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June 4, 2020 – Hot weather with high temperatures 10 to 15 degrees above average resulting in moderate to high heat risk continues through tomorrow. Cooler weather with some chances for showers and thunderstorms Friday through the weekend.

Discussion

The upper level pattern continues to have an upper low off the coast of southern California, while Four Corners ridging extends over NorCal, bringing hot and dry weather.

Another day of hot temperatures is expected today with afternoon Valley highs once again peaking into the 100s. Some daily temperature record highs are in jeopardy. The daily record of 102 for Sacramento Executive could potentially be tied or broken, with the NBM projecting a 38% chance of this happening. The same could happen for the downtown record, which is 103. The forecast of 104 for Modesto would tie the record for the date. Heat Risk levels are widespread Moderate to locally High. The Heat Advisory remains in place until 8 pm this evening. Temperatures fall back to near normal values Friday as a trough begins to approach the West Coast Friday, bringing cooler and wetter weather for the weekend.

Precipitation chances begin Friday night in the northern mountains and far northern Sacramento Valley as a cool upper low from the Gulf of Alaska approaches. Showers spread to the Sierra mountains and foothills after midnight. Instability increases in the afternoon Saturday with isolated thunderstorms possible mainly north of I-80. Gusty winds and small hail look to be the main threats with any storms that form. Dry weather is expected to continue in the southern Sacramento, northern San Joaquin valleys and the Delta.

As the cool low moves into NorCal Saturday night into Sunday, snow levels are expected to fall to near pass levels. Most snow accumulation should be limited to higher peaks, where a few inches of wet snow are possible. Pass levels could see an inch or 2, bringing brief periods of slippery conditions in showers.

Weekend temperatures will be significantly cooler than seen in recent days. Valley and Delta highs in the 70s are expected, 60s in the foothills.

Extended Discussion (Monday through Thursday)

An upper level trough will be pushing east early next week and we will see an upper level ridge begin to build into NorCal. This will bring warming temperatures throughout the week. Highs will start out a bit blow normal before warming back to near to a bit above normal by mid week. No precip is expected throughout the week and we will see mainly clear skies with the exception of Tuesday where some clouds will be possible in northern parts of the area.