19/112 PM.
Another storm is expected to move through the area Thursday into Friday bringing moderate rain and mountain snow above 6000 feet. High pressure will return for Thanksgiving week that will warm temperatures and keep the storm track well north of southern California.
(Wed-Sat), 19/158 PM.
One more dry evening tonight before the next storm system moves into the area Thursday. Models have generally lowered the rain projections since yesterday by around 10-20%. That still fits in with the 0.50-1" coast/valleys. 1-2" foothills and mountains forecast, but nudging towards the lower side of those. And the highest amounts are still expected to be in LA County. It's important to keep in mind, though, that despite the overall lowering of amounts, there are still 10-20% of the solutions that are twice that amount. This is due to the uncertainty of the movement of the cutoff low.
Also, there is a convective risk with this system with the best chances of that being in LA County overnight Thursday into Friday morning. Models are showing 300-600 CAPE with lapse rates as high as 8C/km. So there is likely going to be a big spread in rain amounts over short distances, depending on where the heavier downpours develop. Latest high res models indicate a 60% chance of rain rates around a half inch per hour between Pasadena and the Orange County line, starting around 10pm Thursday and peaking around 3 am Friday. While the overall risk for burn scar debris flows is low, it's certainly not zero. Based on these models the risk would be higher across eastern LA County than western. And in addition to that, there is a low chance (5% or less) of a weak tornado, with the best chances across southeast LA County.
The upper low is expected to move south of LA County Friday but wrap around showers from the northeast are possible, especially in LA County through the day. The ultimate movement of the upper low will largely determine how much additional rain falls but most of the model solutions indicate just light showers the rest of Friday and possibly even into early Saturday morning.
There is enough cold air with this storm to bring snow to some of the local mountains above 6000 feet, especially in LA County where a Winter Storm Watch is in effect. Will re-evaluate tonight based on the later model runs and decide whether to go with an Winter Weather Advisory or go with a Warning. Lower snow amounts expected in Ventura County where a Winter Weather Advisory is in effect.
After a chance of morning showers in LA County Saturday the remainder of the day and weekend is expected to be dry but cool.
(Sun-Wed), 19/203 PM.
Expecting a dry week through Thanksgiving and likely through at least next Saturday. Highs will warm up modestly with most areas in the mid 60s to low 70s all week with no significant winds expected and minimal if any marine layer stratus.
20/0332z.
At 2330Z at KLAX, there was no marine layer nor inversion.
There is a 10% chance of -SHRA for KWJF and KPMD through 20/06Z.
High confidence in VFR conds at all sites until 10Z, moderate confidence in TAFs thereafter. A cold front will bring -SHRA to +RA from north to south, with heaviest rain expected KSBA and south after 18Z. IFR to MVFR conds likely with rain, but localized LIFR possible with heavier rain. Lower confidence in wind direction and speed due to dependence on the location of the upper level low moving over the region, especially for coast and valley areas south of KSMX.
KLAX, High confidence in TAF through 15Z, moderate confidence thereafter. Timing of rain may be off +/- 3 hours. LIFR to IFR conds possible with heavier rain. Lower confidence in wind direction, but moderate confidence in S-E winds 20/13Z - 21/18Z. A long period of strong east winds from around 21/04Z to 21/16Z are possible, with low confidence. Moderate confidence in east wind component remaining over 8 knots through the aforementioned time frame.
KBUR, High confidence in TAF through 15Z, moderate confidence thereafter. Timing of rain may be off +/- 3 hours. Rain may heavier at times, especially after 20/21Z. LIFR to IFR conds possible with heavier rain.
19/201 PM.
A storm system will swing south through California, bringing gusty winds, a large west-northwest swell, rain, and potential thunderstorms Thursday into the weekend. The highest rain and thunderstorm chances exists from Thursday afternoon through Friday afternoon. Any thunderstorm can produce erratic wind shifts, heavy rain, lightning, and even waterspouts.
A combination of Small Craft Advisory (SCA) winds and seas will be common across the coastal waters beginning early Thursday through much of the weekend. Seas will rapidly increase to upwards of 15 feet across the Outer Waters, 10 feet for the nearshore Central Coast Waters, and 6 feet inside the Southern California Bight. Ahead of the cold front associated with the storm system, 10-15 knot southerly winds will occur, then NW winds 20-30 knots will follow in the wake of the front.
Northeast winds 20-30 knots will be common nearshore from Ventura to Malibu Friday morning through Saturday evening. There is a moderate chance these winds reach the Channel Islands across the Santa Barbara Channel. Northeast to southeast winds 10-20 knots are likely nearshore form the Palos Verdes Peninsula south through Orange County. Lower confidence, but winds have a chance of impacting Catalina Island, including Avalon Harbor. SCAs will more than likely be issued tonight after newer high resolution guidance comes in.
The variable winds across all coastal waters will result in rough, confused seas. Low chances, but Gale Force winds are possible virtually anywhere as any changes to the locations of the storm's core can create major differences in wind speeds and direction.
Confidence is low in winds for Thursday through Saturday. It is best to alter any plans and remain in safe harbor until conditions improve.
19/104 PM.
High Surf Advisories are now in effect from Thursday through Sunday night along the Central Coast and Ventura County. There is a 30% chance for High Surf Advisories to be issued for the Los Angeles County coasts during that timeframe.
Highly variable winds will create rough surf conditions across all coasts. In addition to rough surf, there is a chance for thunderstorms Thursday through Friday night at all beaches. Thunderstorms can produce lightning, heavy downpours, gusty- erratic winds, and even waterspouts.
Beach erosion with isolated, minor coastal flooding is possible for west-northwest facing beaches, especially during peak high tide from 8 AM to 1 PM from Friday through Sunday, with highest risk along the Central Coast.
Ca, High Surf Advisory in effect from 3 PM Thursday to 9 PM PST Sunday for zones 340-346. (See LAXCFWLOX). High Surf Advisory in effect from 3 AM Friday to 10 AM PST Saturday for zone 354. (See LAXCFWLOX). Winter Weather Advisory in effect from 10 AM Thursday to 2 AM PST Friday for zone 377. (See LAXWSWLOX). Winter Storm Watch in effect from Thursday afternoon through Saturday morning for zones 379-380. (See LAXWSWLOX). PZ, Small Craft Advisory in effect from noon Thursday to 3 AM PST Friday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 10 AM Thursday to 3 AM PST Saturday for zones 670-673. (See LAXMWWLOX). Small Craft Advisory in effect from noon Thursday to 3 AM PST Saturday for zone 676. (See LAXMWWLOX).
