textproduct: San Joaquin Valley

KEY MESSAGES

1. Warming pattern coming through the weekend before a cooldown next week.

2. Winds become gusty and from the east over the Sierra Crest and eastern Kern County Thursday into the weekend.

3. With low Relative Humidity producing dry conditions, a Fire Weather Watch remains for the Kern County Mountains from Thursday AM through Friday PM.

4. Wind Advisory has been issued for the Mojave Desert zones from Thursday AM through Friday night with wind gusting up to 55mph.

5. A pattern change may be upon us early next week as a disturbance crosses the West and introduces unsettled conditions.

DISCUSSION

Time for your favorite part of the day, reading the Area Forecast Discussion (with some sarcasm)! The shivering temperatures the past few days have been a relieving welcome, but the low pressure system that caused them is pushing eastward into the Great Plains, aside from a shortwave trough cutting off down into Baja California. Sucks, because we deserve the lower temperatures more than them, wouldn't you agree? Mother Nature must not think so, as thereth existeth some heat on the horizon. This heat will be caused by a "tag team" from a high pressure system building over northern California and the Northwest states, along with a Mono wind- like event bringing hot dry air dry adiabatically downslope along the Sierras and Kern Mountains. This atmospheric setup is called a "Rex Block", where the westerly wind moves north around the high and to the south around the low, resulting in a "backwards S" shaped pattern with the strong easterly to northeasterly winds in the middle of the block moving into the Central Valley. The term Rex Block sounds cool, its like a dinosaur playing with legos! As a result of this, temperatures will gradually warm across central California, nearing ten degrees above season averages again this weekend. While this doesn't approach the boiling point like last time, you may still sweat a bit this weekend. Current probabilities for afternoon highs to exceed 90 degrees for both Friday and Saturday currently sit at 55-70%, resulting in widespread Minor HeatRisk. A lack of greater HeatRisk levels is due to cooler overnight temperatures compared to the previous heat wave earlier this month. Anything above minor would be very mean of Mother Nature.

Relative humidity values will be rather summer-like across the region, with minimums largely between 15 and 20 percent beginning Wednesday and lasting through the weekend except for at the highest elevations. The stronger pressure gradient in between the Rex Block results in moderate probabilities (more than 40%) for maximum wind gusts to exceed 35 mph over the Sierra Crest and Kern County Mountains. Thereth also existeth moderate probabilities (greater than 50%) for maximum gusts to exceed 55 mph in the Mojave Desert Slopes. There are even localized probabilities in the Southern Mojave Desert to exceed 60mph Friday night. As such, we have issued a Wind Advisory for the Mojave Desert active Thursday morning through Friday night. Da winds be gustin, so be careful!!

Into next week, ensemble cluster analysis shows agreement in a low pressure system passing through central California after dropping in from the north Pacific, with potential to bring precipitation to the region. As of now, there is a 25 to 35 percent probability for measurable rainfall (greater than 0.01") over 12 hour periods starting Tuesday afternoon and extending into late Wednesday in the San Joaquin Valley, and greater probabilities with increasing altitude. Because this time period is currently days 6 and 7 in analysis, confidence in any precipitation from this storm is low to moderate at best. As we get closer to the weekend, it would be nice to see this scenario verify. Another note, lowered snow levels associated with this colder system has moderate probabilities for the peaks to receive a trace or more of snowfall. Although Frosty the Snowman did not make an early October appearance from the last disturbance, there are chances of him coming next week.

AVIATION

VFR conditions will prevail for the next 24 hours.

FIRE WEATHER

Stronger wind gusts developing Thursday and Friday across the higher elevations of Kern County paired with minimum relative humidities approaching 15 to 20 percent will bring an increased risk for fire danger. Overnight recoveries reaching 40 percent at best will extend the threat into the overnight hours as well. Due to this, a Fire Weather Watch has been issued for the time period, focused on the areas from Frazier Park and Pine Mountain Club to the areas between Lake Isabella and Tehachapi.

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 6 AM Thursday to 10 PM PDT Friday for CAZ337>339. Red Flag Warning from 3 AM Thursday to 10 PM PDT Friday for CAZ592>597.