29/1223 PM.
Little change in weather conditions is expected through Thursday with temperatures 3-6 degrees above normal. Areas of morning low clouds and fog are possible near the coast as well. A major and long lasting heat wave will begin Friday and last through all of next week at least with with dangerously hot temperatures.
(Tue-Fri), 29/958 PM.
***UPDATE***
Highs today reflected the northerly offshore winds, with toasty 80s and 90s along the Santa Barbara south coast and for many valleys and interior areas. The Central Coast saw cooler highs in the 60s and 70s. Offshore winds peaked last night, with the offshore LAX- BFL gradient reaching 3.6 mb and gusty Sundowner winds up to 64 mph. The offshore gradient remained around 2 to 3.6 mb through much of the day, leading to plenty of warming for downsloped areas. Expecting this to shift, as gradients shut off and onshore flow returns for tomorrow. As flow weakens, any patchy fog that forms tonight may become dense. Northerly offshore winds are gradually expected to return, along with building high pressure leading to a warming trend into the end of the week.
***From Previous Discussion***
, A VERY DANGEROUS AND LONG LASTING HEAT WAVE NEXT WEEK AND LIKELY EXTENDING INTO THE SECOND WEEK IN OCTOBER,
Most of the area (except southern LA County) experienced several degrees of warming today as pressure gradients turned briefly and lightly offshore with some breezy north to northeast winds, mainly in the mountains. Onshore gradients will return Wednesday, leading to roughly 5 degrees of cooling as well as areas of low clouds and fog in the morning.
A warming trend will return Thursday but really kick into gear Friday and over the weekend as a long duration high pressure system settles in over the entire West coast. Most of the ensembles also show a light to moderate offshore flow as well which will push the hot temperatures all the way to the coast, especially south of Pt Conception. By Friday Downtown LA and other intermediate coastal areas will warm into the lower 90s, while the valleys heat up to the upper 90s to 105. These are 10-15 degrees above normal. Based on the latest guidance the chances for heat advisories in LA/Ventura Friday are 70-90%. Central Coast areas will not be quite as warm but still at least 5-10 degrees above normal.
(Sat-Tue), 29/139 PM.
Short term as well as longer range models continue to indicate a very long lasting and dangerous heat wave that will likely continue at least into the second week of October as a strong high pressure ridge persists along the West coast. Models are also indicating that the persistent high pressure will be accompanied by a light to locally moderate offshore flow which means coastal areas will be very hot as well. Based on the latest projections, the warmer LA Valley areas will reach at least 105 by Saturday with a 10-20% chance of 108-110. And Downtown LA is expected to reach the mid to upper 90s by Saturday with a 20% chance of 100. And these temperatures are expected to persist (give or take a few degrees) through at least the end of next week and likely into the following week (starting Oct 13).
With these numbers in mind, Extreme Heat Warnings will likely be needed as early as Saturday for LA County. Heat advisories may suffice for Ventura and southern Santa Barbara County through the event, but the longer the heat wave lasts with little cooling, the more likely it will be that advisories will need to be upgraded to warnings. And as of now most of the projections show the Central Coast staying just below heat advisory level but there's at least a 30-50% chance that temperatures and the length of the heat wave will require at least some targeted heat advisories there.
30/0218z.
At 2237Z at KLAX, there was no marine layer or inversion.
High confidence in VFR TAFs for KPRB, KWJF, and KPMD. There is a 15% chance for brief IFR cigs at KSBA after 13Z. Moderate confidence in VLIFR conds at KSBP/KSMX tonight, with a 20-30% chance for VFR conds to prevail, higher at KSBP.
Moderate confidence in remaining TAFs. VFR conds expected through at least 06Z, then there is a chance for IFR-MVFR conds to return, highest chances for LA County coastal sites after 10Z.
KLAX, Moderate confidence in TAF. Gusty onshore winds will be common this evening. There is a 20% chance for VFR conds to prevail. There is a 60% chance for east wind component reaching 10 knots between 10Z-18Z. Gusts up to 18 kt are possible.
KBUR, High confidence in VFR TAF. 20% chance for IFR conds after 12Z tonight.
29/821 PM.
Small Craft Advisory (SCA) winds and steep seas affecting all the inner waters (including the nearshore waters along Los Angeles and Orange Counties) through late tonight, and for the outer waters through late Wednesday night.
Southerly swell from Polo (SSE) is decreasing fairly rapidly. These swells will create larger waves and surf nearshore, which could impact some south exposed harbor entrances.
Conditions are likely to improve to below SCA levels Wednesday into next weekend, except for occasional northwest SCA winds near Point Conception in the afternoon/evening hours.
29/815 PM.
The surf from Hurricane Polo has peaked and will lower rather quickly through Wednesday, but strong rip currents may linger. The high tide came in 1.0 to 1.2 feet above prediction today and above 7.0 feet MLLW. While the high tide will be lower on Wednesday compared Tuesday, it will lower only a little and will likely still be above 7.0 feet for morning high tide. With all that in mind, the Coastal Flood Advisory and High Surf Advisory have been replaced them with a lower-tier Beach Hazards Statement to cover through Wednesday for the rip current and tidal overflow potential.
While we will get a break from the coastal flooding concerns for the rest of the week, another hurricane swell (from soon-to-be Hurricane Rachel) will likely bring a larger-than-Polo south swell to southern California for the early to middle part of next week. Thankfully tides at that time will not be extreme, but they should be around 6.5 feet which is high enough to cause some concern, but it all depends on how big the surf ends up.
Ca, Beach Hazards Statement in effect through Wednesday afternoon for zones 87-349-350-354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 645-650-655. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Wednesday for zones 670-673-676. (See LAXMWWLOX).
