Lingering isolated showers will diminish by early this evening. Dry conditions will prevail through the rest of the forecast period. A warming trend is expected tomorrow through early next week. Areas of moderate HeatRisk expected in the valleys and major HeatRisk in the low deserts Sunday through Tuesday.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
At 12 PM, there were still a few lingering showers in the eastern San Diego valleys. A rainfall summary is headlined on our weather.gov/sandiego homepage and details observed rainfall over the past 24 hours. Shower chances will become more confined to the eastern valleys and foothills this afternoon before diminishing by early this evening. Dry conditions will prevail through the rest of the forecast period.
An upper level ridge of high pressure will begin to build over the Eastern Pacific Wednesday and Thursday, eventually expanding east over California for the weekend into early next week. This will result in a steady warming trend for Wednesday into early next week, with the hottest conditions Sunday through Tuesday. Current forecast has moderate to major HeatRisk in the low desert, with minor to moderate in the valleys and High Desert. Confidence is highest for temperatures in the low desert where the NBM temperature guidance matches up with ensemble guidance from the ECMWF and GEFS. Confidence in how hot it will get is lower for areas west of the mountains where NBM guidance is running about 5 to 6 degrees warmer than other ensemble guidance.
Current forecast follows the NBM with temperatures as much as 15 to 20 degrees above average for the inland valleys, high desert, and lower coastal slopes of the mountains by Monday.
By Tuesday, most of the ensemble guidance indicates the ridge aloft will weaken, which will bring a few a few degrees of cooling to the area. Weak onshore flow should be maintained through the forecast period, which would moderate temperatures along the immediate coast. Additionally, areas of at least patchy night and morning low clouds and fog are expected to be present along the coast potentially into portions of the western valleys.
051800z. Coast/Valleys, SCT-BKN low clouds based 3-6 kft expected through this afternoon. Coverage will gradually become predominately BKN again after 03Z Wed with bases lowering to around 2000-3000 feet MSL overnight. Intermittent scattering through the overnight hours. Low clouds clear to the coastline 16-18z Wed.
.Mountains/Deserts, Coastal slopes will occasionally be obscured in FG between 3000-6000 feet MSL where clouds intersect terrain through 06Z Wed. Isolated -SHRA in mountains through 02Z briefly lowering cloud bases and vis. Elevated westerly gusts 20-30 kts along desert slopes and into deserts with isolated gusts of 40 kts through mountain passes. This will create moderate to strong up/down drafts and local LLWS in the lee of mountains. Patchy BLDU reducing vis in the deserts. Winds slowly diminish 06-12z Wed.
No hazardous marine conditions are expected through Saturday.
Ca, None. PZ, None.
