17/306 AM.
A few degrees of cooling are expected today with temperatures returning to normal over the weekend. Morning low clouds and fog will return to many coastal areas today and each day through early next week. A warming trend is expected by the middle of next week as upper level high pressure builds into the area.
(tdy-Sun), 17/300 AM.
Not much change in the upper level pattern over srn CA today thru Sun with the region under the SW periphery of a large western U.S. upper level high centered mainly between WY and CO. H5 heights over the forecast area will be generally in the 589-591 dam range thru the period. The upper level flow will start out mostly southerly thru Sat then turn more SE into Sun. Some monsoonal moisture will push back into SW CA this weekend with an increase mid level clouds at times, and by Sun some afternoon cu buildups cannot be ruled out in the mtns along with a non-zero chance (10%) of a shower or thunderstorm especially in the VTU/L.A. County mtns. Even so, it looks like the bulk of the monsoonal moisture will remain east of L.A. County thru Sun.
Pressure gradients will be onshore and increase over the next couple of days. This will promote cooler temps from the recent very hot weather, along with an increase in coastal night and morning low clouds and fog. Overall, it looks like temps will be near normal to several degrees below normal across the region today thru Sun. Afternoon highs should range from the 70s to low 80s for the coast, mid 80s to mid 90s for the vlys and lower mtns, and 90s to around 100 for the deserts.
(Mon-Thu), 17/303 AM.
The large western U.S upper level high center is forecast to drift S from Colorado on Mon to the area around New Mexico and the northern Texas panhandle by Thu. Southwestern CA will continue to be on the western periphery of this large upper level high, with H5 heights slowly increasing to 592-594 dam during the extended period.
The flow aloft will mostly be from the SE with monsoonal moisture expected to continue to push into the area. Precipitable water values are forecast to be in the 1.25 to 1.40 inch range for the most part which is about 150 to 160 percent of normal for this time of year. Although the deepest moisture and instability is forecast to remain east of L.A. County during the extended period, it does look like the best chance of afternoon convection will come Wednesday and Thursday over the mountains. For now, there is only a minimal chance of showers late Thu in the fcst for the eastern L.A. County mtns. Otherwise, there is a non-zero chance (10%) for a thunderstorm to develop in the mtns especially Wed and Thu. As we draw closer to early next week, we should have a better idea of the chance and extent of afternoon convection for the middle of next week.
Otherwise, it look like varying amounts of night and morning coastal low clouds and fog will prevail during the extended period, with a warming trend thru the middle of next week. By Wed, afternoon highs are forecast to top out around 100 degrees for the warmest vlys and lower mtns, with 80s edging closer to the coast. With potentially weaker onshore pressure gradients for Wed and Thu, high temps could actually wind up being a few degrees warmer than is currently forecast.
17/1142z.
At 0853Z at KLAX, the marine layer was 1400 ft deep. The top of the inversion was at 2900 ft with a max temperature of 25 C.
High confidence in VFR TAFs for KPRB, KBUR, KVNY, KPMD, and KWJF.
Moderate confidence in coastal TAFs, where MVFR to IFR CIGs and MVFR VSBYs are forecast this morning and again tonight. There is a 40% chance for restrictions to be off by +/- 2 hours in onset and dissipation timing, and off by one category in minimum restriction. There is also a 30% chance that no low clouds may affect KSBP at all this morning.
KLAX, Moderate confidence in TAF. Dissipation and onset of MVFR CIGs is expected to occur within 2 hours of 18Z today and 03Z this evening. There is a 50% chance of east wind component exceeding 6 knots thru 18Z today and a 30% chance of this occurring tonight after about 06Z.
KBUR, High confidence in VFR TAF.
17/153 AM.
For the outer waters, Small Craft Advisory (SCA) level winds are expected to persist for the most part through late tonight, then winds and seas will largely be below SCA levels across these waters Saturday through Tuesday night.
For the inner waters N of Point Sal, winds and seas are likely to remain below SCA levels through the forecast period.
For the southern inner waters, conds will largely remain below SCA levels through the forecast period, except over the western SBA Channel there is a 20% chance of SCA wind gusts Sunday evening and a 40% chance of SCA wind gusts Tuesday evening.
17/305 AM.
Over the eastern Pacific, Tropical storm Elida is expected to strengthen to hurricane status today and move to the north and west well off the Baja coast. Another tropical disturbance is expected to strengthen early Monday and generally follow the path of Elida to the northwest.
These tropical cyclones will produce southerly swells which will propagate northward and begin affecting south-facing beaches by Sunday with building long period surf. This activity will likely persist through next week. Additional swells will likely arrive later next week due to strong storms across the southern Hemisphere adding to the mix, likely producing more significant hazardous beach conditions at that time.
Ca, NONE. PZ, Small Craft Advisory in effect until 3 AM PDT Saturday for zones 670-673-676. (See LAXMWWLOX).
