High clouds today and tonight with clear viewing conditions for firework shows. Slow warming trend through Monday with lingering moisture before more substantial warming and a shallower marine layer for next week. Minor to moderate HeatRisk returns for the inland areas and deserts next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
A very light band of rain showers moved through Orange County and far northern San Diego county this morning, but little to no accumulation was recorded. The morning sounding showed ample moisture in the mid and upper levels, evident with the ongoing high cloud cover we have today region-wide. The high clouds also helped to push out our marine layer, which eroded before it was able to make it very far inland this morning. While high clouds will prevail today, no further rain showers are expected for anywhere outside of the highest points of the San Bernardino Mountains, which have a 10-15% chance to briefly see some light rain early this afternoon.
Conditions for firework viewing for coastal cities tonight will be quite favorable, as the marine layer will struggle to move back in early this evening, likely not filling in until closer to 10PM- midnight. For the deserts, periodic gusty winds at or above 15 mph this evening may impact things some, but winds should significantly weaken for everywhere but the mountain passes and desert slopes by 9PM. As mentioned before, no precipitation is expected for fireworks viewing. Inland valleys and the IE may be more prone to lingering air pollution from fireworks, with further information found in the Air Quality Alert from the SCAQMD.
After today, weak troughing will hold in place while high pressure begins to build over the Four Corners. Temperatures will warm ever so slowly through Monday while low level moisture hangs around, with more noticeable warming in the deserts. By Tuesday, the thermal ridge axis will pivot with high pressure spreading into Southern California, and a more substantial warm up is expected by mid week. The marine layer will become more shallow, allowing even the coastal valleys to warm. Temperatures peak Wednesday/Thursday as the high becomes elongated over the Southwest and minor to moderate HeatRisk returns for the deserts and inland areas through the end of the week. If you work outdoors, make sure to have plenty of water and take frequent breaks! Friday and beyond, an approaching low off the coast of CA should begin to push the high back towards the Four Corners, hopefully allowing for at least a subtle cooldown for next weekend.
041730z. Coast/Valleys, A few low clouds have been drifting in with bases 1,000-1,500ft MSL with the main cloud deck sitting around 9,000-12,000ft MSL. These mid layer clouds are expected to continue through most of the period but, clear just enough along the coast to allow low clouds to form with bases 800-1,500ft MSL after 05-06Z. Low clouds clear 17-18Z Sunday.
Otherwise, SCT-BKN high clouds lift slightly to AOA 15,000 feet MSL with coverage beginning to decrease late this evening. Local and brief 4-6 mi vis restrictions 04-07Z will be possible due to fireworks smoke this evening.
No hazardous marine conditions are expected through next Thursday.
Ca, None. PZ, None.
