30/247 AM.
Cooler conditions will occur today and Monday. More warm, tropical moisture could return Tuesday through Thursday. Marine layer clouds will gradually redevelop, and increase in coverage Sunday into early this coming week.
(tdy-Tue), 30/944 AM.
***UPDATE***
Cooling temperatures are expected today and Monday as a trough develops along the West coast. Temperatures are trending several degrees cooler already this morning, in some areas by as much as 10-15 degrees. In addition, PW's are down considerably as well which means humidities and overnight lows will be lowering as well.
No significant changes to the forecast today. Still expecting temperatures to trend slowly warmer by mid to late week as the trough weakens. And will be paying close attention to next weekend and early next week as there are some solutions bringing the next tropical system off Mexico right up into the California bight with PW's well over 2" along with strong south swells.
***From Previous Discussion***
Troffing will continue over srn CA as a series of upper lows moves through the PACNW. Hgts will fall from 588 dam Saturday afternoon to 582-584 dam Mon and Tue. Onshore flow will increase both today and Monday but there will be significant offshore trends on Tuesday.
Just a few low clouds this morning mostly across western SBA county. Low cloud coverage will increase Monday morning with the falling hgts and increased onshore flow. The Central Coast, VTA coast and LA coast will likely have good stratus coverage. The offshore trends and influx of some subtropical moisture will likely disrupt the marine layer stratus on Tuesday limiting it to the Central Coast.
The lowering hgts and increased onshore flow will bring 3 to 6 degrees of cooling each day (only 1 to 2 across the Central Coast) and by Monday max temps will be 4 to 8 degrees blo normal with vlys highs only in the mid 80s to lower 90s. Not much change in temp Tuesday, but it will be a little more humid as some subtropical moisture stream in.
This subtropical moisture influx will lead to a 15 to 20 percent chance of showers and thunderstorms focused over LA and Ventura County Tuesday afternoon and into the evening.
(Wed-Sat), 30/248 AM.
Rather benign weather is on tap for the xtnd period. There is good agreement between the medium range mdls that a troffing pattern will persist through Saturday. At the sfc there will be mdt onshore flow to the east in the afternoons along with weak offshore flow from the north in the mornings. This should develop a night through morning cloud pattern for most of the csts save for the SBA south coast where offshore flow overnight should keep that area clear.
Slowly rising hgts will bring a degree or two of warming each of the four days. Even with this warming most areas will have below normal temps with the major exceptions of the LA/VTA csts and the San Gabriel Vly.
Some subtropical moisture is possible early next week (Sep 7-9) but there is a fair amount of mdl disagreement on this.
30/0947z.
At 0832Z at KLAX, the marine layer was 900 feet deep with an inversion to 2900 feet with a temperature of 28 degrees C.
Fair confidence in TAF at KSBP with a 20% chance for LIFR-IFR conds from 13Z-17Z.
Moderate confidence in TAF for KSMX. VFR fcst timing may be off by an hour and there is a 20% chance for VLIFR conds and FG.
High confidence in VFR TAFs at remaining sites. Less than 10% chance for IFR conds for LA County coastal sites 13Z-17Z.
KLAX, High confidence in TAF. There is less than 10% chance of BKN005-009 conds 13Z-17Z. Good confidence in any east wind component remaining below 7 kt.
KBUR, High confidence in TAF.
30/857 AM.
High confidence in Small Craft Advisory (SCA) northwest winds (20-30 knots) and steep, choppy seas for the outer waters through late tonight. These hazardous conditions will reach into the nearshore waters along the Central Coast and into the Santa Barbara Channel today, especially during the afternoon/evening hours. Local wind gusts may approach 35 knots near Point Conception through tonight. Conditions are expected to improve Monday with only local SCA level wind gusts near Point Conception Monday and Tuesday. Chances for more widespread SCA winds increase Wednesday into the remainder of the week.
Ca, Beach Hazards Statement in effect through Monday afternoon for zones 354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Monday for zones 645-650-670-673-676. (See LAXMWWLOX).
