We've enjoyed a welcome break from the wet and wild weather that has plagued most of California much of this winter. However, the break is rapidly coming to an end. For those of you enjoying the postcard perfect skies and warm temps, I suggest you get out and make the best of it. The jet stream is heading back into our area later this week, and may hurl storm after storm across the state once again. I'll get into the forecast in a moment, but let's take a look at where we are currently.
STATISTICS SO FAR THIS WINTER
Nearly all weather stations throughout the state of California are reporting above normal rainfall since October 1, 2016... which is the official start of the winter rainy season. The southern portion of the state is above normal, and as one travels north, rainfall becomes even more extreme. In many locations in the Sierra Nevada Mountains of Central and Northern California, rainfall (and rainfall equivalent of the snowfall) are currently on par with the wettest season to date ever recorded for those areas (back in 1982 for much of the Central Sierras, and 1969 for much of the Southern Sierra). Here are some official statistics:
- Actual Rainfall (Oct. 1 - present): 5.32 inches
- Normal Rainfall (Oct. 1 - present): 3.22 inches
- Surplus: +2.10 inches (or 165% of normal to date from October 1)
Other Cities across the street have impressive totals as well (Oct. 1 - present):
- Actual Rainfall: 12.94
- Normal Rainfall: 8.66
- Surplus: +4.08 (149% of normal to date)
- Actual Rainfall: 17.26
- Normal Rainfall: 10.55
- Surplus: +6.71 (164% of normal to date)
- Actual Rainfall: 24.49
- Normal Rainfall: 11.55
- Surplus: +12.94 (212% of normal to date)
- Actual Rainfall: 34.34
- Normal Rainfall: 21.40
- Surplus: +22.63 (154% of normal to date)
These rainfall readings are very impressive. Many areas in the central and northern areas of the state have seen rainfall totals that are more than double the averages. This has led to many reservoirs filling very close to or even exceeding capacity (as was the case with Lake Oroville several days ago, which crested over it's emergency spillways for the first time in history). Even those reservoirs that aren't filled stand a good chance of being filled in the weeks to come, as another strong jet stream is set to hit California. Here are the latest reservoir readings throughout California.
Six reservoirs are already above 90% capacity, and the spring snow runoff season hasn't even begun yet. It is likely that many reservoirs will soon need to utilize emergency overflow, as they will be at capacity. This will certainly spell trouble for Lake Oroville, which has been damaged due to the extreme runoff.
The official drought map as of February 7, 2017 shows that 41.6% of the state is no longer in a drought. Extreme rain and snowfall has made up the deficits that took several years to accumulate. That leaves 58.54% of the state in some level of drought. However, the severity has been greatly diminished, with no areas of the state considered "Exceptional Drought", and less than 1% considered "Extreme Drought". This map will likely improve greatly with several more weeks of rainfall and mountain snow ahead of us.
WEATHER TO BECOME WET AGAIN
The jet stream is strengthening across the Pacific, and is headed for Southern California by the end of the week. A series of storms are lined up for Thursday night - Saturday, and it appears this particular cycle may be a direct hit for Southern and Central California.
This storm is expected to stall slightly as a rapidly deepening surface low pressure system develops just off the coast late Friday or Friday night. This is expected to bring very strong southerly winds along the coast and mountains, and is expected to allow moisture to easily flow up and over the mountains into the deserts. This particular setup is not particularly conducive for high winds in the Coachella Valley (although they are still possible at times), but it is conducive for heavy rainfall and a diminished rain shadow effect, especially since there will be a subtropical moisture tap feeding into the system. Current estimates are that some areas of the Coachella Valley could receive up to 1 inch of rain Friday through early Saturday. This would easily be enough to cause the flooding of roads and intersections during periods of higher rainfall. Higher 2 day rainfall figures are expected in the nearby mountains, with 2-4 inches in the San Jacinto Mountains and 2-7 inches in the San Bernardino Mountains. Snow level is expected to remain near 7,000 feet for most of this system, with 1 foot or more of snow above that level.
Rainfall amounts of this magnitude will easily fill the Whitewater River, as well as the Tahquitz Creek and Araby Wash with additional flows. Local roads may be susceptible to temporary closures, such as Indian Canyon and Gene Autry Trail south of I-10, Vista Chino east of Gene Autry, and Cathedral Canyon Road, among others. Water is currently flowing across Cathedral Canyon Dr. in Cathedral City, and the latest storms haven't begun yet.
Skies will likely become partly cloudy by Saturday afternoon with only scattered showers expected, and much cooler temperatures.
Computer models suggest large amounts of rain for much of the west coast the next 5 days. Here's the latest imagery from NOAA:
SUNDAY - WEDNESDAY
Sunday is expected to be mostly dry, perhaps a bit breezy, and rather cool. Temps will likely stay in the 60's or low 70's at most. For Monday-Wednesday, the computer models are all over the place. Some show a few weaker systems moving through, with a focus on Central and Northern California. Others show dry weather for a few days. The potential exists for additional showery weather for the desert areas at times, with dry intervals in between. Those traveling to Central or Northern California should be prepared for additional storms, flooding rains and high winds. For us here the possibility exists for more wet weather as well, although it likely won't be severe.
BEYOND NEXT THURSDAY...
Long range computer models are forecasting another stormy pattern during this time period. The details are too far away to settle on with much confidence, but the potential exists for more strong storms, heavy rainfall, and heavy mountain snows later next week. This could spell trouble for Lake Oroville.
Interestingly, the models are showing a strong high pressure system building over the Gulf of Alaska again, which tends to cause "atmospheric rivers" to be directed toward California. The forecasts will need to be monitored, as California can only handle so much more water!
The forecasts also predicting a nearly record breaking "MJO", which causes a reversal of the normal trade winds along the equatorial West Pacific. Westerly winds blowing along and north of the Equator can cause the ocean temperatures to warm higher than normal, and move east toward North and South America. In the past, if several of these weather "MJO" reversals occur during the winter months, they often display the precursor to a future El Nino condition.
After a few boring weather years, one can hardly describe this winter in California as boring! Be careful out there and pay attention to media reports as the system approaches.