29/906 PM.
Night through morning low clouds and fog coverage will continue through Friday. Much cooler and cloudy conditions with showers and gusty winds are expected over the upcoming weekend.
(Tue-Fri), 29/929 PM.
***UPDATE***
No significant changes were needed to the forecast database this evening. The marine layer induced stratus clouds have rapidly spread across much of the coast and making progress moving inland this evening. A Catalina Eddy should continue to deepen overnight helping to push stratus further inland and lift the base of the clouds.
***From Previous Discussion***
High confidence in seasonally low impact weather through Friday with relatively small day to day changes in temperatures. Some buildups have already developed across the mountains with a 10 to 20 percent chance of showers across the higher mountains, especially the Ventura County mountains today and continuing each day through Friday.
A weak trough will pass through the region Wednesday and Thursday, leading to a much deeper marine layer with low clouds pushing well into coastal valleys if not lower mountain passes during this timeframe with patchy fog and drizzle possible, especially for valleys and south facing foothills. This type of pattern will support gusty but probably sub advisory winds focused across the interior Wednesday and Thursday afternoon in particular. A reverse clearing pattern is possible Wednesday and Thursday where low clouds linger in the valleys and especially foothills longer than at the coast on those days.
(Sat-Tue), 29/137 PM.
High confidence in an unseasonably strong storm to push through the region this weekend with gusty northwest to onshore winds, but low confidence in precipitation amounts (if any) and timing. Widespread advisory level winds will be possible sometime Saturday into Sunday including many coastal areas. Where precipitation does occur it will likely be under a quarter of an inch (except up to around a half of an inch in the mountains), with the Central Coast to mountains the most favorable to receive light amounts. Snow levels will largely be between 5000-7000 feet, although may dip to around 4000 feet Saturday night into Sunday morning with light accumulations generally above 5000 feet. The unusually cold (but moisture starved) system for this time of year will support a 10 percent chance of a thunderstorm over the mountains and deserts. Any thunderstorms that do form could be slow moving, leading to locally heavier rainfall with embedded hail or graupel. It will feel much like a mid winter storm temperature wide with highs only in the 50s to low 60s for most (10-20 degrees below normal). A late season frost is possible for the coldest interior valleys Sunday or Monday mornings. Otherwise seasonably quiet weather with rebounding temperatures is likely early next week, although there’s a 20 percent chance of some shower activity lingering into early Monday.
30/0405z.
At 03Z at KLAX, the marine layer was around 1500 feet deep. The top of the inversion was around 2700 feet with a temperature of 18 C.
High confidence in TAFs for KPRB, KWJF, and KPMD. There is a 20% chance for LIFR to IFR conds at KPRB after 10Z.
Moderate confidence in TAFs for remaining sites. South of Point Conception, most sites will see IFR conds before 08Z, then MVFR after as the Catalina Eddy strengthens overnight. For KSMX and KSBP, there is a 30% chance respectively that sites will remain IFR or greater through the period. There is a 30% chance for LIFR conds at KBUR/KVNY any point after cigs arrive before 15Z. Timing of flight cat changes could be off +/- 2 hours, but high confidence in arrival of cigs.
KLAX, High confidence in TAF. Cigs have already arrived and should remain in place through at least 18Z Wed. There is a 30% chance cigs scatter between 18Z and 00Z Wednesday. There is a 30% chance of an east wind component of 8 kt 12Z-18Z.
KBUR, Moderate confidence in TAF. There is a 30% chance of LIFR conds once cigs arrive until 15Z. Cigs should arrive around or shortly after 06Z.
29/200 PM.
In the outer waters, good confidence (60% chance) that Small Craft Advisory (SCA) conds will continue much of the time thru Wed morning in the northern zone (PZZ670) and in the southern two zones (PZZ673/676) thru tonight (60% chance). There is a 30% chance that SCA conds will continue thru late tonight or early Wed for the southern two zones. SCA conds are not expected across the outer waters Wed night thru early Fri. SCA conds are likely (>80% chance) Fri afternoon thru Sun night, with a 50% chance of GALE force winds Sat afternoon/night.
In the inner waters N of Pt Sal, SCA conds are likely (50% chance) this afternoon/eve. There is a 40% chance of SCA level winds Wed afternoon/eve. SCA conds are not expected Wed night thru Fri morning. SCA conds are likely (70% chance) in the afternoon/eve hours Fri through Sun, with a 40% chance GALES Sat afternoon/eve.
In the Santa Barbara Channel, there is a 30% chance of SCA level winds in western portions during the afternoon/eve hours today and Wed. SCA conds are not expected late Wed night thru Fri morning. SCA conds are likely (70% chance) during the afternoon thru late night hours Fri through Sun, with a 40% chance of GALES across western sections Sat afternoon/eve.
In the southern inner waters, SCA conds are not expected thru Sat morning, then are likely (70% chance) beginning in the the afternoon Sat and continuing thru Sun.
Ca, Beach Hazards Statement in effect through Wednesday evening for zones 362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 9 AM PDT Wednesday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 673-676. (See LAXMWWLOX).
