textproduct: San Diego

SYNOPSIS

Cooler weather each day with a deeper marine layer making it further inland into mid-week. Afternoon temperatures through Wednesday will generally be 2-5 degrees below normal. High pressure strengthens late week with warmer temperatures into the weekend.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Mid level water vapor satellite places an upper level low over Oregon and Washington, poised to continue to move across the northern portion of CONUS. This low brought an end to the abnormally hot weather SoCal had experienced the past week, and allowed for the marine layer to redevelop and thicken this morning. This system also has aided in tightening the gradient, producing stronger onshore flow with afternoon gusts today and tomorrow around 35-50 mph through wind-prone passes and along the desert slopes. While this low will meander eastward along the border with Canada on Monday, a second trough will swing down from the PacNW and form a closed low over southern Oregon and NorCal by Wednesday. This secondary low will reinforce the cooler weather we've had, maintaining a cooling trend through at least Wednesday. As such, high temperatures Mon-Wed will hover around 2-5 degrees below normal with overnight low temperatures also slightly below normal for everywhere but the deserts which will remain a bit hotter with slightly better humidity to the east. The marine layer will continue to deepen and make it further inland each morning into at least mid-week, with some hi-res guidance indicating it may be deep enough to sustain some patchy morning drizzle on Tuesday, although chances of this occurring are low.

The low will weaken a bit as it becomes absorbed in the upper level pattern and pulled northward later this week. As the low departs, subsidence over the Pacific to the southwest of San Diego will increase, with upper level ridging developing over CA Friday and Saturday. This will return the area to warming trend for the late week, although guidance is chaotic with the long-range pattern as the GFS attempts to return the region to troughing Sunday and beyond while the ECMWF maintains the warmer ridge.

AVIATION

131800Z...Coasts/Valleys...Low clouds near 1500 ft MSL will begin to clear this morning, with mostly clear skies this afternoon. Increasing confidence for cigs to return to coastal TAF sites after 01Z this evening. Cigs will be near 1200-1700 ft MSL ft MSL covering coastal TAF sites. Confidence low to moderate on cigs making it into KONT after 08Z, better confidence KSBD stays clear. VIS reductions of 3-5SM in elevated inland valleys (HZ/BR) and down to 0-5SM where clouds intersect terrain in the IE and surrounding foothills. Scatter out 16-18z Mon. with intermittent SCT-BKN cigs possible after 21z along the beaches.

Mountains/Deserts...VFR conditions prevail through the TAF period; typical late afternoon S/W winds gusting 15-25 kts (up to 35 kts through the Banning Pass) expected.

MARINE

West-northwest winds expected to gust up to 20 knots in the outer coastal waters this afternoon. Otherwise, no hazardous marine conditions are expected through Thursday.

SGX WATCHES/WARNINGS/ADVISORIES

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