textproduct: San Joaquin Valley

UPDATE

Updated Aviation Section.

KEY MESSAGES

1. Lake Wind Advisory continues for West Side Coastal Mountains north of 198 and San Luis Reservoir through 11 PM PDT today, July 5th, beware of unsettled waters.

2. Weak disturbance moving the California will allow for a slight chance of afternoon thunderstorms across the Sierra Nevada Crest today.

3. Dry and breezy conditions create elevated fire risk into next week, especially in the Mojave Desert.

4. Near-normal temperatures expected across the area today, then a warming trend over the holiday weekend.

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

DISCUSSION

The cyclonic flow pattern over Central California is expected to remain in place through at least the beginning of next week. The cyclonic flow is expected to lift out of the area as an area of high pressure attempts to retrograde toward the Four Corners area. Before this happens, will see a weak disturbance surge through California with a potential for unsettled conditions over the Sierra Nevada. While the disturbance will be too weak for lower elevation convection, orographic enhancement will provide the additional lift to maintain mountain convection Sunday Afternoon. Additionally, the cyclonic flow pattern will keep windy conditions going over the mountain passes as a Lake Wind Advisory will remain in effect through Sunday Night as strong wind blow through Pacheco Pass.

Before the middle of next week, Probability of Exceedance (PoE) of reaching 100 degrees remains below 20 percent across the San Joaquin Valley (SJV) through Monday. By Tuesday, PoE of reaching 100 degrees rises above 25 percent for the south end of the SJV with a steady rise in PoE from Mid-week into the latter part of next week. The Mojave Desert quickly hits triple digit temperatures as PoE of 100 degrees reaching above 90 percent by Tuesday. PoE only goes up from Wednesday through Saturday as triple digits will have high confidence of occurring across the SJV and Mojave Desert. During this period, ensemble SJV temperature analysis places the 90th percentile values between 102 and 107 degrees. Ensemble mean temperature places highs closer to 100 degrees this that time frame.

We see little or no precipitation for the period, other than the slight chance for afternoon high Sierra thunderstorms each afternoon. Current Probability of Thunder is showing as much as 15 percent along the Sierra Crest with lower values near 5 percent for lower elevations down to 7,000 feet. Otherwise, most areas will remain dry.

The latest CPC outlook continues to favor above average temperatures for both the 6-10 day and 8-14 day periods. They're also favoring of leaning above normal (33-50% chance) as moisture surging north from Monsoon origins. This trend is indicated in both the 6-10 day and 8-14 day periods. As temperatures rise, the area of high pressure will form and allow for southerly winds to push moisture northward. The CPC is also highlighting a Slight Risk (20-40%)for Hazardous temps from the 11th through the 17th, with the 12th through the 15th being a Moderate Risk (40-60%).

AVIATION

VFR conditions expected across the area for the next 24 hours, with a broken band of light showers moving through the Valley for the next few hours. Slight chance (10-15%) of thunderstorms along the Sierra Nevada Crest from Tulare County northward between 20Z SUnday and 03Z Monday.

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.