Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
155 PM EDT Thu Sep 10 2026

Forecast Bulletin 10 September 2026 at 1750 UTC:

Significant rainfall accumulation will persist across southern
Central America, western Colombia, Orinoquia and northwestern
Amazon.

Expect moderate to locally heavy rainfall along Sierra Madre
Occidental, the Mexican Transvolcanic Belt and over the Greater
Antilles.

Mexico and Northern Central America . . .
An upper-level high-pressure system centered north of the Gulf of
California will interact with a couple of upper-level low-pressure
systems that extend from western Mexico to the central North. This
pattern will favor upper-level divergence across Sierra Madre
Occidental and Llanura Costera del Pacifico today through Saturday
while the cut-off low over central northern Mexico merges with the
secondary system to the southwest. Lower-level circulation will
support moderate moisture convergence and slightly above normal
precipitable water (PWAT) anomalies over Sierra Madre Occidental
and  the Mexican Transvolcanic Belt over the next three days. Rain
accumulation maxima of 15-35 mm are expected today over
northwestern Mexico with moderate accumulations further south. By
Friday and Saturday, main areas of precipitation will develop over
the Mexican Transvolcanic Belt due to the upper-level dynamic
reorganization. On Saturday, strong low-level moisture advection
and topography will increase daily rainfall totals over northern
Central America, especially over Belize, eastern Guatemala and
northwestern Honduras.

The Bahamas and Caribbean . . .
Moderate to locally heavy rainfall is expected to develop over
Hispaniola and portions of Cuba and Jamaica today. This rain will
be triggered by a tropical wave moving across the region, which
will enhance low-level moisture convergence and interact with
local topography to produce localized heavy rainfall. As the
tropical wave propagates westward on Friday to early Saturday, it
will find better structured upper-level support over Cuba, where
rainfall accumulation maxima of 25-50 mm are forecast. In the tail
of the tropical wave, a plume of Saharan dust will move in to
suppress showers across the eastern portion of the region.


Northern South America and southern Central America . . .
Strong, persistent low-level vorticity over southern Central
America, combined with high PWAT anomalies and tropical wave
passages, will sustain heavy rainfall over the next three days.
Two tropical waves extending over central Colombia and Orinoquia
today, in addition to some lower-level troughs, will support
moderate precipitation across the region while propagating
westward. Daily rainfall maxima of 40-80 mm are expected over
Costa Rica to western Colombia today and Saturday linked to the
passage of these two tropical waves. Rainfall totals will increase
over Trinidad and Tobago to the Orinoco Delta region due to the
influence of the ITCZ. 



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  21N   29W  31W  33W  35W  37W  40W  42W  45W  48W 
TW  17N   35W  37W  39W  41W  43W  45W  47W  50W  53W
TW  12N   44W  46W  48W  51W  54W  57W  59W  61W  63W   
TW  20N   71W  73W  76W  78W  80W  83W  86W  89W  92W 
TW  17N   80W  82W  84W  86W  89W  92W  95W  97W  100W
TW  15N   94W  97W  100W  103W  107W  Abs  ---  ---  ---
TW  20N   108W  110W  111W  112W  113W  114W  115W  116W  117W




Sanchez-Perez...(WPC)