Marine Weather and Tide Forecast for Vallejo, CA

DISCUSSION

***Early Monday Morning Update***

Widespread Moderate HeatRisk with areas of Major HeatRisk today have lead to issuance of a short-term Heat Advisory for the Sacramento Valley, northern San Joaquin Valley, and foothills of the Sierra. Overnight model runs and warmer than forecast low temperatures have led to product issuance this morning. Hottest temperatures of 104-108 in the northern Sacramento Valley, with 102-106 elsewhere.

Today-Tuesday...

Split flow aloft persists over interior NorCal as the region remains sandwiched between troughing across the Pac NW and ridging across SoCal and the Desert Southwest. This pattern effectively limited onshore flow and induced some offshore flow to northern portions of the forecast area as well. As a result, overnight low temperatures in the northern Sacramento Valley and Sierra thermal belts remained elevated in the 70s. With the Pac NW trough expected to eject eastward into Monday, little pattern change is expected until Tuesday. Another period of breezy north winds is anticipated overnight into Monday morning, with gusts 20 to 30 mph possible along and west of the I-5 corridor and north of I-80.

Widespread triple digit high temperatures were observed on Saturday throughout the Valley and another afternoon of similar to slightly warmer temperatures is anticipated. Given the continued depressed onshore flow and periodically breezy offshore flow in the north Valley, overnight low temperatures are expected to follow similar trends both tonight and Monday night. Current probabilities for high temperatures greater than 100F sit around 70-95% for the Delta, Valley, and lower foothills. Additionally, 50-80% probabilities of high temperatures greater than 105F are forecast for the northern Sacramento Valley with 15-30% probabilities through the remaining Valley. As a result, moderate HeatRisk is expected prevail area wide. The combination of low daytime humidity values into the lower teens and upper single digits, limited overnight humidity recovery, and periodically breezy to gusty winds will continue to introduce elevated fire weather conditions to the northern Sacramento Valley and surrounding terrain, Burney Basin, and Sierra foothills through Monday.

Wednesday through next weekend...

Ensemble guidance across the mid to late week period has begun to shift as the Pac NW trough ejection is being better resolved. The ridge axis that was forecast to center over the Desert Southwest is now showing indications of a westward shift to center over the Great Basin and SoCal. This shift in the upper level pattern will introduce rising heights aloft to interior NorCal and potential for a weaker onshore flow signal. While A slight 1-3 degree cool down is likely Wednesday-Thursday as the pattern becomes more ridge dominant, additional warming with limited overnight relief and a return to widespread Moderate HeatRisk is possible late week into next weekend. Despite marginal humidity recovery improvements for Delta Breeze influenced locations, low daytime humidity and poor overnight recovery is likely to continue for much of interior NorCal throughout the extended forecast period.

AVIATION

VFR conditions are expected to prevail over the next 24 hours. Winds generally remain 12 kts or less at TAF sites from Interstate 80 southward. West to southwest gusts up to 18 kts in the Delta from 00Z until 12Z Monday. North to west winds increase through the northern Sacramento Valley and Shasta County mountains after 03Z Monday, with periodic gusts 15 to 25 kts through 21Z Monday.

STO WATCHES/WARNINGS/ADVISORIES
Heat Advisory from 10 AM this morning to 10 PM PDT this evening for Butte County Below 1000 ft-C. San Joaquin County including Stockton-C. Solano County including Fairfield-C. Stanislaus County including Modesto-C. Yolo/NE Solano including Woodland- Central Colusa County Incl. I-5-Central Glenn Co & Interstate 5- Central Motherlode 1000-3000 ft-E. Diablo Range Above 1000 ft- Eastern Colusa County-Eastern Glenn County-N. Motherlode 1000- 3000 ft-N. Sac Valley in Tehama County-NE San Joaquin Valley Below 1000 ft-Sac Metro/W. El Dorado/Amador County-Sacramento County Delta-San Joaquin County Delta-Shasta County Foothills 1000-3000 ft-Shasta Metro-Sierra (Tehama-Plumas) 1000-3000 ft- Southern Motherlode 1000-3000 ft-Sutter/Yuba counties below 1000 ft-Tracy Triangle Below 1000 ft-W Tehama Co Foothills 1000-3000 ft-W. Glenn/Colusa Foothills 1000-3000 ft-W. Stanislaus County Above 1000 ft & I-5-W. Yolo County including Capay/I-505-Yolo / Solano County Hills.