Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
356 PM EST Wed Feb 26 2025

Forecast Bulletin 26 February 2025 at 2050 UTC:

A divergent MJO phase is expected to continue for the rest of the
week across the Tropical Region.

Across the Atlantic Basin, Caribbean, Central America, and
Mexico...

In general for the rest of the workweek, the rainfall totals over
the region are expected to be relatively modest. Most areas are
expected to observe brief showers, especially over the Caribbean
islands. The daily rainfall accumulations across portions of the
Caribbean, Central America, and Mexico are expected to be
generally under 25mm. The main exception would be portions of
Hispaniola on Thursday into Friday, where up to 35mm is forecast
with a slight chance of strong thunderstorms.

An upper level trough, with axis over Cuba will move east over the
next couple of days over the Greater Antilles. This upper trough
could provide instability over Hispaniola on Thursday afternoon
and evening, which could combine with relatively low mid-level
temperatures to increase the potential of isolated strong storms.
A weak upper trough will move into the central Caribbean by Friday
night, but the impact on rainfall development is not expected to
be too significant. The upper level winds will be generally under
60KT across the region, with the exception of the areas associated
with the trough currently over Cuba and some areas of northern
Mexico and the northern Gulf coast. The mid-levels will also have
a trough moving through the Greater Antilles for the next few
days, but a weak mid-level shortwave trough lingers over
Hispaniola until Saturday.  

In the lower levels, there is a Cold front and an associated
trough across the western Tropical Atlantic that will continue
moving east, while a stationary front over Mexico into northern
Central America will weaken and dissipate by Thursday. Meanwhile,
another cold front will come down from the US into the northern
Gulf Coast and the western Atlantic by Thursday. By Friday, the
west end of the frontal boundary will dissipate, while the cold
front prevails over the western Atlantic. Otherwise, the low
levels will have a series of troughs that will be passing through
the area, but the locally enhanced precipitation with these
troughs seem to be minimal, as the consensus rainfall model
solutions are in agreement that the rainfall totals will be
relatively minimal. In terms of overall available moisture, there
is a sharp line of above average moisture ahead of the cold front
over the Atlantic into the central Greater Antilles and Caribbean,
which will remain mainly stationary for the rest of the workweek.
Other areas will have near to below normal moisture.

Across Tropical South America...

The main story continues to be the persistent showers and
thunderstorms that keep affecting western Colombia and Ecuador.
The story will continue for the rest of the workweek. Deeper then
normal moisture, the presence of the southern ITCZ ending in the
west coast of Ecuador, low-level onshore flow and slightly warmer
than normal waters, are all contributing to the moisture being
pushed inland and causing the development of showers and
thunderstorms. The latest guidance was indicating that the
relative humidity values in the low and mid levels will be above
normal for those portions of northwestern South America. This
means that each day for the rest of the workweek, western Colombia
and Ecuador will have daily rainfall maxima at around 30-80mm with
some areas receiving more or less that that range. 

Across Brazil and adjacent areas, higher than normal moisture
continues to interact with the ITCZ/NET to cause diurnal showers
and thunderstorms over the area. There is drier than normal
moisture over the Guianas, northern Amazonas and eastern and
southern Venezuela, however. These areas with drier than normal
moisture are forecast no rain for the next few days. The nocturnal
LLJ is playing a role in the drier air moving into the area. In
general, the diurnal shower and thunderstorms expected will
encompass a large area, but isolated thunderstorms could be heavy
rain producers. Therefore, most of the area is expected to observe
daily rainfall maxima in the order of 15-35mm each day for the
rest of the workweek, but some areas could observe as much as
60mm, especially across western Amazonas on Thursday.

For a graphical representation and details of the areas with
forecast rainfall:
https://www.wpc.ncep.noaa.gov/international/crb_day1-3.shtml

Alamo...(WPC)