textproduct: San Diego

SYNOPSIS

Below average temperatures with marine layer low clouds and fog reaching into portions of the valleys through Sunday. Gusty westerly winds expected in the mountains and deserts this afternoon and evening. Warming trend expected Monday through at least the middle of next week. Areas of major HeatRisk possible for the deserts and moderate HeatRisk for inland Orange County, valleys, and mountains mid next week. The marine layer will become shallower next week, staying confined to coastal locations.

..Updated Aviation, Marine, and Beaches discussions

The marine layer was slightly shallower this morning down to 2500 ft from 3000 ft yesterday. That did not hamper the inland extent of the cloud coverage this morning, with satellite imagery this morning showing low clouds in the entire coastal basin and through the Cajon Pass. The inversion on the 12Z sounding from KNKX was a little weaker than yesterday, which has helped the speed of clearing. There are also higher chances of the beaches clearing this afternoon.

High temperatures through the weekend will be below average for most locations due to a passing trough. In addition to cooler conditions (and the deeper marine layer), elevated southwest to west winds can be expected. Gusty winds this afternoon and evening for the mountains and deserts will reach gusts of 30 to 40 mph and with local gusts to 55 mph in the northern Coachella Valley below the San Gorgonio Pass.

A more zonal patter on Monday will result in a few degrees of warming, with continued warming for the area through at least mid- week as an area of high pressure aloft builds over the southwest US and drifts west over California. Current forecast follows the NBM for Tuesday through next Thursday which will bring high temperatures 5 to 12 degrees above average with areas of moderate HeatRisk away from the coast and areas of major HeatRisk in the low desert. Hottest conditions based on current forecast are expected to be Tuesday through Thursday. Ensemble guidance is also indicating an increase in precipitable water for the middle to end of next week. That would result in warmer than normal overnight low temperatures, limiting overnight relief from the heat and making it feel humid. As far as the marine layer goes, the building high pressure and influx of moisture will result in a shallower marine layer and limited low cloud development.

The spread in potential forecast solutions starts to increase for the middle to end of next week. Ensembles are indicating the possibility of a shortwave trough moving through California during the middle to end of next week, which would result in increased onshore flow and cooler conditions, especially for the coasts and valleys. By Thursday, the spread in NBM high temperatures is 9 to 11 degrees between the 10th percentile of guidance (cooler) and 90th percentile (warmer. Depending on how the upper level pattern develops, there is a potential for the above average conditions and elevated HeatRisk to continue into the end of next week for inland locations.

AVIATION

200630Z...Coast/Valleys...Low clouds are getting a late start this evening with just a finger of low clouds around 1500ft MSL poking into KCRQ. Low clouds with bases 1500-2000ft MSL will slowly form over the next few hours, mainly over San Diego COunty, but is expected to be patchy in nature and not to the same extent as was seen last night. Inland vis restrictions 1-5SM will be possible where low clouds intersect terrain. Low clouds will scatter out 16- 19Z. Low clouds redevelop after 01Z Sunday beginning over coastal SD County.

Mountains/Deserts...VFR conditions expected through the TAF period. Breezy westerly winds with gusts 30-45 kts, locally 50 kts through mountain passes into deserts through 10Z. Local vis reduced in BLDU. Moderate up/downdrafts in lee of mtns. Westerly winds 30-40 kts redevelop through mountain passes into deserts after 18Z.

MARINE

No hazardous marine conditions are expected through Thursday.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement through Sunday evening for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.