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Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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392 FXUS66 KLOX 131746 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 1046 AM PDT Tue Aug 13 2024 .SYNOPSIS...13/1226 AM. Temperatures will remain near normal this weekend with little day-to-day changes. Night- to- morning low clouds and fog will push into coastal areas at times. && .SHORT TERM (TDY-THU)...13/947 AM. ***UPDATE*** Dense fog that occurred this morning along the Central Coast and Santa Ynez Valley is retreating as the morning sunshine intensifies. Low clouds and fog are currently only present at the Central Coast and Ventura County beaches, and is expected to clear by around noon today. The temperature forecast for today has been adjusted upwards slightly for some locations, including San Luis Obispo and Santa Barbara, to align with 24-hr temperature trends. However temperatures are generally still expected to be a couple degrees cooler than yesterday as a result of a decrease in 500 mb heights and decreasing onshore flow. Sundowner winds are likely to be advisory level across the Santa Barbara Southwest Coast tomorrow night and again Thursday night. Gusts are expected to be 30 to 45 mph, and temperatures across the whole Santa Barbara South Coast (including Santa Barbara City) will be several degrees warmer than normal. ***From Previous Discussion*** Low clouds were widespread on the Central Coast and in the Santa Ynez Valley this morning, as they have been during the past few mornings. The difference was S of Pt. Conception, where there was a more expansive area of low clouds off the coast, some of which had already surged into southern L.A. County. W-E pressure gradients were about the same as they were on Mon morning. N-S offshore gradients have increased slightly across SBA County, and have gone from onshore to neutral across L.A. County. However, there were no wind issues early this morning. This afternoon, there will be some gusty winds in the Antelope Valley and thru the Highway 14 Corridor, but winds should remain below advisory levels. N-S gradients will increase across SBA County later today and tonight, with gusty winds likely across the southwest coast of SBA County and the Western Santa Ynez Range. Even there, winds should stay just below advisory levels. Slight height falls with a weak trough pushing in the West Coast and some cooling at 950 mb should lead to a couple of degrees of cooling in most areas today. The exception may be across southern SBA County foothills, where north winds may bring some warming if they surface by evening. The weak upper trough will move east of the region later today and tonight, and an upper level high will begin to build into the forecast area from the southwest. Moderate onshore pressure gradients from W to E will keep gusty winds Wed afternoon and evening across the Antelope Valley and the Highway 14 Corridor Wed, but again, likely below advisory levels. N-S gradients across SBA County will increase, likely enough for some wind advisory level winds across the southwestern coast and the western Santa Ynez Range late Wed afternoon into Wed night. Gusty winds are also likely in the I-5 Corridor Wed night. Expect the low cloud pattern tonight/Wed morning to be similar to that of this morning, confined to the coastal plain, except it should remain clear across the south coast of SBA County. Height rises and some warming at 950 mb should lead to some warming in most areas Wed, but do not expect max temps to be much (if at all) above normal in most areas. The upper high will strengthen a bit Thu, and heights will rise slightly. There may be some reduction in low cloud coverage Wed night/Thu morning as the marine layer thins. Expect another round of gusty W winds in the Antelope Valley and Highway 14 Corridor Thu afternoon and evening, with advisory level NW to N winds possible across southern SBA County late Thu/Thu night. Max temps should be up slightly on Thu, with highs peaking near 100 degrees in the Antelope Valley and the hottest valley locations west of the mountains. .LONG TERM (FRI-MON)...13/500 AM. The upper high will shift just to the east of the forecast area Fri as a broad trough moves into the eastern Pacific. The upper high will strengthen and move to a location just to the southeast of the Four Corners area Sat, then it will move little thru Mon. Meanwhile, a trough will linger just to the west of CA Sat thru Mon. The position of the forecast area between these two upper features will make for a rather uneventful weather pattern Fri thru Mon. Southwesterly flow aloft is expect most of this period, which should keep any monsoonal moisture and any chance of showers/tstorms to the east of the region. Heights will fluctuate slightly thru the period. In a very general sense, based on heights and pressure gradients, expect some cooling Fri and Sat, with small warming Sun and Mon. Night/morning low clouds and fog will be confined to the coastal plain and possibly the lower valleys. Do not expect wind issued Fri and Sat, except for some gusty afternoon/eve winds in the Antelope Valley. N-S gradients will become increasingly offshore across SBA County Sun and Mon, so expect some gusty NW winds across southwestern SBA County during the late afternoon thru evening hours on those days. && .AVIATION...13/1746Z. At 1702Z at KLAX, the marine layer was 1300 ft deep. The top of the inversion was at about 4800 ft with a temperature of 23 C. High confidence in CAVU TAFs for KPRB, KBUR, KVNY, KPMD, and KWJF. Moderate confidence in LA coastal TAFs. Timing of cat changes may be off by +/- 2 hours from current fcst. There is a 20-30% chance of IFR conditions after cigs arrive. VFR conditions expected at these sites by 17Z. Low to moderate confidence in remaining coastal TAFs. Timing of cat changes may be off by +/- 4 hours. Minimum flight cats may be off by one cat at any point after cigs arrive. There is a chance that KSBA (30%), KOXR (20%), and KCMA (40%) site will remain VFR through the period. KLAX...Moderate confidence in TAF. Timing of cat changes may be off by +/- 2 hours from current fcst. There is a 30% chance of cigs lower than 005 at any point between 08Z and 13Z. 20% chance of VFR conditions before 17Z. No significant east wind component expected. KBUR...High confidence in CAVU TAF. && .MARINE...13/908 AM. For the outer waters, moderate to high confidence in current forecast. Small Craft Advisory (SCA) level winds and seas expected through at least Sunday night. There is a 20-30% chance of low end gale force wind gusts in the afternoon thru late night hours Wednesday thru Friday, and a 10% chance Saturday and Sunday. For the inner waters north of Point Sal, moderate confidence in current forecast. SCA level winds and seas are likely (60-70% chance) in the afternoon through evening hours through tomorrow night. There is a 50-60% chance of SCA level winds and seas in the afternoon thru evening hours Thursday and Friday, and a 30-40% chance Saturday and Sunday Sunday. For the inner waters south of Point Conception, moderate confidence in current forecast. There is a 30-50% chance of SCA level wind gusts for the western Santa Barbara Channel during the afternoon into late evening hours through Thursday, and a 20-30% chance of SCA level winds Saturday and Sunday in the afternoon to evening hours. Otherwise, conds will remain below SCA levels over the southern inner waters through Sunday night. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for zones 645-670-673-676. (See LAXMWWLOX). && $$ PUBLIC...DB/Schoenfeld AVIATION...Lewis MARINE...Lewis/Lund SYNOPSIS...Munroe/KL weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox