An upper ridge will build over the region creating a warming trend along with sunny skies through this week. Morning marine layer clouds will likely be disrupted Thursday morning as offshore flow develops. Record high temperatures expected for several locations Thursday and Friday. Flow turns weakly onshore for the weekend, which may provide some relief to coastal areas. However, most of Southern California remains hot and dry through the weekend. Another, potentially stronger ridge will begin to take shape by early next week with more record high temperatures currently in the forecast.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
.his evening, The afternoon sounding shows the marine layer marginally shallower than last night but with a little stronger inversion. Satellite imagery shows high clouds streaming southward in northerly flow over a ridge with a N-S axis to the west along with marine layer low clouds extending from the coastal mtn slopes to the beaches and increasing in coverage.
Temperatures begin to trend upward noticeably on Wed as the high pressure ridge shifts eastward toward the coast. Temps west of the mtns will go from the 60s and 70s today to the 70s and 80s for Wed. A marine layer presence will moderate temperatures somewhat near the coast.
By early Thursday, a surface high moving into the Great Basin will bring us offshore flow with northeast to east winds gusting 25-35 mph along coastal slopes, through passes, and locally into the valleys. This will disrupt the marine layer low clouds but the degree to which the clouds are dissipated may be inhibited if the inversion strengthens. The offshore flow and building high pressure aloft will likely bring record high temps across most of Southern California both Thursday and Friday. A few monthly records could even be threatened as highs in the coastal basin climb to 20-30 degrees above normal. Highs could reach the mid to upper 90s for inland valley zones and upper 80s to near 90 for the coast. Nbm probability of exceeding 85 degrees is 80% for downtown San Diego both days.
The high pressure ridge weakens for the weekend in response to an approaching low pressure trough, and onshore flow returns. This will likely bring some cooling relative to Friday for the coastal basin. However, 500 mb heights will remain well above normal through the weekend. Temperatures 10 to 20 degrees above normal (locally 25 degrees above normal inland) will still be enough to break some record highs for inland areas.
For next week, the majority of the guidance indicates another upper ridge building in from the west. Therefore, there is high confidence in well above normal temperatures and dry conditions to continue through next week. In fact, there is some indication that temperatures next week could be even higher than what is forecast for this week. However, exactly how hot it will be and for how long is still to be determined.
110500z, FEW low clouds have been moving in and out along the coast around 1,000-2,000 ft MSL. Currently there is a large patch of low clouds at 2,500 ft MSL hanging out in the SD Valley and have been slowly spreading towards the coast just south of KCRQ and right to the western edge of KSAN. Still expecting low clouds to lower and increase in coverage after 07-09Z to 900-2,500 ft MSL, mainly in the coastal basin. CIGs will gradually scatter out between 16-19z. VFR conditions are expected there after.
No hazardous marine conditions are expected through Sunday.
Ca, Heat Advisory from 10 AM Thursday to 8 PM PDT Friday for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire- San Diego County Coastal Areas-San Diego County Valleys.
PZ, None.
