Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
935 FXUS66 KSGX 080353 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 853 PM PDT Sun Jul 7 2024 .SYNOPSIS... Slightly cooler west of the mountains Monday, with heat continuing in the deserts. Temperatures climb region-wide Tuesday and Wednesday with only minor cooling Thursday. Increasing moisture by late week will lead to slight chances of monsoon showers and thunderstorms over the mountains. The marine layer will maintain its presence near the coast and far western valleys, with clouds in the evenings and patchy fog each morning. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Evening update... Overall temperatures were similar to if not slightly lower than yesterday for the mountains westward and the high deserts, and similar to slightly warmer in the lower deserts where low level moisture mixed out a little earlier. For Monday, expect minor warming for the mountains and inland valleys as the marine layer becomes more shallow, with more warming in the lower deserts as gulf moisture mixes out even earlier and 850 temps increase. The Excessive Heat Warning for the mountains and Inland Empire were allowed to expire at 9 PM as it looks like criteria won`t be reached on Monday, however, it additional heat products may be needed for these areas as well as the inland valleys of San Diego County for Tuesday through Wednesday or Thursday as the warming trend continues and HeatRisk increases to High again. Previous discussion... Forecast Highs Tuesday-Thursday: Coast: upper-70s to low-80s. Inland Orange/San Diego County Valleys: mid-80s to mid-90s, approaching 100 degrees along the foothills in San Diego County. Inland Empire: upper-90s to 110. Mountains: low-90s to around 105. High Desert: 107-112. Lower Deserts: 112-121. The ridge axis slowly progresses eastward towards the Four Corners region by Thursday and Friday, allowing an increase in low and mid-level moisture as winds shift to the south-southeast. GEFS/EPS PWAT ensemble trends peak over the weekend, leading to the most favorable time to see any monsoonal activity. This will promote cooler temperatures to near normal values, but with muggier conditions, especially in the deserts. NBM storm probabilities peak on Saturday and Sunday with a 10 to 20 percent chance for higher terrain into the deserts. && .AVIATION... 070330Z...Coast/Valleys...Mostly clear conditions this evening with marine low clouds generally offshore. Low clouds redeveloping and impacting coastal sites 04-08Z, moving inland again 15-20 mi overnight, locally to 25 mi. Bases similar to this morning`s, generally 700-1100 ft MSL, with locally impacted VIS 0-3 SM where low clouds and terrain intersect. There is a 30% chance for low clouds to make it as far inland as KONT, best chances 10-16Z Mon. Clouds clearing to beaches 15-17Z Mon, returning to vcnty coastal sites earlier 02-07Z Tue. Mountains/Deserts...Mostly clear skies with unrestricted VIS through Monday. West winds increasing again after 20Z Mon, gusts similar to slightly weaker than today`s peaking at 25-35 kts over and east of the mountains. Weak to moderate up/downdrafts over and east of the mountains. && .MARINE... No hazardous marine conditions are expected through Friday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning until 9 PM PDT Thursday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...SS AVIATION/MARINE...CSP