2. Materials and Methods
2.1. Obtaining and Understanding Extreme Weather and Climate Data for Use in Vulnerability Assessments
2.2. Data for Historic Extreme Weather Events
2.3. Projected Climate Data from Climate Modeling
2.4. Assessing Historic Extreme Weather Event Frequency and Trends
2.5. Assessing Future Projected Climate
3.1. Analyzing Climate Projections and Extreme Weather Patterns
3.2. Patterns of Extreme Weather Event Frequency
3.3. Example of Trend Analysis: Statewide Wind Event
3.4. Future Climate Projections
3.5. Utilizing the Results
Conflicts of Interest
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|Cold/Wind Chill||Frost Freeze||Lightning|
|Dust devil||Hail||Strong wind|
|Excessive heat||Heat||Thunderstorm wind|
|Extreme cold/wind chill||Heavy rain||Tornado|
|Flash flood||Heavy snow||Winter storm|
|Flood||High wind||Winter weather|
|Freezing fog||Ice storm||-|
|Weather Event Category||NWS Event Type(s) Included||NWS Extreme Weather Event Definition|
|Cold||Cold/wind chill||Period of low temperatures or wind chill temperatures reaching or exceeding locally/regionally defined advisory (typical value is −18° F or colder) conditions, on a widespread or localized basis. There can be situations where advisory criteria are not met, but the combination of seasonably cold temperatures and low wind chill values (roughly 15° F below normal) must result in a fatality. In these situations, a cold/wind chill event may be documented if the weather conditions were the primary cause of death as determined by a medical examiner or coroner. Normally, cold/wind chill conditions should cause human and/or economic impact. This event is only used if a fatality/injury does not occur during a Winter Precipitation event|
|Extreme cold/wind chill||A period of extremely low temperatures or wind chill temperatures reaching or exceeding locally/regionally defined warning criteria (typical value around −35° F or colder), on a widespread or localized basis. Normally these conditions should cause significant human and/or economic impact. However, if fatalities occur with cold temperatures/wind chills but extreme cold/wind chill criteria are not met, the event is recorded in the database as a Cold/Wind Chill event. This event is only used if a fatality/injury does not occur during a Winter Precipitation event.|
|Hot||Heat||A period of heat resulting from the combination of high temperatures (above normal) and relative humidity. A Heat event occurs and is recorded whenever heat index values meet or exceed locally/regionally established advisory thresholds. Fatalities or major impacts on human health occurring when ambient weather conditions meet heat advisory criteria are reported using the Heat category. If the ambient weather conditions are below heat advisory criteria, a Heat event entry is permissible only if a directly-related fatality occurred due to unseasonably warm weather, and not man-made environments.|
|Excessive heat||This results from a combination of high temperatures (well above normal) and high humidity. An Excessive Heat event is reported in the database whenever heat index values meet or exceed locally/regionally established excessive heat warning thresholds, on a widespread or localized basis. Fatalities (directly-related) or major impacts to human health occurring during excessive heat warning conditions are reported using this event category. Fatalities or impacts to human health occurring when conditions meet locally/regionally defined heat advisory criteria are reported within the Heat event category instead.|
|Wind||Strong wind||Non-convective winds gusting less than 50 knots (58 mph), or sustained winds less than 35 knots (40 mph), resulting in a fatality, injury, or damage. Inland counties which experience strong winds/damage associated with tropical cyclones are recorded under the Tropical Depression or Tropical Storm category, as appropriate, rather than as a Strong Wind event.|
|High wind||Sustained non-convective winds of 35 knots (40 mph) or greater lasting for one hour or longer or winds (sustained or gusts) of 50 knots (58 mph) for any duration (or otherwise locally/regionally defined), on a widespread or localized basis. In some mountainous areas, the above numerical values are 43 knots (50 mph) and 65 knots (75 mph), respectively. The High Wind event name is not used for severe local storms, tropical cyclones, or winter storm events. Events with winds less than the High Wind event threshold numbers, resulting in fatalities, injuries, or significant property damage, are encoded as a Strong Wind event.|
|Thunderstorm wind||Winds arising from convection (occurring within 30 min of lightning being observed or detected), with speeds of at least 50 knots (58 mph), or winds of any speed (non-severe thunderstorm winds below 50 knots) producing a fatality, injury, or damage. Maximum sustained winds or wind gusts (measured or estimated) equal to or greater than 50 knots (58 mph) are always entered. Events with maximum sustained winds or wind gusts less than 50 knots (58 mph) are entered only if they result in fatalities, injuries, or serious property damage.|
|Twister||Funnel cloud||A rotating, visible extension of a cloud pendant from a convective cloud with circulation not reaching the ground. This would include cold-air funnels which typically form in a shallow, cool air mass behind a cold front. The funnel cloud should be large, noteworthy, or create strong public interest to be included in the database.|
|Dust devil||A ground-based, rotating column of air, not in contact with a cloud base, usually of short duration, rendered visible by dust, sand, or other debris picked up from the ground, resulting in a fatality, injury, or damage. Dust devils usually result from intense, localized heating interacting with the micro-scale wind field. Dust devils that do not produce a fatality, injury, or significant damage are also entered as an event if they are unusually large, noteworthy, or create strong public interest|
|Tornado||A violently rotating column of air, extending to or from a cumuliform cloud or underneath a cumuliform cloud, to the ground, and often (but not always) visible as a condensation funnel. In order for a vortex to be classified as a tornado, it must be in contact with the ground and extend to/from the cloud base, and there should be some semblance of ground-based visual effects such as dust/dirt rotational markings/swirls, or structural or vegetative damage or disturbance. An Enhanced Fujita (EF) or Fujita (F) Damage Scale value is entered, depending on the year of occurrence.|
|Hydrologic||Heavy rain||An unusually large amount of rain which does not cause a Flash Flood or Flood, but causes damage or other human/economic impact. Heavy rain situations, resulting in urban and/or small stream flooding, are classified as a Heavy Rain event or another suitable event that occurred at the same time.|
|Flash flood||A rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within six hours of the causative event (e.g., intense rainfall, dam failure, ice jam-related), on a widespread or localized basis. Ongoing flooding can intensify to flash flooding in cases where intense rainfall results in a rapid surge of rising flood waters.|
|Flood||Any high flow, overflow, or inundation by water which causes or threatens damage. In general, this would mean the inundation of a normally dry area caused by an increased water level in an established watercourse, or ponding of water, generally occurring more than six hours after the causative event, and posing a threat to life or property. This can be on a widespread or localized basis. River flooding may be included in the Flood category. However, such entries should be confined only to the effects of the river flooding, such as roads and bridges washed out, homes and businesses damaged, and the dollar estimates of such damage|
|Lightning||Lightning||A sudden electrical discharge from a thunderstorm, resulting in a fatality, injury, and/or damage directly related to the lightning strike. Anyone seeking or receiving medical attention following a lightning incident is counted as a lightning injury. Anyone reporting numbness, a tingling sensation, a headache, or other pain following a lightning incident, whether or not they receive treatment, is also counted as an injury.|
|Hail||Hail||Frozen precipitation in the form of balls or irregular lumps of ice. Hail 3/4 of an inch or larger in diameter will be entered. Hail accumulations of smaller size which cause property and/or crop damage, or casualties, are also recorded.|
|Drought||Drought||A deficiency of moisture that results in adverse impacts on people, animals, or vegetation over a sizeable area. Conceptually, drought is a protracted period of deficient precipitation resulting in extensive damage to crops, resulting in loss of yield. There are different kinds of drought: meteorological, agricultural, hydrological, and social-economic. Droughts are rated as D0, D1, D2, D3, or D4 based on the intensity of the moisture deficiency and other factors. A drought event is included in the database when the drought is rated as a D2 classification, or higher.|
|Winter||Winter weather||A winter precipitation event that causes a death, injury, or a significant impact to commerce or transportation but does not meet locally/regionally defined warning criteria. A Winter Weather event could result from one or more winter precipitation types (snow, or blowing/drifting snow, or freezing rain/drizzle), on a widespread or localized basis.|
|Sleet||Sleet accumulations meeting or exceeding locally/regionally defined warning criteria (typical value is ½ inch or more).|
|Freezing fog||Fog which freezes on contact with exposed objects and forms a coating of rime and/or glaze, on a widespread or localized basis, resulting in an impact on transportation, commerce, or individuals. Freezing fog can occur with any visibility of six miles or less. Even small accumulations of ice can have an impact.|
|Frost/Freeze||A surface air temperature of 32 °F or lower, or the formation of ice crystals on the ground or other surfaces, over a widespread or localized area for a period of time long enough to cause human or economic impact.|
|Heavy snow||Snow accumulation meeting or exceeding locally/regionally defined 12 and/or 24 h warning criteria, on a widespread or localized basis. This could mean such values as 4, 6, or 8 inches or more in 12 h or less; or 6, 8, or 10 inches in 24 h or less. In some heavy snow events, structural damage, due to the excessive weight of snow accumulations, may occur in the few days following the meteorological end of the event.|
|Winter storm||A winter weather event which has more than one significant hazard (i.e., heavy snow and blowing snow; snow and ice; snow and sleet; sleet and ice; or snow, sleet and ice) and meets or exceeds locally/regionally defined 12 and/or 24 h warning criteria for at least one of the precipitation elements, on a widespread or localized basis. Normally, a Winter Storm would pose a threat to life or property.|
|Ice storm||Ice accretion meeting or exceeding locally/regionally defined warning criteria (typical value is 1/4 or 1/2 inch or more), on a widespread or localized basis. This event is also recorded for a fatality/injury that results from hypothermia in a power loss situation due to an ice storm.|
|1||Obtain “impact value” for each infrastructure/weather event combination. For each infrastructure type, average the survey results regarding impact (range from 1–4) for that particular hazard (weather event) and infrastructure type (e.g., locks). This produces a numerical value—the “impact value” for each hazard/asset type combination indicating the impact to each infrastructure type when exposed to the particular weather event type (column two from Table 2).|
|2||Obtain current vulnerability scores (impact value x frequency). For each county, multiply the average annual frequency of each aggregated weather event (column one from Table 2) times the aggregated weather event impact score for that infrastructure/weather event combination.|
|3||Obtain future vulnerability scores. Take the current vulnerability scores and apply percent increase/decrease for precipitation and temperature, and/or regression slope for future straight-line wind and tornado frequencies where these factors are relevant to the weather event type.|
|4||Rank counties by future vulnerability scores. Assign each spatial unit (e.g., county) a vulnerability score ranking by asset/weather event combination based on the value of a units vulnerability score relative to other units. Add an additional category ranking the sum of future vulnerability scores across all aggregate extreme weather event types to account for those counties that may not have high vulnerability rankings in any one infrastructure/weather event combination, but where infrastructure is likely to be exposed and damaged from a significant number of different weather events.|
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