Marine Weather and Tide Forecast for Rancho Tehama Reserve, CA

DISCUSSION

Today

A weak cold front is traversing Northern California this afternoon. Latest Visible satellite depicts a narrow area of mid- level clouds streaming southeast across the area, while cumulus clouds are developing along the Sierra this afternoon. Mostly dry weather is expected to prevail today, but there is a low chance (less than 10%) of light mountain showers for the higher terrain in Shasta County. Afternoon temperatures are running 15 to 25 degrees cooler compared with yesterday's readings, with highs generally in the 70s. Breezy onshore winds will continue to weaken through this evening.

Cold temperatures are forecast to the mountains, with overnight temperatures in the mid 20s to mid 30s in the Sierra tonight.

...Sunday-Monday...

A cold An upper-level trough over the Pacific NW will evolve into a closed low and continue digging southward, approaching the area early Sunday. In addition, some moisture advection from remnant of Rachel will nose into portions of the Sierra Nevada. This will promote an increasing chance of wetting mountain showers to the Sierra and foothills Sunday and Monday. Colder air aloft will bring some shallow instability Sunday and Monday, capable of produce brief heavy downpours and a chance of isolated thunderstorms.
Rainfall total amounts forecast from a quarter to half of an inch for the Sierra, with the highest amounts south of I-80. While few hundredths for the Sierra foothills. Some CAMs are showing some nocturnal showers moving across the area from the south- southwest Sunday night into Monday.

This system will bring the first measurable snowfall of the season in the Sierra Sunday night trough Monday. Snow levels are expected to be above 7500 feet through Sunday, before lowering between 6000-7000 feet late Sunday night into Monday. Forecast amounts are between 0.5-4 inches mainly above 7000 feet, with 2-4 inches possible at the highest peaks. However, uncertainty remains on the exact snow amounts.

In addition, northerly winds are forecast to developed and increasing along the Sacramento Valley tonight through Sunday. Gust 30 to 40 mph are expected, with the strongest winds along and west of the I-5 corridor Sunday morning. Winds slightly diminish Sunday afternoon, but remain breezy into Monday morning. Daytime relative humidities are expected to return to the low 20s on Sunday, with some areas into the teens possible. Critical Weather Conditions are expected due to the gusty north winds and low relative humidities over Northern Sacramento Valley and adjacent foothills. A Fire Weather Warning is in effect from 7 AM Sunday to 5 AM Monday.

...Tuesday-Friday...

High pressure and upper-level ridge will build in quickly in the wake of the aforementioned closed low translating eastward. Any lingering mountain showers are expected to dissipate Tuesday morning as drier airmass moves in. Generally dry weather, with continuing below normal temperatures is expected on Tuesday.
Ensemble members are in a good agreement with the upper-level ridge continue building on Wednesday, before amplify and bring above -average 500 mb heights over the western CONUS Thursday and Friday. This will bring a drier and warming trend across northern interior California, with high temperatures back to the 80s. Breezy north to northeast winds are anticipated for the Sacramento Valley and adjacent foothills, and to the Sierra Thursday and Friday. There is a potential for Elevated Fire Weather conditions due to breezy north winds and low relative humidity (15-25%) over the Sacramento Valley and adjacent foothills.

AVIATION

VFR conditions continue across interior NorCal next 24 hours. Breezy winds over the Southern Sac. Valley with winds 8 to 12 kts and gusts up to 20 kts until around 03z Sunday before weakening through the evening. North to northeast wind develop over the northern Sac. Valley (RDD,RBL) with winds 10to 15 kts gusting up to 20 to 30 kts into 18z Saturday. The Delta will continue to see gusty southwest winds up to 15 to 25 kts until 06z Sunday.

STO WATCHES/WARNINGS/ADVISORIES
Red Flag Warning from 7 AM Sunday to 5 AM PDT Monday for Central Glenn Co & Interstate 5-N. Sac Valley in Tehama County-Shasta Metro.