Above average temperatures will return tomorrow and prevail through the remainder of the forecast period. Warmest conditions will be Sunday through Tuesay with areas of moderate HeatRisk expected in the valleys and High Desert and major HeatRisk in the low deserts. The marine layer and weak onshore flow will keep coastal areas cooler.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Today kicks off a warming trend that will continue through next Monday. This warming trend will result in above average temperatures for much of the next week, with the biggest departure from normal in the inland valleys, mountains, and deserts. This warming will bring temperatures 7 to 15 degrees above average for inland locations through Saturday.
An upper level ridge of high pressure will expand over California and strengthen early next week. This will bring temperatures 15 to 20 degrees above average for the far inland valleys, mountains, and deserts. Current forecast has moderate to major HeatRisk in the low desert, with minor to moderate in the valleys and High Desert Sunday through Tuesday. Ensemble guidance from the ECMWF and GEFS are more inline with the NBM on the latest runs, although the deterministic NBM guidance is running closer to the maximum values of the EC and GEFS ensemble guidance especially for Monday. The geographical proximity of the deserts to the center of the high pressure increases confidence in the temperature forecast for that area. There still remains some uncertainty on how warm it will get west of the mountains as prevailing onshore flow will spread cooler coastal air inland with the afternoon sea breeze.
By Tuesday, most of the ensemble guidance indicates the ridge aloft will weaken or move east, which will bring a few degrees of cooling to the area. The upper level pattern becomes more uncertain for Wednesday, with some solutions maintaining weak ridging and others showing weak troughing. Current forecast has a few additional degrees of cooling between Tuesday and Wednesday. 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 at times through the forecast period.
061800z. Coast/Valleys, VFR and SKC with surface gusts below 20 kts. Low clouds around 1500-2000ft MSL return vicinity KSAN 01-5z before spreading into most coastal areas by 12z Thurs. Chances for MVFR CIGs at KSAN overnight are 60-70%, and 50% for KCRQ and 40% for KSNA. Clearing should occur by 17z for all locations.
.Mountains/Deserts, Generally SKC and VFR, with intermittent FEW-SCT clouds AOA 10,000ft MSL over mountains this afternoon and evening.
No hazardous marine conditions are expected through Sunday.
Ca, None. PZ, None.
