Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
283 FXUS66 KSGX 151635 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 935 AM PDT Mon Jul 15 2024 .SYNOPSIS... Monsoonal moisture will bring some thunderstorms with locally heavy rain over the mountains and deserts this afternoon, followed by very isolated showers and thunderstorms over the mountains on Tuesday afternoon. After some drier days, the monsoon moisture and chances of thunderstorms could return toward the end of the week. Temperatures will be near normal, climbing to above seasonal normals the second half of the week. Coastal low clouds will continue nights and mornings. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Coastal low clouds this morning had their standard coastal coverage and are undergoing a fairly standard clearing pattern. Mostly sunny skies should result for coast and valleys by late morning. Farther inland, the cumulus clouds are already starting to form over the mountains. That will lead to some thunderstorms over the mountains for the afternoon, with a few drifting off into the deserts (most likely the high desert). Overall, the monsoon moisture is decreasing, so the monsoon event won`t be as exciting as yesterday`s, but a thunderstorm or two could present some trouble in the form of isolated flash flooding. The best model guidance shows a pretty clean finish on the chances of thunderstorms by 6 pm or so. Moisture continues to decrease through Wednesday, right now just enough for a very slight thunderstorm chance Tuesday afternoon over the mountains. With the monster high pressure ridge over the West taking a temporary break, temperatures will mellow out from the extremes of the last two weeks; max temps rise to around normal today and Tuesday. The ridge begins to strengthen again Wednesday to start yet another warming trend, and max temps rise several degrees above normal in the mountains and deserts. The trend continues so that the entire region goes a little above normal by Thursday. With the ridge axis to our north, that will re-open the monsoon door allowing more mid level moisture to come into SoCal from Mexico. Models and ensembles differ quite a bit on the extent of moisture, and the resulting chances of thunderstorms, but it appears we`ll have an increasing chance toward the end of the week. Right now we have small chances in the mountains starting Friday afternoon, with higher chances over the weekend expanding into the deserts. We haven`t forgotten you, coastal low clouds. The cloud coverage will remain very similar each night and morning. Rinse and repeat. If any minor trend can be detected, it would be slightly lesser coverage in time and space for the latter half of the week. && .AVIATION... 151540Z...Coast/Valleys...BKN-OVC clouds with bases 500-1200 ft MSL extending 15-20 miles inland should scatter out 16-19Z, with the potential for low clouds to locally linger at beaches this afternoon. Low clouds are expected to redevelop and move inland 04- 08Z Tue, with bases 700-1200 ft MSL, and are expected to reach 15-20 miles inland by 14Z. Confidence in clearing time at KSAN of 18Z is moderate. Mountains/Deserts...TSRA expected 19Z Mon-02Z Tue in the mountains with BKN100. Heavy rainfall, erratic winds, and strong up/downdrafts expected where storms develop. There is a 20-25 percent chance of RA/TSRA in the deserts 20Z Mon-00Z Tue, with the potential for strong outflow gusts and lightning from nearby storms to impact KPSP and KTRM. && .MARINE... No hazardous marine conditions are expected through Friday. && .BEACHES... Long period SSW swell (200-210 degrees) of 3ft/16-18 sec will bring surf of 4-6 ft to Orange and northern San Diego County beaches. Sets to 7 ft are possible on Tuesday and Wednesday. The highest surf will occur on southwest facing beaches. There is a high risk of dangerous rip currents. A Beach Hazard Statement is in effect for Tuesday morning through Thursday evening. The surf will gradually decrease Thursday through the weekend as the period decreases to 14-15 sec and the swell height falls to 2 ft. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement from Tuesday morning through Thursday evening for Orange County Coastal Areas-San Diego County Coastal Areas. PZ...None. && $$ PUBLIC...MM AVIATION/MARINE/BEACHES...Small