997
FXCA20 KWBC 101551
PMDCA

Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
1151 AM EDT Mon Mar 10 2025

Forecast Bulletin 10 March 2025 at 1600 UTC:

In the larger scale, the Tropical region is transitioning from a
divergent phase of the Madden-Julian Oscillation to a more
convergent phase. Model guidance is suggesting that the eastern
Caribbean and tropical South America is expected to have more
divergence aloft, while the convergent phase of the MJO is
entering west through Mexico and Central America by Tuesday. By
the end of the work week and into the weekend, the convergence
associated with the MJO is expected over the majority of the
forecast region, according to the CFS.

...Mexico and Central America...

On Monday, a weakening stationary front is expected over the
Yucatan Peninsula, into central Guatemala and portions of east
Chiapas by the evening, entering from Cuba. As the southern region
is governed by the Subtropical Ridge and lower amounts of
precipitable water, total precipitation is expected to remain
below 15mm in the Yucatan Peninsula and into Chiapas, and maxima
of 20-40mm in central Guatemala, south Belize, and west Honduras
on Monday. As the frontal boundary continues propagating east away
from the Yucatan Peninsula, and low amounts of available moisture
remain, expect Tuesday and Wednesday to be generally dry in
southern Mexico. Over north Honduras, a trough associated with the
remnants of the aforementioned frontal boundary enhances
convection in the area, where expect maxima of 15-30mm in north
Honduras on Tuesday. By Wednesday, weak moisture plumes in the
easterly trades enter north Honduras where it will favor maxima of
15mm in the region. Similarly over other region of Central
America, weak moist plumes will favor minimal amounts of
precipitation ranging between 10-15mm per day over the forecast
period.

In northwest Mexico, an upper trough is located offshore to the
west of the Baja California Peninsula, where an associated frontal
boundary is expected to make landfall by Tuesday morning, where it
will quickly weaken, yet bring moisture into northern Baja
California and northwest Sonora. On Tuesday, expect maxima of
20-40mm in west Baja California, and maxima of 15-20mm in
northwest Sonora as the base of the upper trough and a trough axis
extends over the region. This system is expected to weaken rapidly
and propagate north and east into the southwest United States. Dry
conditions are expected in western Mexico as dry air is left
behind and a generalized upper level ridging extends into
northwest Mexico by Wednesday evening.

...Caribbean Basin...

On Monday, a frontal boundary extends from the eastern seaboard of
the United States into the northern Bahamas, western Cuba and into
the Yucatan Peninsula. A potential for marginal and isolated
thunderstorms may lead to some severe weather as an upper level
trough extends into the Bahamas, favoring unstable conditions in
the area. However, due to the low amount of available moisture,
precipitation totals are expected to remain below 15mm in the
Central Bahamas and in Cuba. On Tuesday, the cold front propagates
east and south into Turks and Caicos, east Cuba and becomes
stationary in the southern regions of Cuba by Tuesday evening.
Even with the presence of the upper level trough over the north
Caribbean, the amount of available moisture is not conducive to
heavy precipitation and totals are expected to remain below 25mm
in east Cuba and below 10mm in The Bahamas. A prefrontal trough
over Hispaniola may favor maxima of 15mm on Tuesday. On Wednesday,
the frontal boundary remains stationary over Hispaniola and in
southern Cuba, where convergence along the terrain may favor
orographic lift in Hispaniola and maxima of 15-30mm. Localized
higher amounts are possible. A weak prefrontal shear line develops
over Puerto Rico and will favor maxima of 15mm. Similar amounts
are expected in southern Hispaniola in association with the
frontal boundary.

...Tropical South America...

Over the next several days, troughs embedded in the easterly trade
winds are interacting with the ITCZ/NET and will favor isolated
and scattered heavy precipitation in north Brasil and the Amazon
River Basin. Areas of diffluence are expected in the Eastern and
Central Amazon Basin as the upper trough in eastern Brasil extends
into the tropical northern region of the country. By Tuesday, an
axis of an upper level ridge over the central Atlantic Ocean
extends into the Guianas and Venezuela, interacting with the upper
trough in northern Brasil and enhancing ventilation for deep
convection over the Amazon Basin. These conditions are expected to
retrograde to the west as the upper level ridge extends westward,
interacting with the strengthening Bolivian High over the western
and central Amazon Basin by Wednesday. Support from the available
moisture will favor moderate precipitation totals over the next
three days. On Monday, maxima of 30-60mm from south Venezuela to
Amazonas-Brasil, while from Suriname to Amapa-Brasil expect maxima
of 20-35mm. Assistance from moist onshore flow into west Colombia
and west Ecuador will favor maxima of 20-40mm in Ecuador and
maxima of 15-30mm in Colombia. On Tuesday, maxima of 25-50mm is
expected in the Central Amazon Basin, while maxima of 20-40mm are
expected in the Guianas and Ecuador. On Wednesday, expect maxima
of 25-50mm in from Canaima, into the southern Guianas and into the
Eastern Amazon Basin. Maxima of 20-45mm are expected in the
western Amazon Basin, while maxima of 20-35mm are expected along
the northern Guianas and into portions of northern Brasil. Similar
amounts are expected in northwest Colombia.

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

Castellanos...(WPC)

$$