A strong area of high pressure will bring hot weather through the middle of the week for areas away from the coast. Slight cooling occurs by the weekend as 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 and thunderstorm chances to inland areas with greater humidity for the entire region.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
It's getting warm out there, highs by late morning have eclipsed 100 degrees in parts of the lower deserts. A lovely walk outside our office was had, but that early July Sun angle definitely made those 70s feel quite toasty! Moderate (level 3 of 5) to Major (level 4 of 5) HeatRisk is now expected for inland regions through Friday, as the heat alerts have been extended one more day. We would like to remind everyone to practice good heat safety: drink plenty of water, seek shade, and take breaks if working/spending time outside, and check on family, friends, and neighbors. Hiking in the mountains is also discouraged! During this time period, high temperatures in the lower desert will be near 115 degrees and near 100 to 110 in the high desert. Areas of the Inland Empire will warm up to 105 degrees each day as well, with plentiful 90s in the SD/RIV County mountains and inland valleys. Low temperatures will cool off pretty well for most areas, but the lower deserts will remain warm in the upper 70s and 80s.
The area of high pressure over the region this week will move to the northeast by this weekend. This will give the opportunity for the flow aloft to move in from the southeast, bringing in greater monsoonal moisture to the region in the form of higher humidity and chances for showers and thunderstorms. Saturday will remain dry, where humidity will first start to increase. Models indicate PWAT's peaking by Sunday through Monday, along with a noted indication of increased CAPE across inland areas. Southeast flow aloft becomes more apparent by Sunday (possibly as early as early Sunday morning), where slight chances of rain begin to be introduced for parts of the region. Daily chances for showers and thunderstorms will be across primarily the mountains and deserts, locally into the eastern parts of the valleys in Inland Empire and San Diego County, through at least the middle of next week. The forecast shows the highest chances of storms on Monday afternoon across our mountain areas. With this flow pattern, higher humidity will remain across the entire region, including coastal areas, for this weekend into the foreseeable future.
081730z. Coast/Valleys, Low clouds have cleared inland locations but are hanging onto the OC coast and a few areas of the SD coast. These low clouds based around 1,400ft MSL should clear at least OC in the next hour with a 30-40% chance of it sticking along areas of the SD coast through 20Z. VFR conditions will prevail through 02-04Z when low clouds with bases 700-1,100ft MSL will start developing along SD coast. Low clouds will increase in coverage and push north and inland up to 20 miles 07-09Z. Clouds will begin to clear inland locations after 15Z, clearing most coastal sites by 18Z.
.Mountains/Deserts, VFR conditions prevail through the TAF period.
No hazardous marine conditions are expected through Tuesday.
Ca, Heat Advisory until 8 PM PDT Friday 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 Friday for Coachella Valley- San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
