Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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341 FXUS66 KLOX 161134 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 434 AM PDT Sun Jun 16 2024 .SYNOPSIS...16/345 AM. Warm to hot conditions are expected again today, although it will be a bit cooler in most areas. More significant cooling is likely Monday, then minor changes through Wednesday. Temperatures will then trend upwards by the end of this week. Gusty north to northwest winds will affect portions of the region, including southern Santa Barbara County, the Interstate 5 cooridor, Antelope Valley, and the Central Coast, through at least Monday night. && .SHORT TERM (TDY-TUE)...16/434 AM. Strong NW to N winds continued across much of southern SBA County, the mountains from eastern SBA County thru L.A. County, through the I-5 Corridor, in the foothills of the Antelope Valley and in the Santa Clarita Valley. Temperatures were still in the mid 70s to around 80 degrees in some foothill locations of SBA County and L.A. County early this morning. An eddy circulation has developed across the inner waters, and low clouds have pushed into southern L.A. County. Expect low clouds to push in to most of the L.A. County coast this morning, and possibly into the San Gabriel Valley. N of Pt Conception, areas of low clouds have developed across the southern portions of the Central Coast and the Santa Ynez Valley due to upslope flow against the north slopes of the Santa Ynez Range. Clouds should clear in most areas by mid morning. There will probably be areas of smoke from the Post Fire across portions of L.A. County today. An unseasonably strong and cold upper low will move into and across Washington state today, then into Idaho and eventually Montana tonight and Mon. To the south of this upper low, a trough will sharpen across CA later today and tonight, then it will move east and flatten Mon. Strong westerly flow aloft will continue across the region through tonight, then fast west to northwest broadly cyclonic flow will continue through Tue. At the surface, N-S gradients will remain strong right through early Tue. As a result, a long duration strong northwest to north wind event will affect many parts of Southwest California through at least Mon night. Winds will likely be strongest this morning, and again late this afternoon through late tonight, with gusts to 60 to 65 mph in the more favored locations. High Wind Warning level winds may be somewhat less widespread tonight, but they will still likely occur across southwestern SBA County, the interior mtns of SBA County, the Ventura County mtns, through the I-5 Corridor, and in the western foothills of the Antelope Valley. While winds should drop below High Wind Warning levels in southeastern SBA County this morning, winds will likely remain at advisory level at times through late tonight, and possibly again late Mon and Mon night. Advisory level NW winds will likely continue in the Antelope Valley through late tonight, and will likely redevelop this afternoon and evening on the Central Coast. There will likely be another round of gusty NW winds in the Santa Clarita Valley tonight after a lull later this morning, and wind advisories may have to be extended there through at least late tonight. With falling heights and some cooling through the atmosphere, max temps today should be a few degrees lower than they were on Sat in most areas. However, they should still be somewhat above normal. Temps will be very tricky across southern SBA County, as warm downslope northerly winds will be battling with the cooler marine air pushed northward by the eddy circulation in the inner waters. It does appear that there will be significant cooling in southeastern SBA County today, especially near the coast from the city eastward. However, max temps may still jump again late in the afternoon or evening, and since it remained fairly warm this morning, the chance of heat stress may be a bit higher than the max temps might suggest. After some consideration, have decided to leave the Heat Advisory as is for southern SBA County especially since it includes the foothills which will likely get very warm again today. Low clouds and fog will likely be a bit more widespread tonight/Mon morning across coastal sections of L.A. County, and clouds will likely push into the San Gabriel Valley and possibly eastern portions of the San Fernando Valley. By late tonight, some stratus could push into coastal sections of Ventura County. Once again, expect some night thru morning low clouds and fog across southern portions of the Central Coast and in the Santa Ynez Valley. Expect skies to clear in most areas by late morning. Heights falls and cooling at 850 mb and 950 mb should bring several degrees of cooling to most areas on Mon. As mentioned, there will be another spike in the NW winds late Mon into Mon night, but expect winds to be mostly in the Wind Advisory level range. The low level flow will try to turn more northeasterly Tue morning, as pressure gradients between KLAX and KDAG turn weakly offshore. This should bring an end to the gusty NW winds in most areas by late Mon night, but some gusty NE winds are possible in the mtns of L.A. County Tue morning. With the increased NE low level flow shown by the latest models, there may be somewhat of a reduction in night thru morning low clouds and fog across L.A. County Mon night/Tue morning. Max temps may actually rise a bit on Tue as heights rise slightly and both N-S and W-E gradients will be offshore to start the day. .LONG TERM (WED-SAT)...15/308 PM. There is good agreement among the GFS and ECMWF that the trough will persist over the region through Thursday, and that upper level heights will trend upwards through Friday. Late Friday into the weekend there is greater uncertainty in the upper level pattern, with the potential for a weak ridge to begin to build. Daytime highs are expected to slowly trend upwards Thurday through the weekend, crossing over to above normal for much of the region on Friday. The north-to-south gradient is expected to weaken Wednesday and even flip to onshore at times. Onshore flow (both from the west and south) is generally expected to be dominant through the period, and thus morning low clouds and fog are likely. However with rising upper level heights, the marine layer depth, and thus the inland extend of stratus will be limited to the coastal planes and will at times struggle to reach the coastal valleys. Clouds may cling to some beaches all day, especially in Los Angeles and Ventura Counties. Even with less dramatic pressure gradients than in the short term, gusty northerly-to-westerly winds will continue during the evenings for some wind- prone locations (e.g., the I-5 cooridor, the Antelope Valley and foothills, the Santa Barbara Southwestern coast). At this time, wind in the extended period are likely to be much lower impact than in the short term. && .AVIATION...16/1033Z. At 1000Z at KLAX, the marine layer was 800 feet deep. The top of the inversion was at 3400 ft with a temperature of 25 C. Overall, moderate to high confidence in TAF package. For most sites, CAVU conditions are anticipated through the period. However for KLAX, KLGB, KSMO and KSMX, CIG and/or VSBY restrictions will be possible 12Z-17Z. Gusty north winds will continue through the period. Light turbulence and LLWS will be likely across the mountains and foothills. KLAX...Moderate confidence in 12Z TAF. There is 40% chance that IFR conditions will not develop 12Z-17Z. For tonight, moderate confidence in return of CIG/VSBY with a window of +/- 2 hours for timing of return. No significant easterly wind component is expected. KBUR...High confidence in 12Z TAF as CAVU conditions are expected through the period. There is a 20-30% chance for smoke to produce some MVFR VSBYs and/or BKN040-060 conditions. && .MARINE...16/138 AM. For the Outer Waters, high confidence in current forecast. Winds are expected to remain at Gale force levels through Monday. So, GALE WARNINGS will remain in place during this time (with a 20% chance of Storm force winds through Sunday night). Seas will peak in the 12 to 15 foot range through Monday. For Tuesday through Thursday, winds will subside, but remain at Small Craft Advisory (SCA) levels while seas drop below 10 feet. For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. There is a 60-80% chance of Gale force winds through tonight and a GALE WARNING remains in effect. Seas will peak between 10 to 13 foot through tonight. For Monday through Wednesday, there is a 60-80% chance of SCA level winds. On Thursday, winds and seas should remain below SCA levels. For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For the western Santa Barbara Channel, high confidence in Gale Force Winds continuing through tonight with a GALE WARNING remaining in effect. The winds will be strongest from mid channel and westward. For Monday through Thursday, there will be a 60-80% chance of SCA level winds across the western half of the Santa Barbara Channel. Elsewhere across the southern Inner Waters, there is a 20-30% chance of SCA level winds today with high confidence in winds and seas below SCA levels Monday through Thursday. Across all of the coastal waters, steep and dangerous seas can be expected through early this week. && .BEACHES...16/139 AM. Short-period wind waves, due to gale force winds over the nearby coastal waters, will generate significant surf conditions along the local beaches today through Monday. High surf, 4 to 7 feet, will impact the beaches of Ventura county. For the beaches along the Central Coast as well as Los Angeles county, elevated surf conditions will continue through Monday. Along with the surf conditions, dangerous rip currents can be expected into early this week. && .FIRE WEATHER...15/843 PM. && Gusty northwest to north winds are expected to continue through Monday, peaking in intensity tonight with a secondary peak Sunday night into early Monday. Wind gusts of 30 to 50 mph will be common at times through the period for the Central Coast, mountains of Santa Barbara, Ventura and northwest Los Angeles County as well as Antelope Valley (strongest in the mountains and deserts). Isolated gusts to 65 mph will be likely in the strongest periods of wind across the Santa Ynez Range and I-5 corridor. Meanwhile, a warm and dry air mass will remain in place, with widespread 8 to 15 percent humidities across the interior on Sunday, and 12 to 20 percent on Monday. Poor overnight recoveries in the foothills are also expected. The warm and dry air will continue to descend into some coastal foothills on Sunday, including portions of southern Santa Barbara County. The combination of gusty winds, warm temperatures, and low humidities will continue to bring elevated to brief critical fire weather conditions across southern Santa Barbara county through Sunday night, and all interior areas through Monday. There is an increased risk for fast growing grass fires over much of the area, that could transition into wildfires where the fuel beds are most abundant and dry. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement in effect through Monday evening for zones 87-340-346-362-366. (See LAXCFWLOX). Wind Advisory remains in effect until 11 AM PDT this morning for zone 88. (See LAXNPWLOX). Wind Advisory remains in effect from 11 AM this morning to 8 PM PDT this evening for zones 340-341-346-347. (See LAXNPWLOX). High Wind Warning remains in effect until 11 AM PDT Monday for zones 349-351-353-376>378-381. (See LAXNPWLOX). Heat Advisory remains in effect until 8 PM PDT this evening for zones 349>352. (See LAXNPWLOX). High Wind Warning remains in effect until 11 AM PDT this morning for zones 350-352. (See LAXNPWLOX). High Surf Advisory in effect until 7 PM PDT Monday for zone 354. (See LAXCFWLOX). Wind Advisory remains in effect until 3 AM PDT Monday for zones 356-383. (See LAXNPWLOX). PZ...Gale Warning in effect until 2 AM PDT Monday for zones 645-650. (See LAXMWWLOX). Gale Warning in effect until 7 PM PDT Monday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...DB/Schoenfeld AVIATION...RAT MARINE...RAT BEACHES...RAT/Cohen FIRE...Gomberg/Munroe SYNOPSIS...DB weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox