Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
511 FXUS66 KSGX 082107 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 207 PM PDT Wed Oct 8 2025 .SYNOPSIS... A low pressure system off the West Coast will draw tropical moisture from Priscilla northward into the area for Thursday into Friday night with increasing chances for showers and a chance for thunderstorms. Cooler with drying for Saturday through Monday. For Tuesday and Wednesday of next week, a low pressure system moving to near the West Coast will bring a chance of showers. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Tonight through Friday... Low clouds will continue to fill back in by later this evening along the coast and then advance inland ahead of the approaching trough, and remnants of Priscilla moving up over the area. Some of the mid level clouds from the tropical system to our south will begin to make their way up over the region by early in the morning tomorrow. The latest track of Priscilla has remained similar to previous models, which shows that a majority of the moisture streaming up over the area from tomorrow through Friday to be located over San Diego County. For this reason, the mountains of San Diego will likely have the best chance of thunderstorms developing overhead during the afternoon. Otherwise, it will just likely be on and off showers falling from a relatively high based mid-level scattered to broken cloud deck for most of the areas tomorrow, with most of the coastal and inland areas likely receiving between 0.01-0.10" through Saturday. PWAT values are still pushing 200, so if a storm does develop, it could put down a heavy amount of rain in a short period of time, of possibly a half an inch or greater per hour. Having said this, it doesn`t appear that the system is well organized, which could indicate that it is undergoing much weakening and may not have as much moisture associated with it as the remnants make their way over the region. Given the higher PWATs, if there is a stronger shower or possible storm the develops and remains nearly stationary, it could cause some flash flooding problems, which is especially the case for Friday afternoon as the depression moves closer to the CWA, with an increase of instability. By Saturday morning, the system will begin to pull away from the area and there will only be a slight chance of thunderstorms for the mountains and deserts. Temperatures will also increase a bit, and moisture increasing will keep temperatures quite a bit more modified and warmer over Saturday through the mid half of next week... The longwave trough with an area of low pressure upstream will continue to approach the region, and the tightening of the pressure gradient at the surface will cause winds to increase and become rather strong and gusty on Saturday for the high deserts, and areas prone to stronger winds due to gap flow. This will also allow for temperatures to begin to cool off, and this will continue going into the early part of next week, with the chance of rain as a series of troughs will bring about a chance of precipitation and also keep temperatures on the cooler side through the mid part of next week. && .AVIATION... 082000Z....Coasts/Valleys...SKC area-wide this afternoon. Areas of low clouds with bases around 1200-1800 feet MSL will gradually redevelop and spread inland starting 01-03Z Thu. Less uniform coverage than this morning and mostly confined to San Diego County. Patchy coverage of low clouds possible elsewhere 12-16Z Thu. Any low clouds scattering out again by 15-17Z Thu as showers begin to push in from the south. Mountains/Deserts...Mostly clear and VFR conditions through tomorrow morning. High clouds and scattered -SHRA moving in from the south after 12Z Thu. Slight chance (15-25%) TSRA after 21Z Thu. && .MARINE... Northwest wind gusts around 20 kt near San Clemente Island each afternoon/evening Thu through Sat. There is a slight chance of thunderstorms Thursday through Friday. Lightning, erratic winds, choppy seas, and/or reduced visibility in heavy rain likely in vicinity of any thunderstorms. && .BEACHES... There is a 5-15% chance of thunderstorms producing lightning Thursday and Friday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...Stewey AVIATION/MARINE/BEACHES...KW