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.

..UPDATED AVIATION DISCUSSION

Today through tomorrow night...

The latest GOES Night Fog at 4:30 AM reveals that most of the coastal areas and inland stretching up to 15 miles in some areas within San Diego and Orange counties have been inundated with low clouds and overcast skies. These clouds may make it into the southern portion of the IE, namely the Temecula/Murrieta area, otherwise these low clouds will likely remain in place through sunrise, then given how shallow the inversion is with the latest NKX 12z sounding, alluding to a shallow marine layer, also gives confidence to a relatively quick mixing and scatter out of these clouds within the first couple of hours after sunrise occurs.

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

271130Z....Coast/Valleys...Low clouds based 0600-1000 ft MSL have developed and pushed inland, up to around 15 miles in some areas. 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 Tue., with similar bases initially, and then slightly lowering throughout the rest of the forecast period as they fill in along the coast. Low clouds begin to scatter from the inland to the coast beginning around 16-17z Tue.

Mountains/Deserts...VFR prevails with FEW-BKN mid-level clouds around 10-15k ft MSL will continue to scatter throughout the day and move out by later this evening. CU/TCU development possible over the mountains this afternoon, although chances of precipitation will be very minimal.

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.

BEACHES

A persistent long-period southwesterly swell (2-3 feet at 17-19 seconds) keeps surf elevated at around 3-5 feet with sets to 6 feet into Wednesday. By Wednesday afternoon/evening, a much higher amplitude swell associated with Hurricane Genevieve is set to build. Some uncertainty exists in exactly how strong this swell will be as it depends on the strength and track of Genevieve, but current guidance suggests the swell could be around 5-7 feet, with a period around 14 seconds. Should this come to fruition, breaking waves of 9- 11 feet are possible for south-southwest facing beaches for Thursday and Friday.

In addition to elevated surf, tides are expected to increase to a height of 6.0 to 6.5 feet MLLW by for this evening's high tide and continue at that height through most of the week. The combination of surf and tides will likely result in at least minor tidal overflow during the evening high tides. More notable coastal flooding is possible when the high tides combine with the elevated surf brought with Genevieve's swell later this week. It is worth noting, that with the effects from this year's El Nino, observed tides have been consistently about 0.3-0.5 feet below many baseline predictions.

A Beach Hazard Statement remains in effect through 6PM Wednesday due to the elevated surf, rip current risk, and concern for minor tidal overflow. Additional products for coastal flooding and high surf are looking increasingly likely for later this week.

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.