FXCA20 KWBC 161828 PMDCA 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) $$