One final morning with a deep marine layer and more widespread drizzle and/or light rain for Friday with below-normal temperatures prevailing through Sunday. Ridging with a drying trend sets in next week, and HeatRisk may return for the deserts early week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
A robust marine layer this morning due to a large upper level low over Central CA allowed for some drizzle, but only a few areas recorded any accumulation. This low has been quite impactful this past week, providing significantly cooler weather than typically observed for the end of May. Even as the clouds continue to dissipate through this afternoon, loss of heating this morning will help keep high temps today around 5-15 degrees below normal. The cooler weather isn't quite over yet as the low will slowly meander out of California and into the Great Basin on Friday, paving the way for a deeper marine layer Friday morning and more widespread drizzle or light rain, especially across San Diego County and the coastal/western valleys. Any accumulations are expected to be light, generally 0.03" or less through Friday morning, but there may be some noticeable wet spots on the road for the Friday morning commute. As the low moves up and out, expect one final afternoon of gusty west winds across the deserts and through the mountain passes, where gusts may exceed 30 mph at times.
Drier air will quickly move in and a slow warming trend begins as the low departs. Zonal flow aloft will keep temperatures mild through Sunday, with more substantial warming into next week as defined ridging sets in due to a large upper level low moving into the PacNW coast. Confidence is increasing in minor to moderate HeatRisk setting in for at least the desert regions as early as Monday, especially the low desert, with greater chances moving into mid week. Depending on the thermal ridge axis and the shallower marine layer, impactful heat may also be observed for the inland areas and valleys by mid-week as highs return 5-10 degrees above normal. This warmer weather looks to prevail into at least the end of the week with lackluster movement in the aforementioned low.
281900z, Coast/Valleys/Coastal Mountain Slopes, VFR with FEW-SCT clouds based around 4500-5500ft MSL. Clouds near 5000ft up against the higher terrain redevelop around 01Z Fri, and FEW-SCT clouds 2500- 3500ft for the coasts/valleys, increasing to BKN generally after 04Z. DZ/-RA is possible again between 06-18z Fri, with chances around 20-30%. Clouds will begin to clear at a similar time as today, around 18-21Z.
Higher Mountains/Deserts, Mostly clear skies and VFR conditions expected through the TAF period. Westerly gusts this afternoon for the mountains and desert slopes with gusts around 20-30 kts, locally up to 40 kts through passes. Winds remain somewhat elevated for many spots into the early overnight hours tonight, but eventually weaken after 12z Fri.
No hazardous marine conditions expected through Sunday.
Ca, None. PZ, None.
