Warmer conditions expected through early next week with a shallower marine layer and periods of weak offshore flow. Warmest days are expected to be Sunday and Monday. Cooler conditions expected by the middle to end of next week. A cooler, windier, and wetter pattern is expected to develop towards the end of next week with low confidence in details.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Evening update, Marine layer low clouds have already spread back into the San Diego County Coastal areas and portions of the valleys, with patchier coverage over Orange County. Elsewhere skies are clear. Surface pressure gradients are weakly offshore, currently at -5.5 mb SAN-TPH and -1.3 mb LAX-DAG. Any northeast to east winds tonight will be be confined to the foothills with gusts up to 20-25 mph. Offshore flow will be too weak to have much of an in impact on the low clouds, especially with a weak coastal eddy in place. Patchy fog is possible over the coastal mesas and western valleys tonight, but any dense fog would be extremely isolated. Clouds will clear to the coast by late Saturday morning.
Previous discussion, Strengthening high pressure aloft and periods of offshore flow will bring warming conditions across the area, particularly to the coast and valleys this weekend. The peak of the heat is expected for Sunday and Monday when highs will be as much as 12-17 degrees above seasonal averages. Areas of minor to moderate HeatRisk are expected, with the highest HeatRisk expected in the western valleys. Weak to locally moderate northeast to east winds are expected on the coastal slopes of the mountains and through passes and canyons. Strongest winds are expected on Sunday when gusts of 30-40 mph are expected in the favored locations.
An area of low pressure will develop off the US West Coast early next week and slowly move east through the week. The incoming low pressure will weaken the high pressure over California and displace it to our east around the middle of the week. Uncertainty in the timing of the low pressure's forward progression continues, with guidance continuing to trend slower. If the eastward progression stays slower, that would keep the high pressure and warmer temperatures over SoCal further into next week than currently thought. About 20 percent of ensemble cluster analysis solutions show the high still over the Arizona/California border on Wednesday, with the rest of the solutions showing the high further east. Ensemble cluster analysis for next Thursday is showing about 80 percent of model solutions keeping the incoming low offshore, with 10 percent showing the low over California, and 10 percent have the ridge axis still over the California/Arizona border. It continues to look more likely that any measurable rainfall that occurs will fall during the end of next week. The eventual depth and strength of the incoming low will also have an influence on our wind, temperature, and potentially snow forecast. Current forecast for next week follows the NBM with best chances of precipitation on Friday and a cooling trend from Tuesday onward. There is still plenty of uncertainty surrounding the details of next week's forecast so stay tuned!
080400z, Coasts/Valleys, Somewhat patchy low clouds based 900-1200 ft MSL with tops to 1400 ft have moved inland to about 15 miles in San Diego Co and started to develop along the Orange County coast. CIGs may drop slightly overnight to 600-1100 ft MSL, with VIS reduced to 3-6 SM over higher coastal terrain. Low clouds clearing to the beaches 18-20Z but likely to linger along the immediate coast through Saturday. Low clouds 500-900 ft MSL move back ashore after 00Z Sun.
Mountains/Deserts, Clear skies and VFR conditions through the period.
No hazardous marine conditions are expected through Wednesday.
Ca, Beach Hazards Statement until 2 AM PST Saturday for San Diego County Coastal Areas.
PZ, None.
