13/726 PM.
A warming trend will continue this week, with dangerous expected for many areas Tuesday through Thursday. A few showers and thunderstorms could impact interior areas during the afternoon hours on Tuesday. Gusty northwest to north winds are forecast for southern Santa Barbara County and the LA and Ventura interior mountains during the afternoon and overnight hours Tuesday and especially Wednesday. Cooler weather is expected Friday and through the weekend.
(Mon-Thu), 13/814 PM.
***UPDATE***
Temperatures rose across much of the area today, and with monsoonal moisture in the vicinity, conditions were very warm and muggy in spite of some cloud cover. Highs were 95 to 100 degrees in the warmest valleys, otherwise 80s to lower 90s were observed in the coastal valleys and interior coastal plain. Closer to the beaches the highs were in the 70s. Convective showers affected the eastern San Gabriels and Antelope Valley this afternoon. Although no lightning was observed, isolated rain showers affected the areas mentioned with amounts of 0.12 inch or less.
Otherwise, the forecast remains on track with temperatures rising through the next two days, peaking on Wednesday, and then decreasing through late in the week. This significant heat wave is caused by strong high pressure aloft and weak offshore gradients on Wednesday. Temperatures on Tuesday will build into the mid 90s to around 105 in the valleys, and mid to upper 80s in the interior coast and coastal valleys, including Downtown LA (89 degrees) and mid to upper 70s at the coast. The Extreme Heat Warnings and Heat Advisories in effect for most of the area will persist through Thursday evening. During the heat wave, it is very important to avoid the heat of the day as much as possible, especially between 10AM and 7PM.
As for the monsoonal moisture, it will persist into Tuesday although decreasing some. There will again be a chance of showers and slight chance of thunderstorms, generally 20 to 40 percent over the mountains and deserts, highest over the eastern San Gabriels and the higher Ventura Mountains.
***From Previous Discussion***
One additional significant weather factor will be the expected development of strong and hot Sundowners across the Santa Ynez Range and down into the foothills and coastal areas of the Santa Barbara County south coast. Winds will start up Tuesday evening but peak Wednesday evening gusting to 35-50 mph with local gusts up to 60 mph possible in the foothills and mountains. Add to that the very hot airmass in place and downsloping effects, temperatures could easily reach the 90s all the way to the coast and possibly around 100-102 in the foothills. A Fire Weather Watch is in effect for all of the Santa Barbara South Coast and Mountains Wednesday into Thursday morning.
2-4 degrees of cooling is expected Thursday but highs will still be 6-12 degrees above normal.
(Fri-Mon), 13/154 PM.
Very gradual lowering of midlevel heights later this week into the weekend, combined with the eventual influx of deep moisture from distant, low-latitude East Pacific storms bringing increasing cloudiness, along with reinforcing onshore flow, will all contribute to temperatures slowly cooling to near-normal readings by next weekend. Hot conditions will still be present on Thursday when heat headlines remain in effect. While a few diurnally enhanced showers cannot be ruled out over the high terrain late this week and into the weekend owing to the increasing moisture, confidence in the development of this activity is too minimal for mention in the forecast at this time. Otherwise, the onshore flow will bring an increase in night through morning patchy low clouds and fog across coastal areas by next weekend.
14/0314z.
At 0034Z at KLAX, the marine layer depth was 900 ft. The top of the inversion was at 2500 ft with a max temperature of 26 C.
At 00Z, High confidence in the valley and desert TAFs, but Low confidence in the coastal TAFs. Patchy low clouds are possible during the night through morning hours, resulting in lower certainty in CIGs for coastal areas. From KSBA northward to KSBP there is a chance of LIFR to IFR conds overnight, with IFR to MVFR conds further south. The timing is also low certainty.
There is a 20-30% chance of showers and thunderstorms at KPMD/KWJF from 13/18Z through 14/00Z. These storms would be capable of producing erratic winds, turbulence and heavy rainfall.
KLAX, Low to Moderate confidence in the 00Z TAF. Timing of flight cat changes may be off +/- 2 hours. CIGs may be intermittent in nature. No significant east wind component expected.
KBUR, High confidence in the 00Z TAF. There is a 10 percent chance of IFR CIGs overnight. No wind issues expected.
13/740 PM.
NW winds are expected to strengthen to Small Craft Advisory (SCA) levels across the Outer Waters Tuesday afternoon and will continue through Thursday night. There is also 20% chance of Gales later Wednesday into Thursday. Seas are forecast to build over 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 at times through this period, mainly during the afternoon and evening hours. While a few showers may drift across the local waters through early parts of this week, thunderstorms are unlikely.
13/740 PM.
Dangerous rip currents and breaking waves with elevated surf are expected for coastal areas and the beaches of Los Angeles, Ventura, Santa Barbara, and San Luis Obispo Counties, as enhanced southerly swell continues. A Beach Hazards Statement remains in effect through Wednesday evening for these areas. Minor coastal flooding will be possible during the evenings, given abnormally high tides of 7.0 to 7.6 feet. Later this week and into the weekend, distant storms over the East Pacific waters well south of the area could produce increasing southerly swell resulting in even more significant beach hazards by the weekend.
Ca, Heat Advisory remains in effect until 10 AM PDT Tuesday for zones 38-88-343>345-353-368-372-373-375>380-548. (See LAXNPWLOX). Extreme Heat Warning in effect from 10 AM Tuesday to 8 PM PDT Thursday for zones 38-88-349>353-356>358-368>375-378>383-548. (See LAXNPWLOX). Heat Advisory in effect from 10 AM Tuesday to 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 Wednesday evening for zones 340-346-349-350-354-362-366. (See LAXCFWLOX). Fire Weather Watch in effect from Wednesday afternoon through Thursday morning for zones 349>353-376>378. (See LAXRFWLOX). PZ, Small Craft Advisory in effect from noon Tuesday to 3 AM PDT Friday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM Tuesday to 3 AM PDT Friday for zone 673. (See LAXMWWLOX). Small Craft Advisory in effect from 6 PM Tuesday to 3 AM PDT Friday for zone 676. (See LAXMWWLOX).
