textproduct: San Diego

SYNOPSIS

Weak to locally moderate northerly Santa Ana winds will set in through this morning and continue into Sunday morning, turning easterly for Sunday night into Monday. Weaker offshore flow will follow through at least Wednesday for gradual warming and dry conditions. Confidence in the late week pattern is still uncertain with the potential for a low pressure system to bring some cooling and a return of onshore flow, or for high pressure and offshore flow maintaining warmer and dry weather.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

Today through tomorrow...

As the upper level low exits the region, surface winds out of the north will switch around to more of an easterly direction by later in the day. Some of these gusts initially through Cajon Pass may occasionally reach Wind Advisory criteria, especially by later in the morning through the afternoon, where occasional gusts may approach 50 mph. The downsloping winds will also allow for high temperatures to be slightly warmer from where they were yesterday, and this warming trend will continue into tomorrow as high pressure builds back in. These winds will gradually weaken going into tomorrow, as the surface pressure gradient loosens. The weak offshore winds will also help to keep any development of the marine layer mostly confined over coastal waters, although some of this may creep onshore right along the coast by later in the afternoon as onshore winds become more predominant. Overnight, there will be significant cooling under mostly clear skies, which will allow for some of the wind-sheltered valleys of the inland areas to become quite cold, with even some possible areas of frost for some of the higher mountain valleys, along with the possibility of patchy fog as well.

Tuesday through Saturday...

By Tuesday, and going into the mid part of the week, the region will become more influenced by a strengthening ridge over the Great Basin. This will result in the gradual warming trend continuing into Wednesday, before beginning to break down as a major shortwave trough upstream propagates closer towards the region towards the end of next week. With this, there are going to be a few systems tracking across northern California, and the tail end of the associated boundary may give some areas of SoCal some measurable precip Thursday thru Friday, although this is still quite far out in the forecast and is therefore subject to change. The southerly flow by later next week will also help to warm up temperatures slightly Fri thru Sat. The marine layer will likely remain quite disorganized for the next couple of days, with offshore winds being more persistent. These winds will begin to transition back to being predominantly onshore flow going towards the end of next week, which will subsequently help to allow the marine layer to become more persistent by late evening through early morning, especially along the coast. There are some of the ensemble members which are also hinting at a slight chance of precip from the tail end of a frontal boundary from Thur thru Fri, though this is still quite far out in the forecast period and thus is subject to change.

AVIATION

251000Z...Increasing upper level clouds AOA 20k ft and VFR conditions through the period. Otherwise, gusty north to northeast winds along coastal slopes, and downwind of the Cajon Pass into the Inland Empire through 20Z. Gusts 20-35 kts along coastal slopes (locally 40 kts through the Cajon Pass) and 15-25 kts for portions of the Inland Empire. LLWS downwind of the Cajon Pass and VCTY KSNA possible through 12Z. Winds weaken after 20Z then strengthen again early Mon morning to similar levels.

MARINE

No hazardous marine conditions are expected through Thursday.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Wind Advisory until 1 PM PST this afternoon for San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-Santa Ana Mountains and Foothills.

PZ...None.