High pressure will continue to strengthen and move closer to the region through the middle of the week, bringing hotter weather and increased heat risk to inland regions. Slow cooling occurs by the weekend as the area of high pressure moves to the northeast. In its wake, monsoonal moisture moves into the region on Sunday into at least the first half of next week. This will bring increased rain chances to inland areas with greater humidity for all.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, Low clouds cleared beautifully off the coast this morning with clear skies remaining over inland areas. Time to turn up the heat this week! High temperatures will begin to feel warmer each day through Thursday as a 595 dm high over the Arizona/New Mexico border moves east and subtly strengthens. By Wednesday and Thursday, 850 mb readings go near to just over 30C over the deserts, highest over all on Thursday when the peak of the heat is expected to occur. High temperatures will range from 100-105 across the Inland Empire, locally higher in the high desert. Lower deserts will see hot temperatures near 114-117 degrees. Even the mountains will be hot, so please do not venture outdoors during the late morning or afternoon hours as temperatures soar into the upper 80s to mid 90s. High temperatures for select mountain areas on Wednesday and Thursday will be near 95 in Julian, and upper 80s in Idyllwild, Big Bear and Lake Arrowhead. Moderate to major heat risk is expected during this time for inland regions, so please take breaks, drink plenty of water and check on family and friends if you must be outside for long periods of time.
Temperatures will be near average toward the coast as the marine layer keeps these regions generously cooler in the 70s and lower 80s. Low clouds will move into the coast and far western valleys each night.
..by Friday, the area of high pressure slowly weakens, which will pull down temperatures by a few degrees, but still warm. The high begins to shift to the northeast as a troughing pattern develops off the West Coast. Clockwise flow around the high with the help of the trough off the coast will help funnel in subtropical moisture from the south and southwest. This will aid in an increase in humidity and a chance for showers and thunderstorms as the monsoon begins to wake up. Saturday looks to remain dry, with slightly more humid conditions.
By sometime on Sunday, the area of high pressure moves closer to the Four Corners region, providing a better opportunity for increased moisture to enter the Desert Southwest. Model guidance is in good agreement on increasing PWAT values through the early part of next week. Exact details on timing and who sees rain or storms from this is still very preliminary. NBM shows chances for precipitation starting Sunday into at least the middle of next week across the mountains and deserts, locally into far inland valleys. As for temperatures, the region will still remain warm with highs well into the 90s across the Inland Empire and high desert, and 80s for the mountains and western valleys.
071730z. Coast/Valleys, Low clouds have cleared most of the area with just a few low clouds around 1,200ft MSL wafting in. Clear skies will dominate this afternoon with low clouds at similar bases (900-1,300ft MSL) beginning to redevelop along the San Diego County coast after 01-02Z Wednesday and push inland (15-20 miles) and north after 07-09Z. Low clouds begin to clear 14-16Z Wednesday, clearing land areas by 17-18Z.
.Mountains/Deserts, VFR conditions prevail through the TAF period.
Gusts around 20 to 25 kts are expected at times this afternoon and evening in the outer waters, especially near San Clemente Island. See the Small Craft Advisory for more details. Otherwise, no hazardous marine conditions are expected through Monday.
Ca, Heat Advisory from 10 AM Wednesday to 8 PM PDT Thursday for Riverside County Mountains-San Bernardino County Mountains- San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains.
Extreme Heat Warning until 8 PM PDT Thursday for Coachella Valley-San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, Small Craft Advisory until midnight PDT tonight for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
