Moderate HeatRisk for the mountains and Inland Empire will continue through Saturday with major to locally moderate HeatRisk for the deserts. There could be some influx of monsoonal moisture in southeast flow aloft for next Sunday and Monday with a slight chance of afternoon showers and thunderstorms for the mountains.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
(today through Thursday), The strength of high pressure over southern California will change little through Wednesday, then slowly strengthen for Thursday through Saturday. There may be a shallow influx of lower level moisture into the lower deserts for tonight and Thursday from outflow from thunderstorms over northern Mexico. Nights would be a little warmer for the lower deserts and days a little cooler if that happens.
HeatRisk will decrease slightly for today and Wednesday, then increase slightly for Thursday through Saturday but will generally be moderate for the Inland Empire and for the mountains except at the highest elevations with major to occasionally moderate HeatRisk for the deserts. The Extreme Heat Warning for the deserts has been extended through Saturday and a Heat Advisory has been issued for the Inland Empire and for the mountains for today through Saturday.
High temperatures through Thursday will be generally a few degrees above average near the coast to 5 to locally 10 degrees above average for some inland areas. High temperatures will range from the mid to upper 70s near the coast to the 90s to 103 for the Inland Empire with 110 to 115 for the lower deserts.
Night and morning low clouds will spread into coastal areas late each night.
(Friday through Monday), Slow warming of high temperatures will continue for inland areas through Saturday with high temperatures on Saturday ranging from the mid 70s to lower 80s near the coast to the mid 90s to 105 for the Inland Empire with 112 to 116 for the lower deserts.
For Sunday and Monday, high pressure will begin to slowly weaken with the flow aloft becoming more southeasterly. This would allow for some additional influx of monsoonal moisture into the area. High temperatures for Monday of next week would be within a few degrees of average for the coast, valleys, and mountains and a few degrees above average for the deserts. Low temperatures would be a few degrees above average for the coast and valleys and 5 to 10 degrees above average for the mountains and deserts.
High temperatures for next Monday would range from the mid to upper 70s near the coast to the 90s for the Inland Empire with 106 to 110 for the lower deserts. There will also be a slight chance of showers and thunderstorms for the mountains for Sunday afternoon and Monday afternoon.
041800z. Coasts/Valleys, Low clouds eventually scattering out along coast by 20Z, but with patches persisting. Low clouds around 1000 feet MSL will redevelop over coastal areas 02-05Z and into western valleys overnight. Inland vis reduced 1-5SM. Scatter out Wednesday 16-17Z.
.Mountains/Deserts, Mostly clear skies and unrestricted VIS through Wednesday morning.
No hazardous marine conditions are expected through Saturday.
Ca, Heat Advisory until 8 PM PDT Saturday 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 Saturday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass near Banning.
PZ, None.
