderstorms in Baja California Sur. As such,
there is a marginal risk for severe weather for Baja California
Sur, and precipitation is expected to peak at around 20-35mm
today. After Saturday, a low-level ridge will enter from the
Pacific and is expected to stabilize the environment in the Baja
Peninsula and Sonora.

On the east coast of Mexico, a cold front is expected to move into
the Gulf from the southern United States early next week. As the
front begins to enter, the low-level flow at the tail end of the
front will change from a westerly regime to a northeasterly flow,
which will allow for the transport of moisture to flow onshore
into Veracruz beginning on Monday morning. The low-level flow will
be strong at this point, potentially exceeding 30kts, and is
expected to strongly enhance orographic effects. The heaviest
precipitation is expected early next week, past the forecast
period, however, moderate to potentially heavy precipitation will
begin for this region on Sunday, with 20-35mm expected.

In Honduras and Nicaragua, a plume of moisture associated with a
low-level trough, currently located in the central Caribbean, will
propagate westward before reaching the eastern coasts of Honduras
and Nicaragua on Saturday morning. The presence of an upper-level
ridge will be located over the Caribbean Sea, and the western
periphery of the ridge will be located over much of Central
America, particularly Honduras and Nicaragua. This will enhance
upper-level divergence, and additional low-level moisture
convergence is expected as the trough moves inland into Nicaragua.
The heaviest precipitation is expected to occur beginning on
Saturday morning, with a maximum of 20-35mm expected in Nicaragua
and parts of eastern Honduras.

The Caribbean and Bahamas:

In the Lesser Antilles, a westward propagating low-level trough
with an associated plume of moisture originating from the ITCZ
will bring precipitation to the Windward Islands on Saturday.
Instability will be slightly enhanced during this time due to the
presence of an upper-level trough, and with the addition of
low-level moisture convergence, moderate precipitation is
anticipated. Expect a precipitation maximum of around 20-35 on
Saturday in the Windward Islands.

Much of the rest of the Caribbean will experience calm and drier
conditions due to the presence of an upper-level ridge promoting
anti-cyclone circulation and overall subsidence. Any precipitation
will be in the form of locally induced showers.

Tropical South America:

The aforementioned low-level trough from the eastern Caribbean
will move moisture into Trinidad and Tobago and parts of the
Guianas over the next three days. Moisture flow into the region
will be persistent, and heavy precipitation should be expected for
this region, with daily precipitation maxima of around 20-45mm. In
the interior regions of tropical South America, moisture will
continue to move from the eastern portions of the Amazon and will
provide fuel for convection due to localized, diurnal, and
orographic effects, with daily heavy precipitation expected,
particularly in southern Venezuela and northwest Brazil. In
western Colombia, weak westerly flow onshore will aid in bringing
precipitation, which with orographic enhancement, will result in
localized high precipitation totals. The heaviest precipitation is
expected today, with a maximum of 25-50mm possible in localized
areas of western Colombia.


Positions of Tropical/Easterly Waves Initialized at 12 UTC
TYP SOF  INIT  06/00  06/12  07/00  07/12  08/00  08/12  09/00
--  --    --    ---    ---    ---    ---    ---    ---    ---  

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

Blanco-Alcala...(WPC)