902 FXCA62 TJSJ 100921 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 521 AM AST Wed Oct 10 2018 .SYNOPSIS...A slightly drier airmass will reduce the rainfall coverage during the day today through early Thursday. A wetter and more unstable weather pattern is expected starting later on Thursday and continuing into the early portions of next week as an upper-level low will combine with deep tropical moisture associated with a developing surface low-pressure area and also from a tropical wave that will be moving from the east. && .SHORT TERM...Today through Friday... The available moisture will decrease somewhat through the day today, particularly for the northern portions of the forecast area. There is also an upper ridge over the local area today, but an upper trough will gradually develop to the west of the local area by Friday, which will gradually dig to the west southwest for the next couple of days after that. Even though moisture will decrease slightly this afternoon, there will still be enough moisture that will combine with the local effects to cause the development of showers and thunderstorms across the interior, western and southwestern PR this afternoon. There is also a chance of showers across eastern Puerto Rico and the northern USVI. Even though the upper trough is expected to develop by Friday to the west of the local area, the chances of thunderstorm continues in the short term. Not to mention the fact that the available moisture will start to increase once again on Thursday afternoon and we will continue to have higher than normal moisture on Thursday afternoon and Friday and for the next several days after that, with precipitable water values near 2 inches. So given the current setup, we expect a somewhat rainy pattern for the next few days, with the thunderstorms mainly in areas of convergence, such as sea breeze convergence and also downstream from the islands and the Luquillo Mountain Range into the San Juan metro area, especially for Thursday and Friday. Little change in the temperatures is expected, with the max temps in the mid to upper 80s across the lower elevations and in the low 80s across the higher elevations. .LONG TERM...Saturday through Thursday... The wet and unstable weather pattern will prevail across the region during the weekend into early next week as the upper-level trough, which will be situated north of the region, will combine with deep tropical moisture not only associated with a developing surface low-pressure area over the central Caribbean, but also from a tropical wave that will be moving in into the forecast area late Sunday into Monday. This will provide a favorable environment for enhanced shower and thunderstorm activity across the forecast area during this time period. A return to drier weather conditions is expected by the middle to latter half of next week as a drier airmass will be moving in from the northeast, therefore, limiting the shower activity. && .AVIATION... VFR conds expected across the local terminals through 10/17Z, due to SHRA/TSRA possibly affecting TJMZ thereafter. However there will be SHRA in the general area that may cause VCSH across most of the local terminals through the forecast period. Winds will be mainly from the east to ENE at 15KT and gusty with sea breeze variations past 10/14Z. && .MARINE...Seas will continue to range between 4 to 6 feet across the Atlantic waters and local Caribbean passages. Therefore, small craft operators are urged to exercise caution across these waters. Elsewhere, seas of 3 to 5 feet are expected to prevail. Northerly swell associated with Hurricane Leslie, located across the central Atlantic Ocean, will continue to produce a high risk of rip currents across the northern beaches of PR and Culebra for today. && .PRELIMINARY POINT TEMPS/POPS... SJU 87 79 90 79 / 40 20 60 40 STT 91 81 87 81 / 40 20 50 40 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through this afternoon for Culebra-North Central-Northeast-Northwest-San Juan and Vicinity. VI...None. AM...None. && $$ SHORT TERM...JA LONG TERM....GL