Santa Ana winds expected Thursday through Saturday, with the strongest and most widespread on Friday. Additionally, moderate to major HeatRisk is expected for coastal areas. Cooler conditions will spread inland Sunday, with greater cooling and chance of showers next Tuesday and Wednesday.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
We're already seeing an offshore pressure gradient from San Diego to Tonopah, NV. As of 11 AM there were weak north to northeast winds being observed with gusts mainly 20 to 25 mph, a few local gusts to 30 mph in windier locations. For Thursday, an upper level high will develop over Northern California, with low pressure retrograding back towards Southern California. That will strengthen the offshore pressure gradient and increase winds. For Friday and Saturday, that low will remain just southwest of San Diego off the coast of northern Baja, maintaining a strong offshore pressure gradient.
Winds on Thursday will be mainly out of the north/northeast, with the strongest winds on the foothills and below passes in the San Bernardino and Santa Ana mountains. Winds are expected to be strongest and most widespread Friday and they develop more of an easterly component. The ECMWF Extreme Forecast Index on Friday has gusts in the 80th to 90th percentile and locally into the 95th to 99th percentile. Wind gusts have the potential to exceed 65 mph in the typically windy spots like near the Cajon Pass, in wind prone canyons in the Santa Ana mountains, and in wind prone spots in the San Diego mountains. Santa Ana winds could extended to coastal areas on Friday, with a 30 to 50 percent chance of local wind gusts greater than 35 mph. Winds become weaker and easterly on Saturday, with gust 30 to 40 mph in the valleys and below passes, and gusts up to 50 mph on mountain foothills and below passes. Weaker offshore winds may continue on the coastal mountain slopes Sunday with onshore flow expected to return by Monday.
The location of the upper level low to the southwest of San Diego, will help keep relative humidity elevated and could elevate chances of showers in the deserts. Right now chances are 10 percent or less, with low confidence in measurable rain.
High temperatures on Thursday will be a few degrees below average for the mountains and valleys with coastal areas as much as 12 to 18 degrees above average. High temperatures on Friday will be a few degrees warmer for most locations, bringing highs closer to 15 to 20 degrees above average for coastal locations. Moderate HeatRisk is expected for the coast into the western San Diego County valleys for Thursday through Saturday with Major HeatRisk for some coastal areas on Friday. Conditions will remain above average but cool a few degrees on Saturday with continued cooling west of the mountains into next week.
We're monitoring the potential for precipitation Tuesday and Wednesday of next week. There remains differences in the models with the GEFS guidance trending more inside and the ECMWF showing a more westerly track. While there remains the most uncertainty in the precipitation forecast, there is higher confidence in cooler and windier conditions.
141800z, SKC and VFR today and tonight. Areas of northeast localized winds gusting 15-20 kts in the mountain foothills increasing after 10Z with gusts 20-45 kts, spreading into inland valleys after 12Z, including into parts of the IE.
Isolated northeast gusts could exceed 20 knots Friday into early Saturday. Otherwise, no hazardous marine conditions are expected through Sunday.
A prevailing southerly swell will continue most of this week, generating surf 3-6 feet with local sets to 7 feet, along with strong rip currents. Late morning high tides near 6.5 feet will continue through Thursday, producing minor coastal flooding. Tides are expected fall below 6.5 ft MLLW after the Thursday morning high tide, diminishing the threat for coastal flooding.
Ca, Beach Hazards Statement through Thursday afternoon for Orange County Coastal Areas-San Diego County Coastal Areas.
Heat Advisory from 10 AM Thursday to 8 PM PDT Saturday for Orange County Coastal Areas-Orange County Inland Areas-San Diego County Coastal Areas.
High Wind Warning from 6 AM Thursday to 8 PM PDT Saturday for San Bernardino and Riverside County Valleys-The Inland Empire.
High Wind Warning from 8 PM Thursday to 8 PM PDT Saturday for San Diego County Valleys.
High Wind Warning from 6 AM Thursday to 8 PM PDT Friday for San Bernardino County Mountains.
High Wind Warning from 6 AM Thursday to midnight PDT Saturday night for Riverside County Mountains-San Diego County Mountains-San Gorgonio Pass near Banning.
High Wind Warning from 6 AM Thursday to noon PDT Saturday for Santa Ana Mountains and Foothills.
Wind Advisory from 6 AM Thursday to noon PDT Saturday for Orange County Inland Areas.
PZ, None.
