SHORT TERM
Tonight through Sunday...

Calm weather conditions persisted today across the area. The presence of a very dense Saharan Air Layer helped to inhibit shower formation in the islands. Therefore, no rainfall activity was observed today. Today, highs were seen in the low to mid 90s along the coastal and urban areas, especially over the northwestern and western coastal municipalities of Puerto Rico and Saint Croix. In the other hand, temperatures remained in the 80s in the higher elevations. Winds prevailed from the east at 10 to 20 mph with higher gusts.

A surface high pressure located in the central Atlantic will continue to dominate the local weather conditions for the next several days. The drier airmass over the region will persist until midweek promoting mainly fair weather conditions and limited shower activity. Nonetheless, by Sunday the latest model guidance suggest the arrival of patches of moisture across the islands.
Passing showers will move over portions of eastern Puerto Rico and the U.S. Virgin Islands during the morning hours, followed by afternoon activity in the western side of Puerto Rico. A seasonal pattern will return by the beginning of the workweek with warm to hot temperatures.

LONG TERM
Monday through Friday...

PREV DISCUSSION... /issued 449 AM AST Fri Jul 26 2024/

TUTT induced perturbations in the trades will reach the islands from the east on Monday and early Tuesday morning. This will promote seasonal weather conditions across the islands, with passing trade wind shower across the USVI and eastern sections of PR during the night and early morning hours, and afternoon thunderstorm development over the interior and western PR.
Increasing the risk for urban and small stream flooding. Later on Tuesday, a weak SAL moves in and hazy skies and limited shower activity should prevail.

For Wednesday and Thursday, guidance still suggest an increase in moisture content and breezy trades between 20-25 knots as a tropical wave streams across the northeastern Caribbean. The precipitable water content increases between 2.00-2.25 inches during this period. The risk for urban and small stream flooding will increase in general across the islands. Lingering moisture on Friday will enhance the diurnal convection, and at the same time another Saharan Air Layer is forecast to reach the eastern Caribbean.

AVIATION

(18Z TAFs)

Dense Saharan Air Layer will maintain hazy skies and reduced visibilities around 6SM across the local flying area through the forecast period. East winds at 15-20 kts, with stronger gusts and sea breeze variations will continue, diminishing to 5-10 knots after 26/23Z.

MARINE

Surface high-pressure located in the central Atlantic will continue to support moderate to fresh easterly winds and choppy seas for small crafts over the next few days. A strong Saharan dust event will continue to affect the local islands at least until early Sunday, resulting in hazy skies and limiting shower activity. Increased shower with thunderstorm activity is likely from Sunday onward.

BEACH FORECAST

Increasing winds will promote a moderate risk of rip currents across most beaches of St. Croix, and the east and southern coasts of Puerto Rico.

SJU WATCHES/WARNINGS/ADVISORIES
PR...Excessive Heat Warning until 5 PM AST this afternoon for PRZ001>003-005-007-008-010>013.

VI...Excessive Heat Warning until 5 PM AST this afternoon for VIZ001- 002.

AM...None.