Swell Matrix

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard Ca

511 am PDT Sat Sep 22 2018

Synopsis

22/406 AM.

Daytime temperatures will be a bit above normal today. An upper low tracking to the north of the region will bring some cooling Sunday, with little change on Monday. High pressure will cause some warming beginning Tuesday or Wednesday, with slightly above normal temperatures for much of the rest of the week.

Short Term

(tdy-Mon), 22/406 AM.

Low clouds were widespread in all coastal areas and have pushed into the Salinas and portions of the Santa Ynez, San Gabriel and VTU County valleys. Clouds have begun to retreat westward across the San Gabriel Valley, and if this trend continues, skies may actually clear there by morning.

Profiler data was showing a marine layer of just over 1000 feet deep, and shows 3-5 degrees of warming from 1200 feet and above during the past 24 hours. Pressure gradients, though still onshore have weakened some during the past 24 hours.

Expect any clouds in the valleys to clear by mid morning, with clouds across the coastal plain likely clearing during the late morning hours. The wrf indicates some warming at 950 mb, and this matches well with what is being seen on profiler data. This should allow for a few to several degrees of cooling today, especially away from the immediate coast, with temps generally a bit above normal in most areas.

North-south gradients across SBA County may be just strong enough for some locally gusty winds thru and below passes and canyons of the Santa Ynez range this evening, but no major winds are expected.

An upper trough will swing across the Pac NW late tonight/Sun, causing heights/thicknesses to lower some. The marine layer may become a bit deeper, with widespread night through morning low clouds in coastal areas and in the lower valleys. Onshore flow will increase a bit on Sun. This should bring a few degrees of cooling to most of the region Sun, although weak low level northeast flow could mitigate any cooling on the Central Coast.

Heights will change little across the forecast areas Sun night and Mon. Expect little change in the weather across the region, with night through morning low clouds in coastal and lower valley locations, and similar max temps to those on Sunday in most areas.

Long Term

(Tue-Fri), 22/405 AM.

Generally quiet weather across the region next week. Weak ridging and some height rises may bring some warming beginning on Tue across inland sections, and Wed elsewhere, but temps should rise only a few degrees, ending up slightly above normal in most areas for Wed and Thu. Night through morning low clouds should remain confined mostly to the coastal plain. Some cooling may begin Fri as an upper low begins to drop southward from western Canada into the Pac NW.

Aviation

22/1209z.

At 11z at KLAX, the inversion was around 1000 feet. The top of the inversion was around 2900 feet with a temperature of about 26 degrees Celsius.

Overall, Moderate to high confidence in the current TAFs. The departure times of the marine inversion along the coast and in KPRB may vary +/- two hours. There is a sixty five percent chance of IFR/MVFR conditions getting into KLGB and ten percent of it getting into KVNY and/or KBUR. The return of the inversion will have similar timing, locations, and conditions tonight. Otherwise and elsewhere VFR conditions will prevail.

KLAX, Moderate confidence in the current TAF. The departure time of the marine inversion may vary +/- two hours. The return of the inversion will have similar timing and conditions tonight. Otherwise VFR conditions will prevail. There will be no east winds 8 kts or greater during the forecast period.

KBUR, Moderate to high confidence in the current TAF. There is a ten percent chance of IFR/MVFR conditions through 16z. Otherwise VFR conditions will prevail.

Marine

22/321 AM.

For the Outer Waters, There is a forty percent chance of Small Craft Advisory (SCA) level wind gusts across the northern and central outer water zones on Sunday. Otherwise conditions will remain below SCA levels through midweek.

For the Inner Waters, Conditions will remain below SCA levels through midweek.

Watches, Warnings, Advisories

Ca, NONE. PZ, NONE.

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