Marine Weather and Tide Forecast for Hacienda Heights, CA

.SHORT TERM (TDY-FRI)...15/311 AM.

Forecast remains on track. The state will remain under the west side of a large hot upper high that is dominating the country.
Hgts will be fairly constant around 591 dam. The sfc gradients will be the main driver of changes to the sensible weather in the short term.

Today will be the warmest day with the weakest onshore flow (There may even be weak offshore flow from the north in the morning). The marine layer clouds will be largely absent and aside for a few high clouds it will be a sunny day. The weak onshore flow and warming airmass will bring 3 to 6 degrees of warming to the area.
This will pump up temps across the interior coastal sections to the upper 80s and mid 90s. It will be roasty toasty in the vlys, lower mtn elevations and far interior with highs ranging from 100 to 110 degrees (warmest in the western San Fernando Vly). Record highs are a little higher than these values so its likely that few if any records will fall. Today's highs will be 12 to 18 degrees above normal. These highs coupled with above average overnight lows present a dangerous heat environment. Extreme Heat Warnings are in effect for many areas - please see the product LAXNPWLOX for all of the details.

Sundowner winds tonight between 40 and 50 mph could bring very hot evening temps with little overnight cooling to the SBA south coast.

Onshore trends are forecast for Thursday. The marine layer clouds will be at worst patchy across some beaches and it will be another sunny day. The onshore trends will bring 3 to 6 degrees of cooling to all areas. This cooling, while certainly welcome, will not be enough to eliminate the heat risk, esp after another night of above normal low temps.

The big cool down will arrive Friday as onshore flow continues to increase. An eddy will likely help bring low clouds to most of the csts and maybe the lower vlys as well. 5 to 10 degrees of cooling across the board will eliminate the heat risk for the area.

There was hardly any monsoon activity ydy and with PW forecast to drop some more today there is no monsoon threat today.

.LONG TERM (SAT-TUE)...15/310 AM.

Fairly dull summer like weather is on tap for the weekend and next week. The large upper high does not move much at all and the state will remain under the western edge. Hgts will not budge much and will hover around 591 dam. Mdt to stg onshore flow will be in place through at least Monday. Offshore trends will start on Tuesday.

The onshore flow will bring plenty of night through morning low clouds to the csts (The SBA south coast may remain mostly clear as the Sundowners will continue). The hgts may be strong enough to keep the marine layer smooshed enough to keep the stratus out of the lower vlys.

Max temps will cool some on Saturday and will be near or even a few degrees under normal. Expect little change in temps on Sun and Mon. Slight warming is possible Tue and Wed as the offshore trends develop.

There will be an increase in PWATs Sunday and this trend will continue into next week. This will make the temps feel a little more uncomfortable and could lead to some convection over the mtns in the afternoons.

AVIATION
15/1011Z.

At 0832Z at KLAX, the marine layer was 700 ft deep. The top of the inversion was at 2900 ft with a max temperature of 29 C.

Moderate to high confidence in VFR TAFs at all sites, highest confidence away from coasts. There is a 20% chance for LIFR to IFR cigs at KLAX/KSMO/KLGB 12Z-17Z.

KLAX...Fair confidence in TAF. There is a 20 percent chc of BKN004-007 cigs after 12Z-17Z. No significant east wind component expected.

KBUR...High confidence in TAF

MARINE
15/311 AM.

Small Craft Advisory (SCA) level Northwest winds across the Outer Waters and will continue through Thursday night. There is also 40% chance of Gales later today into Thursday, but confidence is not high enough to warrant a Gale Watch at this point. This determination (Gale Warning or not) will likely occur with this morning's forecast package. Seas are forecast to build to near 10 feet in conjunction with these winds. The elevated winds and seas will extend into the western Santa Barbara Channel and nearshore waters along the Central Coast each afternoon and evening through Thursday night.

Winds are expected to improve Friday through the weekend while the northwest swell lowers. However, short period choppy seas from a southerly swell associated with a tropical system to our south and west will impact our waters this weekend.

LOX WATCHES/WARNINGS/ADVISORIES
CA...Extreme Heat Warning in effect until 8 PM PDT Thursday for zones 38-88-349>353-356>358-368>375-378>383-548. (See LAXNPWLOX).
Heat Advisory remains in effect until 8 PM PDT Thursday for zones 87-341>345-347-348-354-355-362-366-367-376-377-549-550. (See LAXNPWLOX).
Beach Hazards Statement in effect through late tonight for zones 340-346-349-350-354-362-366. (See LAXCFWLOX).
Red Flag Warning in effect from noon today to 9 AM PDT Thursday for zones 349>353-376>378. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Friday for zones 645-670-673-676. (See LAXMWWLOX).