Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
348 PM EDT Mon Aug 10 2026

Forecast Bulletin 10 August 2026 at 1950 UTC:

Over the next three days, the main areas of rainfall are expected
over northwestern Mexico, extending across the western region,
portions of the southern region and the Yucatan Peninsula. A mid
level trough will support a rainfall maxima of up to 35mm across
the Gulf of Honduras region. This trough will move into southern
and southeastern Mexico by Wednesday. Another region of interest
is western Orinoquia, northwest Amazon region, and western Amazon
basin, where significant rainfall is expected for today, before
shifting westward on Tuesday across western Colombia and southern
Central America.

Over Mexico and Northern Central America...
In the upper levels, a low pressure circulation is centered over
the northwest, with a trough extending farther south along the
western states, favoring ascending motion over the Sierra Madre
Occidental. An upper level trough extends over the southern Gulf
and Yucatan Peninsula, while another will be extending over
northern Central America. These systems will support convection
across these areas. In the mid levels, a series of shortwaves are
present across the northwestern region to Guerrero state while
other shortwaves will be located from southern Mexico and into the
Gulf of Honduras. They will continue to support isolated areas of
deep convection. In the lower levels, relative humidity values are
significant, but precipitable water (PWAT) anomaly shows values
near the normal along Sierra Madre Occidental region to Sierra
Madre del Sur. Daily rainfall maxima of 20 - 40mm are expected  in
isolated areas from northwestern Mexico to Guerrero, where higher
values of PWAT anomaly are forecasted for today. Throughout the
next few days, the upper level support over northwestern and
western Mexico will move northwestward while an upper level ridge
builds up over the region and main areas of rainfall get
concentrated over the northwest and become more isolated. From
central Mexico into northern Central America, as the upper level
low moves west-northwestward, it will amplify into a couple of
upper troughs supporting the entrance of higher values of PWAT
over the region. Convective precipitation will develop from
Tuesday through Wednesday over this region, with rainfall maxima
of 30mm.

Over the Caribbean, The Bahamas and Southern Central America
region...
A potent surface to low level ridge is dominating the Bahamas and
Cuba, which will continue to suppress precipitation today. A mid
level trough extended from Costa Rica to Hispaniola will support
an increase in PWAT anomaly over the Caribbean basin and a second
one extended over Lesser Antilles will allow the increase later
today as it continues moving westward. An upper level low system
extends from the central Bahamas farther south to Jamaica and
western Hispaniola, but its influence in deeper convection will be
limited by the mid level set up and lack of humidity beneath.
These conditions will keep todayâ€s most significant rainfall
accumulation over eastern Honduras along the coast to eastern
Costa Rica where rainfall maxima of 20 - 30mm are forecasted.
Throughout the next three days, the upper level low and the mid
level trough propagating westward will support the displacement of
the air mass with higher PWAT values farther west into the Central
America region where daily rainfall maxima will increase to 25 -
45mm. On Tuesday, an upper level trough will gain definition over
the Turks and Caicos region, favoring ascent over eastern Greater
Antilles. This trough will linger over the area for at least the
next 48 hours. This trough will be well reflected in the mid
levels and will support a decent increase in PWAT over eastern
Cuba, Jamaica and Hispaniola.

Over Northern South America...
In general the whole region shows below normal humidity levels, so
low level vorticity and orography are expected to be the main
forcing parameters across Orinoquia into Western Amazon Basin
through the next few days. An upper level trough, weakly reflected
in the mid levels, in interaction with enhanced values of
potential vorticity associated with a tropical wave in the lower
level and orographic forcing, will favor ascending movement and
isolated convection over western Orinoquia to western Amazon Basin
region today. The upper level low will linger over Colombia and
the tropical wave will move into western and northwestern Colombia
on Tuesday where daily rainfall maxima of 25 - 40mm are expected.
By Wednesday, the disturbance associated with this tropical wave
will move westward into Southern Central America. Upper level
diffluence over Venezuela will favor ascending motion aloft,
supporting the increase in PWAT. Daily rainfall maxima will be 20
- 40mm, especially over  the southern mountains. A second tropical
wave is expected to move into the region by then, but it will keep
its core of enhanced associated precipitation offshore northern
Guianas.



Tropical Waves Initialized at 12 UTC:
Typ SOF INIT 11/00 11/12 12/00 12/12 13/00 13/12 14/00 14/12
TW 13N  40W  43W  46W  48W  51W  55W  58W  63W  67W
TW 18N  56W  60W  64W  67W  72W  74W  78W  82W  85W
TW 19N  73W  76W  80W  84W  86W  90W  93W  96W  98W
TW 13N  87W  90W  94W  99W  103W  107W  111W  114W  117W
TW 17N  111W  113W  115W  118W  Exits





Sanchez-Perez...(WPC)