15/1247 PM.
A moderate to strong Santa Ana Wind will bring widespread strong winds and critical fire weather conditions to much of Southwest California through Saturday. Additionally, very warm temperatures bring a high risk of heat illness to all coastal areas. A significant cool down is expected Sunday with a chance of widespread rain by Tuesday or Wednesday.
(tdy-Mon), 16/112 PM.
Overall, 12Z models in good synoptic agreement through the period. At upper levels, low to the southwest will undercut the ridge this weekend. At the surface, offshore gradients will gradually weaken with weak onshore gradients returning Sunday and Monday.
Forecast-wise for the short term, main issues remain Santa Ana winds and the heat. As mentioned, offshore gradients will continue through Sunday morning, but will exhibit a weakening trend. At the same time, the upper level support will also weaken. So, will expect the offshore winds to decrease. So, with the afternoon forecast, have extended the current WIND ADVISORIES through 200 PM Saturday. For the LA county mountains, will let the HIGH WIND WARNINGS continue through 800 PM this evening and have issued WIND ADVISORIES from 800 PM this evening through 200 PM Saturday. By Saturday night and Sunday morning, the offshore winds should diminish below advisory levels with a return of weak onshore winds Sunday afternoon through Monday.
The second concern is the heat. With the continued offshore flow, very warm conditions will persist through Saturday. Based on current Heat Risk forecasts, the coastal plain will continue at HEAT ADVISORY levels through Saturday evening. So, will continue with the HEAT ADVISORIES through 800 PM Saturday. For Sunday and Monday, a welcome cooling trend is expected with the return of onshore flow and lowering thicknesses.
(Tue-Fri), 16/112 PM.
For the extended period, models are in decent synoptic agreement through the period. Main feature of note will be an upper low, dropping south off the CA coast on Tuesday then moving inland across the area on Wednesday and Thursday. Models differ slightly in the speed of this low moving across the area, but those differences should be minimal.
So, forecast-wise, main concern in the extended period will be rain chances, associated with the upper low. Looking at the ensembles, most every member from every model indicates some amount of rain between Tuesday night and Thursday morning. However, the range of potential amounts remains quite large. At this time, ensemble means indicate totals between 0.25 and 1.00 inches which is a reasonable early estimate. There is about a 20-30% chance of totals greater than 1.00 inch. Will continue to monitor this situation closely as potential amounts are likely to change from day-to-day.
Other than the rain chances, no significant issues are expected. Temperatures will experience a noticeable cooling trend with high temperatures only topping out in the 60s to lower 70s. At this time, no significant wind issues are expected.
16/1644z.
At 16Z over KLAX, there was no marine layer or inversion.
High confidence in VFR conditions, unless a fire breaks out upwind of an airport. NE-E winds will dominate the next 24 hours, with UDDF near any mountains and LLWS 10-20 knots near most airports, especially those with winds above 20 knots. Moderate confidence on wind forecasts (speed +/- 5 mph and direction +/- 30 degrees).
KLAX, High confidence in VFR conditions through at least Saturday. High confidence in east winds dominating today with little to no west influence. Moderate confidence in speed and timing. 60% chance of east winds in the 8-12 knot range from 18 to 24Z. LLWS 5-15 knots also possible in the 16Z-02Z window. East winds will go below 08 knots by 03Z. There is a 20% chance of east winds around 8 knots returning Saturday 16-20Z.
KBUR, High confidence in VFR conditions through at least Saturday. High confidence in east winds dominating today with little to no south influence. LLWS 15-25 knots also possible at times in the 16Z-06Z window.
16/104 PM.
NE to E winds will bring short period and hazard seas to many nearshore waters into Saturday. Winds will be strongest from Ventura to Santa Monica where winds where pockets of 20 to 30 knot winds will form at times. This is a touch lower than earlier today, so the previous Gale Warning has been replaced with a Small Craft Advisory. Gusts of 10 to 20 knots will likely also affect the nearshore Central Coast waters as well as the waters from Orange County to Catalina Island. These winds will likely have rapid fluctuations. Benign conditions expected on Sunday. If you have the option, go out on Sunday and try to stay off the waters Friday and Saturday. Small Craft Advisory NW winds will increase Sunday Night and Monday, especially off the Central Coast. A moderate- strength storm system is becoming more likely in the Tuesday through Thursday timeframe.
Ca, Wind Advisory in effect until 2 PM PDT Saturday for zones 88-354-355-358-362-370>374-376-377. (See LAXNPWLOX). Heat Advisory in effect until 8 PM PDT Saturday for zones 340-341-346-347-349-350-354-355-362-366>368. (See LAXNPWLOX). High Wind Warning in effect until 8 PM PDT this evening for zones 369-375-378>380. (See LAXNPWLOX). Wind Advisory in effect from 8 PM this evening to 2 PM PDT Saturday for zones 369-375-378>380. (See LAXNPWLOX). Red Flag Warning in effect until 8 PM PDT Saturday for zones 288-354>358-362-369>382-548. (See LAXRFWLOX). Red Flag Warning in effect until 6 PM PDT this evening for zones 342-345-353. (See LAXRFWLOX). PZ, Small Craft Advisory in effect until 2 PM PDT Saturday for zones 650-655. (See LAXMWWLOX). Small Craft Advisory in effect from 9 PM this evening to 2 PM PDT Saturday for zone 676. (See LAXMWWLOX).
