Area Forecast Discussion
Issued by NWS San Juan, PR
Issued by NWS San Juan, PR
045 FXCA62 TJSJ 010124 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 924 PM AST Sun Jun 30 2024 .UPDATE...Up to 2.5 inches of precipitation were seen across Anasco this afternoon accompanied by frequent lightning and 50 Kft tops. Rainfall was limited to less than 0.75 inches just southwest of the Greater san Juan Metropolitan area. Showers have cleared off of the land areas as a patch of drier air moves through. A few showers were seen along the slopes of El Yunque nevertheless. Another patch of moisture is expected later tonight and during the early morning hours with most showers confined to the local waters and eastern Puerto Rico. Dust has reduced some visibilities to as little as 8 SM as Saharan air flows north around Major Hurricane Beryl. This Saharan airmass has been particularly brutal on Saint Croix where another record high temperature for the date (92 degrees) was set. Warm temperatures are expected to persist through Monday before some showers and moisture from Major Hurricane Beryl bring some relief. No changes to the forecast were introduced. && .PREV DISCUSSION... /issued 503 PM AST Sun Jun 30 2024/ SYNOPSIS... A dry air mass and subsidence ahead of Major Hurricane Beryl will limit rain activity through Monday afternoon. The most outer bands of Beryl could bring squally weather across the U.S. Virgin Islands and Puerto Rico from late Monday night into Tuesday. Marine and coastal conditions will gradually deteriorate across the Caribbean and local passages as Major Hurricane Beryl moves far to the south across the Caribbean Sea. Stay tuned for updates on this storm and the Invest 96L, which the National Hurricane Center monitors. SHORT TERM...Tonight through Tuesday... A breezy trade wind pattern will continue as a robust surface high across the Atlantic Basin and Hurricane Beryl stream trade winds across the region. Due to this passing showers remain possible across eastern Puerto Rico and the USVI during the night. By tomorrow a dry air mass that is preceding the moisture field of Beryl and strong subsidence ahead of the strong will be present across the area, limiting rainfall to brief passing showers and causing hot, muggy conditions. However by the evening hours into the night, conditions are expected to deteriorate as the hurricane moves into the eastern Caribbean basin. An increase of wind speeds and passing showers will focus heavy rainfall at times across the southern to eastern half of Puerto Rico including the USVI as Beryl moves well south of the region, currently projected to be over 200 miles south of islands by Tuesday morning. Squally weather is possible and could bring impressive thunderstorm activity that could cause flooding and wind impacts. This pattern will last through Tuesday evening as the system moves westward further away from the area. Following this, drier air fills in behind the storm by Tuesday night causing a dry pattern to prevail before the next system later in the week. The greatest impacts to our islands from Beryl will be across the southern and eastern coastal waters that will experience chaotic seas due to a strong swell on Tuesday. This will cause very hazardous coastal conditions with strong breaking waves in excess of 10 feet at times. Strong winds will also be present throughout this time and as mentioned, thunderstorms and heavy rain will likely be present as well. Stay vigilant as we approach Tuesday and stay informed with the latest forecast. LONG TERM....Wednesday through Sunday... After the passage of Hurricane Beryl south of the local area, a drier airmass will quickly move over the islands. This drier airmass will promote stable conditions on Wednesday with limited shower activity. However, by Thursday onwards tropical activity is expected once again. The National Hurricane Center (NHC) is currently monitoring an area of low pressure located over the eastern Atlantic with a medium to high formation chance over the next 7 days. Latest model guidance suggest that this system will develop as a tropical cyclone before reaching the Lesser Antilles. Nonetheless, this system should remain south of the islands and over the Caribbean waters. At this moment some of the potential indirect impacts associated to this low are: localized flooding, gusty winds, squally weather, and deteriorated marine and coastal conditions. It is too early at this moment to determine the amount of expected rain. Therefore, residents and visitors of Puerto Rico and the U.S. Virgin Islands may continue to monitor the progress of this system as it moves towards the Caribbean. A vast moisture field of this low will persist across the region once it departs on Saturday, promoting afternoon convective activity across the western portions of Puerto Rico. Following the system, more drier air and Saharan Dust particles will take over, enhancing stable and dry conditions for few days. Despite of the expected weather, high temperatures will remain between the upper 80s to low 90s across the islands with heat indices surpassing the mid 100s. AVIATION... (00Z TAFS) VFR conds will prevail across terminals during the next 24 hrs. Convection will develop tomorrow, btwn 01/15z-22z, due to local effects and stronger than usual wind flow. The earliest that the most-outer bands of Beryl may reach the local flying area is aft 01/23z. Land breezes of less than 10 will prevail overnight but not all locations will be free from increasing easterly flow. Expect E winds at 15-20 kt with gusts up to 30 kt possible and sea breeze variations after 01/13z. MARINE... The strong surface high pressure across the Central Atlantic will continue to promote moderate to locally fresh easterly winds over the islands. The latest National Hurricane Forecast trajectory moves Major Hurricane Beryl far to the south of the regional waters late Monday night into Tuesday, deteriorating marine and coastal conditions considerably, especially for the Caribbean Waters and Passages. The outer bands of Beryl may produce squally weather during that time. BEACH FORECAST... Swells from Beryl will create life-threatening rip currents along the south-facing beaches of Puerto Rico and the U.S. Virgin Islands from Monday afternoon onward. High surf along coasts with southern exposure is possible beginning on Tuesday. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...Small Craft Advisory from 6 PM Monday to 6 PM AST Tuesday for AMZ711-735. Small Craft Advisory from 6 AM Monday to 6 PM AST Tuesday for AMZ723-733-741. && $$ SHORT TERM/MARINE...WS LONG TERM....RC UPPER AIR...MMC PUBLIC...GRS