A weaker Monsoon flow will continue this week, maintaining a threat of isolated, afternoon thunderstorms near the mountains, while a shallow marine layer and sea breezes keep the coast cooler, with patchy marine clouds and fog closer to the coast. Temperatures and humidity levels will continue to run a little above normal, until the weekend, when some cooling is expected.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Thunderstorms were quite active today across western AZ and into portions of SE CA, including eastern San Diego County, where some strong thunderstorms developed during the afternoon. Few cells were measured with a rain gage, but based on radar estimations, we had numerous spots between 0.5 and 1 inch running south from the Santa Rosa Mountains, along the desert slopes, and then south of the International Border. The largest area of heavy rain was estimated to be 1.5 to 2 inches east of Julian, which prompted a Flash Flood Warning. Deep moisture remained in this area today, while some drying occurred to the north and west, helping to limit the convection.
A look at our 00Z Miramar sounding shows the source of that drying, a shift in the winds at many levels, now from a more westerly direction. In addition to the winds aloft, our sfc pressure gradient has increased a bit more onshore as well. This is supporting west winds of 15-20 MPH, with gusts to 35 MPH this evening near the San Gorgonio Pass. Satellite imagery shows extensive marine stratus along the Central Coast and just outside the major coastal Islands. Some of this is reforming closer to the coast this evening and should be around over the next few nights.
A persistence of this pattern will likely mean little change in our weather this week. A few thunderstorms could still develop and roam our higher mountains, and deserts, but they shouldn't be as intense, or as numerous as the past couple of days. This could change late in the week if we get another solid Monsoonal surge, but that is far from certain, based on a jumble of model solutions. In play is a subtropical disturbance just now coming onshore in south TX. Broad high pressure steers it west across northern MX this week, but it is not clear how close it will come, or contribute to our weather as we head into next weekend.
150355z, Coast/Valleys, Patchy low clouds with bases 800-1100 ft MSL developing along the coast this evening. Periods of CIGS possible at KSAN/KCRQ after 07Z, and at KSNA after 10Z. Local vis 3- 5 SM where clouds near higher coastal terrain. Clouds/vis restrictions clearing 15-17Z. Patchy low clouds redeveloping near the coast after 16/02Z with similar bases. Otherwise mostly clear with unrestricted vis through Monday evening.
Mountains/Deserts, ISO-SCT SHRA/TSRA developing over the mountains again by 19Z Monday, dissipating by 16/02Z. CB bases near 10,000 ft MSL with tops to 35,000 ft MSL. Strong up/downdrafts and reduced vis in RA VCTY storms. Otherwise mostly clear with unrestricted vis through Monday evening.
No hazardous marine weather is expected through Friday.
Ca, None. PZ, None.
