FFASJU) for Flash Flooding will continue in effect from this afternoon and continuing through through Monday afternoon. && .AVIATION UPDATE... VFR conditions will prevail. However FQT passing SHRA/Isold TSRA with SCT-BKN multi lyr cld lyrs nr FL025...FL050...FL090 across the local flying area. SHRA/Isold TSRA will cont in and around the USVI and terminals, with increasing aftn convection fcst to affect the eastern, central and nrn half of PR, including the TJSJ/TJBQ/TJNR terminals. Brief MVFR expected durg the rest of the prd at most terminals with Mtn Top obscr across the ctrl mtn range of PR. E-SE wnds btw 12-20 kts with ocnly hir gusts especially with convective activity. && .MARINE UPDATE... No change to previous marine discussion. Marine conditions will continue to deteriorate through the weekend, due to combination of increasing winds and an arriving northerly swell. Seas will increase 6 to 8 feet with occasional seas up to 10 feet. Small Craft Advisory is in effect for most of the local waters. Please, refer to the Marine Weather Message (MWWSJU) and the Coastal Water Forecast (CWFSJU) for more info. && && From previous discussion sent at 449 AM AST Fri Nov 4 2022 .SYNOPSIS... The combination of a polar trough and increasing moisture will result in favorable atmospheric conditions for flooding rains. The unsettled weather pattern will continue to today and extend through Monday evening. Puerto Rico and the U.S. Virgin Islands have saturated soils from last week`s rain event. In addition, river streamflows are near to above- normal. Therefore, A flash Flood Watch is in effect Friday afternoon through Monday evening due to the elevated risk of rapid river rises, flash flooding, mudslides, and urban flooding. && .SHORT TERM...Today through Sunday... The forecast remains on track. The tropical wave with axis southwest of Puerto Rico promoted shower and thunderstorm activity across the Caribbean waters during the overnight hours. Showers will persist during the morning hours affecting mostly the south and east Puerto Rico, Vieques, Culebra and U.S. Virgin Islands. Weather will further deteriorate throughout the day as the upper-level polar trough with axis currently southeast of Florida continues to strengthen while sinking southward and settling over Hispaniola by Saturday. The positioning of the trough will be favorable as it promotes a diffluence and divergent pattern aloft with steep low- to mid-level lapse rates. At low-levels, a southerly flow will enhance moisture convergence over the CWA. Widespread convective activity with the potential of frequent lightning, gusty winds, and heavy rain is expected to peak between late afternoon through Saturday evening. Therefore, a Flash Flood Watch will come into effect by this afternoon. Given the vulnerable state of many areas across the islands, there is an increased potential for urban, river and life- threatening flash flooding, as well as debris flow and rockslides. Please continue to monitor for any advisories or warnings issued by our office as this event unfolds. Higher uncertainty remains for Sunday as models now have the area of highest moisture convergence east of the local islands. However, the deep-layered polar trough, although weaker, will maintain unsettled weather conditions across the northeastern Caribbean as it combines with plenty of low-level moisture. Therefore, a continuation of a wet and unstable weather pattern is anticipated for the latter part of the short-term period, although with less coverage of active weather compared to previous day. && .LONG TERM...Monday through Friday... The unsettled weather conditions may continue on Monday. Suppose the flooding rains event occurs throughout the weekend. In that case, saturating even more the soils and increasing the streamflows along local rivers, the risk of flash flooding and mudslides will extend through at least Monday evening. The confidence in the model guidance is moderate because the event is tight to the upper-level feature`s final position and the surface`s low-pressure evolution. That non-tropical low is being monitored by the National Hurricane Center (NHC) and might develop near the Northeast Caribbean or the Western Atlantic. It has a low chance of tropical cyclone formation in the next five days (30 percent). Please refer to the latest Tropical Weather Outlook (TWOAT) issued by the NHC. This non-tropical low plays an essential role in the islands` weather scenario. Therefore, the confidence in next week`s weather scenario is even lower due to high uncertainty about this system`s future path/intensity. However, GFS solution insists on a southerly to southwesterly wind flow through late Wednesday night, from the southeast on Thursday, and more easterly by Friday. Moisture content is now even lower than the previous run cycle, and the upper-level dynamic seems weaker. Therefore, this period could be a transition to better weather conditions with just the typical afternoon convection. && .AVIATION... An unsettled weather pattern will persist through the forecast period. Sct-Num SHRA/SCT-TSRA will develop after 04/17z thru 05/06z with areas MVFR/IFR conds and widespread mtn obscurations. Sfc winds less than 8 kts thru 04/14Z bcmg ESE 8 to 16 kt aft 04/14Z with sea breeze variations, but locally higher near/in TSRA. && .MARINE... Marine conditions will gradually deteriorate this weekend, due to combination of increasing winds and an arriving northerly swell. Seas will increase 6 to 8 feet with occasional seas up to 10 feet. Small Craft Advisory is in effect for most of the local waters. Please, refer to the Marine Weather Message (MWWSJU) and the Coastal Water Forecast (CWFSJU) for more info. A mid to upper-level trough with abundant tropical moisture and a surface low pressure over the southeastern Caribbean will result in unsettled weather conditions and increased thunderstorm activity across the regional waters throughout the weekend. For beachgoers, the risk of rip currents is moderate along the Atlantic Coastline of Puerto Rico, Vieques, Culebra, and the Virgin Islands. The risk of rip currents will increase to high this weekend into early next week for most of the beaches. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...Flash Flood Watch through Monday afternoon for PRZ001>013. VI...Flash Flood Watch through Monday afternoon for VIZ001-002. && $$ $$