It will remain cooler and drier for inland areas through Friday, with patchy night and morning coastal low clouds spreading into portions of the western valleys at times. For the holiday weekend into early next week, Tropical Storm Marie will likely become a hurricane and is expected to remain well to the southwest of the area. However, an increase in surf at the beaches is expected. There could also be an increase in humidity, with more clouds and a chance of showers and slight chance of thunderstorms.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
This afternoon, The marine layer remains about 1500 ft deep and a few low clouds are lingering at the beaches. Otherwise skies are clear. Temperatures are generally near or a few degrees lower than at this time yesterday. Sfc pressure gradients remain onshore and are supporting westerly winds gusting 25 to 40 mph in the mtn passes and canyons, and on the desert slopes.
From previous discussion, A low pressure system along the West Coast will maintain stronger onshore flow at the surface and drier southwest flow aloft through Friday, with continuing near all-time record sea surface temperatures over the coastal waters. High temperatures for the mountains and inland valleys will remain as much as 5 to 10 degrees below average while high temperatures near the coast remain around average. High temperatures will range from the mid 70s near the coast to the mid to upper 80s to lower 90s for the Inland Empire the lower deserts around 100. Low temperatures will be a few to around 5 degrees below average for inland areas. Low temperatures for coastal areas will be mostly in the 60s, in the mid 50s to lower 60s for the valleys, in the 40s to mid 50s for the mountains, and in the upper 60s to upper 70s for the lower deserts. Patchy night and morning low clouds will extend into portions of the western valleys at times.
Tropical Storm Marie continues to strengthen and is expected to become a hurricane in the next 12-24 hours while continuing on a track toward the northwest. In the ensemble guidance, there continues to be a gradual slow shift toward the south and west with the highest track density. There continues to be somewhat greater spread in the track guidance once Marie reaches the longitude of Point Conception.
The most likely scenario remains that the core of Marie will remain well to the southwest of the area. Swell from Hurricane Marie is expected to bring an increase in surf to southern California beaches during the weekend with the biggest surf for beaches in Orange and San Diego Counties from Oceanside northward.
Even with the relatively drier solutions, those with the core of Marie remaining well to the southwest, increase precipitable water values to more than one inch over the weekend. At the drier end of the guidance, the NBM 10th percentile precipitable water value at San Diego increases from around 1 inch for early Saturday morning to 1.7 inches for early Sunday morning with the corresponding 50th percentile values at the same times 1.5 and 2 inches.
The low pressure system near the West Coast could draw some of the mid and high level moisture from Marie into southern California and the Great Basin bringing a chance of showers and a slight chance of thunderstorms. Over time from Saturday into Sunday, where that might occur would be moving slowly northward with time with the rainfall potential increasing with time as well with the increasing moisture content of the atmosphere. However, there remains larger spread in the details.
Nights should be warmer for the holiday weekend. High temperatures for some inland areas could be a little cooler depending on the amount of moisture influx and cloud coverage.
021800z, Coast/Valleys, SKC and VFR through this afternoon and evening. Patchy low clouds based 1400-1900 ft MSL redevelop over coastal areas and nearshore waters after 06z Thu. Best chance for intermittent cigs at coastal TAF sites will be around 12-15z. Any low clouds that develop will clear out again by 16-17z.
.Mountains/Deserts, Mostly clear skies through Thursday morning. Breezy westerly winds mainly through mountain passes and along desert slopes 21-07Z. Gusts 25-40 kts with pockets of moderate up/downdrafts over and in lee of ridges.
No hazardous marine conditions are expected through Sunday. However, wind gusts around 20 knots are expected each afternoon and evening through Thursday in the vicinity of San Clemente Island.
Southerly swells from tropical cyclones will continue this week. A large south swell from Tropical Storm Marie will move into the region Saturday, likely peaking Sunday-Monday. While there is uncertainty in the exact track of Marie which could result in differences in swell and surf direction and height, this will very likely result in elevated to high surf and strong rip and longshore currents. Maximum surf of 6-10 feet is forecast for south/southwest beaches. This will combine with high astronomical tides to increase the potential for tidal overflow and coastal flooding Saturday through Monday, highest chances Monday. Stay tuned as details become clearer in coming days.
Ca, None. PZ, None.
