06/113 AM.
Mostly clear skies, dry conditions, and a general warming trend with periods of offshore winds are likely through the weekend. The warmest and windiest conditions are likely today through Sunday.
(tdy-Sun), 06/149 AM.
Not too much change in the short term forecast compared to previous issuances. An upper level ridge will continue to build over the area today and remain in place through the weekend. At the surface, offshore flow will be increasing through the period.
Forecast-wise for the short term, main issues continue to be the offshore winds and temperatures. For winds, models continue to show the LAX-DAG surface pressure gradient peaking on Saturday between -3.0 to -4.0 mb. As for upper level support, the RRFS and other high resolution models show 850/925mb winds in the 30-40 kt range by Saturday, but weakening by Sunday. The combination of the offshore gradients and upper level support lead to a possibility of some low-end advisory level Santa Ana winds through the period, peaking tonight into Saturday. Based on ensembles, there is a 20-30% chance of advisory-level Santa Ana winds today, with a 50-70% chance on Saturday. Less confidence in Sunday, as both the upper level support and the offshore gradients weaken. Future shifts may be issuing Wind Advisories for the Santa Ana wind corridor across eastern Ventura and western LA counties as NE wind gusts approach 45-55 mph across the mountains, and 30-45 mph elsewhere.
Second concern through the short term period will be temperatures. The combination of the upper level ridge and offshore surface flow will allow for a nice warmup across all areas through the weekend. By Saturday and Sunday, most areas will be 80 to 90 degrees (about 5-10 degrees above normal), with the warmest temperatures near the coasts. As a result, there will be widespread moderate heat risk for the coastal plain and coastal valleys. Fortunately, overnight low temperatures do not look to be too warm so the chances for the need of any heat products look minimal (in the 20-30% range). Given the gusty offshore winds, warming temperatures and dry conditions, there will be elevated to locally critical fire weather conditions across the area today and Saturday. Recent rainfall has helped mitigate the fire threat a bit, but live fuel moistures are still in the 65-80% range which means the area is not "out of the woods" with respect to the fire threat. Red Flag Warnings are in effect for "targeted" LA/Ventura County mountains tonight into Saturday.
(Mon-Thu), 05/1103 PM.
Expecting mostly benign conditions Monday through Thursday. A ridge of high pressure is forecast to build over southern California through Wednesday, before a strong cold front approaches on Thursday. This supports temperatures trending 5 to 10 degrees above normal each day through Wednesday, and some cooling near the coasts Thursday as onshore flow returns. There is some potential for low clouds and fog along the Central Coast Tuesday morning, and additional clouds Thursday as the system nears but otherwise sunny skies are expected with pressure gradients hovering around 0 to weakly offshore. Current ensembles seem on board with rain sometime from Friday into early the following week, but struggle to agree on amounts and exact timing. Hopefully guidance starts to converge on a solution over the next few days.
06/1233z.
At 0824Z at KLAX, there was a sfc-based inversion with a top at 900 ft and temperature of 22 degrees Celsius.
High confidence in all TAFs.
KLAX, High confidence in TAF. No significant easterly wind component is expected.
KBUR, High confidence in TAF.
06/101 AM.
For the Outer Waters, moderate to high confidence in current forecast. Through Saturday, high confidence in a combination of Small Craft Advisory (SCA) level winds and seas prevailing across all of the Outer Waters. For Sunday through Tuesday, there is a 50-70% chance of the combination of SCA level winds and seas continuing.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Through Saturday, moderate confidence in winds and seas remaining below SCA levels, with a 30% chance for SCA level seas today through Saturday. For Sunday and Monday, there is a 50% chance of SCA level seas, but high confidence in winds remaining below SCA levels. For Tuesday, high confidence in winds and seas remaining below SCA levels.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. There is a 40% chance of SCA level northeast winds this morning from Point Mugu to Santa Monica, with chances increasing to 60-70% late tonight through Saturday morning. Otherwise, high confidence in winds and seas remaining below SCA levels through Tuesday.
06/1258 AM.
High tides will build each morning and peak Sunday and Monday at 7.2 to 7.6 feet (MLLW). Meanwhile, a west to northwest swell will slowly build into the area, peaking across the Central Coast today and Monday, and peaking everywhere else around Monday. This combination of high tides and high surf will bring hazardous swimming conditions, dangerous conditions on rock jetties, and a risk for moderate coastal flooding. If you are in the coastal areas, listen to advice from your local officials.
With the daily high tides changing only a little through Tuesday, the risk for coastal flooding will peak when the surf peaks (today and Monday for the Central Coast, and Monday for the rest of the coastal areas). This coastal flooding event will differ in several ways from the past episodes this year. First, while tides will be high, they will not be nearly as high as the record breaking tides from last week. This means that the impacts to harbor areas and Naples Island will generally be minor compared to last week. Shallow flooding should be expected, especially for low-lying walkways, but of a lesser degree less in severity and coverage. Second, for the beach-side coastal areas, the swell is from the west to northwest and not from the south, which characterized the coastal flooding episodes of September and early October. This means that areas hit hard in those events, like Long Beach and Malibu, are less at risk with this upcoming event. For west-facing shores however, the risk is much higher than events in the recent past. Areas like Oceano and Cayucos on the Central Coast, and Ventura on the southern coasts, have elevated risks of moderate coastal flooding. Moderate coastal flooding impacts include things like flooded sandy beach areas, moderate beach erosion, as well as shallow flooding of beach parking lots and bike paths. Isolated damage is unlikely but cannot be ruled out especially considering the extent of beach erosion we have already seen - which limits the natural protective buffer between the ocean and coastal infrastructure.
For the Central Coast, a High Surf Advisory and Coastal Flood Advisory will be in effect through Monday, since there will be an earlier peak to the surf. For all other coasts, a Beach Hazards Statement will be in effect through Tuesday, with a key note that some areas (especially Ventura County) may need to be upgraded around Monday when the surf peaks.
Ca, Beach Hazards Statement in effect through Tuesday morning for zones 87-349-350-354-362-366. (See LAXCFWLOX). Coastal Flood Advisory in effect until 10 PM PST Monday for zones 340-346. (See LAXCFWLOX). High Surf Advisory in effect until 10 PM PST Monday for zones 340-346. (See LAXCFWLOX). Red Flag Warning in effect from 2 AM to 6 PM PST Saturday for zones 288-369-370-375-379. (See LAXRFWLOX). PZ, Small Craft Advisory in effect until 3 PM PST Saturday for zones 670-673-676. (See LAXMWWLOX).
