textproduct: San Diego

SYNOPSIS

Temperatures remain below normal until Wednesday with a deep marine layer and perhaps morning drizzle early week. Warmer weather returns for the end of the week as high pressure builds.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

The marine layer pushed in efficiently this morning, filling in the coastal basin and western valleys. High clouds associated with an upper level low over Central CA will continue to stream into SoCal through the afternoon. Even as the low marine layer clouds burn off, these higher clouds will keep temperatures a bit cooler today as well as decreasing heights thanks to the aforementioned low. Highs this afternoon will be 2-6 degrees below normal, in the mid 70s for coastal areas, 80s for inland spots and High Desert, and 90s for the lower deserts. The cooling trend continues into Monday as the low deepens to the north, encouraging stronger southwest flow and a deeper marine layer both Monday and Tuesday. While moisture isn't robust, both mornings may feature a deep enough marine layer to be sufficient for some localized patchy drizzle.

The low will become absorbed into the larger trough and sweep northward on Tuesday. Behind it, CA will be in transition between a strengthening high over Texas and a large Canadian low north of Washington. The Texas high will attempt to elongate and return the region to at least weak ridging, but influence from the Canadian low may limit the heating towards the end of the week. For now, high temperatures should return to near normal or slightly above, especially for Thursday/Friday as the ridge becomes compressed by the low propagating eastward along the Canadian/US border. This could shift the thermal axis closer to CA and increase temperatures on Thursday around 10-15 degrees compared to Monday's cooler temps. The spread remains wide on high temps later this week, but confidence is growing on a backdoor trough behind the main Canadian low that will stretch down to CA sometime over the weekend, likely cooling temperatures back to normal by Sunday as the ridge is pushed east.

Models are beginning to show the development of a tropical cyclone south of Baja late this week. NHC indicates that there is about a 90% chance of development here in the next 48 hours, although there is no confidence on track until after formation. Early indications suggest should something form, the elongated high may influence the propagation of such a system, and we will keep a close eye on any development here or if there are any impacts associated. Further information can be found at NHC's website at nhc.noaa.gov.

AVIATION

201800Z...Coast/Valleys...Partially masked on satellite by SCT-BKN high clouds, lower marine layer clouds (based near 2500ft MSL) that spread well inland overnight have begun to erode across the inland valleys. Under the influence of a larger storm system spreading into California, SCT marine layer clouds look to remain present along the coasts into the afternoon. Intermittent BKN CIGs remain possible into the afternoon. Come 00z Monday, expecting these low clouds to redevelop and surge back inland, filling the entire coastal basin by 09z. Bases will generally lift to around 2500-3000ft MSL, but could lift above 3000ft overnight. Clouds begin to scatter around 16-18z, but could take until as late as 21z Monday to fully clear out.

Mountains/Deserts...VFR conditions prevail into Monday. BKN high clouds AOA 20000 ft MSL becoming SCT to FEW in the afternoon and overnight.

MARINE

No hazardous marine conditions are expected through Friday.

SGX WATCHES/WARNINGS/ADVISORIES

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