A strong area of high pressure will continue to bring hot weather through Friday. Ever so slight cooling occurs by the weekend into Monday as high pressure moves to the northeast. The high pressure's movement will bring in greater monsoonal moisture for our area by Sunday into at least the latter part 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,
, UPDATED AVIATION DISCUSSION,
Today through tomorrow night,
Currently, the marine layer is slowly expanding further eastward into roughly around 5 miles inland for Orange and San Diego counties, with bases generally between 500 to 1200 ft MSL. These clouds will remain in place through the early morning hours, and then should gradually dissipate fairly quickly for the inland areas, as this layer is relatively thin. This should then further mix out with clearing to the coastal areas by approximately 10 to 11 AM.
High pressure conditions continue to dominate the region. This will translate to another warm day, with Extreme Heat Warning for the lower deserts, and Heat Advisories in place for the Inland Empire through today. There will be an influx of some mid-level monsoonal moisture that will be moving in from the southeast during the morning hours and throughout the day on Saturday. This will help to slightly cool temperatures, especially over the deserts, due to the increase of moisture. This may also result in a rouge shower or storm developing over the mountains during the afternoon. There will also likely be some castellanus clouds, and possible virga (precipitation falling but not reaching the ground), or perhaps even a few rain drops reaching the ground all the way to the coastal areas from some of these clouds as they stream overhead throughout the morning hours. This may also help to break up and disrupt the marine layer, which will likely be similar in nature tomorrow night as it was tonight.
Sunday through Thursday of next week,
By Sunday, a negatively tilted ridge over the entire western region will stretch and expand back towards the west through the mid part of next week. This will result in the production of monsoonal waves to develop during the afternoon over the lower deserts of Arizona, which will then propagate over southern California as they move in from the east, and allow for chances of afternoon showers and thunderstorms over the mountains and deserts each afternoon through Thursday of next week. There could even be a few of these waves propagating further enough westward to bring a slight chance of showers/storms to the coastal areas as well, although given the stability west of the mountains, these will likely fall apart quickly as they do. This will also result in increased humidity values, with more of that summer "mugginess" feeling next week. There will also be increasing heat as a result of the expanding ridge, with 596 dm heights overhead by Wednesday and Thursday of next week. This will likely translate into the need of heat products again, especially for the lower deserts and Inland Empire. The influx of mid-level moisture may help to mitigate these temperatures from getting as hot, but that is to be determined in upcoming days in terms of the development of these monsoonal waves.
101200z. Coast/Valleys, Cigs 700-1200 ft MSL widespread across the coast and western valleys through this morning. Chances for cigs below 1000 ft for coastal TAF sites is highest through 14Z at 80 percent. Vis restricted 1-5SM over higher coastal terrain. Scatter out 16-18Z, but patchy low clouds to persist along immediate coast into the afternoon. Low clouds around 1000-1500 feet MSL to move ashore after 03Z Saturday and continue to fill into the inland valleys throughout the rest of the forecast period (through 12Z), with cigs slightly higher tomorrow evening.
.Mountains/Deserts, VFR conditions through the TAF period.
No hazardous marine conditions are expected through Thursday.
Ca, Heat Advisory until 8 PM PDT this evening 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 this evening for Coachella Valley-San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
