Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
227 PM EST Tue Feb 18 2025

Forecast Bulletin 18 February 2025 AT 1930 UTC

The general rainfall pattern over the region has most of the
Caribbean with modest rainfall accumulations over the next three
days, while northern South America will have daily showers and
thunderstorms, with the highest daily amounts expected over area
in and around the Amazonas and Para of Brasil. Central America
into portions of southern and eastern Mexico will have an increase
in shower activity compared to last week. Across Central America,
Panama is expected to have the most persistent shower activity
each day.

The available moisture will be above normal for most of northern
South America, Central America, and Mexico. The Caribbean will
remain near to below normal, however. That said, there will be
some low level troughs moving through the Caribbean, causing some
localized moisture convergence.

In the upper levels, most of the tropical region will be under a
ridge of high pressure, promoting some stability particularly
across the Caribbean. There will be upper level troughs, but the
axis will remain over water, one across the eastern Pacific, from
100W to 107W and another from 48W to 58W. The upper level winds
will be relatively light today, with most areas observing winds of
40KT or less. Winds will increase late Wednesday into Thursday
across the Yucatan, the Gulf, Cuba, and northern Bahamas, to winds
of 70KT or stronger. These stronger winds could provide some
ventilation aloft for the development of thunderstorms across
Mexico into Central America.

The mid-levels are also mainly dominated by high pressure, but
there is a low pressure in the Caribbean. However, there is a high
pressure just east of Mexico, and another across the central
Tropical Atlantic. There is a ridge that extends from northwestern
South America into the eastern Pacific. By Friday, a mid-level
trough will be over the Caribbean, while high pressure will
dominate elsewhere. The mid-level high pressure across the
tropical Atlantic will be even stronger by Friday. 

The low-level winds are relatively strong across the Caribbean and
the western Gulf coast. The latter is associated with a low
pressure over southeastern Texas and an associated cold front that
is moving south. This low pressure will be moving east, pushing
the cold front into the Gulf and over eastern Mexico, while a warm
front moves north of the Bahamas by Wednesday night. The strong
low-level winds over the Caribbean will persist through the week,
as will the gap flow known as the Papagayo Low-Level Jet. The
Tehuantepecer LLJ will not develop until Wednesday night,
persisting into Thursday night.

In terms of amounts of rainfall, the current pattern, as
previously mentioned, favors significant rainfall over northern
South America. With a diffluent upper level pattern across the
Amazonas and Para, the rainfall forecast has max rainfall totals
of 30-60mm and 40-80mm in some areas for Wednesday, while slightly
lower amounts are expected today and on Thursday. The daily
rainfall amounts across Central America will have daily max values
near 15-25mm each day across isolated areas, with up to 35mm
across northern Central America and southern Mexico on Wednesday
and Thursday. Panama seems to have an increasing chance of showers
each day this week, with max totals up to 25mm today, 35mm on
Wednesday, then up to 45mm on Thursday into early Friday. The
Caribbean is still the area with modest rainfall amounts in its
forecast, generally under 10mm each day with the exception of the
lesser Antilles on Wednesday that will have up to 25mm, then PR
and Hispaniola up to 25mm on Thursday, as a low-level trough
passes by.


Alamo...(WPC)