A moisture surge will bring scattered showers and thunderstorms to the mountains this afternoon and evening with a slight chance of precipitation reaching into the lower elevations. Building high pressure will bring above average temperatures for midweek with highest temperatures on Wednesday. Widespread moderate to major HeatRisk is expected. This will also subdue thunderstorm coverage with only a slight chance of precipitation in the mountains. The high pressure breaks down by Friday into the weekend with temperatures returning to near normal, along with increasing chances for monsoon storms once again. Coastal flooding will impact beaches through Tuesday with evening high tides exceeding 7 feet.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Leftovers from last night's monsoon dinner in Arizona and Sonora is streaming overhead in the form of mid and high level clouds today. Drying can be seen on satellite coming northward from Baja which will aid in a better monsoonal storm development pattern for the day as moisture and elevated instability is locked in place. To note, this morning's sounding shows notable PWAT values around 1.65 inches. Cumulus beginning to build over the mountain crest will produce areas of showers and thunderstorms this afternoon into the early evening. Latest radar imagery and hi-res guidance shows mountains in the San Diego and Riverside mountains seeing the greatest chance for storm activity, though chances reach all the way north into eastern portions of the SBD mts into the high desert. Any storm will be capable of producing bouts of heavy rain, cloud to ground lightning and gusty winds.
Moisture decreases by Tuesday into Wednesday as seen in the latest model guidance as high pressure expands over the region. This will decrease chances for storms in the mountains, but increase high and low temperatures. An Extreme Heat Warning is now in effect for all mountains and western valleys, as well as a Heat Advisory for coastal areas Wednesday through Thursday. Wednesday will be the hottest day with highs well into the 90s for the mountains and coastal valleys, triple digits for the Inland Empire and eastern San Diego Co valleys. Low temperatures will also be in the 70s across much of this region each night. This, along with increased humidity, will give areas moderate (rating 3/5) to major (4/5) Heat Risk. Vulnerable populations and those who are outside for long periods will have a greater chance to see heat impacts and related illnesses. Limited places will be available to cool off, including the mountains, so please limit time outdoors.
The area of high pressure will stick around the central Rockies later into the week, bringing monsoonal moisture around it into the desert southwest. Socal will be right on the periphery each day, where a lower chance for storms will occur each day mainly along the mountain crests from the Mexican border up to the Big Bear Lake region. A slight increase is noted by Thursday and Friday (25-35%). The area of high pressure becomes more focused away from our region, resulting in temperatures sliding back to near normal by Friday into the weekend with humidity remaining.
141600z. Coast/Valleys, Low clouds are currently 1,000-1,500ft MSL along the coast and should scatter out within the next couple of hours giving way to mid/upper level clouds AOA 20,000ft MSL. Afternoon rain and thunderstorms should stick to mountain areas this afternoon but there is a 10-15% chance they could spill into adjacent valley areas. Patchy low clouds are expected to start moving in over the coast after 01-03Z Tuesday, filling in after 06- 09Z. Cigs will be slightly higher with bases 900-1,500ft MSL and will be intermittent at times. Low clouds clear after 16-17Z Tuesday.
Mountains/Deserts, Highest chances for thunderstorms will be over mountain areas with chances in the 40-80% range this afternoon with a 20-50% chance in the high deserts. Expect lightning, erratic gusty winds, and brief heavy rain with any storm development. Areas with the highest probabilities of convection will be in the vicinity of the San Gorgonio and San Jacinto mountain areas. CB bases near 10,000 ft MSL with tops to 35,000 ft MSL. Otherwise variable mid and high cloud cover AOA 20,000 ft MSL.
No hazardous marine conditions are expected through Saturday.
Astronomical high tides peaking 7.0-7.5 ft each day through Tuesday. High tides combine with a modest south swell (3 ft swell at 13-15 seconds from 190 degrees) to generate surf of 3-5 ft for south- facing beaches and 2-4 ft elsewhere. This will produce areas of coastal flooding in low lying areas, boardwalks, beach parking lots, and beach adjacent streets during evening high tides. Highest tides each evening will generally occur between 8 and 10 PM. A Beach Hazards Statement remains in effect through Tuesday evening and contains further details. There will be an increased risk of rip currents through Wednesday.
Ca, Beach Hazards Statement through Tuesday evening for Orange County Coastal Areas-San Diego County Coastal Areas.
Heat Advisory from 10 AM Wednesday to 8 PM PDT Thursday for Orange County Coastal Areas-San Diego County Coastal Areas.
Extreme Heat Warning from 10 AM Wednesday to 8 PM PDT Thursday for Orange County Inland Areas-Riverside County Mountains- San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains-San Diego County Valleys-San Gorgonio Pass near Banning-Santa Ana Mountains and Foothills.
PZ, None.
