217 FXUS66 KLOX 120938 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 238 AM PDT Sat Oct 12 2019 .SYNOPSIS...12/237 AM. Persisting dry, breezy conditions will keep the high fire danger over much of Ventura and Los Angeles Counties through today. Afternoon temperatures will remain above normal today, but should begin cooling off Sunday. Despite the warm daytime temperatures, the Antelope Valley will see low temperatures in the mid 20s to mid 30s early this morning. && .SHORT TERM (TDY-MON)...12/150 AM. Skies were clear in all areas early this morning thanks to a continuation of the dry offshore flow. LAX-DAG gradients were -2.9 mb at 08Z which was up 4 mb in the last 24 hours. Weakening gradients and diminished upper level support have lead to much weaker winds, with some gusts around 30 mph lingering in the mtns and foothills of VTU/L.A. Counties. Otherwise winds in the favored areas were in the 10 to 20 mph range for the most part which will continue into this morning. In addition, light winds and the very dry air mass will allow temps in the Antelope Valley to fall into the mid to upper 20s toward daybreak, especially in the northern parts of the Valley. As a result, the Freeze Warning remains in effect for this area until 8 AM PDT. Please see the latest Non- precipitation Weather Message (LAXNPWLOX) for further details. Generally weak upper level troffiness will persist over swrn CA thru tonight, then a sharper upper level trof will approach on Sun before pushing thru the area Sun night and early Mon. H5 heights will lower to about 569-571 DM with the upper level trof, then recover slightly to 576-577 DM Mon afternoon. The upper level trofs will increase onshore flow thru the weekend, with a slight weakening of the onshore flow expected on Mon. Sunny skies will cover the forecast area today. The marine inversion is expected to gradually become re-established late tonight into Mon morning with low clouds and fog expected to affect the L.A. County coast and Santa Catalina Island. Increased onshore flow and the development of an eddy over the SoCal Bight will help to deepen the marine inversion Sun night. As a result, much more coverage of marine layer clouds and fog can be expected from the coast to the valleys Sun night and Mon morning. Otherwise, mostly clear skies will prevail across the forecast area tonight thru Mon. Temps are forecast to be about 4 to 8 deg above normal for the coast, vlys and mtns today, and a couple of degrees below normal for the Antelope Vly. A cooling trend back to near normal to several degrees below normal will then take place Sun thru Mon. Highs in the warmest vlys and inland coastal areas should reach the mid to upper 80s today, then cool to the mid 70s to around 80 on Sun, and to the 70s on Mon. .LONG TERM (TUE-FRI)...12/153 AM. Some upper level troffiness is expected to linger into Tue over the region, then flat upper ridging with H5 heights around 581-583 DM should move in for Wed. An upper level trof should move thru srn CA on Thu followed by flat upper level ridging for Fri, with a dry westerly flow aloft. Low clouds and fog should affect most coastal areas Mon night into Tue morning, then just a few coastal areas night and morning hours Tue night into Thu morning. Increased onshore flow should bring a deeper marine inversion and more widespread low clouds along the coast into some adjacent vlys Thu night into Fri morning. Otherwise, mostly clear skies will continue across southwestern CA Tue thru Fri. Weak offshore gradient trends Tue morning and Wed morning will help daytime temps to increase to near normal to several degrees above normal thru Wed, followed by increasing onshore gradient trends and cooler temps Thu and Fri. Highs in the warmest vlys and inland coastal areas should reach the upper 70s to mid 80s Tue, 80s on Wed, upper 70s to lower 80s Thu, and mid 70s to around 80 on Fri. && .AVIATION...12/0540Z. At 0530Z...there was a surface-based inversion at KLAX. The top of the inversion was at 1100 ft with a temperature of 25 deg C. High confidence in VFR at all airfields through the period, except for MVFR FU at times near any fires, especially KBUR and KVNY. KLAX...High confidence in VFR through Sat evening, then there is a 50%-60% chance of IFR cigs developing by 10Z late Sat night. KBUR...High confidence in VFR through Sat evening. Periodic MVFR vsby due to smoke will be possible through the period. && .MARINE...11/808 PM. Northeast wind gusts will diminish and shift to the east and southeast overnight. The area nearshore between Ventura Harbor and Malibu could see local gusts to 20 knots, otherwise easterly winds should stay below 15 knots. After Saturday morning, high confidence in winds and seas staying below SCA everywhere through Sunday. NW winds with gusts around 20 kt possible Monday and Tuesday for the waters off the Central Coast with SCA winds possible Wednesday across the outer waters and portions of the waters nearshore. && .FIRE WEATHER...12/157 AM. Through this morning, northeast winds are expected to gust between 15 and 25 mph with local gusts to 30 mph across the wind prone mountains and valleys of Los Angeles and Ventura counties, then switch to onshore and remain breezy this afternoon. With the continuation of widespread single digit humidities, warm temperatures, and breezy conditions, the Red Flag Warning remains in effect for the Los Angeles and Ventura county mountains, Santa Clarita Valley, Ventura county valleys, and San Fernando Valley through 6 PM this evening. Warm temperatures are on track for today, with highs in the 80s to near 90 degrees across many coastal and valley areas. Much of San Luis Obispo and Santa Barbara counties will continue to see elevated to brief critical fire weather conditions due to locally breezy offshore conditions and widespread single digit humidities. Rapid fire spread and extreme fire behavior are still possible with any existing fires and new ignitions. This is a dangerous situation, with critical fire weather and fuel conditions. If a new fire were to start, the environment will still be favorable for very rapid fire spread, long range spotting, and extreme behavior. The public should be urged to use extreme caution with any potential fire ignition sources. Past fires have begun from things like discarded cigarettes, metallic hedge trimmers, welding activities, and campfires. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Freeze Warning in effect until 8 AM PDT this morning for zone 59. (See LAXNPWLOX). Red Flag Warning in effect until 6 PM PDT this evening for zones 244>246-253-254-288-547. (See LAXRFWLOX). PZ...NONE. && .HAZARD POTENTIAL OUTLOOK (MON-FRI). No significant hazards expected. && $$ PUBLIC...Sirard AVIATION...Sirard MARINE...Smith FIRE...Gomberg/Sirard SYNOPSIS...Phillips/Sirard weather.gov/losangeles