Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
319 PM EST Mon Feb 24 2025

Forecast Bulletin 24 February 2025 at 2000 UTC:

In the larger scale, upper level divergent conditions are present
over Mexico, Central America and the Caribbean Basin due to a
disorganized divergent pulse of the Madden-Julian Oscillation that
is currently exiting phase 8, which impacts the aforementioned
regions. These conditions will favor isolated and scattered deep
convection in regions with favorable synoptic conditions. As the
work week continues, the effects of the MJO are expected to
continue to be disorganized as it propagates eastward into Phase
1.

In Mexico...Caribbean Basin...Central America...

On Monday, an upper level trough is deepening just north of the
Yucatan Peninsula and its divergent side is expected over portions
of Florida and north Cuba by Monday evening. In turn, in the lower
levels an associated frontal boundary extends from the north
Bahamas, into central Cuba, and enters the Yucatan Peninsula
through Quintana Roo as it positions along the Sierra Madre de
Chiapas and the Sierra Madre Oriental. The strengthening frontal
boundary will favor deep convection with assistance from the upper
level divergence and trigger severe weather over The Bahamas and
portions of central Cuba. In terms of precipitation, expect maxima
of 35-70mm with an elevated risk of severe weather in northern
Bahamas, Maxima of 25-50mm in the central Bahamas and a moderate
risk of severe weather. While south central Cuba can expect
similar maxima with consistent moist onshore flow associated with
the front and a slight risk of severe weather. Northwest Cuba can
expect maxima of 20-40mm with a slight risk of severe weather. In
Mexico and Central America, the frontal boundary will favor maxima
of 15-20mm in the Yucatan Peninsula, and from south Belize through
central Chiapas.

On Tuesday, the upper level trough will enter the north Caribbean
with its base over Cuba and its divergent side will remain over
The Bahamas and northward. As it propagates eastward, the upper
trough will begin to weaken as the jet streak begins to decrease
speed over the northern Caribbean by Tuesday evening. In the lower
levels, the now stationary front is expected over south Bahamas,
extending into east Cuba, and enters north Honduras, weakening in
central Honduras and into the Sierra Madre de Chiapas. A
generalized weakening is expected in terms of precipitation and
severe weather as the conditions in the upper levels have also
weakened. In central Bahamas, expect a maxima of 30-60mm with a
moderate risk of severe weather. Central Cuba can expect maxima of
20-45mm with a marginal risk of severe weather. Generalized maxima
of 15-35mm are expected elsewhere in the Bahamas with a marginal
to slight risk of severe weather. From Turks and Caicos, east
Cuba, and Hispaniola, prefrontal boundaries have developed over
these regions, favoring generalized maxima of 15-25mm. Similar
amounts are expected in Northern Honduras where expect weak
onshore flow in the lower levels with an increase in available
moisture associated with the cold front.

On Wednesday, the upper level trough has developed a shortwave
trough over the western Caribbean, deepening the upper trough just
northeast of Honduras/Nicaragua by Wednesday evening. The overall
weakening of the upper trough has decreased the upper level
conditions for deep convection, weakening the frontal boundary in
the lower levels. By Wednesday evening the front is expected over
the central Atlantic, and as a weakened stationary front from
south Bahamas into Cuba, and entering north Honduras. In terms of
precipitation, a decrease in available moisture over the Caribbean
Basin and Central America will favor generalized maxima of 15-20mm
in Turks and Caicos, east Cuba, and east Honduras/Nicaragua.
Similar amounts are expected in Puerto Rico with the prefrontal
trough propagating over the island. Similarly, a prefrontal shear
line over Hispaniola will favor maxima of 15-30mm with a
possibility of isolated higher totals.

In Tropical South America...

On Monday, high amounts of available moisture are expected along
the western coasts of Colombia and Ecuador, as well as west and
southerly onshore flow that will interact with the terrain. These
conditions will be favored by the upper level easterly flow that
will provide a generally moist environment to deepen convection in
the region. By Tuesday, the onshore associated with the double
ITCZ in the eastern Pacific Ocean will continue and favor deep
convection in Ecuador and South Colombia. By Wednesday, upper
level conditions are expected to shift to a more westerly flow,
favoring drier air to enter the region and limit deep convection,
and thus expect a decrease in precipitation on Wednesday. In terms
of precipitation, on Monday, expect maxima of 40-80mm in western
Colombia, and maxima of 25-50mm in west Ecuador. On Tuesday,
expect maxima of 35-70mm in west Ecuador and maxima of 25-50mm
from northwest Ecuador to southwest Colombia. By Wednesday, expect
generalized maxima from 20-45mm in both Colombia and Ecuador.

To the east, a drying trend is expected over most of Venezuela and
the Guianas. The elevated amounts of moisture will remain along
the ITCZ/NET along the Equator, where low level troughs are
propagating along the ITCZ/NET and trade winds. These systems will
interact and favor higher amounts of precipitation on Monday and
Tuesday, with a decrease expected by Wednesday as drier air
continues to be advected along the easterly trade winds. On
Monday, expect generalized maxima of 20-45mm from south Colombia
to Amazonas-Brasil, as well as from Amapa to Para-Brasil. On
Tuesday, expect maxima of 20-35mm in north Brasil and 20-45mm in
Amapa-Brasil. By Wednesday, expect maxima of 15-25mm from South
Colombia to North Brasil and maxima of 20-35mm from east Ecuador
to North Peru.

For graphical information:
https://www.wpc.ncep.noaa.gov/international/crb_day1-3.shtml

Castellanos...(WPC)