Swell Matrix

Area Forecast Discussion

Swell Matrix

Synopsis

Surface high pressure settling in over the Central Rockies will bring weak Santa Ana winds to portions of Southwest California Saturday. The dry and cool air mass will also support the first freeze of the season for cooler interior areas this weekend. A ridge of high pressure building into the region early next week will bring a warming trend with record heat possible by Thanksgiving.

Short Term

(tdy-Mon)

Over the next three days a weak 577 DM ridge moving into the area today will grow and expand to 585 DM by Monday afternoon. Strong cold surface pressure over Nevada will generate moderate offshore flow this morning. Offshore flow will continue through Monday but will weaken some each day.

It will be sunny today except in the Cuyama vly where the offshore flow is pushing some low clouds in from Kern county. Sunday will be sunny. Mondays partly cloudy sky forecast seem a little overdone as the ridge looks pretty strong and should shunt the clouds to the north of the area. All of the surrounding offices wanted to keep the clouds in the forecast so they remain, but would not be surprised if future shifts agree to mostly clear skies.

The offshore grads will mix with just a little upper and thermal support and bring low end advisory level NE Santa Ana winds gusts to mountains and most of the vlys of LA/VTA counties this morning and early afternoon. There will be some more NE gusts Sunday morning but they will be weaker and sub advisory.

Cool air will be pushed into the interior from the east. The clear skies and dry air will bring additional cooling to the already cool air and will bring near freezing conditions to Interior Vlys and deserts this morning. More cool air will spill in today and there is a chc of freezes in the SLO and Cuyama vlys and even hard freeze conds in the parts of the Antelope Vly. Please see the product LAXNPWLOX for more details on the frost/freeze advisories and watches.

Max temps will be the main story over the next 3 days esp over the coasts and vlys. Today will be 4 to 8 degrees warmer than ydy and then there will be an additional 1 to 3 degrees of warming both Sunday and Monday. The cool air intrusion will keep the interior from warming much today but the warmer trends will start there Sunday. By Monday max temps will be 8 to 12 degrees above normal.

Long Term

(Tue-Fri)

On Tuesday the ridge grows further and hgts reach 589 DM. Offshore flow continues from the north but the E-W grads will be neutral. Still it will be enough to add a few more degrees to Monday's already warm readings.

The ridge and the offshore peaks on Wednesday as do max temps. There will be some 15 to 25 mph sub advisory wind gusts in the morning. Max temps will increase another 4 to 6 degrees and there will be plenty of max temps in the lower 90s across the vlys and interior coastal sections. Max temps will be 15 to 20 degrees above normal.

The ridge weakens just a touch on Thanksgiving as does the offshore flow. There may be a degree of cooling but more likely max temps will equal Wednesday's warm values.

The ridge flattens out Friday and this will bring cooling to all areas but esp the coast. Still max temps will 10 to 15 degrees above normal.

Aviation

18/12z.

At 10z at KLAX, there was a weak inversion based around 1000 feet. The top of the inversion was around 1600 feet with a temperature of about 17 degrees Celsius.

Overall, Moderate to high confidence in the current TAFs. There will be periods of moderate wind shear and turbulence at KOXR, KCMA, KSMO, KVNY, and KBUR through 15z. Through 17z there is a fifteen percent chance of IFR/MVFR conditions at KSMO, KLAX, and KLGB. Otherwise and elsewhere VFR conditions will prevail.

KLAX, Moderate to high confidence in the current TAF. There is a fifteen percent chance of IFR/MVFR conditions through 17z. Otherwise VFR conditions will prevail. There is a fifteen percent chance of east winds to ten knots through 18z and again 19/09z-16z, otherwise no east winds greater than seven knots are expected during the forecast period.

KBUR, Moderate to high confidence in the current TAF. There will be periods of moderate wind shear and turbulence through 15z. There is a less than ten percent chance of MVFR conditions through 17z. Otherwise VFR conditions will prevail.

Marine

18/200 AM.

Winds across the outer waters will continue to diminish as they shift to the northeast this morning. Locally gusty offshore winds will develop across the nearshore waters from Point Mugu to Santa Monica by midday and may reach Small Craft Advisory (SCA) levels at times near canyon outlets before diminishing late this afternoon.

Winds speeds across the outer waters will increase on Sunday and there is a forty percent chance of speeds reaching SCA levels during the Sunday night through Monday night period.

Watches, Warnings, Advisories

Ca, Frost Advisory in effect until 8 AM PST this morning for zones 37-38. (See LAXNPWLOX). Freeze Watch in effect from late tonight through Sunday morning for zones 37-38. (See LAXNPWLOX). Wind Advisory in effect until 2 PM PST this afternoon for zones 44>46-53-54-88-547. (See LAXNPWLOX). Freeze Warning in effect until 8 AM PST this morning for zone 59. (See LAXNPWLOX). Hard Freeze Watch in effect from late tonight through Sunday morning for zone 59. (See LAXNPWLOX). PZ, NONE.

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