Flood Potential Outlook
Issued by NWS San Francisco Bay Area, CA

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HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
431 PM PST Mon Feb 10 2025

...AN ATMOSPHERIC RIVER TAKING AIM AT THE NORTHERN AND CENTRAL
CALIFORNIA COAST WILL INCREASE THE POTENTIAL OF FLOODING TO AREA
CREEKS AND STREAMS...

* WHAT...Unsettled weather is forecast to return to the region
  this week. The first round of rain is progged to impact areas
  mainly south of the Golden Gate Tuesday night into Wednesday.
  Rainfall amounts will range from 0.10"-0.25" over inland and
  valley locations to 0.25"-0.75" along the coastal mountain
  ranges. Highest precipitation is forecast over the Santa Cruz
  Mountains and Santa Lucia range. A stronger and significantly
  wetter system will move into the area Wednesday night into
  Thursday. Models agree that this system will pack a bigger punch
  with strong upper level jet support and ample moisture
  associated with an atmospheric river that is taking aim at the
  Central Coast. This storm will not only bring heavy rainfall but
  also potentially damaging winds. Given the current location of
  the moisture axis and dynamic features, this system will
  generally favor areas from about San Francisco southward across
  the Central Coast. Overall good news in terms of annual rainfall
  since southern areas are a bit behind the curve so far this
  water year (since Oct 1). An interesting tidbit to include; the
  Central Coast watershed which runs along the coast roughly from
  Monterey to Arroyo Grande is about 4.37" below normal for the
  water year to date. The current forecast for that watershed by
  the end of the week is about 3"-6". There is a slight chance
  (at least 15%) of rainfall rates resulting in flash flooding
  conditions area-wide on Thursday. It is likely that there will
  be more of a focus as the event nears and more information about
  convective rainfall rates becomes clear from high res guidance.
  The system does appear to be rather progressive and should move
  through the region relatively quickly, thus hindering any
  increase in the probability of flash flooding for now. Guidance
  keeps this vigorous wave open and embedded in the flow, so there
  is relatively low stall potential. As far as rainfall totals
  go, the North Bay will still see respectable totals in the 2"-4"
  range, the greater Bay Area will see a range of 1.5"-3" (less
  in the rainshadowed South Bay, more along the peninsula), 4"-6"
  and locally up to 8" in the Santa Cruz Mtns, 2"-3" across the
  Central Coast counties, and 3"-6" along the Big Sur Coast,
  locally up to 8".

* WHERE...Bay Area and Central Coast. Latest model guidance
  suggests the Bay Area and Central Coast will receive the
  greatest accumulation of precipitation with the heaviest
  rainfall expected over the Santa Cruz Mountains and Santa Lucia
  range.

* WHEN...Tuesday night through Thursday. Light to locally
  moderate rainfall expected Tuesday night into Wednesday.
  Moderate to locally heavy rain expected Wednesday night into
  Thursday.

* 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 these
systems 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.

$$

Behringer/CW