Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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595 FXUS66 KLOX 101638 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 938 AM PDT Mon Jun 10 2024 .SYNOPSIS...10/925 AM. Temperatures will warm through Tuesday with better clearing each day. After a brief cooling trend Wednesday and Thursday with possible morning drizzle, widespread warmer temperatures are expected Friday through next weekend with gusty northerly to northwesterly winds. && .SHORT TERM (TDY-WED)...10/938 AM. ***UPDATE*** A weak upper low about 300 miles southwest of KLAX continues to spin away from the area, leading to rising heights and a warming air mass. Onshore gradients have also decreased by 2-4 mb today so the expectation is still for faster clearing today and warmer temperatures, though some beaches may still remain cloudy and cool well into the afternoon. Forecast soundings are indicating significant lowering of the marine layer Tuesday, which makes sense given the upper pattern and gradient trends. Daytime highs expected to rise a few more degrees, especially inland, with highs in the lower 100s in the Antelope Valley and around 90 in the warmer coastal valleys. Expecting the marine layer depth to drop to around 1500 feet in the LA Basin and under 1000 feet along the Central Coast. Still likely some morning low clouds into the valleys tomorrow but clearing off much faster. ***From Previous Discussion*** With lower onshore flow through Tuesday, southwesterly winds are expected to lighten up somewhat over the Antelope Valley and foothills. Wednesday, as gradients are expected to increases, gusty winds are likely to return. .LONG TERM (THU-SUN)...10/331 AM. Thursday into Friday the low will track eastward across the area, with the center expected to remain south of Los Angeles County. This system lacks significant moisture and the highest amount of vorticity will occur overnight, so afternoon showers/thunderstorms over the mountains are unlikely. However, some low impact cumulus clouds may develop Thursday afternoon over high terrain. There is a good chance of drizzle Thursday morning when lowering heights are likely to lift the marine layer. There will continue to be a chance for drizzle Friday and Saturday when heights rise again, compressing the marine layer. Temperatures will keep trending downward for Thursday, because onshore pressure gradients are expected to continue to increase while upper level heights lower. Low clouds and fog will extend far inland overnight and be slow to clear with strong onshore flow. There is however a chance that the cold air aloft will disturb the capping inversion above the marine layer, causing low clouds to scatter out across the region. Friday through the weekend will see a significant change in the overall pattern. Dry NW flow will move into the area and hgts will rise to 587 dam. Temperatures will trend upward through Saturday with little change on Sunday. A strong NW to SE pressure gradient will develop across the eastern Pacific and wind will increase greatly. The winds appear strongest over the coastal waters and the Santa Barbara South Coast, with a significant chance of Sundowners Winds (and Gale Force winds for the waters). Northerly pressure gradients will shift offshore Friday night (peaking around 3 to 4 mbs), which will drive the north to northwesterly winds at the surface. In conjunction, easterly onshore gradients will weaken at this time. This trend will drive up daytime highs by minimizing the influence of marine layer clouds/seabreezes and increasing warm downslope winds (especially for the Santa Barbara South Coast). For the weekend, expect in the 90s across the interior and warmer valleys, 80s for the coastal valleys, and mid to upper 70s at the coasts. && .AVIATION...10/1145Z. At 1105Z at KLAX, the marine layer was 2000 ft deep. The top of the inversion was at 4900 ft with a temperature of 19 degrees C. High confidence in KPMD and KWJF. Good confidence in KPRB, KSMX AND KSBP where there is a 20 percent chc of VFR conds arriving an hour early or an hour late. Low confidence in KVNY TAF with a near 50 percent chc of IFR cigs 13Z-17Z. Moderate confidence in KSBA TAF with 30 percent chc of IFR cigs 13Z-19Z. Moderate confidence in all other sites with VFR transition occur +/- 1 hour of fcst time. Lower confidence again this evening with regard to stratus arrival. KLAX...Moderate confidence in TAF. There is a 30 percent chc of clearing by 19Z. There is a 30 percent chc that onset of low clouds Monday evening will be as late as 08Z. No significant easterly wind component is expected. KBUR...Moderate confidence in TAF. There is a 30 percent chc of clearing by 17Z. Lower confidence in arrival of low clouds tonight with near equal chances between 07Z and 11Z. && .MARINE...10/735 AM. For the Outer Waters, high confidence in current forecast. Today through Thursday, high confidence in winds and seas remaining below Small Craft Advisory (SCA) levels. On Friday, there is a 50-70% chance of both SCA level winds and seas. For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Thursday, high confidence in winds and seas remaining below SCA levels. On Friday, there is a 40-50% chance of SCA level winds in the afternoon and evening hours. For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Today through Thursday, high confidence in winds and seas remaining below SCA levels. On Friday, there is a 30-40% chance of SCA level winds across the western half of the Santa Barbara Channel. The chance of gale force winds is increasing for next weekend and will be monitored. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...MW/Schoenfeld/Rorke AVIATION...Rorke MARINE...RAT SYNOPSIS...MW/Hall/RS weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox