textproduct: San Diego

SYNOPSIS

A warming and drying trend is expected through this weekend as weak zonal flow returns to the region. Thereafter, temperatures will hover slightly above seasonal averages through next week. Marine layer clouds expected for coastal areas and western valleys each night and morning.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Mid-level zonal flow has settled over the region as the low pressure system that brought us the cooler, showery weather of the past few days has moved northeast into the Intermountain West. As a result, today's weather has been significant warmer and drier than yesterday's. Taking a look at observed 24 hour temp change, temperatures at 11:30 AM today are anywhere from 2 to 22 degrees warmer than those at 11:30 AM yesterday. 24 hour change in relative humidity shows much drier air away from the coast. In both cases, the mountain regions have seen the biggest change, followed by the deserts and inland valleys.

This trend will continue for Sunday, when forecast high temperatures are 2-10 degrees warmer than today's, to a few degrees above the daily average temperatures. Thanks to southerly flow and a coastal eddy circulation, areas along the coast will see greater cloud cover tonight, which will help mitigate warming in these areas Sunday. Clouds will start in southern San Diego County late this evening and gradually creep northwards and into western valleys overnight.

Monday will see another degree or so of warming as zonal flow amplifies into a very weak ridge for the day, then temperatures generally level out for the rest of the week with no more than a few degrees difference in temperatures each day under weak troughing. Low level marine layer clouds will return each evening and linger through the mornings for the coasts and western parts of the valley, starting out on the shallower side then deepen slightly towards the end of the week, getting slightly further inland. All-in-all, we're looking at pretty typical late May/early June weather with warm temperatures and average, mild daily breezes.

By next weekend into early the following week, model solutions regarding the position, amplitude, and timing continue to diverge, with the ensemble mean continuing to indicate gradual cooling for late next week.

AVIATION

301800Z...Coast/Valleys...Mostly clear skies through late this evening. Low confidence on exact timing of cloud formation; most guidance suggests low clouds based 800-1300 ft MSL begin to develop off the coast around 06z Sun, slowly filling into coastal areas (in patchy fashion) through 10z and perhaps as late as 12z for Orange County coastal areas. VIS reductions 0-5SM (and patchy FG) in valleys east of the I-15 corridor in San Diego County. Scatter out 15-17z.

Mountains/Deserts...Mostly clear and VFR conditions through tonight with elevated onshore winds later this afternoon and early evening.

MARINE

Northwest wind gusts will approach 20 kts over outer coastal waters this afternoon and evening. Otherwise, no hazardous marine conditions are expected through Tuesday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.