07/1254 PM.
A warming trend will continue into early next week. Temperatures will reach the mid 70s to 80s across much of the region through Friday, warming to the 80s and 90s over the weekend through Tuesday. 100 degree readings may occur locally in the warmest valleys on Mother's day and Monday.
(tdy-Sun), 07/1214 PM.
Winds will strengthen to advisory levels later this afternoon into the overnight across the SW SB coast/western Santa Ynez range. Wind advisories may be needed again for that timeframe on Friday.
Expecting more low clouds tonight into tomorrow morning across the same areas. There is a better chance for marine layer stratus across the LA Basin tomorrow morning. This is due to increasing onshore flow indicated by a 1 mb pressure rise (LAX-DAG). In addition, a weak to moderate Catalina Eddy is expected to develop overnight. Whether or not low clouds arrive into the San Fernando Valley is dependent on its strength. This is currently forecasted. However, there is a 30% chance clouds do not arrive.
The ridge will continue to build over the area Today. High temperatures are expected to be noticeably warmer (especially across the interior) rising into the mid 60s to 70s for csts/vlys and 80s across the interior. Temps may push 90 degrees across the Antelope Valley.
On Friday, high temperatures will be somewhat similar maybe a couple degrees warmer or cooler depending on the evolution of marine layer stratus in the morning hours. This is especially true for areas south of Point Conception.
The combination of strongest ridging and weak onshore flow will result in Sunday (Mother's Day) and Monday being the warmest days for this warm spell. The exact magnitude of the pressure gradients will determine how much the sea breeze will influence max temperatures across the csts and vlys. Most ECWMF ensembles support enough influence to keep the csts in the 70s-80s, and the valleys in the mid 90s. However, there is a handful of solutions that would support heat advisory across some of the valleys (20% chance). Temperatures could also reach 100 F across the Antelope Valley.
(Mon-Thu), 07/1211 PM.
The latest trend across the majority of models (except for GFS) has been for a "kicker" trof to push out the ridge to the east. This would solidify a cooling trend to begin on Tuesday. Above normal temperatures likely to continue across the interior through the middle of next week. Increasing onshore flow should bring back marine layer stratus which will keep coastal locations relatively cool (near normal).
07/1810z.
At 17Z at KLAX, the marine layer was 900 ft deep. The top of the inversion was around 3400 ft with a temperature of 22 C.
High confidence in TAFs through 03Z for all TAFs and for the whole period for KPMD and KWJF. After 03Z, moderate to low confidence in remaining sites due to uncertainty in marine layer clouds. Timing of flight cat changes could be off by +/- 2 hours. There is a 30% chance of VFR conds remaining at KOXR, KCMA, KBUR, and KVNY through the period, and a 30% chance of IFR conds at KSBA and KPRB 11Z-17Z Fri.
KLAX, Moderate confidence in TAF. Timing of flight cat changes could be off by +/- 2 hours, with cigs as low as BKN004 upon arrival before lifting through the late night/morning hours. No significant east wind component expected.
KBUR, Moderate confidence in TAF. There is a 30% chance of VFR conds remaining through the period.
07/150 PM.
SCA level NW winds are expected to strengthen each day through Saturday for the outer waters. Winds may approach Gale Force levels Friday (15% chance), with a better chance (30%) for Gale Force winds Saturday afternoon and evening. SCA level winds are also likely during the late afternoon into evening hours across the nearshore waters along the Central Coast and into at least western portions of the Santa Barbara Channel and near the Channel Islands through Saturday.
Short period seas will build during this timeframe especially across the outer waters - reaching around 10 feet Friday through Saturday night.
Winds and seas should diminish throughout the day on Sunday. By Monday, conditions should be much calmer and likely below SCA levels.
Ca, Wind Advisory remains in effect from 5 PM this afternoon to 3 AM PDT Friday for zones 349-351. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 9 PM PDT this evening for zones 645-650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Saturday for zones 670-673-676. (See LAXMWWLOX).
