textproduct: Los Angeles

SYNOPSIS

15/237 PM.

Night through morning marine layer clouds will continue for the coast and valleys, shrinking in coverage each day into next week. Cooler than normal temperatures continue through this weekend, then warmer than normal temperatures return next week, with widespread moderate Heat Risk potentially occurring away from the immediate coast.

LONG TERM (WED-SAT)

15/236 PM.

There is now good agreement amongst models that the upper level ridging will remain over the Western US, bringing hot and dry conditions to Southwest California Wednesday through Friday. Boundary layer temperatures continue to edge upward during this period, with further weakening of the onshore pressure gradients. During this time period, there is increasing confidence that high temperatures will peak in the 93-105 degree range for valleys, lower mountains, and deserts. In addition, the weakening of the onshore gradients will likely allow heat to expand into the inland portions of the coastal plain. Downtown LA will likely climb in the 90 to 95 degree range during this time. With these projected temperatures, there is moderate confidence that heat advisories will be issued for many areas away from the immediate coast at some point between Tuesday and Friday. Ensemble data shows less certainty in the upper level pattern and resultant temperatures for next weekend. There is still the potential for the hot and dry pattern to extend into next weekend, but definitely less confidence than Tuesday-Friday. Overnight lows will also start to warm in the extended period, especially in the foothills and lower mountains, which will add to the heat discomfort.

This long duration of hot and dry weather will bring widespread elevated fire weather conditions away from the coast next week, with the potential for large vertical plume growth across the interior. The marine layer is expected to be fairly shallow,thus dense fog may become an issue in some coastal areas. The north- south pressure gradient will allow for weak to potentially moderate Sundowner winds across southwest Santa Barbara county, with Friday night likely being the best chance for moderate winds. Aside from gusty winds across southwest Santa Barbara County, interior mountains and desert will likely see an uptick in northwest to north winds overnight.

AVIATION

16/0537Z.

At 2346Z at KLAX, the marine layer was at 1400 feet deep. The top of the inversion was near 2500 feet with a temperature of 24 C.

High confidence in VFR TAFs for KPMD & KWJF.

Low to moderate confidence in remaining TAFs, lowest south of Point Conception. Arrival of cigs for current VFR sites be off +/- 3 hours and 30% chance KSBA/KBUR/KVNY may remain VFR. 40% chance for IFR cigs KBUR/KVNY, low chances elsewhere. KSMX/KSBP may remain MVFR or higher. Patchy marine layer will also cause conds to bounce between VFR and MVFR/IFR. Arrival of cigs at end of period may be off +/- 4 hours.

KLAX...Low to moderate confidence in TAF. SCT to OVC conds likely through 12Z, then OVC likely with VFR transition sometime from 16Z-20Z. 10% chance for brief IFR cigs tonight. Arrival of cigs Sunday may be off +/- 4 hours from TAF. 30% chance of IFR conds late Sunday. No significant east wind component expected.

KBUR...Low confidence in TAF. 30% chance VFR conds prevail. 40% chance for 005-009 cigs when cigs arrive..

MARINE

15/1024 PM.

Moderate to high confidence in forecast. Current Small Craft Advisory (SCA) for gusty winds over the outer waters from near Point Conception southward to San Nicolas Island and in the vicinity of the Channel Islands looks on track. May see a lull in these winds early Sunday morning, but winds will quickly rebuild late Sunday morning into the afternoon.

Good chance for SCA winds to be ongoing Sunday afternoon/evening through much of the week over the outer waters, with SCA winds expanding into the northern outer waters Monday afternoon/evening. Tuesday and Wednesday, local gale force gusts will be possible.

For the inner waters, SCA winds are possible during the afternoon to evening hours for the Santa Barbara Channel Sunday and for the Santa Barbara Channel and inner waters north of Point Sal Monday and Tuesday. Wednesday looks more favorable for SCA winds for the inner waters north of Point Sal. Local gusts near 25 kt are possible for portions of PZZ655 Sunday evening and Monday evening.

Building short period seas are expected, likely rising to around 7-8 feet over the outer waters.

LOX WATCHES/WARNINGS/ADVISORIES

CA...NONE. PZ...Small Craft Advisory in effect from 3 PM Sunday to 2 AM PDT Monday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Monday for zones 673-676. (See LAXMWWLOX).