A much needed weather pattern change is developing across the American West. High pressure is being replaced by a series of storm systems across the Pacific Ocean, stacked up all the way west to Asia.
Dry and record breaking warmth will be replaced by periods of clouds, high winds, cooler temps, and a chance for precipitation across Southern California the next few days. Most of the severe weather associated between now and Monday will affect the Central and Northern portions of California, with still respectable weather expected for the southern part of the state. However, the deserts may not receive much rainfall due to rain shadowing from our nearby mountains. More on that in a moment.
The satellite image as of Friday afternoon shows a parent low pressure anchored south of Alaska, and it is nearly stationary. Several smaller systems, marked by 1, 2 and 3 above, are located south of the parent low, and are all headed east toward California. An "atmospheric river" of subtropical moisture is delineated by the yellow line, which will add juice to each of the storms hitting California in the next 7 days.
This is the weakest of the systems, but it will continue to bring high clouds to our area through Saturday morning. As the cold front approaches and low pressure develops into the Great Basin, this system will likely to create increasing winds tonight. Winds will blow W20-30, G45 at times between now and Saturday morning... with higher gusts possible. Winds will likely remain confined to the normally windier areas including the I-10 corridor, as well as in the high deserts along hwy 62 and 247. A few sprinkles are possible tonight in the coastal areas to our west, but the deserts should remain mostly dry. Temps will remain mild tonight, 55-65. Saturday will see partly cloudy skies behind the first weak system, with winds W15-30 along the I-10 corridor at times. Highs Saturday mostly in the mid-upper 80's.
This storm will move into S. Cal Saturday night and Sunday morning. Clouds will increase again throughout all areas, with increasing winds once again. Winds WNW20-30 G45 through the I-10 corridor and higher desert areas are expected, with some southern areas seeing a slight chance of wind gusts near 40. As the cold front moves through Sunday morning, there is a 50% chance of mostly light rain showers for several hours. Rainfall amounts are expected to be rather light for the deserts... likely under 0.10 inch. Temps will cool Sunday into the upper 60's to low 70's.
This storm will have the most energy associated with it, but rainfall amounts are still tough to predict. At this time, it appears the system will deepen off the coast. Ahead of it, strong winds W30-45 G55-70 are possible Sunday night or Monday. This could create large areas of blowing dust and sand. The exact placement of the low pressure will have dramatic effects on our rainfall and snowfall potential. Currently, computer models predict 1 foot of snow above 7,000 feet for this system... but with only 0.25 inches of rain possible here in the Southern Deserts due to rain shadowing by the nearby mountains. However, a slight wobble to the southwest could cut these rainfall amounts dramatically, and leave us with more wind and less rain. I'm beginning to see signs that the windier and drier option may occur, with heavier rains from Orange County west. Stay tuned.
Tuesday through Thursday will likely heat back up into the 80's, before another strong system plows through CA sometime next Friday or Saturday.
Although this next storm cycle may not be a huge rainfall producer for the deserts, due to a predicted unfavorable wind setup, it is expected to bring excessive rainfall to the rest of the state. Many areas will see over 1-2 inches of rain in the rest of Southern California the next 5 days, with many areas further north seeing 7-10 inches of rain! We may feel a bit jipped, but the rest of the state will not!
Stay tuned for any updates to the forecast the next few days!