Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
306 PM EDT Mon Jun 01 2026

Forecast Bulletin 01 June 2026 at 1910 UTC:

Mexico and Northern Central America...
A mid to upper level trough extends from the south-central United
States into southern Mexico and Guatemala, where its divergent
side remains over the Yucatan Peninsula, interacting with the
periphery of a mid to upper level ridge over the west Caribbean.
This region over south Mexico, the Yucatan, and north Central
America will see enhanced precipitation due to a tropical wave
that is expected over Guatemala and the south Yucatan region,
where expect moderate to locally heavy precipitation, enhanced by
the upper level trough in the region. The surrounding regions of
southern Mexico, the northern Yucatan, Belize, west Honduras and
El Salvador can expect light precipitation on Monday. By Tuesday,
the tropical wave is expected to enter the Gulf of Tehuantepec,
where the northern portion of the wave will begin to separate from
the wave and weaken, while the southern portion of the wave over
the Pacific Ocean is expected to continue westward, while
interacting with the Sierra Madre del Sur and portions of Chiapas
and Tabasco, into Guatemala. To the east of the wave, expect
moderate precipitation totals while the west of the front, over
the Sierra Madre del Sur, expect light to moderate precipitation.
On Wednesday, the tropical wave is expected to enter Guerrero and
extend southward into the eastern Pacific Ocean. The Sierra Madre
del Sur region and parts of the Eje Volcanico Transversal can
expect moderate precipitation due to the presence of the tropical
wave. A new tropical wave is entering northern Central America,
favoring light to locally moderate precipitation, limited by the
presence of the mid to upper level ridge over the western
Caribbean.

South Central America and Northern South America...
The southern portion of Central America is affected by the mid to
upper level trough over the western Caribbean, interaction with a
troughing the reaches northern Venezuela on Monday afternoon.
There is an enhanced area of diffluence between Panama and west
Venezuela, that will favor ventilation for deep convection on
Monday into Tuesday. A tropical wave is expected over Panama on
Monday favoring moderate to locally heavy precipitation in eastern
Panama and west Colombia, while high amounts of moisture over west
Venezuela and east Colombia will favor moderate to heavy
precipitation. To the east, a tropical wave is expected in eastern
Venezuela, where expect moderate precipitation. An additional
tropical wave extends from the Central Atlantic Ocean into French
Guiana, favoring light to moderate precipitation in the eastern
Amazon Basin and the Guianas region. On Tuesday, the tropical wave
over Panama enters Costa Rica by the evening hours, favoring
enhanced cyclonic rotation by the monsoon trough in the low
levels. Moderate precipitation totals are expected over Costa Rica
and Panama. In association with the enhanced cyclonic circulation
in the eastern Pacific, expect long fetch moist onshore flow into
western Colombia, favoring deep convection and heavy precipitation
along the western coasts of Colombia and northwest Ecuador. To the
east, the two tropical waves are continuing their westward
propagation, entering western Venezuela, and between Suriname and
Guyana by the evening hours of Tuesday. Locally moderate to heavy
precipitation is expected over the northern portions of South
America on Tuesday. On Wednesday, the tropical wave over Central
America continues to favor enhanced cyclonic rotation over the
region, also enhancing long fetch moist onshore flow into the Osa
Peninsula region of Costa Rica, through southern Panama, and into
western Colombia. Heavy precipitation is expected over the region.
To the east, a tropical wave enters the Andes region of Colombia,
undergoing enhanced orographic lift over much of the eastern
Colombia and western Venezuela. To the east, the tropical wave
over over eastern Venezuela is being affected by dry air in the
environment, limiting deeper convection over the region. Expect
light to moderate precipitation for much of east/central
Venezuela, Guyana, and the eastern Amazon Basin.

Caribbean and the Bahamas...
The western Caribbean is seeing the presence of a mid to upper
level ridge that is expected to remain over the region over the
next three days. In the lower levels, a robust Saharan Air Layer
is entering the eastern Caribbean, favoring drier conditions for
much of the region, and thus the east Caribbean can expect trace
amounts daily over the next three days. In the north, an upper
level trough is extending from the eastern United States, favoring
the development of a frontal boundary in the United States eastern
seaboard, and extending prefrontal troughing over much of the
Bahamas, where expect light precipitation on Monday. Similar
conditions are expected on Tuesday, where the Bahamas and north
Cuba can expect light precipitation. The mid to upper level trough
reaches the northern Bahamas in the evening hours of Tuesday into
early Wednesday as a frontal boundary approaches by Wednesday
afternoon, favoring light to locally moderate precipitation totals
on Wednesday over the Bahamas and central Cuba.

Positions of Tropical/Easterly Waves Initialized at 12 UTC
TYP SOF INIT 02/00 02/12 03/00 03/12 04/00 04/12 05/00 05/12
TW  11N  34W  37W   40W   43W  46W   48W   51W   53W  56W
TW  10N  50W  53W   55W   57W  60W   62W   64W   66W  68W
TW  10N  61W  63W   67W   70W  72W   74W   77W   79W  81W
TW  17N  75W  78W   80W   82W  84W   87W   89W   91W  93W
TW  21N  88W  90W   92W   94W  96W   99W  101W  102W 103W
TW  15N 103W 107W  110W  113W 117W  DISS  ---   ---   --- 

Castellanos...(WPC)