Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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811 FXUS66 KLOX 301031 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 331 AM PDT Tue Apr 30 2024 .SYNOPSIS...30/248 AM. Mostly clear skies and warmer temperatures will prevail across the region through this week, although some night through morning coastal low clouds and fog can be expected at times through Wednesday. Gusty northwest to north winds will prevail over the mountains and deserts through Wednesday, then turn NE and gusty over portions of Ventura and Los Angeles Counties Wednesday night into Thursday. There is a slight chance of rain with cooler temperatures later in the upcoming weekend. && .SHORT TERM (TDY-THU)...30/316 AM. Slightly cyclonic NW flow over the area with 576 dam hgts over the state. Moderate offshore flow from the north will combine with the upper level NW flow and produce advisory level winds across the mtns (including the Santa Ynez range) and the Antelope Vly. A weak eddy has spun up due to the strong NW flow across the outer waters. This eddy has brought low clouds to the LA coast and the San Gabriel Vly. The offshore flow is not strong enough to in these area to keep the low clouds at bay. The low clouds will, however dissipate earlier than normal due to the offshore flow. Most areas will warm 2 to 4 degrees today with local 6 degree warm ups across the Central Coast and Santa Ynez Vly. Stronger NW flow aloft tonight will keep the advisory level winds going. There will be weaker offshore flow from the north and actual onshore flow to the east which will bring more low clouds to the csts and some lower vlys. The low clouds will dissipate by or slightly after mid morning. The wind advisories continue through mid afternoon but the latest high rez ensemble based guidance indicates that the winds may come in lighter than forecast and the advisories may be taken down early. The switch to onshore flow to the east and the more extensive marine layer will bring 2 to 3 degrees of cooling to most locations. A little trof moves through the state Wed night and Thursday. At the same time higher pressure will setting in to the NE and offshore flow from the both the north and east will develop. Look for a minimal Santa Ana event on Thursday morning. The winds will most likely remain under advisory levels. The offshore flow will chase away any low clouds and it will be a sunny day. Max temps will warm with the lack of marine layer and compressional heating. Most areas will see 2 to 5 degrees of warming. .LONG TERM (FRI-MON)...30/331 AM. The GFS and EC deterministic and mean ensembles are in good agreement Fri and show hgts falling a late season upper low moves southward down the coast. The offshore flow from north finally turns onshore and the onshore flow to the east increases to moderate levels. The marine layer stratus should make a decent return and will be slower to clear. Look for 2 to 4 degrees of cooling and a return to near normal temps. The weekend forecast is looking a little clearer (well cloudier) now as the EC is now trending to the wet GFS. Not all the way however so there is still uncertainty in the 2 day forecast. The upper low will move south and the swoop to the east. The big question is how far will it swoop and when. The EC keeps the upper low more to the north while the GFS persists in its track all the way down to SBA county. The ensembles all pretty much take their positions somewhere in between these two deterministic positions. All in all for the two day period about a 50 percent chc of rain for SLO and western SBA county and a 20 to 30 percent chc for SE SBA county and LA/VTA counties. If rain does come to the area rainfall totals will be in the tenth to quarter inch range. There will be an increase in low mid and high clouds. Cooler for sure with 3 to 6 degrees of cooling each day. Drier NW flow is on tap for Monday with weaker onshore flow. Rising hgts and sunnier skies will bring 2 to 5 degrees of warming. MAx temps will still end up in the 60s and lower 70s or 4 to 8 degrees blo normal. && .AVIATION...30/0712Z. At 06Z at KLAX, the marine layer was 700 ft deep with an inversion top at 1600 ft and a maximum temperature of 19 C. High confidence in TAFs, except for KLAX, KLGB and KSMO (30% chc of no cigs), and KOXR (15% chance of IFR cigs 14Z-17Z Tue). Light turbulence and LLWS is possible over and near to hier trrn. KLAX...Moderate confidence in TAF. There is a 30% chance of no cigs developing through the period. Good confidence in any east wind component remaining below 5 kts. KBUR...High confidence in TAF. && .MARINE...30/326 AM. For the outer waters, current Gale Warnings look on track with gusty NW gales expected to continue through at least tonight. Swell will continue to be steep and choppy, a significant hazard to small vessels in particular. Then, Small Craft Advisory (SCA) conds are expected for the outer waters, Wednesday through Sunday. However, there is a 30% chance of gales persisting into Wednesday night and resurfacing again Thursday afternoon and evening. For the inner waters N of Pt. Sal, SCA level winds are likely through tonight. Then, there is a 60% chance of SCA winds during the afternoon and evening hours Wednesday through Friday. Seas are expected to be above SCA level through Wednesday. For the Santa Barbara Channel, SCA level W-NW winds are expected across the western portion during the afternoon through late night hours today and Wednesday. Then, there is a 20-30% chance of SCA winds each afternoon/evening Thursday and Friday across the extreme western portion. Winds will likely remain below SCA levels for eastern portions of the channel through Friday night. Saturday afternoon through Sunday, there is a 30-40% chance of widespread W to NW SCA level winds across the entire inner waters. For the southern inner waters, there is a 20% chance of SCA level W to NW winds across northwestern portions, near Anacapa Island during the late afternoon through late evening hours through Wednesday. Otherwise, good confidence in conds remaining below SCA levels through Friday night. Saturday afternoon through Sunday, there is a 30-40% chance of widespread W to NW SCA level winds across the entire inner waters. && .BEACHES...30/158 AM. Persistent strong winds and outer water swell heights of 10-15 feet with a 10 second period will lead to high surf (8-12 feet) along the Central Coast through tonight. Surf will be highest across northwest-facing beaches. There is a 40% chance of high surf advisory criteria lingering through Wednesday evening. NO coastal flooding is expected. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...High Surf Advisory in effect until 2 AM PDT Wednesday for zones 340-346. (See LAXCFWLOX). Wind Advisory now in effect until 3 PM PDT Wednesday for zones 349-351>353-376>378-381-383. (See LAXNPWLOX). Wind Advisory in effect until 3 PM PDT Wednesday for zone 379. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Wednesday for zone 650. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Wednesday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...Rorke AVIATION...Lund MARINE...Lund/Phillips BEACHES...Lund SYNOPSIS...Sirard weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox