Point Piedras Blancas to Point Sal from 10 to 60 NM Marine Forecast
|Today...Nw Winds 10 To 20 Kt With Gusts To 25 Kt. Strongest Western Portion. Combined Seas 11 To 12 Ft Dominant Period 20 Seconds.|
|Tonight...Nw Winds 15 To 25 Kt With Local Gusts To 30 Kt, Becoming N 20 To 30 Kt With Local Gusts To 35 Kt After Midnight. Strongest Western Portion. Combined Seas 10 To 13 Ft Dominant Period 17 Seconds.|
|Tue...N Winds 20 To 30 Kt With Gusts To 40 Kt, Becoming 15 To 25 Kt With Gusts To 35 Kt In The Afternoon. Strongest Western Portion. Combined Seas 9 To 11 Ft Dominant Period 16 Seconds.|
|Tue Night...N Winds 15 To 20 Kt With Gusts To 25 Kt, Becoming Ne 10 To 20 Kt After Midnight. Combined Seas 7 To 9 Ft Dominant Period 15 Seconds.|
|Wed...N Winds 10 To 15 Kt. Wind Waves 2 Ft Or Less. Nw Swell 5 To 6 Ft At 13 Seconds.|
|Wed Night...N Winds 10 To 15 Kt. Wind Waves 2 Ft Or Less. Nw Swell 4 To 5 Ft At 13 Seconds.|
|Thu...Nw Winds 10 To 20 Kt With Gusts To 25 Kt. Combined Seas 6 To 7 Ft.|
|Fri...Nw Winds 15 To 20 Kt With Gusts To 25 Kt. Combined Seas 6 To 7 Ft. Slight Chance Of Showers.|
| Area Forecast Discussion|
...UPDATED National Weather Service Los Angeles/Oxnard CA
416am PST Monday Jan 18 2021
updated aviation discussion
There will be weak offshore flow today and temperatures will begin to cool down. Very strong northeast winds will affect the area late tonight through Wednesday morning, especially across Los Angeles and Ventura Counties. It will likely remain dry except for possible showers over the eastern San Gabriels on Tuesday. There will be a widespread chance for light rain Friday into Saturday with significant cooling.
.SHORT TERM (TDY-WED)...18/313 AM.
Today will be the calm before the (wind) storm. There is about 2 MB of offshore flow from both the north and the east. There will be some weak canyon winds this morning but nothing near advisory levels. A little bit of energy, currently over the Bay Area, will move over Srn CA today. It will not do much to today's weather save for a little bit of cirrus but it will set the stage for tomorrow. The lowering hgts and weaker offshore flow will bring 4 to 8 degrees of cooling to the area today.
Tonight the little trough that ran overhead during the day will move off to the west of Baja. Simultaneously a cold upper low will retrograde out of NV. The upper flow will turn to the NE through at least 700 MB it will be accompanied by a grip of cold air advection. A cold dome of surface high pressure will build into NE Nevada and the offshore LAX-DAG gradient will increase to somewhere between 6 and 8 MB. 850 MB upper support will be about 50 KT at midnight and 65 kt shortly after sunrise. All of these ingredients will combine to produce warning level gusts between 60 and 70 mph (70 to 80 mph in the mtns). High wind warnings have been issued for much of LA and VTA counties starting at 10pm tonight and continuing through the predawn hours of Wednesday morning. Many areas not covered by the high wind warnings will see advisory level winds. Please see the product LAXNPWLOX for details. These winds will also dramatically increase the fire danger - please see the fire weather discussion below for all of the details.
The upper low will retrograde over LA county during the day Tuesday and it will bring some clouds with it and somewhat strangely it will bring just enough moisture, instability and dynamics to create a slight chance of showers over the eastern LA mtns. The highest elevations might see an inch maybe two but because of the cold air advection some areas as low as 3500 feet may see a dusting.
The massive cold air advection will completely overwhelm the compressional heating and max temps will fall 10 to 15 degrees. Cst/Vly temps south of Point Conception will be in the mid to upper 60s. There will be less cold air advection across the Central Coast and temps there will rise into the lower 70s.
On Wednesday the upper low will be well to the SW of LA. The offshore flow will be similar in strength to Tuesday but there will be less upper support and much less thermal support. There will likely be advisory level gusts across much of LA and VTA counties. The lack of cold air advection and the continued offshore flow will bring 5 to 10 degrees of warming to the entire forecast area.
.LONG TERM (THU-SUN)...18/312 AM.
Both the EC and the GFS agree that a substantial change in the weather is coming in the xtnd period.
On Thursday a little Probability of Precipitation up ridge moves over Srn Ca in between the departing upper low and a cold upper low moving out of the Pac NW. There will still be some offshore flow but it will be 2 to 3 MB weaker than it was on Wednesday. Looks for some sub advisory canyon winds in the morning. The coasts and vlys will cool (The Central Coast may see 8-10 degrees of cooling) due to the reduced offshore flow while the interior warms as the airmass warms.
On Friday an upper low moves down the coast and into the San Joaquin Vly in the evening. On Saturday the low is forecast to open up into a pos tilt trough with the axis oriented from the center of NV to Srn VTA county. The upper flow will be quite weak over SoCal with the strongest winds to the NW SW and S. Deterministic Models as well as their ensembles all agree that this system will bring a some showers to the area on both days but there is no agreement on exactly where or when. There is no moisture tap and the system will be pretty moisture starved so rain rates will be low but some areas (notably the eastern San Gabriels) could receive quite a few hours of rain over the 60 hour period and end up with over three quarters of an inch of rain. it produces will be quite light. For now will broad brush slgt chance to chance probability of precipitation and partly to mostly cloudy skies. This is a cold system and snow levels will be on the low side, but as with the rainfall amounts any snowfall that occurs will be light.
Cooler for sure with 8 to 10 degrees of cooling slated on Friday as the hgts plummet and then an additional 2 to 4 degrees of cooling on Saturday which will bring max temps only into the lower 60s across the coasts and vlys which is 5 to 8 degrees below normal.
On Sunday the trough will slowly move out and skies will clear and the threat of rain will end in the afternoon. Any additional rainfall or snowfall will be minimal. Max temps will rise but will still be 3 to 5 degrees below normal.
High confidence that Small Craft Advisory (SCA) level hazardous seas over 10 feet will continue through at least Tuesday afternoon across the waters along the Central Coast southward to San Nicolas Island. There is also a 30% chance of SCA (Small Craft Advisory) level northwest winds late this afternoon across the northern portion. High confidence that SCA (Small Craft Advisory) level northeast winds will develop by late tonight and last through at least late Tuesday night north of Point Conception. There is a 30-40% chance that winds may exceed Gale force.
High confidence in gusty northeast winds and choppy short-period seas across all the inner waters inside the Southern California Bight and out to all the Channel Islands, San Nicolas Island, and Catalina Island late tonight through Wednesday morning. The strongest winds are expected Tuesday morning through afternoon. A Gale Watch will be in effect from late tonight through Wednesday morning with winds likely peaking between 30 and 40 kt with local gusts to 50 kt. Choppy wind-generated waves of 5 to 8 feet are also expected. These conditions are expected to impact the eastern Channel Islands and Catalina Island. East facing harbors, such as Avalon Harbor and other east facing harbor entrances across the Channel Islands will be affected with strong winds and steep seas. These conditions are hazardous to boaters, and there may be damage to boats that are not anchored properly. Mariners should avoid these areas, or remain in safe harbor until conditions improve.
A long period west to northwest swell will move through the coastal waters today through Tuesday, resulting in high surf and dangerous rip currents on all west and northwest facing beaches. Surf will peak today then slowly subside on Tuesday. There is a chance that surf will subside slower than expected and Surf Advisories may need to be extended past Tuesday night.
For the Central Coast, large breaking waves of 15 to 20 feet will be likely today along favored northwest-facing beaches, then slowly subside on Tuesday. There could be some local sets greater than 20 feet today.
For the Los Angeles and Ventura County beaches, large breaking waves of 6 to 10 feet will be likely today along west-facing beaches, with some higher sets across Ventura County beaches. The west-facing beaches of the Santa Barbara County South Coast will likely see breaking waves of 5 to 8 feet. The surf will slowly subside on Tuesday.
Lingering offshore winds gusting between 25 and 40 mph combined with very warm temperatures and low humidities between 8 and 15 percent will continue to bring elevated to brief critical fire weather conditions to portions of Los Angeles and Ventura counties today. Offshore winds are expected to diminish tonight into Monday morning, then increase again across Los Angeles and Ventura counties by Monday afternoon, with humidities generally in the 15 to 25 percent range.
A very strong and damaging north to northeast wind event is likely between late Monday night and Wednesday morning. The strongest and most widespread winds are expected to be Tuesday mid morning through Tuesday night when widespread damaging wind gusts of 60 to 80 mph will be likely in the mountains, foothills, and some valley locations in Los Angeles and Ventura counties. Even coastal areas (including portions of the LA Basin) will likely see locally damaging wind gusts of 50 to 60 mph. Portions of San Luis Obispo and Santa Barbara counties (especially the mountains and Central Coast) could see strong northeast to east winds with this event Tuesday into Tuesday night, with wind gusts of 30 to 50 mph, except locally 60 mph across the higher terrain. Due to the uncertainty with the track of the upper low and the possibility of some moisture entrainment on Tuesday, confidence remains low with the humidity forecast. However there is the potential for humidity levels between 15 and 30 percent for a portion of this strong wind event, with the driest air focused across coastal and valley areas where downslope drying will be maximized. Due to the strength of this upcoming wind event and current state of the very dry fuels, a Fire Weather Watch will be considered for Tuesday with the afternoon forecast. Significant wind impacts will be likely with this event, including the threat of widespread downed trees and powerlines, as well as power outages. Winds are then expected to diminish Thursday through next weekend, with a chance of precipitation Friday through Sunday.
.LOX WATCHES/WARNINGS/ADVISORIES... CA...High Surf Advisory in effect until 10pm PST Tuesday for zones 34-35-39>41-87. (See LAXCFWLOX). High Wind Warning in effect from 10pm this evening to 4 AM PST Wednesday for zones 40-41-44>46-53-54-88-547. (See LAXNPWLOX). High Wind Warning in effect from 4am Tuesday to 4am PST Wednesday for zones 51-52. (See LAXNPWLOX). Fire Weather Watch in effect from this evening through Wednesday morning for zones 234>236-251-252. (See LAXRFWLOX). Fire Weather Watch in effect from late tonight through Tuesday evening for zones 240-241-244>246-253-254-288-547-548. (See LAXRFWLOX). PZ...Small Craft Advisory in effect until 3am PST Wednesday for zones 645-670-673. (See LAXMWWLOX). Gale Watch in effect from late tonight through Wednesday morning for zones 650-655-676. (See LAXMWWLOX). Small Craft Advisory in effect until 3am PST Tuesday for zone 676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK (WED-SUN).
Strong to potentially damaging Santa Ana winds are possible into early Wednesday.