Fair and seasonal weather will continue for the coming week, with a gradual warming trend. The marine layer will gradually decrease in depth with night and morning low clouds not spreading as far inland nor lasting as long into the late mornings. Subtropical moisture will bring some higher level clouds this holiday weekend, but with seasonal temperatures.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Current satellite shows the marine layer clouds have retreated offshore this morning, with upper level cirrus clouds streaming in from the west. 500mb anaylysis depicts a broad but weak upper ridge axis stretched across the southwestern US with an upper level disturbance associated with with Post-Tropical Storm (P-TC) Douglas located on the far southwestern edge of the extended ridge axis. The presence and position of the ridge axis is more defined over our area today, continuing the warming trend seen the last several days. This brings high temperatures right around to just below average for early July: 70s for the coast, mid to upper 80s for the inland valleys, and 95-105 in the deserts. This weekend, as the upper ridge tries to slide westward, the disturbance associated with P-TC Douglas moves northward, passing off the southern California coast tomorrow. The main consequence will be added mid level moisture and cloud cover, serving to moderate high/low temperatures for Saturday and Sunday. However, with the mid level tropical moisture moving through, high resolution guidance simulated composite reflectivity suggests elevated precipitation will occur early Saturday morning, mainly over San Diego County. The caveat is that very little to none of it will actually reach the ground with dry air below the mid level moisture, serving to evaporate the rain. The only places with a shot to see precipitation reaching the ground will be in the mountains, but there is only about a 5% chance of this occurring. Either way, there is good confidence in a bulk of the moisture passing through by the mid-late afternoon, so pleasant weather is expected for Independence Day across the region.
The disturbance passing through Sat/Sun holding the ridge back lifts into the intermountain West by Monday, allowing the ridge to resume strengthening and become more defined across the Four Corners and Desert Southwest through midweek. After the relatively similar, near- average temperatures seen today through Sunday, a gradual warming trend is then expected for Monday-Wednesday, brining temperatures about 5-10 degrees above normal by Wednesday. This sends high temperatures to 110-115 for the lower deserts on Wednesday, with upper 90s to near 100 for the Inland Empire, leading to moderate to locally Major HeatRisk in the lower deserts, with locally moderate HeatRisk for the inland valleys. Clusters (and global ensembles) remain in good agreement with the ridge through Wednesday, placing it at is peak strength for our area, but then begin diverge for the second half of the week. While the disagreement is generally in how far and how quickly it displaces to the west, the overall theme is to kick the ridge to the west, bringing a subtle cooling trend in for the latter half of the week.
031740z. Coast, Low clouds with bases 1200-1600 feet MSL redeveloping after 04Z in San Diego County and after 08Z in Orange County, though cigs may be intermittent. Scatter out of any cigs Saturday around 15-17Z.
Otherwise, Gradually increasing high clouds tonight and Saturday, thickening and lowering to 8000-15000 feet MSL Saturday morning.
No hazardous marine conditions are expected through Tuesday.
Ca, None. PZ, None.
