FXCA20 KWBC 051559

PMDCA 



Tropical Discussion - International Desks

NWS Weather Prediction Center College Park MD

1159 AM EDT Tue May 05 2026



Forecast Bulletin 4 May 2026 at 1600 UTC:



The Bahamas and Caribbean:



A frontal boundary extending from the Atlantic into The Bahamas

will continue to favor low-level moisture convergence over the

islands, maintaining precipitation in the region from today

through Wednesday. Thunderstorms and convective activity are also

expected, particularly early on Tuesday as a result of the

instability generated by an eastward propagating upper-level

trough, reflected at mid-levels. A slight risk for severe weather

exists today over The Bahamas. On Wednesday, an upper-level high

will propagate eastward from Mexico into the Gulf, bringing more

stability to the region. Some upper-level diffluence is

anticipated to happen along the periphery of the high causing some

convection over eastern Cuba, the southern Bahamas, and Turks and

Caicos.



Over the eastern Caribbean, some shallow convection is likely from

Wednesday through Thursday as the upper-level trough propagates,

however a mid-level ridge in the Caribbean, and relatively dry air

will limit precipitation in the region. Daily precipitation due to

diurnal heating and local effects is likely throughout the

forecast period.



Mexico and Central America:



Conditions are expected to remain fairly stable over Mexico

through late Wednesday, with dry air prevailing in the region and

a high at mid- and upper-levels. A more active precipitation

pattern is expected Thursday into Friday, particularly over

northeastern Mexico and along the Sierra Madre Oriental. This will

happen as a frontal boundary approaches the southern United States

and extends into northeastern Mexico, promoting low-level

convergence in the area and increasing moisture in the region. At

upper-levels, speed divergence is also expected, which combined

with the presence of mid-level shortwave troughs will support

convective activity and thunderstorms. The highest accumulations

are anticipated to range from 20-45mm from Thursday through Friday

over northeastern Mexico.



Costa Rica and Panama will receive light to moderate precipitation

throughout the forecast period. This rainfall pattern is linked to

the conditions at lower-levels that will favor wind convergence

and moisture advection, mainly from the Caribbean. The highest

levels of rainfall accumulations are expected today through

Wednesday, as a low-level trough propagates through the region

advecting moisture, but lower accumulations are anticipated

towards the end of the workweek as the precipitable water

availability decreases.



Tropical South America:



Heavy precipitation is anticipated today through Wednesday morning

over the Guianas, the Amazon Delta and the Eastern-to-Central

Amazon Basin in Brazil. This precipitation is associated with the

presence of the ITCZ and the NET that will promote low-level

moisture convergence, while a propagating low-level trough advects

moisture in the area. Upper-level diffluence is also anticipated

along the periphery of the Bolivian High, promoting instability

and the development of thunderstorms.



Light to moderate precipitation is also expected today through

Thursday over the Western Amazon Basin where a low-level trough

will promote low-level convergence.



Rainfall is also anticipated over the Pacific coast of Ecuador and

Colombia throughout the forecast period with moisture being

advected from the Pacific. With relatively weak winds at

low-levels , accumulations are expected to remain on the lower end

today through Wednesday. However, an increase in accumulations is

likely from Wednesday through Thursday, with low-level flow

perpendicular to the coast and the presence of a shortwave trough

enhancing upper-level divergence.



By the end of the forecast period, a drying trend is anticipated

throughout the region, with most of the precipitation expected

over the Eastern Amazon Basin, due to low-level convergence and

over the Pacific coast due to moisture advection. Light rainfall

and thunderstorms are likely over the rest of the region due to

diurnal convection, moisture advection and local effects.







Rivera-Torres...(WPC)



$$