Near normal temperatures expected through Monday, with hotter and humid weather moving into the middle of the week. Thunderstorm chances from the monsoon are in the forecast over the mountains and locally into the deserts each afternoon through much of the week. 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,
, UPDATED AVIATION DISCUSSION,
A decaying storm system that occurred to our south and east last night is moving through the area today, providing clouds and some reports of sprinkles. This cloud cover will limit some afternoon heating today, though the humidity will be more apparent starting today through the upcoming week. These clouds will also further inhibit storm development over the mountains; cumulus may form with some areas of weak thunderstorms but chances remain near 15-25%.
A strong area of high pressure currently over the Northern Rockies will continue to expand into the Northern Plains. Clockwise flow around this system, with the help of a weak trough offshore, will aid to bring in better moisture from the monsoonal wind pattern to our area by Monday. The mountains and deserts have the greatest chances (35-55% chance) to see bouts of heavy rainfall, lightning, and small hail Monday afternoon and evening. Hi-res models show the mountains from the Mexican border up north to Big Bear and into the high desert as the notable places that may see storm activity. Confidence is low to moderate on how far west this moisture and instability will move during this time period with limited chances west of the mountains. Monday's highs will be similar to that of today, as cloud cover from storms in Arizona moving toward our area, which may limit high temperature readings yet again.
A subtle decrease in moisture is seen in the latest model guidance for Tuesday through Thursday as high pressure slowly expands over the region. This will decrease chances for storms in the mountains, but increase high and low temperatures. An Extreme Heat Watch is now in effect for all areas from the coast to below 6,000 feet in the mountains during this time period. There is high confidence that the peak of the heat will be on Wednesday, though confidence is lower on exactly how hot temperatures will be. Highs well into the 90s for the mountains and coastal valleys, triple digits for the Inland Empire and potentially the eastern San Diego Co valleys are in the cards. Low temperatures will also be in the 70s across much of this region. 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 if you are able to do so.
The center of the high looks to retrograde and become more amplified toward somewhere near the Colorado Rockies, which would provide a greater influx of moisture by the end of the week. Nbm has increased chances for thunderstorms returning to inland areas by Thursday into the end of the week, as temperatures return closer to normal. Confidence remains low on where exactly any rain could fall, especially for deserts and the valleys west of the mountains.
140430z. Coast/Valleys, Areas of low clouds developing along the coast after 08Z with bases 900-1200 ft MSL. There is a 40-60% chance of CIGS at KCRQ and KSAN 09-17Z, and a 30-40% chance at KSNA 10-15Z. Low clouds clearing by 18Z. There is a 10-15% chance of showers moving off the mountains into the far inland valleys Monday afternoon, ending by Monday evening. Coverage of low clouds Monday night will be much patchier with low confidence in timing of onset of any CIGS. Otherwise variable mid and high cloud cover at/above 10,000 ft MSL.
Mountains/Deserts, There is a 25-50% chance of thunderstorms over the mountains and high desert between 18Z and 02Z Monday afternoon and evening. CB bases near 15,000 ft MSL with tops to 35,000 ft MSL. Thunderstorms will be capable of producing reduced visibility in RA and gusty outflow winds. Otherwise variable mid and high cloud cover at/above 10,000 ft MSL.
No hazardous marine conditions are expected through Friday.
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.
Extreme Heat Watch from Tuesday morning through Thursday evening for Orange County Coastal Areas-Orange County Inland Areas- Riverside County Mountains-San Bernardino County Mountains- San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Coastal Areas-San Diego County Mountains-San Diego County Valleys-San Gorgonio Pass near Banning-Santa Ana Mountains and Foothills.
PZ, None.
