Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
306 PM EST Thu Feb 13 2025

Forecast Bulletin 13 February 2025 AT 2000 UTC

For the rest of the workweek and into the weekend, the MJO pattern
is forecast to be favorable for upper divergence across the east
Pacific, western Caribbean into the Gulf, and most of South
America. The MJO will be from neutral to upper convergent across
most of the eastern Caribbean into the Atlantic. The MJO may play
a role on the locations that could observe significant convection,
especially across northern and northwestern South America, and
although some shower and thunderstorm activity is expected across
Central America, the rainfall amounts are expected to be modest.
The Caribbean region will remain with a relatively stable
atmosphere, with mainly brief trade wind showers expected. The
daily rainfall accumulations across the Caribbean islands are
forecast to have daily maxima near 10-15mm across some areas, but
even lower accumulations are forecast elsewhere in the Caribbean.
Central America will also have shower activity on the windward
side of the Caribbean-facing coasts, with max daily rainfall
totals generally in the range of 10-25mm. Across eastern Mexico,
an increase in moisture will be observed over the Veracruz and
nearby Mexican states today into Friday as a cold front moves
south into the region. This increase in moisture and nearby
frontal boundary will increase the chances of showers, with up to
45mm of rain expected across the area today. Friday into the
weekend looks much drier, however. Across tropical South America
over the next three days, low-level westerly wind flow will
persist along the coasts of Colombia and Ecuador, which will
continue to play a role in the shower and thunderstorm development
over the west coast of Ecuador and Colombia, as moisture will
interact with the local terrain and the favorable mid and upper
level divergence; which is also enhanced by the divergent MJO.
Although that area has been observing this general pattern for
several days now, the latest guidance does back out a little bit
for Saturday into Sunday, not having as direct westerly flow in
the lower levels as today and Friday, and also suggesting lower
amounts of rain for that period this weekend. Therefore, the
forecast rainfall across western Ecuador and western Colombia has
daily rainfall maxima near 25-50mm today and Friday into Saturday
morning, but it goes down on Saturday into Sunday, with max
accumulations near 40mm.

In the upper levels, a ridge will persist through the end of the
workweek across the Caribbean, promoting general stability.
However, a weak mid level trough is expected to retrograde from
just west of Puerto Rico to the central Caribbean, near Jamaica,
by Sunday morning. This mid level trough will have some vorticity
and is expected to produce some shower activity, though it will
move relatively quickly to the west. Overall in the Caribbean, a
fairly stable atmosphere is forecast for the next few days, which
will allow mainly shallow convection. The mid levels are very dry
across the Caribbean, and the dry air will persist into the
weekend. That said, at the 700mb level, there are some patches of
moisture, generally associated with moisture convergence from
low-level troughs. These pockets of moisture will have above
normal RH values, and will be moving quickly across the Caribbean
into the Gulf. However, the mid levels will be very dry, keeping
the deeper moisture in the lower levels over the region. Across
most of tropical South America, the RH values at the 700 and 500mb
levels are relatively high, with the exception of eastern Brasil.
A diffluent pattern continues to be forecast across most of
tropical South America over the next few days, there is also some
divergence persisting near the west coast of Ecuador and Colombia,
with the model guidance also suggesting some enhanced vorticity in
the area.

At the surface, a high pressure over the central Atlantic will
continue to dominate the Caribbean and the tropical Atlantic into
the weekend. There is also a cold front that is digging south into
the Gulf, but other than an enhanced shower shower activity over
Veracruz in Mexico today, it is not expected to have a significant
impact elsewhere over the next few days. The low level winds are
still expected to be relatively strong into the weekend across the
Caribbean, tropical Atlantic and into the Gulf.

As previously mentioned, the Caribbean will have minimal to modest
amounts over the next few days due to the relatively stable
atmosphere, combined with the breezy conditions pushing shower
activity quickly over any one area. Mexico is expected to observe
dry days Friday and Saturday, with essentially fair weather across
the country. However, the increase in moisture seen today across
eastern Mexico will cause an increase in shower activity, with
forecast rainfall maxima up to 45mm for areas in and around
Veracruz. The Guianas and Amapa of Brasil are expected to observe
showers and thunderstorms over the rest of the workweek as low
level moisture moves in with the trade winds and the proximity to
the ITCZ, with rainfall maxima near 20-40mm today, and 20-35mm on
Friday and Saturday. Dry air is still expected to move into
Venezuela into northeastern Colombia with the nocturnal LLJ each
night into the weekend. Once again, the area with the best chance
of significant rainfall is the tropical region of South America,
especially western Colombia and Ecuador, where daily maxima of
25-50mm is forecast.  Northern Peru, into the Amazonas and Para
states of Brasil will also have diurnal convection, with rainfall
maxima ranging between 25-50mm today. That said, a good portion of
the Amazonas and Para is forecast to have significant rainfall on
Friday and Saturday, with a forecast rainfall maxima of 35-70mm
and 30-60mm respectively.


Alamo...(WPC)