Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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513 FXUS66 KLOX 281158 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 458 AM PDT Fri Jun 28 2024 Updated Aviation section .SYNOPSIS...27/1153 PM. Slight cooling is expected into Friday as high pressure aloft weakens. Gusty northwest winds will affect southwestern Santa Barbara County and the Interstate 5 Corridor tonight. Warmer weather is expected over the weekend as high pressure returns, and above normal temperatures will continue through next week. && .SHORT TERM (TDY-SUN)...28/401 AM. An onshore flow pattern remains in place across the area early this morning. Slight cooling will continue into today as the tail end of upper-level trough of low pressure moving through the northern Intermountain Region will brush the area and slightly increase onshore flow. Night through morning low clouds and fog, which have struggled to form over the last several nights and mornings, are becoming more entrenched along the Central Coast of California this morning, while an eddy circulation near Santa Catalina Island still struggles to form stratus clouds around it. The increase in northwest flow over the offshore coastal waters and parallel to the southern California coastline should permit the eddy circulation to become a little more vigorous. With the shallow marine layer depth along the Central Coast, there is a high-to-likely (40-60 percent) chance of dense fog developing along the Central Coast this morning. A dense fog advisory might be needed for the Central Coast later this morning. 500 mb heights start to climb across the region over the weekend as an upper-level ridge of high pressure over north Texas this morning strengthens and expands westward. A warming trend is forecast for Saturday and Sunday across the region, most pronounced away from the coast. Onshore flow will weaken some, but still remain intact into early next week. A persistent marine layer depth will keep at least patchy low cloud coverage for some coastal areas, but the marine layer depth will be forced to thin some. A warming trend is well reflected in the forecast, but with 950 mb temperatures to reaching around 35 degrees Celsius across the warmest areas, dangerously hot conditions are not forecast at this time. Temperatures will warm to about 5 to 10 degrees above normal for this time of year, though. Closer to the coast, temperatures will remain around normal for this time of year with a continued marine influence continuing and keeping the sea breeze cooling the land mass during the afternoon hours. .LONG TERM (MON-THU)...28/406 AM. The strong upper-level ridge will pull away farther to the east for early next week and allow for a piece of an upper-level trough of low pressure over the Gulf of Alaska to brush the area and increase onshore flow. A little better onshore push should occur into the valleys and foothill area and bring some cooling for Monday. Low cloud coverage should increase some and possibly extend a little farther inland as the marine layer depth deepens some. By late week, the story for the weather pattern will change as a strong high pressure system over the Central Pacific Ocean this morning will build into the West Coast. A hot air mass will develop over the region as 500 mb heights potentially reach 600 decameters over the northern California where the ridge center could end up being anchored. Looking at the latest ensemble forecast members, there is a moderate-to-high chance of widespread dangerously hot weather developing across the region for the latter half of next week. EPS ensemble means suggest high temperatures means climbing through next Saturday. NBM values remain in the forecast for high temperatures for late next week, but as the ridge builds east into Nevada, a southeast flow aloft could develop and open the door for monsoonal moisture to sneak in. This could create some more cloudiness and keeps overnight low temperatures warmer than normal across the region. Minimum temperatures break away from NBM values toward the latter part of the forecast period away from the coast. In addition, the marine layer induced low cloud pattern could become very patchy in nature or even non-existent as the middle level clouds and warmer temperatures will mess with low cloud formation. The increase in subtropical moisture could also develop more typical afternoon and evening showers and thunderstorms with a monsoonal flow pattern. EPS ensemble members suggest precipitable water means climbing close to 1.00 at KLAX. A very slight (10 percent) chance of showers and thunderstorms has been added to the forecast for the mountains and desert on Thursday and Friday, breaking away from WPC and NBM values for late week. && .AVIATION...28/1157Z. At 11Z at KLAX, the marine layer was 1000 feet deep. The top of the inversion was at 6000 feet with a temperature of 22 C. High confidence in CAVU TAFs for desert sites and KPRB/KVNY/KBUR, with southwest wind gusts to 20-30 kt this afternoon and evening at KPMD/KWJF. Moderate confidence in coastal/coastal-valley TAFs, with MVFR-IFR cigs/vsbys this morning, clearing out by this afternoon, and returning late tonight north of Point Conception and in LA County. Onset and dissipation timing of cigs/vsbys may vary by around +/- 2 hours from current forecasts. For KOXR/KCMA, there is a 30% chance for cig/vsby restrictions to develop this morning and again late tonight. KLAX...Moderate confidence in TAF. Aside from onset/dissipation timing uncertainty, 30% chance for cigs to become IFR and vsbys to become MVFR this morning and again late tonight into Sat morning. No significant east wind component is anticipated. KBUR...High confidence in CAVU TAF. && .MARINE...28/155 AM. There is a moderate threat of dense fog late tonight into Friday for the waters along the Central Coast. Moderate confidence in the forecast for Gale conditions ending by 3 AM this morning across the outer waters from the Central Coast to San Miguel Island. Moderate to high confidence in Small Craft Advisory (SCA) winds through late this morning. Winds below SCA levels are then expected through Saturday morning across the waters. Winds will then increase to SCA strength from the northwest across the outer waters Saturday night through Monday night. There is a 40-50 percent chance of High-end SCA winds of 20 to 30 knots across the outer waters, and a 40 percent chance of Gales for the waters from the Central Coast to San Miguel Island. SCA winds are likely to spread into the nearshore waters off the Central Coast, and into the Santa Barbara Channel Sunday afternoon into Sunday night. Steep, shorter period seas will affect the outer waters and portions of the nearshore waters through Monday. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 11 AM PDT this morning for zones 670-673. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Saturday for zone 676. (See LAXMWWLOX). && $$ PUBLIC...Hall AVIATION...Cohen MARINE...Smith SYNOPSIS...jld/Smith weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox