Periods of Heavy Rain and Snow Continue from California through the Northern Rockies; Multiple Rounds of Ice and Snow to Impact a Large Part of the Northeastern States into Next Week

Moderate to heavy rain with a flooding risk will continue for northern and central California, with heavy mountain snow in the Sierras, southern Cascades, and northern Rockies through Friday. A series of winter storms will track from the Upper Midwest to off the Northeast U.S. coast into next week bringing rounds of moderate to locally heavy rain south of their track and ice and snow to the north. Read More >

Severe Thunderstorm (damaging winds & lightning)

Biggest Takeaway:
While not routine, these warnings are something that will occur several times most years. Be inside a sturdy structure. Severe/Damaging Thunderstorms cause most of the instances of wind damage in our region. Wind damage from a severe thunderstorm is 10x more likely than a tornado.

Warning/Trigger for Plan:
NWS Severe Thunderstorm Warning

Advance Notice/Time to Activate & Accomplish Your Planned Response:
Plan on 10-15 minutes advance warning before onset (allow there may be no advance notice, and it may be as much as 60 minutes).

Frequency:
Average is ~10/year at various times of day & night

How accurate are warnings?
If there is a Severe Thunderstorm Warning, it is nearly certain that there will be targeted wind damage in the warning area (and nearby to you). Often though, the damaging winds will not affect your specific location, and will only be "nearby" within a few miles. Most of the time however, you will at least get lightning and very heavy rain. How much risk can you tolerate from a damaging wind gust occurring on your location vs. nearby? The safest course of action is to shelter during the typical 15-45 minutes of the warning.

How do you balance this uncertainty of a direct hit of damaging winds with the potentially deadly consequences if it does hit you?
Damaging winds may be just enough to rip off large limbs (>50mph), or enough to snap down large trees and cause structural damage (>80 mph) - warnings the NWS issues will often include expected wind speed & damage.
Note that large branches and trees are at risk for coming down during a severe thunderstorm. Is that a threat in your location? How do you keep people out of harm’s way from falling trees?
Safest situation:
- In a sturdy, enclosed structure – not a mobile home
  - Away from windows
  - Be as low as possible
    - Winds increase with height
    - If a tree falls into your structure, the upper levels will be most damaged
  - Put as much structure between you and the outside as possible
    - Homes: Typically the lowest level, interior room.
    - Buildings: Typically interior hallways or concrete staircases.
Safety References:
- Thunderstorms, Tornadoes, Lightning...Nature's Most Violent Storms