textproduct: San Joaquin Valley

KEY MESSAGES

1. Upper 90s to triple digits expected to remain prominent through this week before a cooldown over the weekend.

2. Widespread Moderate HeatRisk throughout the forecast area into the weekend.

3. Heat Advisory has been extended until Friday at 10 PM.

DISCUSSION

While this is the start of a new week, the weather continues to be a similar story. Ridge will sticking around until at least this Saturday. Until then, continue to enjoy this blistering October heat! The southwestern portions of the Valley have the highest probabilities of exceeding triple digits today (55-75%), carrying through into Thursday when the probabilities will drop significantly. A slight weakness in the jet stream moved over the area today, bringing some stronger westerly winds and monsoonal moisture from the Desert Southwest. Because of this, there is currently a low chance (5%) for convection along the Sierra Nevada crest. Localized areas of the crest near Yosemite currently have a low chance (10-20%) of seeing at least 0.01 inches of precipitation today. Moderate HeatRisk continues to dominate over our forecast area into Friday, impacting those in the population sensitive to heat related illnesses, and without proper cooling and hydration. As such, we have extended our Heat Advisory through Friday at 10 PM.

Luckily, models currently agree that a trough will move into the PacNW and bring cooler temperatures, but some uncertainty remains regarding the strength of the trough. Cluster Analysis reveals the most likely scenario of the trough moving through our forecast area on Saturday, with an alternative scenario with some decent model representation shows the ridge dominating over the trough. We all hope that the likely scenario verifies, as this time of the year is pumpkin patch time, not stay inside and overheat time. The Climate Prediction Center still has our area under a 40-60% chance for above average temperatures in the 6-10 day and 8-14 day outlooks.

AVIATION

Isolated MVFR conditions in showers along the Sierra Crest between 18Z Mon and 06Z Tue. Otherwise, VFR conditions will prevail for the next 24 hours with surface winds generally below 12 knots.

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

Heat Advisory through 10 PM PDT Friday for CAZ300>322.