Sprinklers or Not?

UPDATE (1pm): Quick frontal passage is expected between 1 and 5 pm, followed by intermittent showers into the evening hours. Radar echoes show some advection happening over Ventura county pushing east-south-east. We’re looking a quick shot of rain followed by gusty winds.

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So far, this year has been pretty dry. Since July, here in Irvine we are running about 60% below normal to-date. Our rain totals will, however, receive a boost today as a trough slides down the coast. It’s on a bit of an inland track right now, but has managed to muster up some moisture out over the ocean. Models show the main region of vorticity sliding overhead sometime between 2pm-6pm, bringing with it our best chance of some prolonged showers. It will also drag down some very cold upper level air, bringing snow levels down to 4,000 feet (or lower – 3,000 feet?? ) and possibly sparking some heavier showers/thunderstorms. Surface high temperatures will struggle to reach 60F.

Here is a satellite image showing the low dropping through Central California:

We should get between 0.25-0.5″ of rain near the coast, with totals increasing toward the mountains. Elevations above 4,000 feet could pick up 6″+ of snow.

Gusty winds will sweep in behind the low, boosting temps a bit for tomorrow up to 70F.

-Mike

A trough will slide into the ridge over the west coast through Tuesday.  Upper-level dynamics and surface features will decrease in intensity as the system nears our coast, Tuesday afternoon.  Although some rain is expected after 1pm, the amounts are uncertain depending on how the system holds-up as it penetrates the ridge.  Rain may not make it to Orange County until Tuesday evening….Or…May not make it at all.  Let’s hope for 0.20+” for Orange County.

This season will continue to be dry and mild through early February for the western U.S..  More Santa Ana events are possible on Feb. 3 with warm temperatures following.  No rain events are likely anytime soon.

The offshore flow ends on Sunday morning but will leave behind warm temperatures and dry conditions for the rest of the day.  Highs on Sunday could reach near 80°F again, capped by the return of a weak afternoon sea breeze. Dewpoints will struggle to approach 40°F Sunday afternoon after being in the teens the past couple days.  Although very dry layer aloft will mix down throughout the day Sunday, the weak onshore push and residual moisture from recent rains could elevate moisture levels.  Cold overnight lows on Sunday will contrast to the warm overnight temperatures of the past two nights.  Low 40s possible for inland Irvine with upper-30s for low-lying coastal areas.  A return to a stronger onshore flow is welcomed Monday with more moisture and much cooler temperatures.

Winds have decreased within the past couple of hours as of 7am Saturday morning.  However, we had a 46mph gust at 1am with gusts frequently exceeding 30mph until 5am.  Offshore winds will continue Saturday morning.  As of 7am, moderate offshore winds are just above the surface.  Temperatures are very warm (64°F) and will rise quickly due to a strong inversion just above the surface.  Look for warm temperatures and dry conditions Saturday with offshore winds.  Winds will decrease throughout the afternoon.

Steep thermal gradients will combine with upper-level support early Saturday morning resulting in strong offshore winds.  Delta thetas>10C are predicted between the high desert and LA basin after 1am Saturday coinciding with moderate flow aloft.  Strongest winds could occur early Saturday morning with gusts exceeding 40mph for inland Irvine.

A weak shortwave will pass through late Thursday night advecting cold air over the deserts with some moisture.  Some clouds are possible against the eastern slopes of the San Gabriels early Friday morning, accentuating the thermal gradient across the ridges.  Northeasterly winds with gusts to 40mph are expected beginning Friday morning for western slopes of Santa Ana mountains with high clouds.  Winds could begin for inland Irvine anytime during the morning hours after 9am. Winds could gust to 30mph.  High clouds during the morning clearing by afternoon, highs near 80F.

Offshore winds invaded inland Irvine Tuesday and Wednesday with gusts to 29mph on Tuesday and 24mph on Wednesday.  Winds have decreased as of Thursday morning and are not expected to return until Saturday morning.  A northwest flow will take over Thursday through early Friday with continued warm temperatures.  Onshore breezes are possible Thursday afternoon for coastal areas with stagnant conditions inland.  A warm, dry and windy weekend is ahead.  January will end with dry and mild conditions.  No rain in sight through early February.

Moderate offshore winds are expected anytime after 11am Tuesday morning for inland Irvine.  Gusts to 40mph are possible until late Tuesday night.  Moderate offshore winds are possible Wednesday morning decreasing in intensity Wednesday afternoon.  Dry and warm conditions are expected Tuesday, Wednesday and Thursday.

Despite rain on Saturday, we are still well below average for this date. This is why rain today is a veryyyyy good thing. A slow slog of moisture will gradually move inland throughout the day today. We don’t expect a major rain event, but the slow-moving nature of the front will keep the clouds and light rain around through most of the day. I. Expecting up to 1/2″ of rain, more in the mountain communities. Unlike Saturday, this storm is colder and is expected to bring snow to the mountains. Here’s a satellite image showing the storm moving inland over California:

Stay dry! -Mike