Cloudier conditions with warm weather is expected today. Santa Ana winds remain gusty this morning, then weaken by this evening across the mountains and western valleys. A low pressure system will bring periods of showers for New Year's Eve and New Year's Day with the potential for more cloudier and wet weather by the end of the week into early next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, NEW AVIATION DISCUSSION FOR 12Z TAFS,
Santa Ana winds continue this morning across the mountains and parts of the western valleys as a surface high straddles the Utah-Nevada border. Winds will peak in intensity after sunrise with gusts near 25-45 MPH, locally higher across mountain peaks and passes. The Santa Ana wind pattern will make for another warm day west of the mountains with plentiful highs in the 70s; even parts of East County San Diego may reach near 80 degrees. The pressure gradient will begin to relax by Tuesday afternoon and evening, leading to weaker winds.
A well defined area of low pressure to our southwest that gave us a nice sunset last evening for some folks will begin to move northward on Wednesday. Models continue to slightly delay onset of precipitation occurring, with a better consensus framed around Wednesday morning. A very dry atmospheric profile today will take it's time moistening up on Wednesday, so showers in the morning look fairly light with south-facing slopes of the San Bernardino Mts receiving the most appreciable amounts through the afternoon hours. Rain showers will become more widespread and a bit heavier by Wednesday evening through Thursday morning. The weather system will also bring increasing southerly winds, where confidence is increasing in seeing wind gusts at the coast near 20 MPH at times. This may impact the New Year's festivities wherever you are, so plan accordingly!
Coastal mountain slopes and Orange County will receive the majority of the rain; highest totals across San Bernardino County Mts. Through Thursday night nearing 2-4 inches. Chances for one inch or more of rain vary in Orange County near 50-70%, closer to 25-50% in western San Diego County. The deserts look to receive rain, but it will be light (mainly under one half inch). A break in the rain looks increasingly likely by late Thursday into Friday as the system departs and is replaced by a weak ridge over the area. Some areas of clear skies may occur, especially across the desert regions. Cooler with highs near average and more humid weather will last through this period as well.
A low pressure system in the Gulf of Alaska will be moving southward toward the West Coast this week. Model trends continue a subtle shift in the weather system's placement further north, leading to decreasing chances for rainfall across our region by Friday night into Saturday. Cloudier and cooler conditions are expected, but the best chance for rain will be for areas closer to the LA Basin. Model guidance begins to greatly diverge by early next week. Another low pressure system off the coast may continue a chance for more rainfall or a ridge over Mexico may begin to build in, resulting in drier and warmer weather. Nbm continues rain chances into early next week, though chances remain low near 30% or lower for measurable rainfall.
301115z, Generally VFR conditions through the TAF period with increasing coverage of BKN-OVC high clouds AOA 10,000ft. Patchy low clouds and -RA are moving up along the coast, but are unlikely to impact any land sites. Gusty offshore winds have largely relaxed across the region, with localized gusts near 20-30 kts possible in the mountain passes and coastal slopes into this afternoon. Elevated offshore winds cease between 00-06z Wednesday. By 12z Wed, VCSH and -RA will begin to impact many locations with reduced VIS down to 5SM and widespread clouds closer to 5,000ft MSL. RA chances increase and spread substantially Wednesday evening.
Strong southerly winds develop by mid day Wednesday, prevailing into Thursday afternoon. Gusts up to 20-25 knots at times. Otherwise, no hazardous marine weather conditions expected through Saturday.
Ca, Wind Advisory until 1 PM PST this afternoon for San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains-San Diego County Valleys-San Gorgonio Pass near Banning-Santa Ana Mountains and Foothills.
PZ, None.
