textproduct: San Joaquin Valley

KEY MESSAGES

1. Lake Wind Advisory for San Luis Reservoir and Lake Isabella through 11 PM PDT Friday, July 10. Beware of unsettled waters.

2. Slow but steady warmup this week, with widespread Moderate Heat Risk by the weekend and isolated areas of Major Heat Risk.

3. Hot, dry, and windy conditions will create elevated fire risk today and tomorrow, particularly in eastern Kern and Tulare Counties.

4. Increased chance for Sierra Nevada thunderstorms late this weekend into next week with monsoonal moisture pushing into our region.

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

DISCUSSION

High pressure building over the Desert Southwest as temperatures continue climbing today. Will expected wide-spread triple digits as 24 hour changes have shown an increase of 3 to 5 degrees. With current temperatures already approaching 90 degrees before Noon, confidence is good that many valley locations will see +100 degrees this afternoon. While this mornings low temperatures fell within the 10th percentile range, can expect afternoon highs to reach the 75th to 90th percentiles as values could reach 101-106 degrees, valley-wide.

Probability of Exceedance (PoE) of reaching 100 degrees across the is high (+70%) for each day except for Monday. On Monday, PoE stays below 50 percent before the big warm-up early next week. By Tuesday, PoE of reaching 100 degrees goes back up to above 80 percent with PoE of 105 degrees in the 10-20 percent range. Higher percentages fall within the San Joaquin Valley portion of Kern County. While some uncertainty exist on the exact timing of the next heat wave, current assessment has it in the Tuesday through Thursday period. Uncertainty does exist as to the extension of the heat into Friday, but for now, will maintain lower-end triple digits for the end of the week period.

Four Corners high is indicative of monsoonal type moisture surging northward and into Central California. Ensemble model guidance shows a rise in the probability of measurable precipitation from near 10 percent on Sunday to values of 60-70 percent probability for at least a tenth of an inch (0.10) over 24 hours periods from Monday Morning through 5 AM Wednesday morning. These percentages were for areas of the Sierra Nevada between Fresno and Tulare Counties. There is also a 20 to 30 percent probability for thunderstorms across this area each day Monday through at least Thursday as there is little deviation in the synoptic pattern through the middle of next week.

If driving or boating in an area with a Wind Advisory, take appropriate precautions.

Water temperatures are still in the upper 60s and low 70s and much colder near water flowing from higher elevations. Exercise cold water safety at all times.

AVIATION

VFR conditions expected across the area 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

Lake Wind Advisory until 11 PM PDT this evening for CAZ300-332.