926 FXCA62 TJSJ 102053 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 453 PM AST Wed Oct 10 2018 .SYNOPSIS...A prevailing east northeast wind flow yielded a slightly drier airmass across the region today. Surface high pressure north of the region will gradually shift eastward into the central Atlantic causing local winds to become more southeasterly by Friday and into the upcoming weekend. A wetter and more unstable weather pattern is expected beginning late Thursday and continuing into the early portions of next week. A Tutt low and associated trough will interact with deep tropical moisture accompanying a tropical wave forecast to enter the eastern Caribbean late Saturday, then move across the region Sunday through Monday. && .SHORT TERM...Rest of today through Friday... Much drier conditions prevailed today across most areas, however residual moisture along with local and diurnal effects lead to afternoon convection over portions of the islands especially in the southwest sections of Puerto Rico. The Tutt and associated trough is expected to gradually amplify and sink southwards to just west of the region by Friday. The prevailing southeasterly wind flow is expected to lift deep tropical moisture accompanying a tropical wave across the region beginning late Thursday through Friday. Therefore, the potential for showers and thunderstorm development across the region will gradually increase across the islands and coastal waters late Thursday through Friday. Expect a fairly moist pattern to begin to unfold starting late Thursday through Friday. This fairly moist environment along will local and diurnal effects will give way to afternoon showers and thunderstorm development each day. .LONG TERM...Saturday through Thursday... The wet and unstable weather pattern will persist through the weekend and into early next week with the approach of the tropical wave and moist southeasterly wind flow. The aforementioned Tutt is expected to interact with deep tropical moisture associated with a tropical wave forecast to move across the forecast area beginning late Saturday through Monday. This overall pattern will support a favorable environment for enhanced shower and thunderstorm activity across the islands and coastal waters area during this time period. Therefore the potential for minor urban and small stream flooding will remain high through the weekend. A drier weather pattern is expected Wednesday through Thursday as a drier airmass is forecast to move in from the east, and a high pressure ridge builds north of the region. This will increase the trade wind flow and therefore limit moisture pooling and shower activity across the forecast area. && .AVIATION... VFR conditions are forecast to prevail today. SHRA will affect TJSJ/TIST/TISX/TNCM/TKPK from time to time. The strongest activity is expected across SW-PR and could affect TJMZ and the vicinity of TJPS. Therefore VCTS are expected at TJPS and brief periods of MVFR are forecast for TJMZ between 10/17-23z. Winds will be mainly from the northeast at 10-15 KT with higher gusts and sea breeze variations diminishing at 10 knots or less after 10/23z. && .MARINE...A small northerly swell around 5 feet continued to affect the Atlantic waters and passages today. This swell is expected to persist until at least Saturday and will create hazardous rip currents along the north and east facing beaches of Puerto Rico. Seas will range between 1 and 5 feet across the Caribbean waters, except across the offshore waters and local passages where occasional seas up to 6 feet will remain possible. Small craft operators should therefore exercise caution. && .PRELIMINARY POINT TEMPS/POPS... SJU 79 90 79 90 / 20 60 40 50 STT 81 87 81 88 / 20 50 40 70 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through Thursday afternoon for Culebra- North Central-Northeast-Northwest-San Juan and Vicinity- Southeast-Western Interior. VI...High Rip Current Risk through Thursday afternoon for St Croix. AM...None. && $$ SHORT TERM...DS LONG TERM....RAM