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Experimental Enhanced Hazardous Weather Outlook

Product Suite Last Updated:     Saturday December 16, 2017     03:30 PM
 
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Severe Thunderstorm Risk
Current time - 6 am
24 Hr. Hazards
Day 1
Tornado
 
 
 
 
 
 
Hail
 
 
 
 
 
 
Thunderstorm Wind Gust
 
 
 
 
 
 
Severe Thunderstorms
Lightning
Flooding
Fire Weather
Fog
Non Thunderstorm Winds
Excessive Heat
Snow & Sleet
Ice Accumulation
Excessive Cold
High Surf
Marine Hazard
Freezing Spray
 
Severe Thunderstorm Arrival Tool Legend         Severe Thunderstorm Safety Tips
 
Risk Level
Definition
None
Severe thunderstorms are not expected today or tonight.
Later Today or Tonight
Severe thunderstorms will be possible later today or tonight .
Next 6 hours
Severe thunderstorms will be possible in the next 6 hours.
Next 3 hours
Severe thunderstorms will be possible in the next 3 hours.
The Severe Thunderstorm Arrival Tool is a resource for municipalities, counties, and SKYWARN storm spotters to plan for possible storm spotter activation on the current calendar day. Other interests can also use the Severe Thunderstorm Arrival Tool to determine the expected time frame for severe thunderstorm potential.
Tornado Risk Legend         Tornado Safety Tips
 Risk Level
Definition
None
No tornado risk.
Limited
Probability of a tornado within 25 miles of a point: less than 10 percent.
Be aware of where your closest interior shelter is located.
Elevated
Probability of a tornado within 25 miles of a point: Equal to or greater than 10 percent.
Be prepared to move to the closest strong interior shelter if you are in a vulnerable location: outdoors, in a motor vehicle, mobile home, or other vulnerable structure.
Significant
Probability of a tornado within 25 miles of a point: Equal to or greater than 30 percent.
Plan to move to your closest strong interior shelter if you are in a vulnerable location: outdoors, in a motor vehicle, mobile home, or other vulnerable structure.
Extreme
Probability of a  tornado within 25 miles of a point: Equal to or greater than 45 percent.
Plan to move to your closest strong interior shelter if you are in a vulnerable location: outdoors, in a motor vehicle, mobile home, or other vulnerable structure.
Hail Risk Legend         Severe Thunderstorm Safety Tips
 
Risk Level
Definition
None
No risk of hail.
Limited
Risk of sub-severe hail (less than 1")
or
Probability of severe hail (1" or greater) within 25 miles of a point: less than 15%
Be aware of potential need to move vehicles, people, and animals for protection.
Elevated
Probability of severe hail (1" or greater) within 25 miles of a point: Equal to or greater than 15%
Be prepared to move vehicles, people, and animals for protection.
Significant
Probability of severe hail (1" or greater) within 25 miles of a point: Equal to or greater than 45%
Plan to move vehicles, people, and animals for protection.
Extreme
Probability of severe hail (1" or greater) within 25 miles of a point: Equal to or greater than 60%
Plan to move vehicles, people, and animals for protection.
Thunderstorm Wind Gust Risk Legend         Severe Thunderstorm Safety Tips
 
Risk Level
Definition
None
No thunderstorm wind risk.
Limited
Risk for sub-severe wind gusts (less than 58 mph)
or
Probability of severe wind gusts (58 mph or greater) within 25 miles of a point: Less than 15%
Be prepared to secure unsecured property to prevent wind damage.
Elevated
Probability of severe wind gusts (58 mph or greater) within 25 miles of a point: Equal to or greater than 15%
Be prepared to secure unsecured property to prevent wind damage. Prepare to move to an interior shelter.
Significant
Probability of severe wind gusts (58 mph or greater) within 25 miles of a point: Equal to or greater than 45%
Plan to secure unsecured property to prevent wind damage. Plan to move to an interior shelter.
Extreme
Probability of severe wind gusts (58 mph or greater) within 25 miles of a point: Equal to or greater than 60%
Plan to secure unsecured property to prevent wind damage. Plan to move to an interior shelter.
Severe Thunderstorm Legend         Severe Thunderstorm Safety Tips
 
Risk Level
Definition Severe Thunderstorm Risk Day 2 to 7
None
No risk of severe thunderstorms.
Limited
Risk for severe thunderstorms with the
Probability of severe thunderstorms* within 25 miles of a point: Less than 15%
Review weather safety tips and emergency kit.
Elevated
Probability of severe thunderstorms* within 25 miles of a point: Equal to or greater than 15%
Review weather safety tips and emergency kit. Identify closest safe shelter.
Significant
Probability of severe thunderstorms* within 25 miles of a point: Equal to or greater than 45%
Review weather safety tips and emergency kit. Identify closest safe shelter.
Extreme
Probability of severe thunderstorms* within 25 miles of a point: Equal to or greater than 60%
Review weather safety tips and emergency kit. Identify closest safe shelter.
Lightning Legend         Lightning Safety Tips
 
Risk Level
Definition
None
No lightning risk
Limited
Thunderstorms expected to be isolated to scattered in coverage. 
Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Be aware for thunderstorms in your area.
Elevated
Thunderstorms expected to be numerous in coverage.
  Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Be prepared to take immediate shelter from thunderstorms and lightning.
Significant
Widespread thunderstorms are expected.
  Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Plan to take immediate shelter from thunderstorms and lightning.
Extreme
Thunderstorms are expected with nearly continuous cloud to ground lightning strikes in and near thunderstorms.
Plan to stop all outdoor activity and move to shelters. Remain in shelters until all danger of wind and lightning has passed.
Flooding Legend         Flooding Safety Tips
 
Risk Level
Definition
None
No Flooding risk.
Limited
Risk of localized flash flooding of small streams and low water crossings, and minor flooding of poor drainage or urban areas.
Be aware of flood prone areas and potential to change your driving course if roadways flood.
Elevated
Risk of flash flooding of several low water crossings, roads, and small streams,
or
Minor River Flooding.
Be prepared to move away from flood prone areas. If you observe flooded roadways, be prepared to change your driving course.
Significant
Risk of flash flooding of numerous roads, low water crossings, and small streams,
or
Moderate river flooding.
Plan to move away from flood prone areas. If you observe flooded roadways, change your driving course or stay off roads completely.
Extreme
Risk of widespread flash flooding of low water crossings, roads, and small streams.
or
Major river flooding.
Plan to move away from flood prone areas. If you observe flooded roadways, change your driving course or stay off roads completely.
Fire Weather Legend         Wildfire Weather Safety Tips
 
Risk Level
Definition
None
 
Limited
The combination of low humidities and windy conditions can promote the spread of wildfires given appropriate fuel conditions.
Elevated
Meteorological conditions support an elevated threat of fire spread. The combination of low humidities and windy conditions can promote the spread of wildfires given appropriate fuel conditions.
Significant
Meteorological conditions support a significant threat of fire spread. The combination of low humidities and windy conditions can promote the spread of wildfires given appropriate fuel conditions.
Extreme
Meteorological conditions support an extreme threat of fire spread. The combination of low humidities and windy conditions can promote the spread of wildfires given appropriate fuel conditions.
The fire weather category for the Enhanced Hazardous Weather Outlook is based primarily on predicted wind, humidity and temperature, and does not account for fuel moisture from recent precipitation, snow cover and recently melted snow.  Appropriate adjustments to the fire environment must be made.
Grassland Fire Weather Legend         Wildfire Weather Safety Tips         Grassland Fire Danger Index
 
Risk Level
Definition
Low-Moderate
Favorable to marginal weather conditions with moderate to high moisture content of grasses and other dry organic material on the ground, indicating that the probability of a fast moving fire is low to a slight potential. Outdoor burning under these conditions can usually be performed with reasonable safety precautions, but should be monitored. Difficulty of fire suppression: Headfire can generally be stopped by road and tracks in low conditions and with water under moderate conditions.
High
Unfavorable weather conditions and low moisture content of grasses and other dry organic material on the ground, indicating that there is a high potential for fire to spread. Outdoor burning should be restricted to early morning or evening hours when wind speeds are usually lower and the relative humidity is higher. Burning is still favorable for well-planned burns by experienced land management personnel. Difficulty of fire suppression: Headfire attack generally successful with water.
Very High
Very poor weather conditions and very low moisture content of grasses and other dry organic material on the ground, indicating that dangerous burning conditions exist. Fires will spread rapidly and show erratic behavior. Outdoor burning is not recommended other than for experienced land management personnel. Difficulty of fire suppression: Direct headfire attack will become increasingly difficult. Spot fires are more likely.
Extreme (GFDI 50-75)
Extreme weather conditions and very low moisture content of grasses and other dry organic material on the ground, indicating that critical burning conditions exist. All fires have the potential to become large and spread quickly and become erratic with extreme fire behavioral characteristics. Difficulty of fire suppression: Direct attack on a headfire will generally fail. Back burn from a secure good line with adequate manpower and equipment. Flanks may become more difficult to control in shifting or erratic winds. Spot fires are likely.
Extreme (GFDI > 75)
Extreme grassland fire weather conditions that are rarely experienced in our area. Very high winds and low humidity with very dry cured grasses. Any fire that starts will spread rapidly and almost impossible to control. Fire suppression: Direct attack will likely fail, especially in heavy fuel loads.
The Grassland Fire Danger Index (GFDI) is a numerical value that indicates the potential for grassland fires to experience extreme fire behavior. The GFDI combines the curing (%), temperature (deg C), relative humidity (%), and the average of the sustained wind and wind gust speed (km/hr).
 
Fog Legend         Fog Safety Tips
 
Risk Level
Definition
None
No risk of fog.
Limited
Fog with visibilities less than or equal to 1 mile.
Elevated
Fog with visibilities less than or equal to 1/2 mile
Significant
Fog with visibilities less than or equal to 1/4 mile.
Extreme
Fog with near zero visibilities.
Non Thunderstorm Wind Legend         Wind Safety Tips     Boating Safety Tips
 
Risk Level
Definition
None

Sustained winds < 20 mph
and
Wind gusts < 30 mph.

Limited
Sustained winds 20-29 mph
or
Wind gusts 30-44 mph.
Be aware that unsecured property may need to be secured from potential wind damage.
Elevated
Sustained winds 30-39 mph
or
Wind gusts 45-57 mph.
Be prepared to secure unsecured property from potential wind damage.
Significant
Sustained winds 40-49 mph
or
Wind gusts 58-64 mph.
Plan to secure unsecured property from potential wind damage and move people and animals to interior shelters
Extreme
Sustained winds > 50 mph
or
Wind gusts > 65 mph.
Secure unsecured property from potential wind damage and move people and animals to interior shelters.
Excessive Heat Legend         Excessive Heat Safety Tips
 
Risk Level
Definition
None
Maximum Apparent Temperature < 85
Limited
Maximum Apparent Temperature 85 to 94
Sunstroke, muscle cramps and/or heat exhaustion possible with prolonged exposure. Be aware to stay hydrated and seek air conditioned locations if needed. Identify air conditioned locations to move to.
Elevated
Maximum Apparent Temperature 95 to 104
OR
Maximum Apparent Temperature greater than or equal to 100 for 4 consecutive days.

Sunstroke, muscle cramps and/or heat exhaustion likely with prolonged exposure. Be prepared to stay hydrated and seek air conditioned locations if needed.
Significant
Maximum Apparent Temperature 105 to 110
OR
Maximum Apparent Temperature greater than or equal to 105 for 4 consecutive days.


Sunstroke, muscle cramps and/or heat exhaustion likely with prolonged exposure. Stay hydrated and seek air conditioned locations if needed.
Extreme
Maximum Apparent Temperature greater than or equal to 110
OR
Maximum Apparent Temperataure greater than or equal to 105 for 5 consecutive days.

Sunstroke, muscle cramps and/or heat exhaustion likely. Stay hydrated and seek air conditioned locations if needed.
Note:
Apparent Temperature is defined as:
  Wind Chill Temperature during the cold season.
  Heat Index Temperature during the warm season.
Snow and Sleet Legend         Winter Weather Safety Tips
 
Risk Level
Definition
None
No snow or sleet.
Limited
Snow and/or sleet with less than 4 inches of accumulation expected.
Be aware of locally hazardous travel conditions on bridges, overpasses, and untreated or secondary roads.
Elevated
Snow and/or sleet with 4 to 8 inches of accumulation expected.
Be prepared to reduce travel speed for hazardous travel conditions especially on bridges, overpasses, untreated and secondary roads.
Significant
Snow and/or sleet with 8 to 16 inches of accumulation expected.
Plan for hazardous travel conditions. Avoid travel if possible.
Extreme
Snow and/or sleet with greater than or equal to 16 inches of accumulation expected.
Travel will be dangerous and may be impossible. Avoid travel unless it is an emergency.
Ice Accumulation Legend         Winter Weather Safety Tips
 
Risk Level
Definition
None
No freezing rain or drizzle.
Limited
Very light freezing rain or drizzle with up to a thin glaze, OR Freezing Fog.
Be aware of locally hazardous travel conditions on bridges, overpasses, and untreated or secondary roads.
Elevated
Freezing rain or drizzle with accumulation less than 1/2 inch.
Be prepared to reduce travel speed for hazardous travel conditions especially on bridges, overpasses, untreated and secondary roads.
Significant
Freezing rain with accumulation of 1/2 inch to less than 1 inch.
Plan for hazardous travel conditions. Powelines and trees may be damaged resulting in localized to scattered power outages. Avoid travel if possible and prepare for possible power outages.
Extreme
Freezing rain with accumulation of greater than or equal to 1 inch.
Travel will be dangerous and may be impossible. Powerlines and trees likely damaged resulting in widespread power outages. Avoid travel unless it is an emergency and prepare for extended power outages.
Frost and Freeze Legend
 
Risk Level
Definition
None
No danger of frost or freeze causing damage to vegetation.
Limited
Patchy frost during the growing season with minor damage to unprotected vegetation.
Be aware that vegetation may need to be protected.
Elevated
Frost expected during the growing season with damage to unprotected vegetation. 
This may include temperatures less than or equal to 32 degrees F for less than 3 hours.
Be prepared to protect vegetation.
Significant
Freeze expected (less than or equal to 32 degrees F for 3 or more hours) during the growing season with significant damage to unprotected vegetation.
Protect vegetation.
Extreme
Hard freeze (less than or equal to 28 degrees F) during the growing season with catastrophic damage to unprotected vegetation.
Protect vegetation when watches and warnings are issued.
Excessive Cold Legend         Extreme Cold Safety Tips
 
Risk Level
Definition
None
Minimum apparent temperature greater than or equal to 0 degrees F.
Limited
Minimum apparent temperature -19 to 0 deg F.
Frostbite and hypothermia may occur with prolonged exposure without proper clothing. Be aware to have proper clothing for exposure and limit or eliminate exposure if possible.
Elevated
Minimum apparent temperature -19 to -29 deg. F
Frostbite and hypothermia could occur within 30 minutes without proper clothing. Be prepared to have proper clothing for exposure and limit or eliminate exposure if possible.
Significant
Minimum apparent temperature -29 to -39 deg. F.
Frostbite and hypothermia will likely occur within minutes without proper clothing. Have proper clothing for exposure and limit or eliminate exposure.
Extreme
Minimum apparent temperature less than or equal to -39 degrees F
Frostbite and hypothermia will occur within minutes without proper clothing. Have proper clothing for exposure and limit or eliminate exposure.
Note:
Apparent Temperature is defined as:
  Wind Chill Temperature during the cold season.
  Heat Index Temperature during the warm season.
Coastal Flood Legend         Flooding Safety Tips
 
Risk Level
Definition
None
No Coastal Flooding risk.
Limited
Winds >= 30mph and Wave Heights >= 8 feet.
These conditions could lead to isolated areas of beach erosion and coastal flooding
.
Elevated
Winds >=35 mph and Wave Heights >=11 feet.
These conditions could lead to scattered areas of beach erosion and coastal flooding.
Significant
Winds >=40 mph and Wave Heights >=14 feet.
These conditions could lead to significant beach erosion and coastal flooding.
Extreme
Winds >= 45 mph and Wave Heights >= 17 feet.
These conditions could lead to widespread beach erosion and coastal flooding.
Swim Risk Legend         Rip Current Safety Tips
 
Risk Level
Definition
None
No Swim Risk.
Limited
A limited risk of swimming hazards imply that large waves and strong currents are not expected along the shore. However, dangerous currents can still form near river mouths and shoreline structures, such as piers or breakwalls, even during low wave heights.
Elevated
An elevated risk of swimming hazards imply that large waves and strong currents are likely along the shore. Only experienced swimmers should consider entering the water. Stay away from river mouths and shoreline stuctures.
Significant
A significant risk of swimming hazards imply dangerous waves and currents are expected along the shore. Swimming conditions may be life threatening to anyone entering the water.
Extreme
 
The Swim Risk grids are only generated during the swimming season, generally from mid June through the end of September.
High Surf Legend         Beach Hazard and Surf Safety Tips
 
Risk Level
Definition
None
No High Surf Risk.
Limited
Wave height >= 2 feet and Wave Period > 3 seconds.
Elevated
Wave Height >= 4 feet and Wave Period > 4 seconds.
Significant
Wave Height >= 6 feet and Wave Period > 5 seconds.
Extreme
Wave Height > 8 feet.
Marine Hazard Legend
 
Risk Level
Definition
None
No Marine Hazards Risk.
Limited
Winds >= 15 knots and/or Waves >= 2 feet.
Elevated
Winds >= 23 knots and/or Waves >= 4 feet.
Significant
Winds >= 34 knots and/or Waves >= 9 feet.
Extreme
Winds >= 48 knots and/or Waves >= 14 feet.
Freezing Spray Legend
 
Risk Level
Definition
None
No Freezing Spray Risk.
Limited
Moderate Freezing Spray Expected.
Elevated
 
Significant
Heavy Freezing Spray Expected.
Extreme
 
 

The Experimental Enhanced Hazardous Weather Outlook is an experimental product that will be posted to this page for evaluation. We encourage your comments or suggestions for improvements using the electronic survey provided. Your feedback will help us determine product utility, if modifications are needed, and whether the product should become part of our operational suite. | Product Description Document

The Experimental Enhanced Hazardous Weather Outlook is a decision support service that supports preparedness and response efforts prior to and during hazardous weather.  This service provides decision makers with convenient access to potential weather hazard information by graphically depicting the risk of weather hazards out through seven days.

 Page Last Updated: 03:30 PM EST Dec 16, 2017