High pressure will strengthen this week with all-time record strong high pressure for March for most of the southwest states and surrounding areas for the latter half of the week will all- time record heat for March for inland areas. There will be weak offshore flow today with east to northeast winds gusting to 30 to 40 mph along and below the coastal slopes of the mountains. For Sunday into early next week, weakening high pressure aloft and onshore flow will allow cooling to spread inland, but with high temperatures remaining well above average, as much as 10 to 15 degrees above average through Tuesday of next week for inland areas.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
(today through Thursday), High pressure will continue to strengthen the next few days with the strongest high pressure on record for March expected during the latter part of this week for large area centered on the southwest states. A shallow marine layer is expected to moderate the heat near the coast. However, record heat will continue for inland areas into next week. A large number of daily heat records are expected to be tied of broken for inland areas, both for high temperatures and for record warm low temperatures. For some locations, records for the month of March will be broke and not necessarily by small margins. Widespread moderate or greater Heat Risk will continue into the weekend except near the coast and for high elevations of the mountains, mostly above 6500 feet.
On Thursday, high temperatures for the inland valleys and lower elevations of the mountains will be as much as 30 to 35 degrees above average. Thursday high temperatures will range from around 80 near the coast to the upper 90s to 103 for the inland valleys with the lower deserts reaching 105 to 110.
(Friday through Monday), Record heat will continue into the weekend with all-time record heat for March for inland areas continuing through at least Friday. For Sunday into early next week, onshore flow and weakening high pressure will begin to spread cooling inland, but with high temperatures for inland areas still 10 to 15 degrees above average for early next week. For early next week, far fewer records for heat will be tied or broken, mostly just daily records and by smaller margins.
170930z, Mostly clear skies today and tonight. Isolated low clouds and fog near the coast through 16Z and again after 05Z tonight into Wednesday, most likely near KSAN. Low confidence of cigs and reduced vis at coastal airports. East to northeast winds gusting 25-30 knots in foothills through 20Z.
No hazardous marine conditions are expected throughSaturday.
A long period (17-19 second) south-southwesterly swell (190-200 degrees) will continue today, bringing occasional surf sets up to 6 feet in Orange County, before gradually decreasing Wednesday. Locally hazardous swimming conditions are expected. A Beach Hazards Statement contains more details.
Ca, Beach Hazards Statement through Wednesday evening for Orange County Coastal Areas-San Diego County Coastal Areas.
Heat Advisory until 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.
Heat Advisory from 10 AM Wednesday to 8 PM PDT Friday for Riverside County Mountains-San Bernardino County Mountains- San Diego County Mountains.
Extreme Heat Warning from 10 AM Wednesday to 8 PM PDT Saturday for Coachella Valley-San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
