11/243 AM.
A cooling trend will affect the region through the weekend with max temps dropping to below normal by Sunday. The sticky tropical air will finally exit the region by this weekend. Marine layer clouds will likely return to many coastal areas.
(tdy-Sun), 11/814 AM.
***UPDATE***
Heat advisories will continue through this evening for coastal areas from Santa Barbara south through Los Angeles due to moderate risk of heat illness from still warm morning temperatures and highs running up to 10 degrees above seasonal normals. Some inland areas are on the fringe of heat advisories due to warm morning temps, but we will leave them since max temps in those areas will run only around 5 degrees above normal.
Otherwise the cooling trend today will start the first over the next few days or so, with very quiet weather on the horizon. Additionally humidities will continue to lower through today, but even more so into Saturday.
The one exception to the quiet weather is the potential for advisory level Sundowner winds tonight through the weekend, likely peaking Saturday or Sunday. A wind advisory has been issued for tonight across the Santa Barbara southwest coast.
We finally saw a return of some marine layer stratus this morning, with some patchy stuff south of Point Conception and a little more solid along the Central Coast. Expecting better coverage tonight.
***From Previous Discussion***
The ridge that brought the very high hgts will flatten out and hgts will fall to a about 588 dam. At the sfc there will be weak to moderate onshore flow in the E/W direction. The N/S gradients will feature weak offshore flow in the mornings and weak onshore flow in the afternoons.
This will kick off a three day cooling trend with most max temps falling 4 to 8 degrees today, 3 to 6 degrees Saturday and 2 to 4 degrees Sunday. By Sunday Max temps will mostly be in the upper 70s to 80s across all of the csts/vlys or 3 to 6 degrees blo normal.
The marine cloud layer is advancing down the coast and there are signs of an eddy. Marine layer stratus will slowly increase in coverage through the period, although the very warm sea sfc temps will have an inhibiting effect.
The real good news is the the humidities will fall back to normal. PWs over srn LA county ydy were near 1.70" and will fall to 1.3" today and then to .85" Saturday.
The decrease in available mositure will eliminate the threat of afternoon convection.
Not much in the way of winds through the short term. Just the typical gusty west afternoon winds in the Antelope Vly and the evening Sundowners west of Isla Vista on the SBA south coast.
(Mon-Thu), 11/928 AM.
Not much change through Wednesday, with zonal flow continuing at the upper levels. Temperatures will remain below seasonal normals. Weak to moderate onshore flow will continue with light northerly offshore flow each night through morning. There will likely be some morning low clouds each day with the greatest coverage across the Central Coast. Skies, otherwise, will be mostly clear.
A good degree of mdl confusion creeps into the forecast later Wednesday into Thursday as the mdls struggle with the handling of some energy coming out of British Columbia. The sfc pattern is also in question as there is wide assortment of possible values ranging from 1mb onshore to 6.5 mb onshore. While the actual outcome regarding how much warmer it will be and how quickly things warm up is still uncertain, ensembles do suggest a slight warming trend Thursday and Friday. So confidence in at least some warming is growing, with the details remaining in question. A majority of the European ensemble members also increase PWATs to over an inch as early as Thursday, so there is also potential for increased mugginess once again. The good news is most members are keeping PWATs below 1.5, much lower than the peak of the extreme heat and humidity this past week.
No significant wind issues are expected, although there will be the usual gusty southwesterly winds each afternoon across the mountains and deserts and the typical near advisory level evening gusts across the SW corner of SBA county.
11/1718z.
At 1622Z at KLAX, the marine layer was 1700 ft deep. The top of the inversion was at 2600 ft with a temperature of 25 C.
High confidence in VFR TAFs for desert airfields (KPMD & KWJF).
Moderate confidence in VFR conditions for KPRB (10% chc of brief LIFR CIGs 12/12Z-15Z), KVNY (15% chc of LIFR/IFR CIGs 10Z-15Z).
For remaining TAFs, low to moderate confidence. Timing of CIG/VSBY restrictions may be off +/- 3 hours & flight minimums by one category.
KLAX, Moderate confidence in TAF. Arrival and clearing of IFR to MVFR Cigs (008-012) may be off +/- 2 hours. No significant east wind component expected.
KBUR, Moderate confidence in TAF. 15% chc of LIFR/IFR CIGs 12/10Z-15Z. No wind issues expected.
11/819 AM.
Conditions are expected to become increasingly hazardous across the outer waters into the weekend. A Gale Watch (50-60% chc) has been issued for PZZ676/673 Saturday evening into Monday morning. The coastal Jet may develop across PZZ670 Saturday evening causing winds to increase there as well, but confidence in winds reaching Gale force is low at this time. Otherwise, widespread SCA winds are expected across the outer waters through early next week. Small Craft Advisory (SCA) conditions are expected to reach into the nearshore waters along the Central Coast and the Santa Barbara Channel at times (especially during afternoon/eve hours) through early next week.
Ca, Heat Advisory in effect until 6 PM PDT this evening for zones 349-350-354-355-362-366>368. (See LAXNPWLOX). Wind Advisory in effect from 6 PM this evening to 3 AM PDT Saturday for zones 349-351. (See LAXNPWLOX). PZ, Small Craft Advisory in effect from 2 PM this afternoon to 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Saturday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Monday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 6 PM PDT Saturday for zones 673-676. (See LAXMWWLOX). Gale Watch in effect from Saturday evening through Monday morning for zones 673-676. (See LAXMWWLOX).
