Palm Springs area weather will transition from tranquil to unsettled rather quickly the next 24-36 hours, as a complex set of low pressure systems move through California.
For the Coachella Valley, the highest impact is likely to be strong or even damaging winds. Some rain is also likely, along with much cooler temperatures the next several days.
As of Thursday afternoon, the satellite images show a lot of cloudiness off the West Coast of the U.S. and Mexico.
STAGE ONE - THURSDAY AFTERNOON
The first low pressure area to move inland over our area is the warmest of the three, seen above as off the coast of Baja. This airmass originated from the deep tropics as a "Kona Low" the past several weeks, which caused periods of heavy rain for the Hawaiian Islands. The two low pressure systems to the north, which are tapping into frigid polar air over Alaska and Northern Canada, are moving south and absorbing the sub tropical system into their circulation. This conveyor belt of moisture from the southwest is responsible for the cloudiness today.
STAGE TWO - THURSDAY NIGHT
As the two low pressure systems combine and move closer to our area later today and tonight, winds will increase, and scattered mostly light showers are possible. Upper level southwest winds will begin to surface, and will likely begin to blow through the San Gorgonio Pass near Whitewater and the terrain will curve the winds to blow southeast into the rest of the Coachella Valley along the I-10 corridor. This weather scenario is also likely to cause south to southwest winds to also surface along the foothills, as the upper air winds are forced around San Jacinto Mountain. Winds may become severe, with gusts over 50 mph in some areas. As is typical with most wind forecasts here, some areas are likely to experience the winds, and other areas may be sheltered by the local terrain.
STAGE THREE - FRIDAY
By Friday, the strongest elements of the storm are expected to move into Southern California. The upper level winds (jet stream) will be directed over our area. Additionally, the local weather models are predicting that there is a decent chance that damaging winds may surface at times (known as "mountain waves"), especially along the foothills from Palm Springs to Palm Desert, from sometime early Friday morning into the afternoon hours. If this occurs, gusts approaching 65 mph could surface at times and cause localized damage. Blowing dust is a possibility as well. The southwest gusts will likely hit the foothill areas, whereas the northwest gusts blowing through the San Gorgonio pass will buffet the areas further north, closer to the I-10 corridor and up along Highway 62 into Joshua Tree. This could possibly be a damaging wind event, so take precautions now to secure loose outdoor items.
Some rainfall is likely at times for the Coachella Valley as well, but total rainfall amounts are expected to be only around 0.30 inch or less. Some areas may not see much rainfall at all, as the mountains under this type of system will likely act as a rain shadow for much of the valley. Much heavier rain is expected in the nearby mountains and coastal areas, with 2-4 inches in the mountains, and just under 1 inch of rain for most urban areas. A Flash Flood Watch is in effect for the San Bernardino Mountains and to the north and west, into much of the rest of Central and Southern California. Most snow will be above 8,000 feet due to the warm sector at the beginning of the storm. Temperatures will plummet Friday night, and the snow level could drop to 3,500 feet, but most of the precipitation will likely be gone by then. It is possible I-5 along the Grapevine north of LA could get snowfall Friday night, in case anyone is headed that direction.
TEMPS TO DROP FRIDAY NIGHT
Thursday: 73/50 - increasing clouds, breezy late, nighttime showers possible.
Friday: 74/41 - strong, possibly damaging winds, some showers.
Saturday: 61/39 - fair with some breezes.
Sunday: 63/40 - fair with some breezes.
Monday: 65/44 - fair and breezes possible.
GOOD NEWS FOR CALIFORNIA WATER SUPPLY
The Sierras will get dumped on by this system, with over 4 feet of new snow possible above about 9,000 feet.
LONG RANGE FORECAST
Next week looks a bit unpredictable. A weak to moderate Santa Ana wind is possible Sunday and Monday, but the confidence in the forecast falls into the low category by Tuesday. A system appears to stall to our south, and a few appear to be headed for the northwest U.S. However, it is unclear which of these systems will affect us, or if the weather will just remain cool and sensible.
In the meantime, enjoy the weather change, and watch for the possibility of extreme wind the next 24 hours or so, with highest likelihood Friday morning or afternoon.