995 FXCA62 TJSJ 061537 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 1137 AM AST Sat Feb 6 2021 .UPDATE...Drier air has moved in and fair weather is being observed across the local islands. This fair weather is expected to prevail through the day, but isolated and brief showers is possible in the afternoon hours across the USVI and western PR. The local wind is currently from the east with sea breeze variations, and coastal areas may observe wind speeds between 15 and 20 mph with occasional gusts. The available moisture will increase for the evening and overnight hours, which will cause an increase in shower activity. Therefore scattered showers are forecast through the night for the USVI and north and east PR, as well as across the local waters. The winds overnight will continue from the east,generally between 10 and 15 mph over the coast, but slightly stronger over the waters. && .AVIATION...No changes from the previous discussion. Easterly winds will prevail for the rest of today with sea breeze variations. The wind speeds will be generally between 13 and 20 knots with occasional gusts. For tonight, the shower activity may increase, and brief VCSH is possible, mainly across TIST, TISX and TJSJ. The overnight winds will continue from the east, at around 10 to 15 knots with occasional gusts. && .MARINE...Wind driven seas will continue to cause choppy to hazardous marine conditions through the weekend. We currently have a Small Craft Advisory for the offshore Atlantic waters, but as winds increase over the waters, most of the local waters will observe hazardous seas, and therefore a Small Craft Advisory will go into effect at 8PM tonight for many of the local waters. There is also a high risk of rip currents for northern PR and Culebra today into tonight. && .PREV DISCUSSION... /issued 456 AM AST Sat Feb 6 2021/ SYNOPSIS... A trend towards drier conditions, with generally fair weather, will continue this weekend. A patch of moisture could bring some additional passing showers tonight into early tomorrow morning, though. Hazardous marine conditions are expected for portions of the local waters this weekend. Therefore, small craft advisories and high risk of rip currents are in effect. SHORT TERM...Today through Monday... For today, breezy conditions and quick passing showers are expected across the U.S. Virgin Islands and the eastern sections of Puerto Rico. Limited afternoon shower development is possible over western PR due to local effects, however, no significant rainfall accumulations are expected. Weather conditions will change this evening and through Sunday morning due to the arrival of an easterly perturbation in the trade wind surge. This will bring frequent showers across the USVI and eastern half of PR, increasing the potential for urban and small stream flooding. Although a drier air mass is forecast to move quickly during the day on Sunday, residual moisture should aid in the development of afternoon showers over western PR. For Monday, another surge in low-level moisture from the east is forecast to move by midday across the region. This will increase trade wind shower activity once again across the USVI/Eastern half of PR during the morning hours, and as it is expected to move later in the day, it will provide better moisture to support afternoon shower activity over mainland PR. LONG TERM...Tuesday through Friday... No major changes to the long term forecast with models still suggesting a mid level ridge over the forecast area and a surface high pressure in central Atlantic dominating the region for most of the workweek. This will maintain an easterly trade wind inversion over the area. GFS suggest that precipitable water values will oscillate between 0.70 inches to 1.44 inches on Tuesday through Friday with variations due to passing patches of moisture embedded in the trades within the 700 mb level. The maximum precipitable water values are forecast for Thursday. As the mid level ridge continues evolving throughout the week, 500 mb northerly winds will cause cold air advection into the area cooling down temperatures between -7 to -8 degrees celsius on Thursday and Friday increasing instability aloft. Therefore, expect mainly fair weather conditions with shallow areas of moisture embedded in the easterly wind flow reaching the islands from time to time. This will cause increased cloudiness and passing showers across PR and the USVI dependent on moisture availability. Shower enhancement due to locally induced effects and sea breeze convergence could develop over interior and western portions of Puerto Rico during each late afternoon. Expect somewhat greater shower activity embedded in the trades between Thursday and Friday due to greater instability aloft. As a result, ponding of waters on roadways and in poor drainage areas will remain possible in isolated areas. Aviation...Mainly VFR conditions are expected across all terminals through the forecast period. However, SHRA is expected to increase from this evening and through early Sunday morning from the east. This may cause tempo MVFR conditions across the USVI terminals and TJSJ. East winds increasing around 15 kts with sea breeze variations and higher gusts after 14z. MARINE... Increasing winds will help to sustain hazardous marine conditions for the offshore Atlantic waters. For the offshore Caribbean waters, as well as in and around the local passages, the winds will lead to the development of hazardous conditions by this evening. Hazardous condition will last into tomorrow afternoon at least, and likely into Monday morning for the offshore Atlantic waters and waters in and around the Anegada Passage. There remains a high risk of rip currents for most north-facing beaches of Puerto Rico, as well as beaches of Culebra and northwestern beaches of St. Thomas. && .PRELIMINARY POINT TEMPS/POPS... SJU 85 75 85 73 / 40 50 50 10 STT 85 74 84 73 / 50 50 40 30 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through late tonight for Culebra-North Central-Northeast-Northwest-San Juan and Vicinity-Southeast. VI...None. AM...Small Craft Advisory from 8 PM this evening to 8 AM AST Monday for Anegada Passage Southward to 17N-Coastal Waters of Southern USVI Vieques and Eastern Puerto Rico out 10 NM. Small Craft Advisory from 8 PM this evening to 8 PM AST Sunday for Caribbean Waters of Puerto Rico from 10 NM to 17N-Mona Passage Southward to 17N. Small Craft Advisory until 8 AM AST Monday for Atlantic Waters of Puerto Rico and USVI from 10 NM to 19.5N. && $$ SHORT TERM...JA LONG TERM....JA PUBLIC DESK...ERG