Ation DISCUSSION,
This morning, The marine layer is around 1500 ft deep with low clouds increasing in coverage over the coastal areas and western portions of the inland valleys. Due to the decreasing depth of the marine layer, low clouds are not expected to reach into the Inland Empire this morning. A large mass of mid and high clouds is moving over the region from the southwest. This is mostly moisture from the remnants of Post-Tropical Cyclone Douglas. There are convective elements embedded in the cloud mass but if any precipitation is produced, it's unlikely to reach the ground due to the deep and dry sub-cloud layer. The widespread cloud cover will inhibit heating today and high temperatures this afternoon could be lower than expected in the mountains and deserts.
By Monday, the upper level disturbance will have moved to the northeast into the Great Basin taking with it the elevated moisture and cloud cover. For Monday through the middle of next week, the warming trend will become more noticeable as the high pressure to our southeast expands westward into SoCal. The marine layer will become even shallower restricting the night and morning low clouds and fog mostly to the coastal areas. Wednesday and Thursday are likely to be the warmest days, with daytime high temperatures 5-10 degrees above normal in the inland valleys, mountains and deserts. Parts of the Inland Empire and the high desert could experience moderate HeatRisk Tue-Thu and the lower deserts could experience moderate to high HeatRsk.
As we approach the end of next week, Fair weather will continue but stronger onshore flow could spread the marine layer influence farther inland resulting in a slight lowering of temperatures west of the mountains along with more low cloud cover during the nights and mornings.
Fair and seasonal weather will continue for the coming week, with a gradual warming trend. The marine layer will gradually decrease in depth with night and morning low clouds not spreading as far inland nor lasting as long into the late mornings. Subtropical moisture will bring some high clouds this holiday weekend, but with seasonal temperatures.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
This morning, The marine layer is around 1500 ft deep with low clouds increasing in coverage over the coastal areas and western portions of the inland valleys. Due to the decreasing depth of the marine layer, low clouds are not expected to reach into the Inland Empire this morning. A large mass of mid and high clouds is moving over the region from the southwest. This is mostly moisture from the remnants of Post-Tropical Cyclone Douglas. There are convective elements embedded in the cloud mass but if any precipitation is produced, it's unlikely to reach the ground due to the deep and dry sub-cloud layer. The widespread cloud cover will inhibit heating today and high temperatures this afternoon could be lower than expected in the mountains and deserts.
By Monday, the upper level disturbance will have moved to the northeast into the Great Basin taking with it the elevated moisture and cloud cover. For Monday through the middle of next week, the warming trend will become more noticeable as the high pressure to our southeast expands westward into SoCal. The marine layer will become even shallower restricting the night and morning low clouds and fog mostly to the coastal areas. Wednesday and Thursday are likely to be the warmest days, with daytime high temperatures 5-10 degrees above normal in the inland valleys, mountains and deserts. Parts of the Inland Empire and the high desert could experience moderate HeatRisk Tue-Thu and the lower deserts could experience moderate to high HeatRsk.
As we approach the end of next week, Fair weather will continue but stronger onshore flow could spread the marine layer influence farther inland resulting in a slight lowering of temperatures west of the mountains along with more low cloud cover during the nights and mornings.
for extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
This evening, the marine layer is about as deep as it was at this time yesterday but the low clouds seem slower to increase in coverage and advance inland. This may be due to a weaker inversion as a result of some cooling just above the inversion.
From previous discussion, Our weather continues to be controlled by the dominant upper ridge currently positioned over southern Arizona and the low/trough centered over the Gulf of Alaska. As a result, the marine layer mixed out efficiently today with sunny skies extending several miles out to sea this afternoon. High temperatures today coming in right around climatological normals to 5 degrees below normal - topping out in the 80s to low 90s for most with 100-110 degrees for the deserts. As we head through the weekend and into next week, this ridge doesn't budge much and stays relatively weak. Still, temperatures increase very gradually through Tuesday, with high temperatures by Tuesday afternoon only a couple of degrees warmer than today. The marine layer will continue to spread inland each night and retreat back to sea each day with depth varying between 700 and 1400ft.
By the middle part of next week, the center of the ridge slides a bit closer to New Mexico, but also broadens and strengthens considerably, bringing more substantial warming for Wednesday and Thursday. Thursday and Friday will likely be the hottest days of the next week, with widespread moderate HeatRisk stretching towards the coasts and high HeatRisk spreading out of the deserts locally to inland valleys. High temperatures reaching or exceeding 100 degrees for inland valleys Thurs/Fri with the deserts likely exceeding 115 degrees (~90% chance). Available moisture will likely be quite below normal for early August most of next week, but recover to closer to normal by the end of the week. Still, chances for any monsoonal thunderstorms by the end of next week stay low, about 10 percent or less.
AVIATION, 020300Z. Coasts/western Valleys, Low clouds based 700-1200 feet MSL are slowly moving inland, reaching its full inland extent by 07Z. Vis reduced 0-5SM over higher coastal terrain and western valleys. Scatter out Saturday 15-17Z. Vfr conditions Saturday afternoon. Low clouds redevelop at the coast around 04z Sun.
Inland Valleys/Mountains/Deserts, Mostly clear with VFR conditions through late Saturday.
MARINE, No hazardous marine conditions are expected through Wednesday.
SKYWARN, Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.
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.
