textproduct: San Diego

SYNOPSIS

Tropical Storm Rachel will impact Southern California tonight into Sunday afternoon. Cooler conditions expected into early next week. Widespread showers and locally heavy rainfall, coastal flooding, and increased winds are expected Sunday. Elevated winds over the mountains and into the deserts will continue into Monday morning. Scattered showers will continue across the coastal basin through the day Monday. Drier conditions expected for Tuesday onward, with an increase in temperatures and potential for Santa Ana winds during the latter half of the week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

Widespread high cloud coverage can be expected across the area today as Tropical Storm Rachel quickly approaches Northern Baja. Radar is indicating areas of rain already with isolated thunderstorms over the coastal waters and San Diego mountains and deserts. Rainfall chances will increase from south to north tonight into Sunday morning as Rachel makes landfall in northern Baja. Winds are also expected to begin to increase through the day continuing into Sunday. Elevated winds over the mountains and into the deserts are expected to continue into Monday morning. Most of the impacts from Rachel are expected to occur between late tonight and early Sunday afternoon, with conditions improving from south to north. Coastal flooding is expected to continue into early next week due to continued elevated tides and lingering elevated surf. Please see the Beaches discussion below for more information on coastal flooding concerns.

Light rain today will become moderate to heavy around midnight for San Diego County. Based on the current forecast, most locations will see their heaviest and most widespread rain before noon, with some potential for moderate to locally heavy rain to continue into the early afternoon for portions of Riverside and San Bernardino Counties. Rainfall totals of 0.40 to 1.25 inches are expected for the coast and valleys with highest totals for southeastern areas, 1.5 to 3.5 inches for the mountains, and 0.50 to 2 inches of rain for the deserts. Maximum rainfall rates of 0.50-0.60 inches per hour for the coast and valleys, 0.50-0.70 inches per hour for the deserts, and 0.70-1 inch per hour in the mountains. Remain alert and heed advice of local officials as areas of flash flooding are possible tomorrow. The San Diego River at Fashion Valley is currently forecast to peak at 7.5 feet (action/monitor stage) around noon on Sunday. Those with interests near the San Diego River should continue to monitor the forecast.

Winds are also expected to increase tonight into Sunday. Tropical Storm force winds are still possible across San Diego county. Outside of tropical storm force wind potential the most likely wind forecast is 25-45 mph through the coastal basin and 50-70 mph near the mountain ridges. Early Sunday, easterly winds expected for San Diego and Riverside county mountains, before turning southwest/westerly. Wind gusts for the coast and valleys are expected to weaken to 20 to 25 mph and be less frequent for the afternoon, before weakening in the evening. Winds are expected to stay elevated from the west over all mountains and deserts into early Monday morning.

Scattered rain showers will continue across the coastal basin into Monday. Drier and warmer conditions expected Tuesday through much of next week. There is a potential for Santa Ana winds to develop for the end of next week. Low confidence in details.

AVIATION

101800Z...Coast/Valleys....Mostly cloudy with BKN-OVC skies AOA 15k ft MSL through the period. ISO SHRA/TSRA as early as 20Z, weakening from south to north, best chance for this in San Diego County inland valleys. Heaviest rain from Tropical Storm Rachel arrives from south to north after 08Z Sun, arriving near 09-10Z VCTY KSAN. As rain nears, expect NW winds to increase and shift to the WSW through mid morning. Highest winds over San Diego County with a 40% chance of winds gusting over 30 kts at KSAN between 12Z-16Z. Cloud bases lowering near 3000 ft and vis down to 3-5SM in heavy rain. Showers becoming lighter and scattered about Sunday afternoon with high clouds remaining.

Mountains/Deserts...Mostly cloudy with BKN-OVC skies AOA 15k ft MSL through Sunday morning. ISO SHRA/TSRA as early as 20Z, weakening from south to north. Low confidence on TSRA activity across the lower deserts, including VCTY KPSP. Heaviest rain from Tropical Storm Rachel arrives from south to north after 10Z Sun, heaviest rainfall expected 10Z-18Z Sun with cigs lowering near 5000-1000 ft MSL in any rain. SW winds increase after 12Z with gusts along the desert slopes 35-55 kts, gusts closer to 25-35kts in the deserts. Winds becoming more localized after 03Z Mon. Clouds beginning to scatter out Sunday afternoon/evening.

MARINE

Isolated thunderstorms possible over the waters through this evening. Gusty northerly winds develop later this evening, turning westerly later in the morning. Winds 20 to 30 knots expected throughout the coastal waters during these time periods. Large fresh swell from the northwest will combine with south swell associated with Tropical Storm Rachel and wind waves to create combined seas 6 to 10 feet Sunday. Choppy, steep, mixed seas and gusty winds will produce conditions hazardous to small craft on Sunday.

Calmer winds and seas expected Monday through the work week.

BEACHES

Surf of 3-5 feet with local sets to 6 feet will continue on south and southwest facing beaches through Saturday. Elevated surf and strong rip and longshore currents will create hazardous swimming conditions. This elevated surf will combine with high tides over 7 feet during the mornings and evenings to produce significant coastal flooding and beach erosion.

Fresh south swell associated with Tropical Storm Rachel will arrive late tonight into Sunday. This will combine with a larger northwest swell and strong winds to produce elevated to high surf Sunday for all area beaches, peaking at 5 to 8 feet with sets to 9 feet. This will pose a hazard to swimmers and lead to very strong rip currents. In addition, morning high tides will continue to be 7 to locally 7.5 feet, continuing the threat for significant coastal flooding through Sunday afternoon. A Coastal Flood Warning is in effect for these hazards through Sunday at 3 PM. Take the necessary actions to protect flood-prone property.

Both winds and swells subside for Monday-Tuesday, and surf will decrease to 3 to 6 feet, though strong rip currents will continue. Morning high tides will continue to be near 7 feet, meaning that minor coastal flooding will continue to be an issue through this period. The Coastal Flood Warning will be replaced with a Coastal Flood Advisory at 3 PM Sunday and continue through 2 PM Tuesday.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Warning until 3 PM PDT Sunday for Orange County Coastal Areas-San Diego County Coastal Areas.

Tropical Storm Watch for San Diego County Coastal Areas-San Diego County Deserts-San Diego County Mountains-San Diego County Valleys.

Flood Watch from 11 PM PDT this evening through Sunday evening for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Bernardino County Mountains-San Diego County Coastal Areas-San Diego County Deserts-San Diego County Mountains-San Diego County Valleys-San Gorgonio Pass near Banning.

Beach Hazards Statement from Sunday morning through Sunday evening for Orange County Coastal Areas-San Diego County Coastal Areas.

Coastal Flood Advisory from 3 PM Sunday to 2 PM PDT Tuesday for Orange County Coastal Areas-San Diego County Coastal Areas.

Wind Advisory from 5 AM Sunday to 5 AM PDT Monday for Apple and Lucerne Valleys-San Bernardino County Mountains.

Wind Advisory from 2 AM Sunday to 5 AM PDT Monday for Coachella Valley-Riverside County Mountains-San Gorgonio Pass near Banning.

PZ...Tropical Storm Watch for Coastal Waters from San Mateo Point to the Mexican Border and out to 10 nm-Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.