16/1259 AM.
Night through morning marine layer clouds will continue for the coast and lowers valleys, shrinking in coverage each day into next week. Cooler than normal temperatures continue today, then warmer than normal temperatures return this week, with widespread moderate Heat Risk potentially occurring away from the immediate coast.
(tdy-Tue), 16/916 AM.
Morning satellite imagery showed solid low cloud coverage north of Point Conception, pushing well inland into the Santa Ynez Valley. South of Point Conception, the low cloud coverage was more disrupted, especially over the LA Basin where low clouds were mainly confined to immediate coastal areas. The marine layer depth continues to shrink from yesterday's values, ranging from 2000 feet north of Point Concpetion to 1500 feet for the LA Basin. As heights continue to build the next couple of days and onshore pressure gradients weaken, looking for marine layer cloud coverage to become less extensive. The absence of cloud coverage this morning is allowing many LA county inland areas to warm more quickly as evident by 9 am temperatures trending 5 to 10 degrees warmer than this time yesterday.
***From previous discussion***
The warming trend is well on track through much of this coming week, with heat likely peaking Tuesday-Thursday. 500 mb heights will continue to increase gradually through Tuesday before plateauing as the large area of high pressure across the Southern United States marches westward. This combined with weakening onshore flow will swing temperatures right back up to around 5-10 degrees above seasonal normals by Tuesday. Overnight temperatures will increase each day as well with most areas south of Point Conception seeing lows drop down to only the mid 60s to low 70s. Fairly widespread moderate Heat Risk will be common away from the immediate coastal areas starting Tuesday, with moderate chances for fairly widespread Heat Advisories away from the immediate coastal areas.
Marine layer clouds will likely be confined to coastal areas by Monday/Tuesday, potentially as early as tonight. The marine layer will help keep temperatures at immediate coastal areas moderate during the warm up.
Northerly winds will begin increasing tonight across southwest Santa Barbara County as well as interior mountain areas, especially the Grapevine. While winds are expected to remain sub- advisory levels, there is a moderate chance for winds to reach advisory criteria in portions of southwest Santa Barbara County Monday night. These increasing winds across southwestern SB County may also delay or completely hinder the formation of marine layer clouds across the south coast of the county as well as Ventura County. If the marine layer does in fact not develop over these areas, temperatures could be warmer than advertised.
(Wed-Sat), 16/114 AM.
Upper level ridging will continue to bring warm and dry conditions to Southwest California through the work work. Onshore flow will also be its weakest Wednesday through at least Friday. The resulting widespread Moderate Heat Risk will also lead to a moderate chance for heat headlines away from the coast through at least Thursday, but increasing model agreement for Friday brings it into play as well. The marine layer will likely be confined just to the immediate coastal areas, and there is a small chance that dense fog will occur as the marine layer depth will be quite shallow.
While winds aren't expected to be of any widespread significance, the increasing northerly pressure gradient will allow for gusty north to northwest winds are likely each night across the interior mountains (especially the Grapevine), deserts, and southwest Santa Barbara County. While widespread advisory level winds aren't likely in the extended period either, there is a chance for portions of southwest SB County to reach advisory levels. As in the short term, increasing northerly winds across southwestern SB County could disrupt the formation of marine layer clouds across the south coast of the county as well as Ventura County. Again, this could result in warmer temps along the coasts.
Next weekend still maintains some uncertainty in the evolution of the upper pattern. Cluster analysis still shows fairly similar chances of weak troughing setting up along the coast vs the ridge maintaining its position out west. Suffice to say confidence from Saturday on is fairly low. While the former solution favor a cooling trend, the latter favor continued hot weather and even a small chance for monsoonal convection.
16/1119z.
At 0803Z at KLAX, the marine layer was at 1000 feet deep. The top of the inversion was near 4000 feet with a temperature of 23 C.
High confidence in VFR TAFs for KPMD & KWJF.
Low to moderate confidence in remaining TAFs, lowest south of Point Conception. Patchy marine layer will also cause conds to bounce between VFR and MVFR/IFR this morning. 30% chance KBUR/KVNY remain VFR. VFR transition may be off +/- 2 hours, lowest confidence KSMX/KSBP. Arrival times tonight may be off +/- 4 hours, lowest confidence south of Point Conception. 20% chance for IFR cigs KOXR/KCMA after 10Z.
KLAX, Low to moderate confidence in TAF. Cigs may bounce between SCT and OVC. VFR transition from 16Z-20Z. 10% chance for brief IFR cigs tonight. Arrival of cigs tonight may be off +/- 4 hours from TAF with 40% chance of IFR. 20% chance no cigs late tonight. No significant east wind component expected.
KBUR, Low confidence in TAF. 30% chance VFR conds prevail. 20% chance for LIFR conds.
16/857 AM.
Moderate to high confidence in forecast. Current Small Craft Advisory (SCA) for gusty winds over the outer waters from near Point Conception southward to San Nicolas Island and in the vicinity of the Channel Islands looks on track. May see a lull in these winds this morning, but winds will quickly increase late this morning through the afternoon.
Good chance for SCA winds to be ongoing from this afternoon/ evening through much of the week over the outer waters, with SCA winds expanding into the northern outer waters Monday afternoon/ evening. Tuesday and Wednesday, local gale force gusts will be possible.
For the inner waters, SCA winds are possible during the afternoon to evening hours for the Santa Barbara Channel today and for the Santa Barbara Channel and inner waters north of Point Sal Monday and Tuesday. Wednesday looks more favorable for SCA winds for the inner waters north of Point Sal. Gusts near 25 kt are possible for portions of the southern inner waters this evening and possibly Monday and Tuesday evenings.
Building short period seas are expected over the next several days, likely rising to around 7-8 feet over the outer waters.
Ca, NONE. PZ, Small Craft Advisory in effect from 3 PM this afternoon to 2 AM PDT Monday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect from 6 PM this evening to 3 AM PDT Monday for zone 655. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Monday for zones 673-676. (See LAXMWWLOX).
