05/1223 PM.
Cloudy, cool, and breezy conditions today will be followed by a warming and drying trend for Wednesday through at least Mother's Day Weekend. There is a chance for widespread high temperatures to be in the 90s Saturday through Monday, with the valley locations generally the warmest.
(Tue-Fri), 05/917 PM.
***UPDATE***
Another cool day as the low system lingered over the area. Overall, we ended up with quite a few areas seeing very light rain totals below 0.05 inches, and some pockets of higher totals near 0.25 inches. Expecting dry weather now through the week as high pressure builds in. Marine layer clouds may return to some coasts tonight, possibly pushing into the coastal valleys of the LA Basin and the Salinas Valley. A Catalina Eddy is forecast to develop in the early morning hours, supporting clouds for the LA area and possibly expanding north towards Ventura County. Looking at an expanding marine layer over the next few days, which will serve to keep the coasts cool. High pressure will allow the interior to warm, and compress the marine layer keeping low clouds and patchy fog closer to the coasts. Temperatures will approach 90 degrees for the deserts and valleys towards the end of the week.
***From Previous Discussion***
Partly cloudy to cloudy skies are present across the region with higher ceilings than the typical marine layer low clouds. North to northeast flow will lead to continued cumulus cloud formation and scattered light showers will be possible through this evening, focused over the north facing slopes of the mountains. The low pressure system is continuing to slide to the southeast and as it exits the region, gusty west to northwesterly winds is impacting the coasts through this evening, with the strongest winds (near advisory level) across the Santa Barbara County south coast and the Ventura County Coast.
A pattern shift in the weather pattern will begin Wednesday. Behind the low pressure system, a ridge of high pressure will build, likely peaking in strength Sunday through early next week. Slight warming on Wednesday will be followed by a more significant increase for Thursday and Friday, when highs in the mid 70s to mid 80s will be common. Overnight into morning marine layer clouds will return for some locations tonight and dense fog will be possible Thursday and Friday morning.
(Sat-Tue), 05/252 PM.
Temperatures will continue to trend upwards over the weekend as the ridge strengthens. The ridge will likely peak Sunday through early next week, when 500 mb heights have the potential reach 590-591 dam. This would be in the 99th percentile of 500 mb heights for this time of year. In addition, there is a chance of weak offshore flow from the north (Saturday), shifting northeast (Sunday and Monday). If this flow pattern develops, then it would result in further warming of high temperature across the valleys, and perhaps more impactful, across the beaches (where conditions generally are quite cool in May). Ensemble models and local temperature study data indicate that high temperatures may be widespread in the mid 80s to mid 90s (10-20 degrees above normal), with local 100+ temperatures possible for the warmest valleys. Saturday through Monday look to be the main peak of heat, just right for a very warm Mother's Day weekend. However, a significant heatwave is not guaranteed, if surface pressure gradients end up onshore, as several ensemble models show, heat will be dampened by a seabreeze at the coasts.
06/0232z.
At 00Z at KLAX, there was a deep moist layer up to 8600 ft.
High confidence in VFR TAFs for desert airfields (KPMD & KWJF).
Moderate confidence in remaining TAFs. Patchy MVFR CIGs possible across the LA Basin (10Z-18Z) and for KSMX, KSBP. There is a 20% chance low clouds do not develop at KPRB. For all sites with forecasted CIGs, low confidence in arrival times.
KLAX, Moderate confidence in TAF. Low confidence in arrival times of cigs. East winds are possible from 09Z to 15Z, and there is a any east wind component should remain below 10 kts.
KBUR, Moderate confidence in TAF. 30% chance of IFR-MVFR CIGs to develop 10Z-15Z Wed. Otherwise, VFR conditions with no wind issues are expected.
05/735 PM.
Small Craft Advisory (SCA) winds will be common across the western Santa Barbara Channel and near the Channel Islands through this evening.
From Wednesday through Saturday, SCA level NW winds are expected to strengthen each day and will peak Friday afternoon and evening. These winds are likely to reach 20 to 30 kts across the outer waters. There is about a 15% chance of GALE Force winds during this timeframe. SCA level winds are also likely at times across the nearshore waters along the Central coast and into at least western portions of the Santa Barbara Channel.
Short period seas will build during this timeframe especially across the outer waters - reaching 10 feet by Friday then peaking up to 11 feet Friday night through Saturday night.
Ca, NONE. PZ, Small Craft Advisory in effect until 3 AM PDT Wednesday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 673-676. (See LAXMWWLOX).
