Snow Impacts in the Sierra Nevada and Great Lakes

Heavy snow over parts of the Sierra Nevada Mountains and Upper Great Lakes will cause slick roads into Monday morning. Travel could be very difficult to impossible in the Sierra Nevada. Read More >

Freezing Rain

Biggest takeaway:
Most freezing rain storms create transportation issues and slip & fall issues. The true ice storms with large accumulations (>1") of glazing/freezing rain on trees and power lines, etc., are catastrophic dangers.

Warning/Trigger for Plan:
NWS Ice Storm Warning (moderate/major) – or – NWS Freezing Rain Advisory (minor).

Advance Notice/Time to Activate & Accomplish Your Planned Response:
* For Ice Storm Warnings, plan for 12-36 hours of advance notice before significant impact.
* Freezing Rain Advisories often have 6-18 hours of advance notice.

Frequency:
* Major ice storms are uncommon in our area, but happen 0-2 times/25 years on average in any one spot.
* Minor icing events are much more common and often happen a few times per winter.

How Accurate Warnings?
* Ice Storms are notoriously hard to forecast since small changes in temperature through the first few thousand feet of the atmosphere can make big changes to the impact of the storm. That said, Ice Storm Warnings should be taken very seriously since the threat can be so catastrophic.
* Freezing Rain Advisories should also garner substantial action since a small amount of icing can make on roads/parking lots/sidewalks can create substantial slip & fall dangers, as well as icy roads with many more accidents.

Major ice storms are catastrophic dangers. This is especially true for those storms that are followed by gusty winds.
- Fortunately, these ice storms are rare in any given location, and occur 0-2 times per generation in any one spot. Unfortunately, that often means they are not planned for since they often haven't happened in the resident's memories. The following threats need to be accounted for:
  - Extended and widespread power outages lasting several days
  - These power outages knock out heat to homes and can cause a hypothermia threat
  - Downed trees blocking roads & driveways blocking access for any rescue needs (dialysis, medical, heart), as well as trapping folks in their homes.
  - Falling trees and power lines under the intense weight of the ice can fall into homes or on people.
  - Communication can be cut as significant ice accumulation can down phone lines and degrade/damage cell towers.
  - The governor of KY called an ice storm a few years ago "the biggest natural disaster in the state's modern history".
  - For those in the Mid Atlantic during the derecho in 2012, think of similar impacts with intense cold, instead of intense heat.
With freezing rain, any amount is dangerous. a small amount of icing can make on roads/parking lots/sidewalks can create substantial slip & fall dangers, as well as icy roads with many more accidents. These events are much more frequent, but plans should be different for a minor event, than you will need for a major/catastrophic event.