02/144 AM.
A major and long lasting heat wave will begin today and last through all of next week with dangerously hot temperatures. Coastal clouds and fog are expected this morning and tonight into Saturday morning, with dense fog possible at times.
(tdy-Sun), 02/900 AM.
***UPDATE***
We are off to the races this morning as temperatures away from the immediate coast (and south of Pt Conception) are already 10-15 degrees above yesterday at this time. And some foothill and lower mountain locations stayed in the low to mid 80s overnight. So no change in the forecast today and through next week with valley highs from 99-107, Downtown in the upper 90s, and beach areas (up to 5 miles inland) in the mid 80s to mid 90s. The heat wave will reach SLO and northern Santa Barbara Counties Saturday.
***From Previous Discussion***
Coastal clouds and fog are expected to be limited to the coasts and perhaps some coastal valleys, with little change to the heights. Will have to watch for dense fog formation as the offshore gradients look quite weak (around 1 mb) this morning. Otherwise, expecting a hot day today through most of the area with building high pressure and ongoing offshore winds. Given the limited sea breeze, the most warming should be near the coasts. However, warming may be somewhat limited for northern Santa Barbara County and San Luis Obispo County as mid to high level clouds move in, and should persist through the day. By the weekend, high temperatures in the upper 80s and 90s are expected for the coasts from Santa Barbara southward.
***A VERY DANGEROUS AND LONG LASTING HEAT WAVE TODAY THROUGH AT LEAST NEXT WEEK***
No significant changes to the short or long term forecasts. A dangerous heat wave will begin today and last through at least next week as a strong high pressure system sets up over the eastern Pacific and West coast. Offshore pressure gradients are already weak today (currently near 0.5 mb), and will increase through Sunday, resulting in offshore gradients to the east and north in the 2 to 4 mb range. So while this is an offshore scenario in October, it's not a traditional Santa Ana as the upper support is not sufficient for persistent gusty winds, though there will be brief periods of some sub advisory level north to northeast winds at times. However, in typical Santa Ana fashion, this heat wave will include the beaches, at least south of Pt Conception.
During this heat wave, warmer valley highs are expected to be 102-107, Downtown LA 99-103, and coastal areas from Santa Barbara to LA 90-98. These are 15-20 degrees above normal.
It will be warming in SLO and northern Santa Barbara Counties as well but delayed by a day. By the weekend expecting highs away from the beaches to reach the low to mid 90s and lower 100s in the interior. Heat advisories may need to be extended in certain areas next week but models have been showing just enough cooling early next week to allow the advisories to drop off.
(Mon-Thu), 02/138 AM.
Monday into the rest of the week will feel a lot like this coming weekend, with ongoing offshore winds and persistent high pressure. Will likely see some fluctuations in temperatures as the offshore gradient weakens a bit early in the week, though there are still some model solutions indicating a little more upper level northeast wind support and subsequently even hotter temperatures around Wednesday into Friday, leading to breaking daily high temperature records. Further out, models indicate tropical moisture along with an upper level trough could lead to cooling temperatures by the following weekend.
02/1634z.
At 16Z at KLAX, there was no marine layer. There was a surfaced based inversion with a top at 1700 ft and a temperature of 30 C.
High confidence in VFR TAFs for all sites expect for KSMX, KSBA, & KSBP. Chance for low clouds (LIFR or lower): KSMX (60%), KSBA (20%), & KSBP (20%). No wind issues expected.
KLAX, High confidence in VFR TAF. Good confidence that any east wind component remains below 8 kts.
KBUR, High confidence in the VFR TAF. No wind issues expected.
02/845 AM.
Generally quiet conditions expected across the coastal waters through the forecast period. Localized Small Craft Advisory (SCA) gusts may occur each afternoon and evening near Point Conception, off the coast of Point Dume, and across the San Pedro Channel.
02/845 AM.
While we will get a break from the coastal flooding concerns for the rest of the week, another hurricane swell (from Rachel) will likely bring a larger-than-Polo south swell to southern California for much of the coming work week. The window of most concern is Tuesday through Friday. Elevated surf up to 5-6 ft is likely with a lower chance of high surf 7ft or higher across exposed south facing beaches. High tides of 6.5-7.0 ft are expected. Unlike previous events, morning and evening tides will be similar. Initially, the swell will have a more SE direction (150-160) targeting areas like Long Beach Tuesday and Wednesday. As Rachel moves westward, the swell direction will become more southerly (170-190) Thursday and Friday targeting areas like Zuma. There is a high risk for Beach Hazard Statements and a moderate risk for Coastal Flood Advisories along the LA/VTA coastline. Stay tuned for future updates.
Ca, Extreme Heat Warning in effect until 8 PM PDT Thursday for zones 38-87-88-349>358-362-366>375-548-550. (See LAXNPWLOX). Heat Advisory in effect from 10 AM Saturday to 8 PM PDT Sunday for zones 341>345-347-348. (See LAXNPWLOX). PZ, NONE.
