11/833 PM.
A gradual cooling trend is expected Friday into the weekend as high pressure weakens. Temperatures should trend warmer again next week. A shallow marine layer will develop tonight and could bring dense fog to the coastal areas through Sunday.
(Thu-Sun), 11/831 PM.
Another very warm day across the region today, with many areas away from the immediate coast climbing well into the 80s. This due to the upper level ridge over the region along with offshore gradients to the north and east. As the ridge begins to slightly weaken, and the pressure gradients trend slightly onshore, looking for low clouds and fog to return to portions of the coast, south of Point Conception. The highest probability of low clouds and fog will be across the LA county coast, with current satellite imagery already showing this occurring in patches. As we transition out of the offshore event, any fog that does form tonight will have the potential for being dense. Current ACARS data over the LA Basin showing a shallow and strong marine inversion, around 500 feet deep. A dense fog advisory may be needed overnight for the LA county coast, and possibly the Ventura coast. Looking for gradual cooling trend the next couple of days, especially near the coast. Low clouds and fog expected to become more widespread into the weekend, potentially reaching some of the coastal valleys.
As for winds, no issues are expected. Gradients remain weak, so any northeasterly winds during the night/morning hours will remain localized and light.
(Mon-Thu), 11/143 PM.
For the extended, 12Z models continue to exhibit decent synoptic agreement through Tuesday then start to diverge Wednesday/Thursday. So, good confidence in forecast for Monday/Tuesday, but lower confidence for Wednesday/Thursday.
For Monday/Tuesday, upper level ridge will "nose" in over the area while weak to moderate offshore pressure gradients develop at the surface. With this pattern, skies should remain mostly clear except for some patchy coastal stratus/fog during the overnight and morning hours as marine inversion may hang tough despite the offshore gradients. As for winds, the upper level support looks rather meager. So, there will be some northeasterly winds in the usual spots, but chances for widespread advisory-level Santa Ana winds look limited. However, the combination of the upper level ridge and offshore gradients will allow for some nice warming with most areas at least 5-10 degrees above normal.
For Wednesday and Thursday, the GFS and its ensemble family keep zonal flow across the area while the ECMWF contingent has some ridging over the area with the high centered southwest of the area (with continued weak offshore pressure gradients). With the GFS solution, there is a chance of the tail end of a weak system, bringing some light rain to northwest San Luis Obispo county which is reflected in the current NBM POPs. The ECWMF solution would keep the entire area dry with warmer temperatures due to the offshore flow. Given the lower confidence in the model forecasts, will not make any adjustments to the current NBM POPs.
A bit further out, extended models continue to indicate a pattern shift with several storms potentially bringing rain to the area during Christmas week. Confidence in any details remains very low, but it is trending towards cool and unsettled conditions during this time period.
12/0528z.
At 0456Z at KLAX, there was a 300 foot marine layer depth. The top of the inversion was 2400 feet and a temp of 24 C.
High confidence in VFR TAFs for KPRB, KSBP, KSMX, KBUR, KVNY, KPMD, and KWJF. Except for a 30% chance for VLIFR to LIFR conds at KSMX and KSBP after 13/00Z.
Moderate confidence in remaining TAFs. VLIFR to LIFR conds at KLAX, KLGB, and KSMO through late morning, with conds improve after sunrise. VFR conds expected through the afternoon, then a return of VLIFR to LIFR conds expected after 02Z. Chance for VLIFR to LIFR conds at KOXR (30%), KCMA (15%), and KSBA (15%) after 10Z.
KLAX, Moderate confidence in TAF. 1/2SM vsbys with cigs VV002-OVC004 common through 16Z, then improving conds until 17Z-20Z, then VFR conds will continue through at least 02Z. Return of 1/2SM-2SM vsbys with cigs 002-004 sometime from 02Z-07Z. 50% chance for 1/4SM vsbys and VV001 cigs through 16Z, then again after 13/06Z. No significant east wind component expected.
KBUR, High confidence in VFR TAF.
11/1230 PM.
High confidence in fairly calm conditions and lowering seas through this weekend. Some patches of dense fog cannot be ruled out initially south of Point Conception with coverage expanding to the northern waters over the weekend.
Gusty NW-W winds will likely return across the Outer waters early next week with Small Craft Advisory (SCA) level winds likely south of Point Conception. Winds will strengthen Wednesday and Thursday, bringing a 30% chance of GALE force winds from Point Conception to San Nicolas Island including the western portion of the Santa Barbara Channel. These winds will likely result in choppy seas.
Ca, NONE. PZ, NONE.
