Southwest flow aloft will bring drying of monsoonal moisture the next few days with surface drying for inland areas as well. High temperatures will continue to cool today, then slowly warm to around average for next Tuesday.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Tonight through Saturday,
Low clouds have struggled to dissipate completely this morning under the blanket of a "baroclinic leaf" transitioning over the region that is associated with a shortwave trough approaching the area. This is also allowing for temperatures to be slightly cooler, and below the seasonal average for this time of year. There is some moisture still lingering over the region, along with just enough forcing to maybe allow for an isolated shower/storm or two to pop off later this afternoon. However, there is not high confidence of this since a majority of the instability is confined to the east of the CWA. Nonetheless, an isolated shower/storm or two developing over the eastern San Bernardino Mountains and then moving out over the high deserts cannot be ruled out. Some of the guidance does show the potential of this, although the consensus, especially with the mid-level flow being out of the southwest, which is not so favorable as more dry air is becoming advected in gives more credence to conditions remaining dry for today and through tomorrow. Winds will also increase later this afternoon across the higher terrain of possibly 50 mph or greater, and within the passes with possible gusts approaching 60 mph for Gorgonio Pass. This will also be the case for tomorrow, except that winds will be slightly lighter than this afternoon. Temperatures for tomorrow will also be slightly warmer, yet still below the seasonal average. The marine layer should fill in better by later this afternoon and into the evening with the presence of better onshore flow.
Sunday through Thursday,
Through the weekend, there will be a gradual warmup as the ridge to the east begins to expand back towards the west. Conditions should remain dry through then, as monsoonal moisture is suppressed further to the south. Temperatures will continue to warm into the early half of next week as the ridge further builds, and there could be pulses of monsoonal waves moving up from the southeast around the high centered over the desert southwest, which may increase chances of getting afternoon thunderstorms over our mountains and deserts during the afternoon hours. Best chances at this time look to be on Tuesday of next week, although even for this day, the mid-level flow initially beginning out of the southeast earlier in the morning turns more southwesterly by later in the day, with less favorability for development. Temperatures will return to around average through Wednesday, and then slowly begin to drop off going into the latter half of next week as the ridge weakens. Ensembles also reflect similar trends, with mostly dry conditions likely persisting through the end of next week.
131800z. Coast/Valleys, Patchy low clouds near KSAN will be stubborn to fully clear this afternoon, but otherwise VFR conditions will prevail. Low clouds will move inland early in San Diego County after 23Z with clouds extending into most valleys by 12Z. Bases will be around 2200 feet MSL with local vis 3-5SM inland. Scatter out Friday 16-18Z.
Regionwide, BKN clouds at/above 15000 feet MSL (with SCT clouds 10000 feet MSL over mountains through 00Z) and unrestricted vis, clearing west to east after 10Z Friday.
No hazardous marine conditions are expected through Monday.
Ca, None. PZ, None.
