National Weather Service United States Department of Commerce

Severe Weather and Flooding in the Ohio Valley and Mid-Atlantic; Winter Storm in Alaska; Heavy Rains in Hawaii

Severe thunderstorms may produce a few tornadoes, scattered damaging winds, isolated severe hail, and flash flooding across the upper Ohio River Valley and parts of the Appalachians tonight. A strong storm in western Alaska continues to produce heavy snow, strong winds, and blizzard conditions into the mainland. Heavy showers and isolated thunderstorms may cause flash flooding in northern Hawaii. Read More >

WHAT DOES THAT WARNING MEAN?

 

When a warning is issued during the winter season, will you know what it means, and will you know how to respond?   During this Colorado Winter Weather Preparedness Week, please become familiar with our list of potentially life-saving winter weather products. 

 

This statement contains warning and advisory criteria for Colorado west of the continental divide.  Criteria east of the divide will be provided today in a separate issuance by the Boulder forecast office.

 

OUTLOOKS

 

A Hazardous Weather Outlook is issued daily by each National Weather Service office serving Colorado.  The outlook provides information on potentially hazardous weather out to 7 days into the future.  Also, the Weather Story, a graphic of expected hazardous weather, is posted daily on National Weather Service web sites serving Colorado.

 

WATCHES AND WARNINGS

 

A Winter Storm Watch is issued when hazardous winter storm conditions are possible within the next 3 to 4 days, but the timing, intensity, or occurrence may still be uncertain.

 

In contrast, a Winter Storm Warning is issued for potentially life-threatening winter storm conditions, such as heavy snowfall or a combination of snowfall and blowing snow, which are likely to occur within the next 1 to 2 days. Required snowfall amounts are based on based on the amount of snowfall a forecast zone to area typically receives.  These areas are shown on the map below along with the required snowfall amounts.

Winter Storm Warning and Advisory Criteria

  Advisory Warning

Lower Valleys

1" to 2" in 12 hours

2" to 4" in 24 hours

>2" in 12 hours

>4" in 24 hours

Valleys

3" to 6" in 12 hours

4" to 8" in 24 hours

>6" in 12 hours

>8" in 24 hours

Mountains

4" to 8" in 12 hours

6" to 12" in 24 hours

>8" in 12 hours

> 12" in 24 hours

 

A Blizzard Warning is issued when the following conditions are expected to occur for at least 3 hours:

 

Sustained winds of 35 mph or greater,

and considerable falling and/or drifting snow

with visibilities frequently less than 1/4 mile.

 

A High Wind Warning is issued for the following conditions:

High Wind Warning and Wind Advisory Criteria

  Wind Advisory High Wind Warning

Low Elevations

Sustained Winds of 30 - 39 mph for 1 or more hours

Winds Gusts of 45 - 57 mph

Sustained Winds of 40 mph or greater for 1 or more hours

Wind Gusts of 58 mph or greater

High Elevations

Sustained Winds of 40 - 49 mph for 1 or more hours

Wind Gusts of 58 - 74 mph

Sustained Winds of 50 mph or greater for 1 or more hours

Wind Gusts of 75 mph or greater

 

A Wind Chill Warning will be issued for the following wind chill temperatures...

 

High Elevations...minus 35 degrees Fahrenheit or colder.

 

Lower Elevations...minus 25 degrees Fahrenheit or colder.

 

A Dust Storm Warning will be issued for the following conditions:

 

Visibility reduced to 1/4 mile or less in blowing dust,

and sustained winds of 25 mph or greater for at least one hour.

 

ADVISORIES

 

Advisories for winter weather are issued for potentially hazardous conditions which are considered more of a nuisance than a life-threatening situation. However, if caution is not taken the advisory events could become life-threatening.

 

Winter Weather Preparedness Week in Colorado will continue through Saturday.  Additional Public Information Statements will be issued throughout the remainder of this week to help you know how to respond when hazardous winter weather threatens.