textproduct: San Diego

SYNOPSIS

A gradual cooling trend begins today and will continue through Wednesday, bringing temperatures around 5 degrees above average by midweek. The upper level ridge will shift west again towards the end of the week and restrengthen with increasing confidence that this setup could provide us with the hottest temperatures of this summer thus far, especially by Saturday. Some monsoonal moisture transiting over the region by later in the week and into the upcoming weekend may also provide a slight chance of afternoon showers and thunderstorms for our mountains and deserts.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

Today through tomorrow night...

Low clouds have continued to struggle to form overnight, with only some patchy areas of low ceilings and fog, mainly along the coast of northern San Diego County, and around the Oceanside to Camp Pendleton districts. Elsewhere, skies have continued to clear. Temperatures still remain quite mild at midnight, with mostly low 70s at this hour (midnight).

The ridge is beginning to shift a little further east today as there will be further influence by an area of troughing upstream, which is going to continue to usher in relatively drier air into the mid levels, and likely limit the chance of any thunderstorm development this afternoon as the mid-level moisture becomes more suppressed and confined over Arizona. This troughing will also allow for a very gradual cooling to take place today through tomorrow, although highs will still be running around 5 to 10 degrees above average for most locations. The marine layer will likely struggle again to develop tonight, and remain mostly in place along the coastal areas of San Diego County, then slowly extend further into some of the inland areas closer to daybreak.

Wednesday through the upcoming weekend...

Slight cooling will continue through Wednesday, then the troughing upstream will begin to weaken and allow for the upper level ridge to further strengthen and expand back towards the west. This will allow for temperatures to increase again well back above the seasonal average for this time of year, by as much as 15 degrees for some locations, especially within the Inland Empire. By Saturday, there could be several locations within the IE topping out around 110 and above, and likely warranting the issuance of more heat products at that time. If planning to be outdoors for this upcoming weekend, it would be wise to prepare for this heat by ensuring that there are plenty of drinking fluids, as the combination of the increase heat could put those sensitive to heat as risk of dehydration. There will also be a better push of monsoonal waves transitioning around the plateau high located around the Four Corners region by later this week, which will allow for influxes of mid-level moisture to move in over the region and possibly allow for a few showers and afternoon development of thunderstorms over the mountains and deserts, yet this will all be decided on the timing of these pulses of moisture as they transition over our area. Otherwise, hot and dry conditions will continue to be the case into the upcoming weekend.

AVIATION

270600Z....Coast/Valleys...Patchy low clouds based 1100-1400 ft MSL have developed just offshore and will continue to push inland and up the coast through 12z. VIS reduced along elevated coastal terrain and locally in elevated valleys up to 15 miles inland. Low clouds mostly scatter 16-17z. 30% chance that brief cigs possible at the immediate coast after 21z as low clouds begin redeveloping early. Otherwise, VFR conditions prevail Monday afternoon until another round of low clouds push inland likely after 04z with similar bases.

Mountains/Deserts...VFR prevails with FEW-BKN mid-level clouds around 10-15k ft MSL for Monday. A few stray showers are possible over the mountains and into the adjacent deserts Monday afternoon.

MARINE

Calm conditions into the early half of next week with waves 3 to 5 feet and afternoon wind gusts near 15 kts or less through Tuesday. Waves increase in the outer waters mid to late week with waves expected around 5 to 7 feet.

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 Wednesday afternoon for Orange County Coastal Areas-San Diego County Coastal Areas.

Heat Advisory until 8 PM PDT this evening for Orange County Coastal Areas-Orange County Inland Areas-Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Coastal Areas-San Diego County Mountains-San Diego County Valleys-Santa Ana Mountains and Foothills.

Extreme Heat Warning until 8 PM PDT this evening for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass near Banning.

PZ...None.