A warming trend will occur through the weekend across the area. Light offshore winds will occur across northern areas of the coastal slopes and surrounding valleys Thursday morning through Friday morning. An area of low pressure off the coast will move closer to our region by the first half of next week bringing in cooler weather.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Update: The area of low pressure associated with the low pressure system that just transitioned across the region continues to progress towards the east and over the Great Basin, with continued clearing and the return of high pressure conditions in its wake. With the clearing, and lack of clouds due to weak offshore winds for the next couple of nights, the marine layer is going to be nearly non-existant for most of the coastal and inland areas, and this could allow for radiational cooling to be quite efficient, and will give way to some of the inland areas making it down into the 40s, especially the further inland you go. Along with this will be the possibility of some patchy fog developing in some of the inland valleys where there is still antecedent soil moisture from recent rainfalls, and especially where it is wind-sheltered. High temperatures will be slightly warmer tomorrow, and this will continue going into the weekend with a gradual warming trend and dry conditions persisting through early next week. Deterministic models (and some of the ensemble members) have a trough deepening and then cutting off with an upper level low that is going to possibly influence the region with some cooler temperatures and the return of a chance of rain again possibly by next Tuesday, although this is still way to soon to be reliable at this time.
(Previous discussion submitted at 141 PM):
The Pacific storm that caused rainy and windy conditions has moved into the Great Basin. Onshore flow has eased with drying continuing to occur this afternoon as clouds slowly scatter for those along and west of the mountains. Pressure heights will continue to rise as the storm system moves further into the Great Plains and high pressure strengthens offshore. A weak area of low pressure will become a cutoff low off the coast by Thursday into the weekend, where upper level winds will begin to turn out of the north and east. This will lead to a weak offshore wind pattern, with highest winds occurring over the coastal slopes and passes of San Bernardino and Riverside Counties. There is a 25-35% chance in seeing wind gusts over 30 MPH in these regions and across the Inland Empire Thursday morning to Friday morning. As heights begin to rise into the weekend, a warming trend will occur across Southern California. By the weekend, we can expect highs to become closer to average with widespread 80s from the lower desert to the Inland Empire/SD valleys and 70s closer to the coast up into the foothills and high desert.
The cutoff low will continue to spin off the coast into early next week as high pressure starts to build into the Desert Southwest and a trough dips into the Pacific Northwest. The interactions between these three features is still not completely resolved in the model guidance as we look toward next week. Confidence is growing that the trough to the north will not be able to move far enough south to bring any wet weather. The movement of the cutoff low will also be dependent on how expansive the high pressure area becomes. Stronger upper level flow aloft may be able to hamper the area of high pressure southward, being able to bring the cutoff low over our region. This scenario is reflected in the latest forecast per NBM, where a cooling trend is observed with a deepening marine layer west of the mountains.
160300z. Coast/Valleys, VFR expected to prevail with FEW-SCT low clouds near 3000 ft MSL around KSAN through early Thursday morning. Thursday evening/night also likely mostly clear, with 10% or less chance for CIGs along the coast.
.Mountains/Deserts, Mostly clear with prevailing VFR through Thursday.
No hazardous marine conditions are expected through Sunday.
Ca, None. PZ, None.
