Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
258 PM EDT Thu Jul 23 2026

Forecast Bulletin 23 July 2026 at 1900 UTC:

The mid-to-low level trough associated with Tropical Storm Bertha
will be arriving into northeast Mexico by late in the evening
today, when there will also be an increase in vorticity advection
and moist air advection. The tropical system will create a
weakening along the periphery of a pre-existing mid-to-upper level
ridge, which is situated across the United States southern plains
and southwest region. The remnants of the tropical system will
continue to be transported westward for Friday and Saturday. With
its passage across northern Mexico, anticipate an increase in
convection. By early Saturday morning, the mid-level trough will
arrive into the west coast of Mexico. At the same time, there will
be a moistening trend along the coasts of Sinaloa and Nayarit,
which will be responding to the arrival of the tropical system
remnants. Thus, expect an increase in precipitation coverage early
Saturday morning and continuing through the day. The low-to-mid
level trough will be exiting the continent and arriving into the
Baja California Peninsula by Saturday afternoon. Moisture will
still linger in the region after the remnants of the tropical
system exit the region, however, precipitation coverage will
become isolated.

Meanwhile across the northern Caribbean, there is currently a
cut-off upper level low that will begin to extend into the
southwest Caribbean Sea starting today. Also in south Central
America, a diffluent upper level will begin to develop, being
driven primarily by convective feedback. These two features will
be supporting the enhancement of divergence for Thursday and
Friday. At the same time, a tropical wave will be arriving into
the Caribbean Sea and due to the presence of the upper trough,
there will be a significant increase in moisture across Nicaragua,
Costa Rica, and Panama as the tropical wave moves across these
countries for Thursday and Friday. Furthermore, the Caribbean Low
Level Jet (CLLJ) will remain active for the next three days,
reinforcing moisture pooling along its exit zone and cyclonic
rotation across Costa Rica and Panama. Thus, expect elevated total
precipitation maxima for Thursday and Friday. By Saturday, the
upper trough will be located across the southern Gulf (west of the
Yucatan Peninsula and the tropical wave will be moving into the
Yucatan Peninsula and Belize. The upper trough will again
reinforce upper divergence, helping with the development of deep
convection for Saturday. The highest precipitation accumulations
will be across Belize and the higher terrain of eastern Guatemala.

Across the Greater Antilles, however, available low- to mid-level
moisture combined with an upper-level low centered over the
Bahamas will support isolated to scattered convective
precipitation today and Friday, with maximum rainfall amounts of
15–20 mm possible. By Saturday, this upper-level low is expected
to drift westward and weaken further, allowing drier and more
stable conditions to spread across the Greater Antilles.
Meanwhile, by Saturday, an approaching tropical wave is forecast
to weaken the low- to mid-level inversion over the eastern
Caribbean. Combined with an increase in low-level moisture, this
will enhance atmospheric instability and favor the development of
some convective precipitation across the Lesser Antilles. Farther
south, increasing moisture and instability are also expected over
the Guianas and the Amazon region, leading to a higher likelihood
of convective precipitation in these areas.

SOF  INIT  24/00  24/12  25/00  25/12  26/00  26/12  27/00  27/12
20N  35W  37W  40W  44W  48W  52W  55W  57W  61W
15N  58W  61W  66W  69W  74W  78W  82W  85W  87W
11N  70W  73W  77W  81W  85W  87W  89W  93W  95W
13N  94W  97W  99W  100W 103W ABS  ---  ---  ---

Tinoco-Morales...(WPC)