Marine Weather and Tide Forecast for Geyserville, CA

DISCUSSION

Today-Mid Week:

Warm and dry weather continues as high heights aloft persist over the next several days. The brief period of ridging aloft is already transitioning to southwest flow early this morning, which is then expected to continue into the early week ahead. This minor pattern shift aloft will usher in slightly cooler, yet still above normal, high temperatures today and Monday.

Lighter winds will also accompany this shift and despite the more zonal direction aloft, surface winds look to continue following offshore and terrain driven trends from the north to east. This will yield increasing potential for patchy fog development in the Valley and Delta from Interstate 80 southward both this morning and Monday morning. Probabilities for visibility less than 1 mile continue to sit around 40-60% both mornings.

As the upper level pattern begins to see more influence from a deep trough that has been churning over the Gulf of Alaska over the last several weeks, an additional period of brief ridging aloft is expected to build into interior NorCal Tuesday into Wednesday. Valley winds look to remain largely unchanged but periodically breezy downslope east-northeast winds along the Sierra and into the upper foothills do look to develop during this period. Despite this, current probabilities for wind gusts greater than 25 mph along the Sierra only sit around 10-30% at this time. The primary impact of the expected ridging though will be a return to widespread afternoon high temperatures around 10 degrees above normal on Tuesday and Wednesday. Resultant high temperatures in the low to mid 70s are forecast for the Valley and foothills with 60s to low 70s at higher elevations.

Late Week Into Next Weekend:

Ensembles continue to indicate the potential for a shift toward an active weather pattern, with chances for heavy rain, heavy mountain snow and breezy winds. However, cluster guidance still indicates uncertainty regarding the position and timing of the upcoming trough. The anticipated southward progression of deep troughing over the Gulf of Alaska toward the California coast remains the largest piece of uncertainty at this time. With increasing ensemble consensus for a further southward trajectory of the initial ejecting shortwave Wednesday-Thursday, precipitation onset for interior NorCal is now favoring Friday into next weekend at the earliest. Regardless, the CPC 8-14 Day Outlook (Nov. 15-21) does continue to highlight a moderate risk for heavy rain and heavy mountain snow, as well as a slight chance for high winds which can be anticipated once the pattern does indeed shift. Be sure to stay up to date with the latest forecast information and check back for updates as we get closer.

AVIATION

VFR conditions are generally expected to prevail at TAF sites over the next 24 hours, although a 40-60% chance for MVFR/IFR cigs in FG/BR at Valley and Delta sites is forecast through 16z this morning. Similar potential for MVFR/IFR cigs in BR/FG possible after 09z Monday as well. Light winds persist across the forecast period, remaining less than 12 kts at TAF sites, but still from a generally north to east direction.

STO WATCHES/WARNINGS/ADVISORIES
None.