North Bay

ESFMTR A SERIES OF STORMS WILL BRING PERIODS OF RAINFALL TO THE REGION LEADING TO POTENTIALLY RAPID RISES ON AREA CREEKS AND STREAMS * WHATA series of storms over the next week will bring periods of light to moderate rainfall to the region. The first in the series of storms is a shortwave trough that will move into the North Bay Wednesday evening and slide south across the region Wednesday night into Thursday. Confidence has increased significantly with this system and it is expected to bring light rain across the North Bay and the San Francisco Bay Area. The higher elevations of the North Bay will likely see around a half an inch of precipitation while North Bay valleys see around a quarter of an inch. Bay Area locations south of the Golden Gate, including the Santa Cruz Mountains, will see a tenth to a quarter of an inch. Less than a tenth of an inch of rain is forecast across the Central Coast. A stronger, more significant rainfall event is anticipated to impact the region Friday and Saturday. This second system is a significantly stronger low pressure system accompanied by a moderately strong cold front. The latest model guidance depicts rainfall beginning Friday evening in the North Bay and progressing southward across the Bay Area and Central Coast overnight into Saturday. While we expect these totals to change a bit, current solutions bring 3 to 5 inches of precipitation to the North Bay coastal range and 1 to 2.5 inches to the North Bay Valleys, 0.5 to 1 inch in the Bay Area, and Monterey Bay region, 1 to 2 inches across the Santa Cruz and Santa Lucia mountain range, and a trace to 0.25 inch over the interior portions of Monterey and San Benito counties. Showers will linger into Sunday. Area streams and creeks will only see a slight to moderate rise with the first storm, and while streams are expected to stay below action/monitor stage with this storm it will prime the soils for quicker and more noteworthy rises with subsequent storms. The second stronger and wetter storm will result in greater and more rapid rises on small creeks, streams and rivers. Main stem rivers are currently forecast to remain below flood stage, however the 10% probability of exceedance (very low chance) show GUEC1- Russian River at Guerneville (10%), SHEC1- Napa near Saint Helena (9%), and APCC1- Napa near Napa (7%) may rise slightly above minor flood stage on Saturday. A few other rivers to keep an eye on that show higher probability of reaching Action/Monitor or Minor flood stage according to the latest CNRFC forecast are MWEC1 - Mark West Creek at Mirabel Heights has a 70% probability of reaching Action/Monitor Stage and a 45% probability of reaching Minor flood stage on Saturday. CTIC1 - Laguna De Santa Rosa at Stony Pt Rd near Cotati has a 64% probability of reaching Action/Monitor Stage and a 41% probability of reaching Minor flood stage on Saturday. GEYC1- Russian River at Geyserville has a 27% probability of reaching Action/Monitor Stage and a 14% probability of reaching Minor flood stage on Saturday. * WHERESonoma and Napa Counties. Latest model guidance suggests the North Bay will receive the greatest accumulation of precipitation with the heaviest rainfall expected over the North Bay coastal range and mountains. * WHENFriday through Sunday. Light to Moderate rainfall expected over the North Bay Friday and Saturday. The heaviest rainfall accumulation is expected Friday and Saturday. Showers will linger into Sunday. * ADDITIONAL DETAILS...In addition to the moderate rainfall and localized ponding of water in low-lying or poorly drained areas, such as freeway offramps. Locally strong and gusty winds may result in downed trees, and potential power outages. Confidence is high that we will receive rainfall from this system however, confidence is moderate with respect to the exact location and timing of the most intense rainfall. Details regarding this storm will likely change as the system nears. Therefore, stay tuned to the latest forecast for the most up to date weather information.More