Area Forecast Discussion

KEY MESSAGES

-Critical fire weather conditions in the Sacramento Valley through 5 PM PDT this evening due to gusty north winds and low humidity. -Well above normal temps in the lower elevations with widespread Moderate HeatRisk / Areas of Major HeatRisk into the weekend & triple-digit highs Thursday-Saturday. -Significant warm-up Monday-Tuesday for the northern and central Sacramento Valley, with increasing Areas of Major HeatRisk

DISCUSSION

It's sunny with well above normal temperatures this early afternoon, 2-5 degrees warmer than yesterday. North winds mainly peaked this morning, with gusts to 30 to 40 mph in the Sacramento Valley, strongest along and west of Interstate 5. Humidity levels barely recovered overnight, so far (around noon) have dropped into the range around 10 to 20 percent, likely drying further by late afternoon down into the single digits in some locations. The winds have combined with the low humidity to bring extended periods of critical fire weather conditions for the Northern Sacramento Valley and into the foothills of the northern Coast Range, with a Red Flag Warning remaining in effect through 5 PM this evening. Winds will remain breezy through the afternoon but should continue to decrease, becoming much lighter by evening. Even after the Red Flag event is over, expect low humidity levels and periods of breezy onshore winds into next week, bringing elevated fire weather conditions into early next week. Onshore flow, increasing humidity and cooling temperatures are expected mid to late week, lessening fire weather concerns.

Triple digit Valley highs are expected this afternoon and continue through at least the early weekend in many locations. Widespread Moderate HeatRisk is expected starting this afternoon, with areas of Major HeatRisk on Friday, and less so on Saturday across mainly the foothills. Delta breeze influenced locations will see some cooling through the weekend, while the northern Sacramento Valley, mountains, and foothills are forecast to see just slightly lower highs. The Heat Advisory continues for the northern and central Sacramento Valley and adjacent foothills through 11pm Saturday, June 13. While other areas in the Valley will benefit from the Delta breeze cooling influence, especially in the evening, it remains important for everyone in interior NorCal to practice heat safety! Stay cool and hydrated, and consider checking in on those more sensitive to heat.

Early next week high temperatures have trended higher for the northern and central Sacramento Valley, and could see even higher temperatures than for late this week. Major HeatRisk areas have also been trending larger there. Temperatures are forecast to trend lower mid to late week.

Mainly dry weather is expected into next week, but can't completely rule out a few stray showers or an isolated thunderstorm over the Sierra crest south of US HWY 50 over the weekend into Monday. Weak troughing and instability should at least produce some afternoon cumulus buildups in that area.

AVIATION

VFR conditions with clear skies over the next 24 hours. North winds linger through the northern/central Sacramento Valley today with sustained winds 10 to 20 kts and gusts 20 to 30 kts until around 00z Friday. After 00z, winds shift to the west-northwest across the southern Sacramento Valley and northern San Joaquin with gusts up to 15 to 20 kts until 09z Friday and will linger after 12z for the Delta. North winds 5 to 10 kts remain over the northern Sacramento Valley into 18z Friday.

STO WATCHES / WARNINGS / ADVISORIES

Heat Advisory until 11 PM PDT Saturday for Butte County Below 1000 ft-Central Colusa County Incl. I-5-Central Glenn Co & Interstate 5-Eastern Colusa County-Eastern Glenn County-N. Sac Valley in Tehama County-Shasta Metro-Sierra (Tehama-Plumas) 1000- 3000 ft-Sutter/Yuba counties below 1000 ft-W Tehama Co Foothills 1000-3000 ft-W. Glenn/Colusa Foothills 1000-3000 ft-W. Shasta County 1000-3000 ft.

Red Flag Warning until 5 PM PDT this afternoon for Butte County Below 1000 ft-C. Yolo/NE Solano including Woodland-Central Colusa County Incl. I-5-Central Glenn Co & Interstate 5-Eastern Colusa County-Eastern Glenn County-N. Sac Valley in Tehama County-Shasta Metro-Sutter/Yuba counties below 1000 ft-W. Glenn/Colusa Foothills 1000-3000 ft-W. Yolo County including Capay/I-505-Yolo / Solano County Hills.