Not as hot with high temperatures returning to near normal today into much of next week. Monsoonal moisture remains in place through next week for continued chances of showers and thunderstorms over the mountains and occasionally into the deserts each afternoon and early evening.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION/MARINE/BEACHES DISCUSSION,
Mid level clouds from earlier convection are moving across the region this morning. Based on current satellite trends, it does not appear that enough cloud cover will be in place to inhibit convection this afternoon. With weak southerly mid-level flow in place, expect convection to be focused over the mountains and locally into the high desert. The 00Z KNKX sounding had around 1.5 inch of precipitable water, which is forecast to increase slightly today. Sufficient PW combined with weak steering flow/near stationary storms will increase the risk of flash flooding this afternoon where stronger storms occur. Some CAMs are showing hourly rainfall amounts in excess of 1 inch, and 90th percentile 1 hour precipitation from the REFS is around 1.25 inch, though very localized.
For the remainder of the forecast area, low clouds and patchy fog along the coast and up to a few miles inland will clear by late morning. The upper level high continues to weaken with high temperatures returning to near normal, though continued humidity will keep nighttime temperatures elevated.
The upper level pattern remains largely unchanged this weekend through next week with broad upper level ridging across the Central US, weak troughing off the West Coast, and a pair of tropical systems passing by to the southwest. This will maintain southerly or easterly flow aloft and monsoonal moisture across the region. Moisture and instability decrease slightly this weekend into early next week for less widespread convection with lower rainfall rates each afternoon. Both the EC and GFS ensemble means show an increase in precipitable water towards the middle of next week, though the spread is somewhere on the order of 0.5" or more, likely due to differences in the placement in the upper level high. Around 51% of the members have the high in a more favorable position near the Four Corners region, while the remaining 49% have the high centered closer to Texas, putting us on the fringes of the moisture for lower precipiation chances. Otherwise just minor fluctuations in temperatures with highs generally in the mid to upper 70s along the coast, upper 80s to 90s in the valleys, upper 70s to low 90s in the mountains, upper 90s to low 100s in the high desert, and 100-110 in the low desert.
171800z. Coast/Valleys, Multiple cloud decks with very patchy low clouds along the northern San Diego County coastline/southern Orange County coastline with bases around 1100-1500ft MSL along with increasing high clouds AOA 15,000ft MSL. Low clouds will continue to erode but high clouds should prevail through the afternoon. Low clouds with similar bases will develop tonight and spread into San Diego County after 05z Sat before moving up to Orange County likely not until 08z. These clouds will be very patchy with potentially intermittent CIGs at times through the night. Any low clouds that develop should begin to move back towards the coast around 16z Sat.
.Mountains/Deserts, Periods of high clouds AOA 15,000 ft and VFR conditions expected throughout the period. SCT Cu based 10-12 kft MSL and ISO-SCT SHRA/TSRA develop over the mtns this afternoon, most likely 20Z Fri through 01Z Sat. Any storms that develop may produce lightning, gusty winds, and vis reductions.
No hazardous marine conditions are expected through Wednesday.
High amplitude southerly swell (4-5 ft with a period of 12-13 seconds) will build Saturday into Sunday, bringing elevated surf and strong rip and longshore currents for Sunday through at least Tuesday. Highest surf, up to 7-8 ft, will be along south and southwest-facing beaches. Surf falls a bit after Tuesday and into Wednesday before another stronger southerly swell (3-4 ft with a period of 15 seconds) brings another round of elevated surf for the end of the week and into the early weekend.
Ca, None. PZ, None.
