Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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009 FXUS66 KLOX 012128 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 228 PM PDT Wed May 1 2024 .SYNOPSIS...01/207 PM. Areas of night and morning low clouds and fog will be present near the coast for the remainder of this week. Otherwise, dry conditions and near-normal temperatures are expected through Friday. This weekend, a storm system will pass by to the north of the area. The main impacts from this system across southern California will be areas of light precipitation late Saturday into Sunday, along with cooler temperatures and gusty winds. For next week, temperatures will warm back up to near-normal readings, with dry conditions expected. && .SHORT TERM (TDY-SAT)...01/207 PM. Northwesterly midlevel flow will persist for the remainder of this week between an upper trough being reinforced over the western states, and a midlevel ridge well offshore over the Pacific waters. The enhanced flow aloft combined with nocturnal drainage flow will support wind gusts of 45 mph and a Wind Advisory this evening into tonight for the Interstate-5 Corridor and the western Antelope Valley Foothills. Gusty northwest winds are expected across portions of the Antelope and Santa Clarita Valleys to the southern VTA County mountains and the SBA County interior mountains, and there is a 40% chance that the Wind Advisory would need to be expanded to include these areas. A similar pattern will support gusty northwest winds over these areas Thursday night and Friday morning, though the chance for a Wind Advisory becoming needed over these areas is lower -- 30% chance. Otherwise, in general, dry conditions and mostly clear skies are expected across the region through the remainder of this week. An exception will be over coastal areas and nearby valleys, where neutral to slightly onshore pressure gradients will favor night and morning low clouds and fog in the marine layer. There will be a 30% chance for localized Dense Fog Advisories to become necessary in conjunction with this activity. Temperatures will be near-normal for the remainder of this week, with high temperatures from the mid 70s to the lower 80s in most areas. Some change in these conditions is expected going into Saturday, as temperatures cool by a few to several degrees as midlevel heights fall in response to a deep upper cyclone moving southeast along the Pacific Northwest coast. Gusty west-southwest to west- northwest winds are expected area-wide on Saturday, as enhanced tropospheric flow in the southern periphery of this cyclone overspreads the area. While moisture will deepen over the area well in advance of this system for Saturday and Saturday evening, cooling aloft will tend to disrupt marine layer continuity and related fog development. However, low clouds and drizzle could occur within the deepening moist layer. .LONG TERM (SUN-WED)...01/215 PM. The aforementioned deep upper cyclone will track east-southeastward across the Intermountain West on Sunday. A shortwave trough pivoting around the southern semi-circle of the cyclone may bring sufficient ascent and midlevel cooling to yield a few showers over the area late Saturday afternoon through Sunday. Ample dry air aloft should keep precipitation amounts below one-tenth inch, and many locations may not experience precipitation. A light dusting of snow could occur over the highest elevations of northern VTA and LA Counties, though significant precipitation impacts with this system appear to be unlikely. However, temperatures will be noticeably cooler across the region on Sunday, with most locations only experiencing high temperatures in the lower to middle 60s -- around 10-15 degrees below normal in many areas. Looking further ahead, dry conditions are expected areawide for next week, as midlevel heights rise behind the departing upper cyclone and attendant shortwave trough. Local pressure gradients for next week are expected to turn more neutral to offshore in response to surface ridging north of the area -- beneath subsidence in the wake of the departing upper cyclone. While this pressure pattern will likely still facilitate diurnal wind fluctuations and sea-breeze development, the development of a pronounced marine layer fostering low-cloud and fog development appears unlikely through at least the middle of next week. As a result, clear skies and a warming trend are expected for early to middle parts of next week, with high temperatures rebounding to the mid and upper 70s in most areas Monday through Wednesday. && .AVIATION...01/1800Z. At 1746Z at KLAX, the marine layer was 3400 ft deep with an inversion top at 4700 ft with a temperature of 15 C. Low to moderate confidence in coastal TAF sites and KBUR and KVNY, with high confidence elsewhere. Timing of flight cat changes could be off by +/- 2 hours, and cigs may develop one category lower than forecast in for coastal sites in Ventura and L.A. counties. There is a 30% chance of no cigs developing for KSMX, KSBA, KBUR, and KVNY. KLAX...Low to moderate confidence in TAF. Timing of flight cat changes could be off by +/- 2 hours, and cigs as low as BKN008 are possible. High confidence in any east wind component remaining less than 6 kt. KBUR...Moderate confidence in TAF. Timing of flight cat changes may be off by +/- 2 hours, with a 30% chance of no cigs developing tonight, and a 30% chance of cigs as high as BKN015. && .MARINE...01/157 PM. For the outer waters, wind are currently below Gale Force at most location. This lull is expected to be short lived, with a 70% chance of gales redevelop this afternoon and tonight. Another lull in wind is possible Thursday morning, followed by an 80% chance of gales Thursday afternoon and night. At least SCA wind are expected much of the time through Sunday, and Sunday afternoon and night there is a 40% chance of gales returning. SCA level seas are expected through Friday night followed by a 40-50% chance of SCA seas on Sunday and Monday. For the inner waters N of Pt. Sal, SCA level winds are likely to continue through tonight, followed by a 80% chance of returning during the afternoon/evening Thursday and Friday (25% chance of brief gales during these times), and a 40% of SCA winds Saturday afternoon/evening. SCA winds are then likely (70% chance) Sunday and Monday. Current SCA level seas will subside Thursday night, followed by a 20% chance of returning Sunday and Monday. For the Santa Barbara Channel, SCA level winds will affect the western portions of the the channel this afternoon and evening, with a 20% chance of reaching the central/eastern portions. Thursday onward, SCA level winds are generally expected to only impact the extreme western portions of the channel, until Saturday afternoon. Saturday afternoon through Sunday night there is a 40-50% chance of widespread NW SCA winds for the entire channel, with the potential (20% chance) for gales on Sunday. For the southern inner waters, there is a 20% chance of SCA level W to NW winds near Anacapa Island this evening. Otherwise conditions are expected to remain below SCA levels until Saturday afternoon. Saturday afternoon through Sunday there is a 40-50% chance of widespread NW SCA winds for all the inner waters, with the potential (20% chance) for gales on Sunday. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory in effect until 5 AM PDT Thursday for zones 378-381. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Friday for zone 645. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Friday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...Cohen AVIATION...Schoenfeld MARINE...Schoenfeld/Lund SYNOPSIS...Cohen weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox