High pressure will strengthen this week with all-time record heat for March for some inland locations for the latter half of this week. There will be weak offshore lower-level flow for today with northerly gusts to 25 to 35 mph along and below the coastal slopes of the mountains and on Tuesday with east to northeast gusts to 30 to 40 mph. Some cooling is expected for next Sunday and Monday, but with high temperatures for inland areas still 10 to 15 degrees above average for Monday of next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
(today through Wednesday), High pressure aloft off the California coast will move slowly eastward this week and slowly strengthen with the strongest high pressure aloft over southern California centered around Thursday. The current record for highest 500 mb height for San Diego for March is around 590 DM. The previous earliest the 500 mb height for San Diego has reached 594 DM is May 22nd. The earliest for 595 DM is early June.
There will also be weak offshore lower-level flow for today with north winds gusts to 25 to 35 mph below the Cajon Pass and near the coastal foothills of the Santa Ana Mountains. Offshore flow will be slightly stronger on Tuesday with east to northeast gusts to 30 to 40 mph.
The marine layer is around 1200 feet deep early this morning with satellite imagery showing coastal low clouds extending inland into northwestern Orange County.
The greatest warming of high temperatures for today, of around 8 to 12 degrees, will be for inland coastal areas with most areas warming another 4 to 8 degrees on Tuesday. On Wednesday, a weak coastal eddy could bring a few degrees of cooling for inland coastal areas into the western valleys with the mountains and deserts warming another few to around 5 degrees.
High temperature records for today are most likely to be tied or broken in portions of the valleys and lower deserts. On Tuesday, high temperatures near or exceeding daily records are most likely for the mountains, deserts, and valleys with widespread record high temperatures on Wednesday. Some of those could exceed the existing daily record by more than 5 degrees with some exceeding the existing monthly record for March.
(Thursday through Sunday), The heat is expected to peak for most areas on Thursday or Friday with record high 500 mb heights for March over southern California. Widespread record heat will continue through Saturday. Weakening high pressure aloft and onshore flow will begin to spread cooling inland on Sunday and Monday, but with high temperatures for inland areas for Monday of next week still 10 to 15 degrees above average.
The currently forecast low temperatures for Idyllwild of 64 for both Friday and Saturday would be the earliest for such a warm low temperature at Idyllwild by almost three months, the current earliest date for such a warm low temperature being June 16th (2021).
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.AVIATION, 161100Z, Coasts, Patchy low clouds and fog mainly in northwest Orange County this morning. Bases around 400-800 feet MSL and vis 3- 6SM. Scatter out should occur by 15-16Z. Extremely isolated low clouds tonight into Tuesday.
Valleys/Mountains/Deserts, Locally gusty north-northeast winds gusting to 25 knots in foothills and locally into valleys through 22Z today.
161100z, Coasts, Patchy low clouds and fog mainly in northwest Orange County this morning. Bases around 400-800 feet MSL and vis 3- 6SM. Scatter out should occur by 15-16Z. Extremely isolated low clouds tonight into Tuesday.
Valleys/Mountains/Deserts, Locally gusty north-northeast winds gusting to 25 knots in foothills and locally into valleys through 22Z today.
No hazardous marine conditions are expected throughFriday.
A long period (17-19 second) south-southwesterly swell (190-200 degrees) builds to 2-4 feet with sets to 5 feet this afternoon into Tuesday, then decreasing Wednesday. Locally hazardous swimming conditions are expected. A Beach Hazards Statement contains the details.
Ca, Beach Hazards Statement through Wednesday evening for Orange County Coastal Areas-San Diego County Coastal Areas.
Heat Advisory from 10 AM this morning to 8 PM PDT Friday for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire- San Diego County Coastal Areas-San Diego County Valleys- Santa Ana Mountains and Foothills.
Extreme Heat Watch from Thursday morning through Friday evening for Coachella Valley-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.
PZ, None.
