textproduct: San Joaquin Valley

KEY MESSAGES

1. A warming trend continues through much of the week.

2. Minor to Elevated Heat Risk across the area throughout the week.

3. Fire risk increasing Wednesday and again this weekend.

4. Practice safety around lakes, rivers, and streams, as water is still running cold.

DISCUSSION

Quasi-zonal flow will keep conditions stable for the next few days and allow ridging to build in, leading to a steady increase in temperatures. Highs across the Valley are expected to be in the low to upper 90s Wednesday, increasing to the mid 90s to low 100s on Friday. This will create minor to elevated heat risk across the area throughout the week. Be sure to take appropriate heat precautions and check in on vulnerable people and animals.

Though the Omega Block is expected to break down, clusters are confident that significant ridging will build back over the middle and eastern US soon thereafter. Whether this will become another Omega Block or simply a prominent ridge is yet to be seen. Regardless, it will likely steer a few low pressure systems our way and help to moderate temperatures.

The first such system will approach the area this weekend, originating from the Pacific Northwest. Likely an inside slider, it will bring cooler, drier air, which will help to break the warming trend and bring more pleasant temperatures in the mid 80s to low 90s this weekend. The downside of this will be increased fire risk, particularly Saturday, when the combination of drier air and stronger winds will create concerning conditions, particularly in eastern Tulare and Kern Counties. There is also increased fire risk along the Mojave Desert Slopes and toward Frazier Park Wednesday due to hot and windy conditions. Though winds are not expected to rise to Advisory levels, they will still be of a level sufficient to cause increased fire concerns.

While temperatures are quite warm, lakes, rivers, and streams are still running very cold, with lake temperatures in the upper 60s and much colder where water is entering from higher elevations. These temperatures pose significant risk to both human and animal swimmers; appropriate cold water safety should be practiced at all times.

The general ridging pattern will lead to increased air stagnation. Ozone levels are expected to be elevated the next few days. Vulnerable populations should take precautions.

AVIATION

VFR conditions expected across the central California interior for the next 24 hours.

AIR QUALITY ISSUES

Elevated ozone levels expected the next few days. Vulnerable populations should take precautions.

CERTAINTY

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

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

None.