Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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194 FXUS66 KLOX 301629 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 929 AM PDT Tue Apr 30 2024 .SYNOPSIS...30/857 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. Locally breezy winds will continue over the mountains and deserts through Wednesday, then turn NE over interior portions of Ventura and Los Angeles Counties Wednesday night into Thursday. Cooler temperatures are expected Friday through the weekend with a slight of rain. && .SHORT TERM (TDY-THU)...30/922 AM. ***UPDATE*** Marine layer this morning is close to 2000 feet deep but was primarily just impacting coastal LA County, though it has crept up to the Ventura County coast as well. Gusty north winds overnight have tapered off but some local gusts to around 40 mph still ongoing through the Grapevine between Whitaker Peak and the Kern County line. Winds are continuing to decrease and will likely end the wind advisory this morning. An uptick in winds are expected again this evening and overnight tonight but winds expected to remain at or below 40 mph. One potentially notable change in the forecast for Thursday is that models now are much weaker with the offshore push. The LAX- DAG gradient was forecast to drop to -5.1mb but today`s NAM has brought that almost all the way back to 0. So the big warm up for Thursday will likely not happen and any northeast winds would be confined to the far interior areas at most. ***From Previous Discussion*** Tonight 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 switch to onshore flow to the east and the more extensive marine layer will bring 2 to 3 degrees of cooling to most locations Wednesday. 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...30/1207Z. At 1122Z at KLAX, the marine layer was 1400 ft deep with an inversion top at 3300 ft and a maximum temperature of 19 C. Moderate confidence in KOXR, KCMA, KSMO, KLAX, KLGB. Low confidence in KBUR and KVNY through 18Z then high confidence. High confidence in all other TAFs. Timing of flight cat changes could be off by +/- 2 hours. Cigs could return as low MVFR rather than IFR Tues night. There is a 50% chance of Bkn006-010 Cigs at KVNY and KBUR through 18Z. KLAX...Moderate confidence in TAF. Timing of flight cat changes could be off by +/- 2 hours. There is a 30% chance of BKN010-015 Cigs upon arrival Tues night. Good confidence in any east wind component remaining below 6 kts. KBUR...Low confidence in TAF through 18Z, then high confidence. There is a 50% chance of Bkn006-010 Cigs through 18Z. && .MARINE...30/929 AM. For the outer waters, current Gale Warnings are on track with gusty NW gales expected to continue until late tonight. Swell will continue to be steep and choppy. After gales subside, 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. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...High Surf Advisory in effect until 2 PM PDT Wednesday for zones 340-346-354. (See LAXCFWLOX). Wind Advisory remains in effect until 3 PM PDT Wednesday for zones 349-351>353-376>379-381-383. (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...MW/Rorke AVIATION...Lund MARINE...Lund/Schoenfeld SYNOPSIS...MW/Sirard weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox