Winter Weather Guide

Types of Snow

Powdery Snow

Light, fluffy snow that forms in very cold conditions. While beautiful, it can create dangerous driving conditions due to reduced visibility and drifting.

• Accumulation Rate: Moderate to High
• Road Impact: Significant drifting potential
• Closure Likelihood: High with significant accumulation

Wet Snow

Heavy, moisture-laden snow that forms near the freezing point. Creates hazardous conditions due to its weight and tendency to freeze.

• Accumulation Rate: High
• Road Impact: Severe, especially with freezing
• Closure Likelihood: Very High

Ice Conditions

Freezing Rain

Rain that freezes upon contact with cold surfaces, creating a glaze of ice. One of the most dangerous winter weather conditions.

• Ice Accumulation: 0.25-0.5 inches possible
• Road Impact: Extreme hazard
• Closure Likelihood: Very High

Sleet

Frozen raindrops that bounce on impact. Creates immediate slippery conditions but easier to treat than freezing rain.

• Accumulation Rate: Moderate
• Road Impact: Significant
• Closure Likelihood: High

Temperature Factors

Wind Chill

The "feels like" temperature that combines air temperature and wind speed. Critical for determining outdoor safety.

• Danger Threshold: Below -15°F
• Exposure Risk: Frostbite possible in 30 minutes
• Closure Likelihood: High when severe

Ground Temperature

Surface temperature affects how snow and ice accumulate and bond to roads. Crucial for predicting road conditions.

• Critical Range: 28-32°F
• Road Impact: Varies with temperature
• Treatment Effectiveness: Decreases below 15°F

Wind Factors

Wind Speed

High winds can create dangerous conditions through reduced visibility and drifting snow, even with minimal snowfall.

• Danger Level: Above 35 mph
• Visibility Impact: Severe
• Closure Likelihood: High with drifting

Blowing Snow

Previously fallen snow lifted and blown by strong winds. Can create whiteout conditions and deep drifts.

• Formation: Winds over 25 mph
• Duration: Until winds subside
• Road Impact: Severe drifting

Visibility Conditions

Heavy Snowfall

Rapid accumulation of snow reducing visibility to near zero. Creates immediate hazardous conditions.

• Rate: Over 1 inch per hour
• Visibility: Under 1/4 mile
• Impact: Immediate road coverage

Whiteout

Severe winter weather condition where visibility is reduced to near zero by snow or blowing snow.

• Duration: Minutes to hours
• Travel: Extremely dangerous
• Safety: Shelter immediately

Road Conditions

Black Ice

Nearly invisible ice layer on roads, especially dangerous due to its unexpected nature. Common in early morning hours.

• Visibility: Very Low
• Formation Time: Overnight/Early Morning
• Risk Level: Extreme

Snow Pack

Compressed snow on roads that can become very slick. Difficult to remove once bonded to the road surface.

• Formation: After vehicle traffic
• Treatment: Requires special methods
• Duration: Can last several days