Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
228 PM EDT Fri Oct 16 2026

Forecast Bulletin 16 October 2026 at 1829 UTC:


An upper-level trough extending over the U.S. today will support
wind divergence over Chihuahua and Coahuila early today while
continuing to propagate eastward. The associated surface cold
front will support strong moisture convergence as it moves
southeastward. A pre-existing upper-level cut-off low centered off
the coast of Tamaulipas will be captured by the wind pattern
moving north of it, favoring upper-level divergence over the
Yucatan Peninsula and western Cuba. Enhanced mid-level vorticity
will support deep convection over the region surrounding the
western Caribbean. A tropical wave is extending over the Yucatan
Peninsula, creating extended areas of strong vorticity while
enhancing upward moisture transport along the Yucatan Peninsula
into Central America. Hurricane Trudy, centered off the coast of
Guerrero, will propagate northwestward, supporting significant
moisture advection into central and southern Mexico today. These
three systems will be the major drivers of forecast disturbances
today over Mexico and Northern Central America.

Abundant moisture convergence and vorticity advection, due to the
cold front and the tropical wave propagation, will trigger
widespread thunderstorms along the Mexican Gulf coast into
northern Central America over the next three days. Daily rainfall
maxima of 25-50 mm are expected, with localized maxima of 50-100
mm along the Mexican Gulf coast. Hurricane Trudy will leave
maximum accumulations in the range of 25-50 mm today along the
coast of the Sierra Madre del Sur. As the core of its main
circulation approaches western Mexico on Saturday, heavy rainfall
and thunderstorms are forecast, with accumulation totals exceeding
100 mm likely. By Sunday, the highest accumulations will occur
along the coast of Nayarit and Jalisco, with a maximum of 25-50
mm.

Significant vorticity advection across western Cuba and a series
of low-level shortwaves developing further east will support
isolated thunderstorms today. As the cold front propagates,
enhanced vorticity and upper-level divergence across central to
western Cuba into the northern Bahamas will interact with strong
low-level moisture convergence to trigger scattered thunderstorms
with a marginal risk of severe weather throughout the weekend.  

A disturbed low-level circulation pattern across Central America
to the coast of Colombia will enhance moisture convergence over
this region today. A cut-off low, embedded in the monsoon trough,
will move off western Costa Rica, while a series of low-level
troughs develop over the southern Caribbean Sea today supporting a
significant increase in the precipitable water anomaly. Mid-level
vorticity advection from the Colombian Andes northwestward and
upper-level ventilation over Central America will support rapid
upward moisture transport, mid-level saturated air and general
instability to sustain heavy storms over the next three days.
Local terrain will favor higher accumulation totals over Costa
Rica and eastern Panama.

Elevated low-level relative vorticity values over Panama Bight
will favor heavy rainfall accumulations today along northwestern
South America, from Colombia into northern Ecuador. These
favorable conditions will be advected outward on Saturday by the
700-mb wind flow while the flow at 850 mb and lower will continue
advecting moisture inland to support orographic showers along the
Colombian Andes over the weekend.

Widespread areas of low-level cyclonic vorticity across the
central to western Amazon basin will support deep convection and
scattered thunderstorms over the next three days. A tropical wave,
extending over Orinoquia into the central Amazon Basin, will
support storm development over southern Venezuela and the
northwestern Amazon Basin over the next few days.  Over the
Colombian Caribbean region, the tropical wave passage will lead to
scattered showers and moderate rainfall accumulations on Saturday
that will be more isolated on Sunday. Low-level moisture advection
over the Guianas into the eastern Amazon Basin will interact with
the abundant low-level vorticity present over the whole region to
favor moisture convergence and storm development over this region
on Sunday. 


Tropical Waves Initialized at 12 UTC:
TYP SOF  INIT 17/00 17/12 18/00 18/12 19/00 19/12 20/00 20/12  
TW  13N  39W  41W   43W   46W   48W   50W   52W   54W   56W
TW  19N  65W  67W   70W   72W   74W   76W   78W   80W   82W
TW  17N  87W  88W   89W   89W   90W   92W   93W   94W   96W


Sanchez-Perez...(WPC)