683
FXCA20 KWBC 052003
PMDCA

Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
303 PM EST Thu Nov 05 2026

Forecast Bulletin 05 November 2026 at 2000 UTC:

A broad upper-level ridge over Mexico maintains primarily dry
conditions on Thursday before the intrusion of a cold front into
the northeast triggers moderate rainfalls across Tamaulipas on
Friday. By the start of the weekend, an upper-level trough digging
from the southwest United States into Northwest Mexico, coupled
with a jet streak, will provide significant dynamical forcing and
ventilation for convective development over Chihuahua, Coahuila,
and Nuevo Leon. Rainfall accumulations of 15 - 25mm can be
expected with localized 35mm possible on Saturday. While the
frontal boundary becomes stationary over Tamaulipas on Saturday,
limited mid- and low-level moisture profiles will keep convection
widespread, producing daily accumulations of up to 25mm over the
region.

Across Central America and western Caribbean, precipitation
activity remains driven by weak, broad low level circulation. On
Thursday and Friday, a low pressure system meandering near the
East Pacific coast of Nicaragua will push long-fetch, moisture
onshore, producing moderate to heavy rainfall along the Pacific
coasts of Costa Rica and Nicaragua. By Saturday, there is
uncertainty in model guidance on the location and strength that
this low-pressure system will enter into Central America. Some
models indicate that there is potential for organization and
strengthening that could drive the enhanced moisture into the Gulf
of Fonseca region, while others indicate a weaker low pressure
entering into southwest Nicaragua. Due to the low confidence, a
more conservative solution is reflected in the charts. Daily
rainfalls along the Pacific coast can amount up to 80mm, but
decrease to localized maxima of 50mm by Saturday. Farther north,
the low-level cyclonic circulation starts pushing more moisture
into the Gulf of Honduras by Saturday. Interactions with localized
terrain and weak mid-level shortwave perturbations, will yield
scattered showers across Belize, Guatemala, and Northern Honduras
amounting to 15 - 25m.

Over the Caribbean Basin, southerly winds favor moisture advection
into Jamaica and the Cayman Islands on Thursday, producing light
showers of up to 20mm with possible localized maxima of up to 35mm
in southern Jamaica. By Friday, northern dry air advection starts
suppressing precipitation across most of the western and central
Caribbean. Conditions become more varied by Saturday, as
upper-level shortwave troughs over central Caribbean induce areas
of diffluence and ventilation over the Leeward Islands and Puerto
Rico. This favorable upper-level ascent combined with moisture
advection from the southwesterly low-level flow in the Caribbean
will induce a favorable environment for convective development in
the area with rainfall accumulations of up to 35mm possible over
the Leeward Islands. Troughing in the central Caribbean will also
induce forcing over Peninsula de Coro and the ABC Islands on
Thursday, with possible rainfall amounts of up to 25mm. Light
showers remain possible on Saturday across eastern Cuba and the
Turks and Caicos due to moisture pulses moving into the area and
enhanced by diurnal heating and local effects.

Across tropical South America, heavy precipitation across the
Pacific coasts of Colombia and Ecuador can be expected through
Friday driven by strong, moist low-level onshore flow from the
East Pacific, with the maximum accumulations of 60mm anticipated
over the northwest Ecuador and southwest Colombia. While low-level
westerlies gradually weaken by Saturday, persistent onshore flow,
low to mid-level saturation, coupled with orographic lift will
continue generating scattered showers along the Pacific slopes. On
the Caribbean coasts of Colombia and Venezuela, offshore winds
associated with the periphery of the broad low level circulation
will act to suppress widespread activity by Saturday, restricting
rain to diurnal heating-driven convective cells. Meanwhile, deep
moisture pooling and persistent low-level trade wind convergence
over the western Amazon Basin and Orinoquia will maintain daily
rounds of light to moderate convection throughout the entire
period, fortified by the periphery of the Bolivia High in central
South America.

Torres-Maldonado...(WPC)
Castellanos...(WPC)
$$