06/911 AM.
Temperatures will continue to be either below or near normal through Monday. A noticeable warming trend will start Tuesday, and heat will peak Wednesday and Thursday, with most temperatures 6 to 12 degrees above normal. Heat away from the coast may be hazardous to anyone outdoors and those without air conditioning.
(tdy-Tue), 06/917 AM.
***UPDATE***
Today and tomorrow will feel a lot like yesterday with highs near to slightly below normal and night and morning low clouds and fog for coast and some coastal valleys.
Latest models are trending less hot for the coming week but still well above normal. Forecast highs may be lowered a few degrees pending the rest of the model guidance coming in this morning. With this in mind will likely not be issuing any heat hazards today.
***From Previous Discussion***
Today and Monday, a weak low pressures system lingering just west of the Bay Area, will keep temperatures several degrees below normal, except for near normal for much of LA County. Starting Tuesday, 500 mb heights will rapidly rise as warm high pressure system over Arizona strengthens and expands into Southern California. Temperatures will increase noticeably by 5 to 10 degrees everywhere except for low elevation coastal areas, where onshore flow (our natural air conditioning) will moderate temperatures. The warmest valleys will see temperatures on Tuesday in the upper 90s, with 100-103 degrees common across the deserts. Even inland coastal areas (including Downtown LA) will approach 90 degrees.
Areas of breezy (but likely below advisory level) winds will continue each afternoon into night, with onshore west to southwest winds across the interior (including the Antelope Valley), and northwest Sundowner winds across southwestern Santa Barbara County.
There remains a slight chance of monsoonal mositure reaching the region, with the ECMWF AIFS Ensembles still hinting at PWATs near or above 1 inch for southern areas. At this point, thunderstorms chances are under 5 percent each day Tuesday and Wednesday, focused over the Antelope Valley and San Gabriel mountains. More likely, the mositure will result in some benign cumulus cloud build-ups over the highest mountains peaks.
(Wed-Sat), 06/348 AM.
This week's heatwave is expected to peak Wednesday and Thursday, when the ridge will be strongest over the region. The temperature forecast remains on track, and confidence is trending upwards, though there remains some uncertainty in exact values. The most likely scenario sees temperatures reaching 95-105 degrees across the warmer valleys, 103-107 across the deserts, and mid 80s to mid 90s for inland coastal plains/valleys. Most areas will be 6 to 12 degrees warmer than normal for this time of year. Heat away from the coast may be hazardous to outdoor workers and those without air conditioning.
Heat Advisories may be issued for the warmest areas (inland valleys), with slight chances for any Extreme Heat Watches/Warnings. The overall HeatRisk currently shows Moderate heat impacts for most areas, except for the beaches. The final decision on heat products may wait until early this week.
Small increases in onshore flow and decreasing high pressure, should bring at least a few degrees of cooling for many areas each day Friday and Saturday. However, some interior areas like the Antelope Valley and interior SLO/SB Counties may remain well above normal.
06/1730z.
At 1632Z at KLAX, the marine layer was 1300 ft deep. The top of the inversion was 3700 feet with a temperature of 21 C.
High confidence in VFR TAFs for desert sites (KWJF and KPMD).
Low confidence in TAF for KPRB after 10Z Sun. There is a 30% chance of IFR cigs arriving. Otherwise, high confidence in VFR conditions. Moderate confidence in remaining TAFs. Timing of CIG/VSBY restrictions may be off by 2 hours and flight minimums by one category. There is a 30% chance of LIFR conds at KOXR/KCMA from 10Z to 15Z Mon. Slightly lower odds (20% chc) of CIGs arriving at KBUR/KVNY through aforementioned timeframe.
KLAX, Moderate confidence in 18Z TAF. Arrival and departure of CIGs may be off +/- 2 hours. Minimum CIG heights may be off +/- 200 feet. No significant east wind component expected.
KBUR, Moderate confidence in 18Z TAF. There is a 20% chance for IFR cigs to return from 10Z to 15Z Mon.
06/740 AM.
Small Craft Advisory (SCA) winds will continue across the Outer Waters and the northern Inner Waters (this afternoon and evening) through tonight. Moderate chances for SCA level winds are expected to stay confined to the waters south of Point Conception Monday and Tuesday, before expanding to include most of the Outer Waters Wednesday/Thursday. Seas will remain below SCA thresholds thru Wednesday.
Inside the southern California bight, there is a moderate chance of SCA level winds each afternoon and evening through mid-week across western and southern portions of the Santa Barbara Channel. Local gusts up to 21 kts may occur near Point Dume, and into the San Pedro Channel during the aforementioned time. Significant wave heights are expected to remain well below SCA thresholds.
Patchy dense fog may affect the coastal waters, especially north of Point Conception overnight and in the morning hours through this weekend.
Ca, Beach Hazards Statement in effect through this evening for zones 87-354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 9 PM PDT this evening for zones 645-670. (See LAXMWWLOX). Small Craft Advisory in effect from 5 PM this afternoon to 11 PM PDT this evening for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Monday for zones 673-676. (See LAXMWWLOX).
