Hot days and warm nights, mainly west of the mountains, will continue through Thursday. Locally gusty Santa Ana winds will continue today, strongest near the coastal mountain slopes. Today will likely be the hottest day, but confidence is improving that Friday will be noticeably less hot and next weekend will be cooler.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
This morning, Temperatures are near or a few degrees higher than at this time yesterday under clear skies. Offshore flow continues, with the windy locations reporting easterly winds gusting 20-35 mph at this hour. Several locations reported broken or tied high temperature records. Please see our Record Event Report.
Today will likely be the hottest day of the week as high pressure aloft and gusty Santa Ana winds combine to produce daytime high temperatures ranging from the mid 90s to low triple digits in the coastal areas and inland valleys. These temperatures are about 15-25 degrees above normal. Daytime high temperatures remain well above normal west of the mountains through Thursday with moderate to high HeatRisk, although slight cooling from the sea breeze will incrementally spread farther inland each day as the offshore flow weakens.
The high pressure ridge aloft will weaken a little on Monday and conditions become a little less stable. Enough for there to be clouds and a slight chance for showers Monday afternoon over the San Bernardino and Riverside County mountains. Any precipitation that occurs will likely be localized and light. The earliest that any model guidance shows marine layer clouds/fog returning to the coastal areas is Wed night/Thu morning, but the models have historically been slow with the return of the marine layer after a Santa Ana event so we'll be monitoring this closely.
Most model solutions are now indicating noticeable cooling on Friday as the high pressure ridge weakens and gets displaced to the south and east in response to a low pressure trough moving in from the northwest. Conditions will still be warm west of the mountains, with daytime high temperatures 10-15 degrees above normal. The coastal areas will likely see high temps in the 80s while the inland valleys will still see high temps in the mid to upper 90s.
For next weekend, Significant cooling is likely as a majority of ensemble members show a low pressure trough deepening along the west coast. Current indications are for temperatures lowering to a few degrees above normal on Saturday then lowering further to a few degrees below normal on Sunday. A slim majority of ensemble members also show slight chances for widespread light rain on Sunday but confidence is still low.
040530z, Coast/western valleys: SKC and VFR through the period. There is a 20-40% chance E/SE winds gusting 10-20 kts could reach parts of the coast from 15-19z Sun, including at KSAN and KCRQ (highest chance at KCRQ). Winds turn onshore W/NW late Sun morning.
Inland Valleys/Foothills/Mountains: E/SE winds increase and expand westward to valleys in the early morning hours 12-15z, peaking between 16-20z with gusts to 15-35 kts. MOD UDDFS expected over coastal slopes. Winds gradually turn westerly this afternoon through the valleys as the sea breeze moves inland.
Otherwise, Clear skies through the TAF period.
No hazardous marine conditions are expected through Thursday.
Ca, Extreme Heat Warning until 8 PM PDT Thursday for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Coastal Areas-San Diego County Valleys-Santa Ana Mountains and Foothills.
PZ, None.
