26/528 PM.
Temperatures will remain above normal across all valleys and interior locations through this weekend. A persistent marine layer will keep temperatures on the cooler side for coastal areas south of Point Conception through Friday. A warming trend this weekend will push temperatures to 10 to 20 degrees above normal. Cooler conditions are likely early next week with rain likely by Tuesday.
(Thu-Sun), 26/820 PM.
Latest satellite and surface observations indicate partly cloudy skies across the area as high clouds stream overhead. Additionally there is some stratus/fog offshore between Catalina Island and San Nicolas Island. Current sounding data indicates marine inversion around 1000 feet in depth. As for winds, some local northwest to northeast winds, gusting 20-35 MPH, are observed across the mountains.
For the short term, models are only indicating minor changes from day-to-day. Upper level high will remain centered over northern Mexico/Texas through Sunday. However, it will gradually weaken with H5 heights slowly decreasing across the area. At the surface, weak to moderate onshore pressure gradients will continue to the east with some weak northerly offshore gradients.
Through the weekend, dry conditions are expected. Cirrus clouds drifting overhead will keep skies partly cloudy through Friday, but clouds will thin out on Saturday/Sunday. Along the coast, stratus/fog will continue to be an issue for the coastal plain and some lower coastal valleys. Stratus coverage looks to be most robust Friday night/Saturday morning.
As for temperatures, there will be minor day-to-day changes across the area as marine influence brings a mixed bag of trends. North of Point Conception, will anticipate some warming on Friday, a bit of cooling on Saturday then a bit of warming on Sunday. South of Point Conception, look for some slight cooling on Friday then slight warming trend Saturday/Sunday. No matter the day-to-day trend, afternoon high temperatures will remain noticeably above seasonal normals.
As for winds, no significant issues are expected. The onshore gradients will generate the typical gusty southwesterly winds across interior sections during the afternoon and evening hours through the weekend. The northerly offshore gradients, and the associated northerly winds, will remain weak through the weekend. So, no advisory-level winds are expected.
(Mon-Thu), 26/820 PM.
For the extended, models continue to indicate an upper level trough developing over the West Coast. As this pattern develops, it will bring a very noticeable cooling trend to the area. In fact, by Wednesday/Thurday, afternoon temperatures will generally only be about 2-5 degrees above normal. So, a very welcome reprieve from the heat the last couple of weeks.
More importantly, this pattern will bring the chance of rain to the area in the Tuesday through Thursday time frame. Due to uncertainty in the timing of rain in the current models, the POPs for any 12 hour period Tuesday through Thursday are generally in the 20-40% range. However, based on the ensembles, there is a high likelihood of measurable rainfall (70-90%) sometime during the Tuesday through Thursday time frame. As for amounts, GFS ensembles are indicating, somewhat surprisingly, higher chances of rainfall totals greater than 0.50 inches than the ECMWF ensembles. Given this uncertainty, will not deviate too much from current thinking of most areas receiving 0.50 inches or less with local amounts up to around 0.75 inches (mainly across northwest San Luis Obispo county and the foothills). Overall, based on model trends the last few days, do not anticipate any significant type of storm.
A quick peek into the Great Beyond, models are not indicating any chances of rain in the April 3-11 time frame.
27/0027z.
At 2328Z at KLAX, there was no marine layer. The top of the inversion was at 2200 feet with a temperature of 23 C.
High confidence TAFs for KPRB, KPMD, & KWJF.
Low to moderate confidence in remaining TAFs. Timing of CIG/VSBY restrictions may be off +/- 3 hours. There is a 30% chance of IFR to LIFR conds at KSMX, KBUR and KVNY overnight. Elsewhere along the coast south of Pt. Conception, flight conds could be off by a category, most likely lowering to LIFR.
KLAX, Low to moderate confidence in the 00Z TAF. Cigs may scatter and reform at times overnight. Low clouds could return as early as 03Z Fri with a 20% chance of LIFR conds 08Z-16Z. No significant east wind component expected.
KBUR, Low to moderate confidence in the 00Z TAF. 30% chance that Low CIGs and VSBY form overnight, with conds most likely LIFR to low IFR.
26/834 PM.
High confidence that Small Craft Advisory (SCA) winds and steep seas will continue through late tonight for the outer waters down to the Channel Islands and the nearshore waters along the Central Coast.
Winds and seas will very likely fall below SCA levels conditions Friday night through Monday night, but there is a 30-40% chance of SCA level winds developing over the outer waters Saturday afternoon into Sunday.
Ca, NONE. PZ, Small Craft Advisory in effect until 3 AM PDT Friday for zones 645-670-673. (See LAXMWWLOX).
