UCLA Weather

from the Department of Atmospheric and Oceanic Sciences.

Tuesday - 5:14pm

Sunny

81°

High - 91°

Low - 61°

Today: Amended...Sunny remainder of day. Clear evening.

Five Day Forecast

Latest Average Hourly Temperatures

Off-shore flow exists over southern California today. However, early this morning, it wasn't strong enough to purge a very shallow, marine layer. So, I pared back temperatures on my original, campus forecast. It held up till about 2:15 PM. Then, vertical air mixing became more prominent (campus dew point temperature...measure of atmospheric, water vapor...began to fall). As of this writing, the UCLA temperature stood at 91 degrees. It could get as warm as my original forecast (93), but ocean breezes may keep it a little lower.

All the computer models show a slightly stronger, surface off-shore flow tomorrow. Wind-wise, higher elevation locales prone to Santa Ana winds should remain on the breezy side. However, like today, peak gusts should stay under 30 mph. Temperature-wise, a little more warming aloft is likely [FYI--very warm air aloft is the reason for temperature disparity this afternoon close to the coast. Near the coast close to sea level, temperatures have hovered in the mid/upper 70s, but locales about a 1000 feet or higher in elevation...places like the Santa Monica Mountains and Palos Verdes peninsula...it's warmed into the mid/upper 90s!]. So, it's likely to get warmer tomorrow than it got today. Overnight low temperatures should also be higher...downright balmy for the higher hillside communities. I didn't bother to amend the UCLA forecast upward (back to my original forecast) due to uncertainties about the shallow marine layer reforming. However, recent satellite imagery suggests that the local marine layer has become diluted or purged in places. If that holds up (as the various models have been predicting for days), I'll revise the campus forecast tomorrow (mid/upper 90s for Wednesday). Needless to say, the widespread, triple digit heat in the valleys will continue for at least a few more days (tomorrow should be warmest day of this week though).

So far, smoke from wildfires in northern California have stay up there. Upper level winds haven't developed a long fetch that would direct smoke into the Southland. However, subtle changes in the wind flow around upper level high pressure potentially could direct that smoke southward for a day or two. Smoke from Southland fires may also head toward the coast in places before the week ends. At least, the smoke layer shouldn't get as bad as it did a few weeks ago (hopefully).

The high pressure aloft that exists along the West Coast will weaken toward the end of the week. While storms will return to the Pacific Northwest states (currently, mostly clear and warmer than normal), changes in southern California will be much more muted. A cooling trend will occur. Marine layer clouds could return as early as Thursday morning (assuming marine layer stays diluted for the next 24 hours). A number of model solutions show a weak, intermittent, coastal eddy, which could help re-establish the low cloud field (inner coastal waters). A return to seasonable temperatures, however, isn't expected till Sunday or Monday. Depending on which longer range model forecast verifies, a few days of slightly cooler than normal weather may occur in the second half of next week. No relevant chance of wet weather in the state is foreseen through next week.

UCLA Forecasts and analyses are written by James Murakami

– posted: 2020-09-29

Data and technology is provided by UCLA's Department of Atmospheric and Oceanic Sciences

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