Monsoonal moisture will increase today and Friday with a slight chance of afternoon showers and thunderstorms for the mountains and deserts. There will be some drying of the monsoonal moisture over the weekend, then maybe a slight increase again for early next week. High temperatures will remain around 5 degrees above average for inland areas into next week with low temperatures 5 to 10 degrees above average for inland areas.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
(today through Saturday), Monsoonal moisture will increase for today into Friday, then decrease during the weekend. There is a slight chance of afternoon showers and thunderstorms for the mountains and deserts for today and Friday with decreasing chances on Saturday.
High temperatures around 4 to 8 degrees above average for inland areas today will cool slightly to around 5 degrees above average for Friday and Saturday. Low temperatures will remain a few degrees above average near the coast to 5 to 10 degrees above average for inland areas.
High temperatures will range from the mid 70s to lower 80s near the coast to the mid 90s to 105 for the Inland Empire with 106 to 112 for the lower deserts. Moderate HeatRisk will continue for the inland valleys, the Apple and Lucerne Valleys, and the mountains for elevations below 6000 feet, with moderate to major HeatRisk for the lower deserts.
(Sunday through Wednesday), There will be some drying of precipitable water for the weekend. For next Monday and Tuesday for Thermal, ECMWF ensemble output for precipitable water has about half of the members with values similar to the higher values for today and Friday with about half having the same or lower values than the lower values for this weekend. There will be occasional slight chances for afternoon showers and thunderstorms for the mountains and deserts depending on moisture availability.
There will be only slight day to day differences in high temperatures with high temperatures generally around 5 degrees above average with high temperatures ranging from the mid 70s to lower 80s near the coast to the mid 90s to 105 for the Inland Empire with 108 to 112 for the lower deserts.
201800z, Coast, Low clouds based 800-1200 ft MSL push onshore to coastal areas around 02z Fri, remaining very patchy and intermittent through 12z as high clouds disrupt their development. These low clouds briefly fill in coverage up to 15 miles inland through 16z Fri, then scatter out. Reduced VIS 0-5SM where clouds intersect terrain along elevated valleys.
Otherwise, SCT to locally BKN clouds above 15 kft MSL through Friday. BKN cumulus at 10 kft MSL towering over mountains and high desert with a 15-20% chance of TSRA 21-02Z. Gusty, erratic winds around any TSRA.
No hazardous marine conditions are expected through Monday.
Ca, Heat Advisory until 8 PM PDT this evening for San Bernardino and Riverside County Valleys-The Inland Empire.
Extreme Heat Warning until 8 PM PDT Sunday for Coachella Valley- San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
