textproduct: San Diego

SYNOPSIS

A slight cooling trend begins today and continues through Wednesday, bringing temperatures down to around 5 degrees above average by midweek. Daytime temperatures rise again for Thursday through next weekend and we could see the highest temperatures of this summer so far by Saturday. Some monsoonal moisture aloft later in the week into the upcoming weekend may also provide a slight chance of afternoon showers and thunderstorms for our mountains and deserts.

..UPDATED AVIATION DISCUSSION

This afternoon...Temperatures range from a few degrees higher to a few degrees lower than at his time yesterday. There was a weak coastal eddy last night and low clouds from a shallow marine layer are persisting at the beaches of San Diego County. High resolution models indicate that a weak coastal eddy will likely return tonight.

A shallow marine layer will persist through the forecast period with night and morning low clouds mostly restricted to the coastal areas and western portions of the San Diego County valleys.

The large-scale pattern will remain quite stable, with high pressure centered over the southern Rockies/Desert Southwest and low pressure centered over the Gulf of Alaska. Through Wednesday, the high pressure over SoCal will weaken slightly in response to a vigorous shortwave trough moving inland to our north. The resulting height falls and weak cyclonic flow aloft will allow the marine layer to deepen a little and the low clouds to spread a little farther inland during the nights and mornings. Temperatures will be generally lower across the region but will be more noticeable nearer to the coast. By Wednesday, temperatures will range from a few degrees below normal in some locations west of the mtns to around 5 degrees above normal in the low deserts.

For Thursday through next weekend...The high pressure center will shift to the southwest and build over the Desert Southwest. This will bring significantly warmer conditions to SoCal, we are likely to see the highest temperatures so far this summer. Models indicate that Saturday will likely be the hottest day, with daytime temperatures ranging from 5-10 degrees above normal in the coastal areas to about 15 degrees above normal in parts of the inland valleys and deserts. Temperatures will range from the high 70s to the mid 80s near the coast, the low 90s to low triple digits in inland OC and SD County, low triple digits to about 110 in the IE, 80s to low 90 in the mtns, up to 113 in the high deserts and up to around 120 in the low deserts. The building high pressure will also make the marine layer shallower and restrict the low clouds to the immediate coast during the nights and mornings. The heat will likely abate slightly for next Monday as the high pressure weakens. Confidence in the coming high temperatures is relatively high due to the stable pattern and good agreement among model solutions.

AVIATION

280600Z....Coast/Valleys...Patchy low clouds based 1000-1400ft MSL increasing in coverage and will continue to push up to 15-20 miles inland. VIS 3-6SM where stratus nears terrain and in the valleys. Clouds clearing to the coast 15-18Z, remaining BKN-OVC at some of the beaches into the afternoon. Low clouds push inland again after 03Z Wed, spreading first into San Diego County and then further up into Orange County likely after 10Z Wed. Bases for Wednesday morning will be similar to today, around 1000-1300ft MSL.

Mountains/Deserts...FEW-SCT Cu AOA 15,000 ft MSL possible through Tuesday evening. Otherwise, SKC and VFR.

MARINE

No hazardous marine weather is expected through Saturday.

BEACHES

A south swell of 3-4 ft feet at 17 seconds will produce surf of 3-5 feet with sets to 6 feet into Wednesday. A Beach Hazard Statement remains in effect through 5 PM Wednesday for the elevated surf, high rip current risk, and minor tidal overflow.

Wednesday afternoon, a south swell associated with Hurricane Genevieve will arrive. Some uncertainty exists in the height of the swell, but current forecast shows a swell (170-180 degrees) of 5 ft with a period of 14-15 seconds late Wednesday into early Friday, becoming more SSW (190-200 degrees) late Friday into Saturday with the period lowering to 12-13 seconds. This may produce surf of 5-9 ft on the south facing beaches north of Oceanside, surf around 3-6 ft elsewhere, and strong rip and longshore currents at all beaches. A High Surf Advisory is in effect from 5 PM Wednesday through 5 PM Saturday. In addition to the high surf, evening high tides will be above 6 ft this week. A Coastal Flood Advisory is in effect from 5 PM Wednesday through 3 AM Saturday for the risk of coastal flooding due to the high tides combined with high surf.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement through Wednesday afternoon for Orange County Coastal Areas-San Diego County Coastal Areas.

Coastal Flood Advisory from 5 PM Wednesday to 3 AM PDT Saturday for Orange County Coastal Areas-San Diego County Coastal Areas.

High Surf Advisory from 5 PM Wednesday to 5 PM PDT Saturday for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.