textproduct: San Joaquin Valley

KEY MESSAGES

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

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

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

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

DISCUSSION

High pressure (heat dome) has shifted from near Las Vegas to over Wyoming in responses to a disturbance forces its way into the Pacific Northwest. This shift will allow for a slight cool down Today as current 24 hour change in temperatures are running 2-4 degrees down from mid-day on Friday. Will see similar conditions on Sunday as the disturbance continues ejecting toward Central Canada, but will also see a increase in the southerly flow over the Desert Southwest. Monday shows the area of high pressure rebounding over the Southwest as temperatures begin and warming trend.

Probability of Exceedance (PoE) on Monday will stay 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 20-30 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.

Climate Prediction Center (CPC) is indicating that the extended time frame of the 6 to 10 day period will remain on the warm side. Current CPC analysis has a 50-60 percent chance that temperatures will likely be above normal conditions.

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

None.