Below-normal temperatures prevail for the entirety of the forecast period. A system arriving Monday/Tuesday will bring additional light rain/snow and gusty winds, along with a marine thunderstorm threat and coastal hazards. Another system late next week may bring similar impacts but with lower confidence.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
Another round of rainfall occurred early this morning, albeit significantly lighter than what occurred on Friday. Most locations saw anywhere from an additional 0.25-0.50" with the latter end of that range more localized to the mountains and foothills. While it's still humid and cloudy out there this morning with a few measly showers near the coastline, drier air will be filtering into the area through the afternoon as weak upper level ridging builds in behind the previous system. Slightly warmer temperatures can be expected on Sunday, just about or slightly below normal, with partly cloudy skies as we enjoy our break in between weather systems. Sunday might be the warmest day of the week as multiple rounds of larger upper level troughs/lows will advance through CA next week, bringing multiple chances for rain and/or winds, along with cooler/well-below-normal temperatures.
The first system of note is going to be a elongated trough stretching from Canada down into Baja, poised to approach the California Bight Monday afternoon. As it approaches, increasing instability over the waters and near the coastline could produce some isolated thunderstorms late Monday/early Tuesday, in a very similar fashion to what occurred Friday morning. Should these thunderstorms develop and be able to move ashore, intermittent heavy rainfall and stronger winds will be possible, most likely pre- sunrise Tuesday morning. Cape values, while mostly unimpressive, do indicate hot spots over the marine waters and into Orange County/IE during this time frame. Soundings indicate that any storms will move quickly, so no widespread flooding is expected. Outside of the thunderstorm threat, some area showers will move across as the open trough moves inland Tuesday morning, with less widespread rainfall as experienced the past two days. Instead of a closed low like the Friday storms, this system will remain an open trough and thus is expected to have less moisture associated with it. While precipitation amounts have been trending down, snow levels associated with this colder system are expected to hover right around 6000ft MSL Tue morning, allowing for some light accumulations at only the highest elevations. Because of the lighter QPF, the pattern does not currently support more than a trace/localized inch or so of snow.
Any and all precipitation with this next system should move out Tuesday afternoon, with another dry spell Wednesday with zonal flow aloft. Temperatures won't have much time to rebound before the following system arrives, and high temperatures continue to slowly fall through the week, bottoming out at 8-15 degrees below normal. Global models have better agreement on the next system today than they have the past several runs, indicating a deepening low will move down along the CA coastline before trekking eastward across Central CA late Thursday. Should this play pan out, the system may bring more cold and windy conditions for SoCal with less rainfall than previously expected. Still, much can change between now and Thursday, with a slide further south providing more ample moisture still a possibility late next week. Once better confidence is had on this low, a more detailed picture can be provided. For now, have maintained at least some rainfall in the Thursday-Friday time frame, as well as light accumulating snow for the higher terrain of the San Bernardino Mountains.
Additional mention and details of impacts with these systems next week are discussed below in the beaches and marine discussions. Please read these below.
150000z, Coast/Valleys, ISO-SCT -SHRA will be in the vcty of the San Diego County coastal sites through tomorrow morning. VIS may be reduced 3-5 SM at times with CIGS 1000-2500 ft MSL. FEW-SCT low clouds based 3-5 kft through the coastal basin this evening will likely become BKN in coverage tonight in San Diego County with SCT -SHRA just offshore. By late Sunday morning, any lingering low clouds should scatter out with mostly SKC and VFR for Sunday afternoon. VCSH will begin to return in the vcty of KSAN towards the end of the forecast period.
Mountains/Deserts, Cloud bases 3-6 kft MSL obscuring higher terrain will be in place through this evening, with ISO -SHRA possible through then. Remaining low clouds over San Diego County mtns this evening will slowly scatter out overnight with mostly VFR conditions by tomorrow morning.
Winds and seas diminish this evening into tomorrow, before increasing again Monday afternoon, with gusts up to 30 kts and seas 8-12 feet for Monday evening through Wednesday morning.
Ca, High Surf Advisory until 10 AM PST Sunday for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
