textproduct: San Joaquin Valley

KEY MESSAGES

1. Temperatures drop drastically into early next week.

2. High wind gusts over 35 mph are likely into Sunday night (65-80% chance) over the San Luis Reservoir with a Lake Wind Advisory issued. Gusts also increase for the Mojave Desert and adjacent slopes as well as the West Side Mountains with a Wind Advisory in effect.

3. There is a marginal (5-15% chance) risk for excessive rainfall in the Mojave Desert and along southern portions of the Sierra Nevada today.

4. There is around a 50-90% chance for 72 hour snowfall greater than 2 inches above 9000 feet from Sunday into Wednesday morning.

DISCUSSION

Waking up today, there was a lovely chill in the air. Looking out towards the East on my morning commute, this forecaster saw clouds. What a welcomed sight after having nothing but clear skies and high 90s for the past week! Its even cool enough for a cup of HOT coffee! For the next few days, the Central Valley will keep up these chilly mornings and cool afternoons. More on that in a moment.

Tropical Storm Rachel have dissipated around 8 AM MST over the Nevada and Arizona border according to the Storm Prediction Center (SPC). With that influx of moisture, the Mojave Desert in Kern Count will see rain today. The bulk of the rain for today is expected to fall by late this morning. This doesnt mean that there cant be a shower or two out in the desert after this time, but it wont be as significant of an amount. The 6 hour observations (as of writing, this would be from 2:30 AM to 8:30 AM) have anywhere of 0.01 inches to 0.10 inches. That area will look to remain cloudy for a majority of the day.

Lets zoom out real quick and talk about why this is happening and what to expect next. Current model guidance shows that a trough will drop into California beginning today. Its expected to stay in the area until Tuesday, when it then begins to move out of the area. With this trough dropping down, itll bring another round of more wide spread precipitation and cooler temperatures. Today, temperatures are expected to stay below 80 degrees, save for Bakersfield, which has a 60% probability of being above that temperature. Rest easy, Bakersfield readers, as temperatures are not expected to get above 83 degrees, as that is a 15% probability of exceeding a high of 83 degrees. This is right around normal for this time of year. The trough moving in will bring gusty winds to the problem spots, with gusts up to 45 mph expected in the Coastal Range in Kings and Kern County and the Mojave Desert Slopes, which can see gusts up to 50 mph. San Luis Reservoir can see gusts up to 35 mph, prompting a Lake Wind Advisory.

Monday is certainly looking to be the coldest day of the week. As the low moves in, temperatures will fall. There is a 30-45% probability of exceeding 70 degrees on Monday. Woah! This forecaster is a desert dweller, so this means sweater weather for me! Merced County, there is a 50-70% chance of exceeding this 70 degree mark, but only a 10-25% chance of exceeding 73 degrees. These colder temperatures are short lived, as the trough moves out on Tuesday and well begin a slow warm up. Well likely see 80s again by Wednesday, as there is a 15-30% probability of exceeding 80 degrees.

Oh? Doth my eyes deceive me? And a chance of snow for the Sierra Nevada? Thats correct, folks! Snow levels are expected to steadily drop to 6,000 feet. However, elevations that are above 9,000 feet will see accumulation greater than 2. However, over the next 3 days, theres a 70-100% chance for areas above that 6,000 feet to receive a dusting of snow. Now, on the Valley floor, we wont see much in terms of rain. Oakhurst only has a 6% probability of exceeding a trace of rain (0.01) on Monday. The Sierra Nevada and Tehachapi ranges will see the bulk of the rain as there is a 44% chance at Tioga Pass to see a wetting (0.10) of rain or more. This will steadily drop as the mountains are followed, dropping to an 15% probability of seeing the same amount or more of rain in Tehachapi. As mentioned above, there will be a warm up after Monday. As the low pressure moves out, ridging will take place once more. This looks to be another extended event, as the Climate Prediction Centers 6-10 and 8-14 day outlook has the Central Valley in a 60-70% (6-10 day) and a 50-60 (8-14 day) chance of above normal temperatures.

AVIATION

5 to 15 percent chance of thunderstorms after 18Z Sunday. IFR to MVFR conditions over the Sierra Nevada in clouds and showers. Otherwise, VFR conditions will prevail for the next 24 hours.

AIR QUALITY ISSUES

None.

CERTAINTY

The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback.

HNX WATCHES/WARNINGS/ADVISORIES

Wind Advisory from 2 PM this afternoon to 8 AM PDT Monday for CAZ337>339. Lake Wind Advisory until 11 PM PDT this evening for CAZ300. Wind Advisory until 11 PM PDT this evening for CAZ304-308-313.