612 FSUS46 KSGX 202300 QPSSGX Quantitative Precipitation Forecast National Weather Service San Diego CA 400 PM PDT Mon Mar 20 2023 Precipitation Forecast in Inches in 6-Hour Periods... [ Beginning times for each period are in local time... ] [ For example...05Thu ] [ ...11Thu is a forecast for 5 AM to 11 AM Thursday ] [ For example...23Thu ] [ ...05Fri is a forecast for 11 PM Thursday to 5 AM Friday] ...Orange County Coastal Areas... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Huntington Beach 0.00 0.31 0.55 0.05 0.12 0.09 0.10 0.05 0.00 0.00 Newport Beach 0.00 0.29 0.57 0.12 0.17 0.13 0.13 0.08 0.00 0.00 Laguna Beach 0.00 0.27 0.75 0.23 0.20 0.10 0.18 0.12 0.07 0.00 San Clemente 0.00 0.18 0.73 0.24 0.20 0.07 0.13 0.10 0.07 0.00 ...Orange County Inland Areas... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Anaheim 0.00 0.30 0.78 0.16 0.18 0.16 0.15 0.09 0.05 0.00 Fullerton 0.00 0.31 0.73 0.10 0.16 0.12 0.18 0.08 0.00 0.00 Brea 0.00 0.34 0.90 0.20 0.21 0.17 0.25 0.12 0.00 0.00 Villa Park 0.00 0.27 0.70 0.25 0.21 0.23 0.12 0.10 0.06 0.00 ...Santa Ana Mountains And Foothills... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Fremont Canyon 0.00 0.27 0.76 0.42 0.27 0.26 0.16 0.11 0.07 0.00 Silverado Canyon, 3 Mi East of Silverado 0.00 0.35 1.70 1.01 0.58 0.29 0.36 0.20 0.06 0.00 Modjeska Preserve 0.00 0.32 1.11 0.61 0.38 0.18 0.30 0.16 0.09 0.00 Santiago Peak 0.00 0.38 1.82 1.00 0.71 0.30 0.37 0.28 0.07 0.00 Santa Rosa Plateau 0.00 0.36 1.52 0.86 0.46 0.15 0.20 0.15 0.06 0.00 ...San Bernardino And Riverside County Valleys-The Inland Empire... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Ontario 0.00 0.24 0.78 0.24 0.25 0.21 0.32 0.23 0.06 0.00 San Bernardino 0.01 0.31 0.55 0.37 0.40 0.21 0.24 0.19 0.07 0.00 Beaumont 0.03 0.33 0.50 0.57 0.71 0.22 0.33 0.37 0.16 0.00 Riverside 0.00 0.26 0.52 0.18 0.28 0.16 0.14 0.10 0.00 0.00 Perris Valley Channel 0.00 0.27 0.47 0.19 0.31 0.09 0.19 0.12 0.05 0.00 Prado Dam 0.00 0.23 0.68 0.32 0.26 0.24 0.11 0.08 0.05 0.00 Temecula 0.00 0.25 0.74 0.55 0.48 0.18 0.15 0.13 0.07 0.00 Hemet 0.00 0.29 0.25 0.39 0.45 0.22 0.21 0.30 0.18 0.00 ...Riverside County Mountains... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Idyllwild 0.00 0.40 0.99 1.14 0.93 1.18 0.61 0.56 0.28 0.00 ...Coachella Valley... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Palm Springs 0.00 0.00 0.11 0.14 0.17 0.23 0.09 0.03 0.00 0.00 Thermal 0.00 0.00 0.02 0.03 0.10 0.00 0.00 0.00 0.00 0.00 ...San Bernardino County Mountains... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu San Antonio Dam 0.00 0.41 0.99 0.77 1.24 0.62 0.96 0.53 0.12 0.00 Lytle Creek 0.00 0.46 2.16 1.36 0.85 0.43 0.62 0.26 0.12 0.00 Wrightwood 0.00 0.34 1.44 1.37 0.95 0.56 0.51 0.12 0.03 0.00 Lake Arrowhead 0.05 0.60 1.50 1.74 1.20 0.68 0.60 0.58 0.18 0.00 Big Bear Lake 0.00 0.28 1.04 1.42 1.10 0.62 0.41 0.38 0.09 0.00 Big Morongo Canyon 0.00 0.03 0.59 1.00 0.38 0.17 0.15 0.09 0.00 0.00 ...Apple And Lucerne Valleys... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Hesperia 0.00 0.08 0.30 0.23 0.62 0.25 0.16 0.05 0.00 0.00 Victorville 0.00 0.05 0.15 0.16 0.48 0.09 0.04 0.01 0.00 0.00 Apple Valley 0.00 0.04 0.08 0.10 0.50 0.09 0.04 0.01 0.00 0.00 ...San Diego County Coastal Areas... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Oceanside 0.00 0.18 0.68 0.38 0.28 0.09 0.17 0.07 0.08 0.00 Miramar 0.00 0.17 0.65 0.41 0.22 0.11 0.13 0.08 0.07 0.07 San Diego International Airport 0.00 0.12 0.60 0.31 0.19 0.08 0.11 0.06 0.07 0.06 Chula Vista 0.00 0.09 0.41 0.18 0.21 0.11 0.10 0.09 0.08 0.07 San Ysidro 0.00 0.07 0.46 0.36 0.40 0.13 0.07 0.09 0.08 0.07 ...San Diego County Valleys... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Fallbrook 0.00 0.22 0.72 0.54 0.40 0.15 0.20 0.17 0.08 0.00 Rancho Bernardo 0.00 0.17 0.55 0.51 0.31 0.11 0.13 0.12 0.07 0.08 La Mesa 0.00 0.13 0.61 0.27 0.27 0.12 0.15 0.09 0.08 0.08 El Cajon 0.00 0.13 0.62 0.30 0.29 0.16 0.17 0.09 0.08 0.08 ...San Diego County Mountains... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Palomar Mountain 0.00 0.39 1.86 1.61 0.99 0.52 0.32 0.32 0.11 0.00 Julian 0.05 0.23 0.88 0.90 0.99 0.90 0.33 0.25 0.11 0.06 Mount Laguna 0.00 0.17 1.54 1.49 1.14 1.12 0.38 0.17 0.05 0.04 Campo 0.00 0.11 0.47 0.57 0.78 0.44 0.16 0.12 0.10 0.06 ...San Diego County Deserts... 17Mon 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 23Mon 05Tue 11Tue 17Tue 23Tue 05Wed 11Wed 17Wed 23Wed 05Thu Borrego Springs 0.00 0.01 0.12 0.11 0.28 0.38 0.18 0.03 0.01 0.00 $$ DISCUSSION... Scattered, mostly light showers will continue through tonight, with total accumulations at lower elevations expected to remain under two tenths of an inch. Upslope flow will help augment rainfall totals on the south and southwest facing coastal slopes to from one-third to to locally three-quarters of an inch. More widespread precipitation will spread into the area from the west, and become moderate to heavy on Tuesday morning as a strong cold front sweeps east across the area. There is also a slight chance of thunderstorms. Expect areas of small stream and urban flooding to develop with soils already nearly saturated. This should diminish during the afternoon as the steady rainfall ends. Scattered showers, and an isolated thunderstorm or two will eventually fill back in as the atmosphere become more unstable. and some of these will be heavy with more local flooding issues possible, especially Tuesday evening. Showers will continue off and on through Thursday morning, but with less coverage. The snow level will fall to 5500 feet (northern mountains) early Tuesday morning, then rise to 6500 feet north to 7500 feet south late Tuesday morning. The snow level will then fall Tuesday afternoon and night to around 4000 feet by early Wednesday morning. The snow level will then fluctuate around 4500 feet for Wednesday afternoon and evening. Through Wednesday night, rainfall and liquid equivalent above the snow level will range from 1.5 to 2 inches near the coast to 4 to 7 inches in the mountains with locally greater amounts. One-half to one inch is expected for the high desert and one-tenth to one- half inch in the lower deserts. Peak rainfall rates, Look to be from 1/2 to 1 inch. These are most likely ahead of the front Tuesday morning on the south-facing coastal slopes. Also, in isolated thunderstorms and heavier showers behind the front. The San Diego River and Santa Margarita River are both forecast to at least rise above monitor stage on Tuesday and could crest close to minor flood stage by late Tuesday evening. With all of the rainfall that will be occurring below the snow level, expect significant runoff, which could contribute to local flooding issues especially at low-water crossings and in poorly drained urban areas. Other areas of concern will be the Whitewater River and Coachella Canal in the Coachella Valley, as well as the Tijuana River watershed. $$