14/509 PM.
Multiple periods of light to moderate rain are expected this coming week. Dry conditions will prevail through Sunday, with the next round of wet conditions set for Sunday night into Monday night, followed by Wednesday night into Thursday night. The risk of significant impacts and flooding exists with the second storm system, as moderate to heavy rain will be possible. Temperatures will remain at or below normal. Very large surf will bring coastal impacts well into the coming week.
(Sat-Tue), 14/750 PM.
***UPDATE***
High temperatures today were largely in the 60s to low 70s, a few degrees warmer than yesterday thanks to sunny skies and a lack of rainfall this afternoon. Little change is expected through tomorrow afternoon, with another few degrees of warming for high temperatures (yet still slightly below normal for this time of year). Then late Sunday, the next round of rain starts to move from North to South, moving into the Central Coast and reaching LA/Ventura late Monday afternoon/evening.
No big changes to the forecast besides slightly adjust PoPs for Monday (increased to slight chance for LA/Ventura Monday afternoon). Otherwise, forecast is in shape and no other updates were needed.
***From Previous Discussion***
Sunny to partly cloudy skies prevailed across the region early this afternoon with little change expected thru sunset. High temps today are expected to be about 3-6 deg cooler-than-normal across the region. Breezy onshore winds will persist this afternoon for the most part, although could be somewhat gusty out of the W and NW at times on the Central Coast.
For tonight and Sunday, the weak upper level ridge overhead will keep the area dry. High temperatures on Sunday will bump up a couple degrees with widespread upper 60s to mid 70s.
Beginning Sunday evening, the next cold front will approach the area. This front will sweep across the area Sunday night through Monday night with a decent chance of rain for many areas. There is also a slight chance of thunderstorms for southeastern L.A. County later Monday night as the tail end of the front moves through. Overall, though, this front does not look too impressive. Current QPF forecasts are very meager with about a third of an inch or less expected across the area (with the best totals across northwest San Luis Obispo county and eastern San Gabriel Mtns). Snow levels look to drop to around 5500 feet Monday evening/night, so a dusting of snow would not be out of the question above that level. Northwesterly winds are expected to increase across the I-5 Corridor and the Santa Ynez Range Monday night with a 30-40% chance of advisory-level winds (especially through the I-5 Corridor).
A drier NW flow will move into the region behind the front Mon night into Tue with clearing skies and cool temps. Highs on Tue should turn out to be about 5-10 deg below normal for most areas.
(Wed-Sat), 14/159 PM.
For the extended period, models are in generally good agreement with regard to a fairly significant storm system expected to impact the area mainly between Wed evening and Thu night.
A Pacific storm front is forecast to approach the Central Coast on Wed with rain spreading into SLO/SBA Counties in the afternoon. Otherwise, increasing clouds and well below normal temps can be expected across the forecast area thru the day Wed.
The main front will move slowly through the forecast area Wed night thru Thu, then there will be lingering showers behind the main front Thu night. At this time, the ECMWF is a bit faster with this front than the GFS. So, confidence in timing remains moderate, but confidence is increasing in the potential for significant widespread rainfall developing. Looking at QPF amounts, this particular frontal passage could be a bit more impressive with deterministic models indicating rainfall totals in the 1-3 inch range, with local amounts of 3-5 inches not out of the question along favored south-facing slopes. Ensemble forecasts also seem to be leaning towards a bit more impressive frontal system than previous ones. Given the potential for some decent southerly flow, orographic effects could easily generate such totals across the foothills. Of course, a lot could change between now and then, so expected totals could change noticeably.
On Friday, there may be some lingering showers in the morning hours. However, the balance of the day is expected to be dry. Weak upper level ridging will bring dry conditions to the area for Sat. Temps will remain well below normal for Fri with only a slight warm-up for Sat.
15/0526z.
At 0433Z at KLAX, there was no marine layer nor an inversion.
Overall, high confidence in the 06Z TAF Package. LIFR conditions are possible at KPRB between 10Z and 16Z, but there is a 40% chance that LIFR conds are periodic and a 20% chance the site remains VFR. Otherwise, CAVU conditions expected at all sites thru fcst pd.
KLAX, High confidence in CAVU conds for the 06Z TAF. Any east wind component expected to remain below 8 kts.
KBUR, High confidence in CAVU 06Z TAF. No wind issues expected.
14/924 PM.
For the Outer Waters, moderate confidence in current forecast. Through Wednesday, high confidence in a combination of Small Craft Advisory (SCA) level winds and seas. However, as the models are underdoing the wave heights, especially for locations near and south of Point Conception. Dangerously large seas are currently observed to be between 18 to 26 feet, and they will lower some into Sunday, but a secondary peak of 13-19 feet is expected on Monday. Additionally, there is a 30-50% chance of Gale force winds on Monday and Tuesday, most likely south of Point Conception.
For the Inner Waters north of Point Sal, high confidence in the combination of SCA level winds and seas, although models continue to underdo the wave heights. Current observations show 18 feet near Point Sal, compared to model forecast of 15 feet. However, the swell is expected to lower some through Sunday, with a secondary peak on Monday (11-16 feet). SCA winds are likely Monday through Wednesday with a chance of Gales Wed night through Thursday night.
For the Inner Waters south of Point Conception, moderate confidence in current forecast. Seas at the mid channel buoy are currently around 12 feet, so forecast has been adjusted to indicate SCA level seas through late Sunday night. For Monday through Thursday, high confidence in SCA level winds developing with a 40-60% chance of SCA level seas. Additionally, there is a 30-40% chance of Gale force winds developing Tuesday night and Thursday night.
There is a continuing threat of dangerous breaking waves at Ventura and especially Morro Bay harbor entrances. Refer to the Marine Weather Statement which has been issued (MWSLOX) for more details.
14/750 PM.
A series of very large, long period west-northwesterly swells will impact the coastline of southwest California through at least Tuesday of this coming week, creating large surf and dangerous conditions at all coasts. The largest surf will be focused along exposed west to northwest facing shores. The surf peaked today but will remain large through Sunday. A potential secondary increase is likely on Monday. Moderate to significant beach erosion and shallow flooding of sea water over low-lying beach walkways, parking lots, and roads is likely, especially in the morning hours near high tide. Large surf will create dangerous rip currents, along with strong long-shore currents, potential sneaker waves, and large shore pound. Impacts will be less for south-facing shores.
The highest risk will be for the Central Coast with potential for at least localized damage to the most vulnerable areas - such as to piers, roads, and structures. A High Surf WARNING is in effect for the Central Coast through late tonight, with impacts such as breaking waves at Morro Bay Harbor entrance and Pismo and Cayucos Piers, as well as widespread beach flooding - including Oceano Dunes State Park and other vulnerable low lying areas (especially during high tide). The peak surf heights are currently between 15 to 20 feet, but will begin to subside after midnight into the morning hours on Sunday, likely falling below Warning levels.
For west-facing beaches in LA/Ventura counties, high surf advisories are in effect with high surf expected to continue through at least Tuesday. There may be a relative "lull" in the surf Sunday before the second swell arrives, but surf and rip currents will still be hazardous. Surf peaked today and there is a low chance for a few sets to 15 feet at the most exposed Ventura County beaches through around midnight.
Ca, Beach Hazards Statement in effect through Tuesday afternoon for zone 87. (See LAXCFWLOX). High Surf Warning in effect until 3 AM PST Sunday for zones 340-346. (See LAXCFWLOX). High Surf Advisory in effect from 3 AM Sunday to 3 PM PST Tuesday for zones 340-346. (See LAXCFWLOX). High Surf Advisory in effect until 4 AM PST Sunday for zones 349-350. (See LAXCFWLOX). Beach Hazards Statement in effect from 4 AM PST Sunday through Tuesday afternoon for zones 349-350. (See LAXCFWLOX). High Surf Advisory in effect until 3 PM PST Tuesday for zones 354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 3 AM PST Wednesday for zones 645-670-673-676. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PST Monday for zone 650. (See LAXMWWLOX).
