Decreasing Santa Ana winds and very dry conditions will continue overnight. Another surge of offshore wind is expected to arrive Wednesday afternoon and night, through Thursday morning. The Santa Ana winds weaken by Friday. A cold upper level storm system is expected to arrive for the weekend and would bring showers and low snow levels late Saturday through Sunday night.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Update: Winds have continued to weaken throughout the evening for a majority of the lower elevations. There are still some gusty winds over the higher terrain, and especially for the southern mountains in San Diego County, where Hausier Mountain near Campo was reporting a wind gust of 40 mph this past hour. These will continue to subside and there will be somewhat of a break in the Santa Ana conditions for about 12 hours as winds further decouple overnight. However, the latest high res guidance continues to show that Santa Ana conditions will begin to spin up again by around 6 AM for the mountains, and then mix down to the lower elevations later in the morning and into tomorrow afternoon.
These winds still look to be on track of increasing by later in the afternoon, but then will diminish by later in the evening. By tomorrow night, even the winds over the higher terrain will subside overnight. Onshore flow will be returning by later in the day on Friday.
By Saturday, deterministic models are keying in on the development of an upper level low which forms and drops down from central California, that still gives portions of the populated areas a 60 to 70 percent probability of seeing greater than 0.10 inches of measurable precipitation, and 50 to 60 percent probability of seeing greater than a quarter of an inch of rain through Sunday. This will all be depended on the track and movement of this U/L low, and will continued to be monitored in the upcoming days to determine which areas will have the highest potential of receiving a much needed wetting rain.
(Previous discussion submitted at 208 PM)
Santa Ana winds have peaked (max gust 102 mph) across the region during Monday evening but a second surge is occurring now (max gust 80 mph). Widespread single digit humidity, including up to the coastal areas. Wind is now weakening but spread out down valleys late morning and early afternoon. Pressure gradient reached about 16 mb gradient from Salt Lake to San Diego behind the short wave trough passage on Monday. Strongest wind was Sill Hill off of Cuyamaca Peak in San Diego Laguna mountains where a gust to 102 mph was measured during Monday evening. The inversion aloft was near 7000 feet MSL so this appears to be trapped mountain wave. Other locations reached 70 to 80 mph gusts in wind prone areas. There were 3 wildfires along I-15 and SR76 and today on Friars road, which ignited Monday evening and just after midnight. Moisture is not around as dewpoint temperatures are observed 0F to minus 40F in the higher terrain and even single digits to -10F to the coast, so humidity recovery was very poor overnight. The offshore wind decreases further this evening and tonight but wind prone corridors will still gust 30 to 40 mph overnight into Wednesday morning.
The next event blends in to the current but a separate cold short wave in the northwest flow will dive further east across the Rockies on Wednesday. This returns a 1045 mph surface high over Salt Lake so we end up to 15 mph gradient from SLC to SAN again.
Break in the weather on Friday and guidance still as an very cold upper low digging west as it drives south from Canada for the weekend. This forms a closed upper low over the California Bight. The dynamics and instability given this track could bring widespread showers and even locally heavy showers favoring San Diego and San Bernardino mountains and foothills. There is some concern the upper low could be elongated or not directly over Socal which would reduce precipitation amounts but right now looks to be wetting rainfall and low elevation snows down to 3500 to 4000 feet MSL with main system overhead on Sunday. Cold air showers could linger into Monday morning.
220430z. SCT-BKN high clouds with bases above 20 kft MSL will remain overhead through Wednesday. Winds remain relatively light overnight, but E to NE winds increase again late Wednesday morning, primarily for the mountains and wind-prone mountain passes. Wind gusts will largely be 25-35 kts in these areas. Offshore Santa Ana winds gradually increase in coverage and speed Wednesday night into Thursday.
NWS San Diego is aware of limited communications of observations from KTRM since January 8th. We are working with the FAA to address this issue.
No hazardous marine conditions expected through early Saturday. A storm system may bring elevated surf and wind gusts Saturday into Sunday.
Ca, Red Flag Warning until 8 PM PST Thursday for Orange County Inland Areas-Riverside County Mountains-Including The San Jacinto Ranger District Of The San Bernardino National Forest-San Bernardino County Mountains-Including The Mountain Top And Front Country Ranger Districts Of The San Bernardino National Forest-San Bernardino and Riverside County Valleys -The Inland Empire-San Diego County Inland Valleys-San Diego County Mountains-Including The Palomar And Descanso Ranger Districts of the Cleveland National Forest-San Gorgonio Pass Near Banning-Santa Ana Mountains- Including The Trabuco Ranger District of the Cleveland National Forest.
PZ, None.
