UCLA Weather

from the Department of Atmospheric and Oceanic Sciences.

Friday - 6:45pm

Sunny

71°

High - 75°

Low - 65°

Today: Sunny day. Some high clouds in the evening but generally clear.

Five Day Forecast

Latest Average Hourly Temperatures

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Changes to the wind flow pattern affecting southern California were minor overnight. The low cloud field was a little more uniform early today (coverage-wise), but inland penetration was very limited in most areas (shallow marine layer). Low clouds cleared most areas quickly, but for some unknown reason (to me), low clouds were still prevalent around most of coastal San Diego County (as of this writing). With the computer models predicting a slightly stronger, on-shore flow, low clouds may be a little more persistent in many areas tomorrow. However, unless the marine layer deepens more than predicted (actually not expected to deep noticeably)., inland penetration should again be limited tomorrow. After tomorrow, building high pressure aloft should limit marine layer clouds to the immediate coast. There potentially could be an absence of coastal low clouds by Tuesday.

Looking at noon temperatures, it was several degrees lower in many areas compared with yesterday (same time). While the marine layer wasn't any deeper than yesterday, it was cooler than it was yesterday (somewhat drier, surface air indicative of some entrainment of cooler air from the open Pacific) This may continue tomorrow as a stronger, on-shore flow should favor more air from the open Pacific getting drawn to the coast. Any further cooling, however, should be minor. Sunday temperatures should be about the same or maybe slightly higher (effects of strengthening high pressure) A more noticeable warming trend is expected on Monday. By then, the marine layer should become minimal, and on-shore flow should be very weak.

Much warmer than normal weather should occur on Tuesday and Wednesday(including the coast). It still remains to be seen just how hot it will get next week, but none of the computer models are predicting an off-shore flow like the one that occurred on 6 July (reached all-time record 111 degrees at UCLA). If no, marginal, surface off-shore flow develops as some models show, temperatures near the coast should not exceed the 80s (includes the campus area). The valleys will be toasty (widespread triple digit heat), but it shouldn't get as hot as a couple weeks ago. The one area that could see similar temperature to the previous event would be the desert region. Some cooling should occur late next week when high pressure aloft should begin to weaken. However, at this point, only a minor cool down is anticipated (best cooling by the coast but still warmer than normal). Warmer than normal weather will probably last through the remainder of the month (less heat than what's expected in the first half of the week).

Some of the longer range models show a potential, "monsoon" moisture incursion over the subsequent weekend. The current, moisture incursion is waning (slow drying trend through the weekend). Water vapor content may fall back to seasonable levels early next week (during the heat wave), but a new moisture incursion could bring muggy weather back at the end of next week (southern mountain/low desert region first). Isolated, brief showers and thunderstorms are possible for the next couple of afternoons. A renewal of such weather in the mountain/desert region would be possible in the final days of the month. At this point, it doesn't look like the threat for showers will include the coastal plain.

UCLA Forecasts and analyses are written by James Murakami

– posted: 2018-07-20

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

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