Tracking Atmospheric River for the West Coast; Space Weather Storming Continues

An atmospheric river will bring threats of gusty to high winds and heavy rainfall to California mainly Thursday into Saturday which may bring areas of flooding and wind damage. Heavy snow will be possible over the Sierra Nevada mountains Thursday into Friday associated with the atmospheric river. Minor to severe geomagnetic storming (space weather) is expected to continue into early Thursday. Read More >

Tidal (if applicable)

Biggest takeaway:
If you are near a tidal body of water, know how high your risk is, and what caliber of tidal flood (or storm surge) it would take to flood your location. Have a plan for that. Coastal Flood Warnings are issued by the NWS for moderate or higher levels of flooding - which is not common. Be able to receive them by phone app, NOAA Weather Radio (“lesser“ Advisories for minor flooding are not tone alerted, but Warnings are alerted), USGS water alert service, other alert services, or ideally a few of these ways. For those in areas threatened by tidal floods, it is one of the most deadly threats.

Warning/Trigger for Plan:
NWS Coastal Flood Warning

Advance Notice/Time to Activate & Accomplish Your Planned Response:
Plan on ~12-24 hours for moderate or higher tidal flooding.
Allow flexibility for a few hours to a few days advance notice.

Frequency:
Moderate to Major tidal flooding is uncommon, but can be catastrophic to shoreline communities. Average ~1 time every 2-3 years for moderate; ~1 time/decade for major.

How Accurate Warnings?
NWS Coastal Flood Warnings and tidal forecasts have seen sharp improvement over the past decade, and are expected to continue to improve substantially in the next decade – particularly in the way we expect to soon “show” people on a map where flooding is expected, instead of “tell” them in a text warning how high the water will be at various shoreline points. Still, it is good practice to always allow leeway in your response for a more substantial tidal flood than expected.

Determine if you are in an area that could have tidal flooding:
- This FEMA web page allows you to pop in your address and see the blue zones which are under the 1% annual chance of flooding (also known as the 100 year flood). This can be a guideline.
If your location is at tidal flooding risk:
- Use this webpage to find the nearest point to monitor your nearest tidal level.
- Receive Coastal Flood Warnings from the NWS.
- Know what levels (height in feet read by the gauge) it would take to threaten your location to various degrees of severity.
- Have a plan for actions you will take if these various levels are expected/reached.
- Use USGS Water Alert service (or similar) to set up an alert for when critical levels are forecast or reached for your location.
- Know the various calibers of river flooding that will be included in the warning:
  - Minor: Nuisance flooding (non-structural, no significant roads)
    The NWS issues a Coastal Flood Advisory for minor tidal flooding.
  - Moderate: Starts to inundate the lowest homes/businesses and roads.
  - Major: Significant flooding of structures, roads, life & property
  - Record: Higher than ever recorded.
Safety References:
- Flood...The Awesome Power