Marine Weather and Tide Forecast for Fort Washington, CA

KEY MESSAGES
1. Early season heat arrives early next week with expected temperatures rising to triple-digit values Monday and Tuesday in the San Joaquin Valley.

3. Moderate Heat Risk expected for the valley areas, with a medium chance for Major Heat Risk.

4. Practice safety around area lakes, rivers, and streams as waters are running cold.

DISCUSSION
Current satellite imagery and surface observations confirm the obvious: warm and dry conditions provided by subtropical ridging. This will remain the case for the coming days, albeit with "hot" being the more appropriate adjective as ridging builds and reaches peak strength on Monday. The NBM places the San Joaquin Valley under a 50-60% probability for afternoon high temperatures above 100 degrees on Monday, increasing to 70% across urban areas. Similar probabilities will be confined to the edges of the valley and greater urban areas on Tuesday.

While overnight lows in the 60s will generally prove to be pleasant and help with daytime recovery, the "thermal belt" valley and foothill areas between 400-1000 ft will only cool to the upper 60s to low 70s, limiting overnight cooling to those unable to access air conditioning. As a result, the prevailing moderate risk for heat illness on Monday and Tuesday has a 50-70% probability to be major in these thermal belt areas such that otherwise healthy individuals are at risk for heat illness should proper actions (drinking plenty of water, limiting time outdoors and in sunlight) not be taken.

Dry conditions will prevail over this weekend into early next week. By Tuesday, there is a slight (10-15 percent) chance for thunderstorms over the higher elevations of the Sierra Nevada as a low pressure system approaches the West Coast. Otherwise, expect winds to once again pick up over the Sierra Nevada crest and into the Kern County desert. In addition, humidity will continue to lower until early next week in the desert and the thermal belts in the foothills and coastal ranges each day as we heat up, and overnight recovery will worsen.

Noticeably cooler temperatures will take place by the middle of next week, but highs remain above seasonal averages with temperatures in the upper 80's to near 90 degrees in the warmest locations. Daytime humidity will remain low in these locations through much of next week, although overnight recovery will improve.

Latest CPC outlooks show continued above average temperatures with a slight tilt in the odds towards above average precipitation at both the 6-10 day and 8-14 day periods.

AVIATION
VFR conditions will prevail for the next 24 hours over Central California.

FIRE WEATHER
Warming out of shade temperatures through this weekend and early next week will result in lowering relative humidities across the region. Minimum RHs in the Mojave desert will fall below 15 percent on Saturday. For Sunday through Tuesday, minRHs are expected between 5 and 10 percent in this area. RHs will fall to or below 20 percent in the San Joaquin Valley and Sierra Nevada Friday afternoon and continue at these values into the weekend. RHs at 15 percent or less are expected for these areas on Monday and Tuesday, with the Tehachapi Range and southern Kern Mountains at or below 10 percent. A downtrend in 100- and 1000-hr dead fuel moistures is anticipated with this warming trend; however, both parameters are expected to remain above critical thresholds. Upsloping winds from the southeast along the eastern Sierra can help to further dry fuels, especially in the portion of the range in southern Tulare County. New fire starts may also spread more quickly with increased gusts along the southern Sierra.

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 from 11 AM Monday to 8 PM PDT Tuesday for CAZ300>317-319-321-332.