The Spotter’s Role What we see at WFO Gray:

The Spotter’s Role To be the eyes of the NWS where severe weather is occurring or has occurred: Reporting storm type or structureReporting storm type or structure Reporting storm impactsReporting storm impacts Reporting damage, flooding or injury from stormsReporting damage, flooding or injury from storms This is the Ground Truth

The Spotter’s Role Ground Truth is the single most important type of information we can get at the NWS office. This is why spotters are so important.

On Today’s Menu Severe Weather – Thunderstorms, tornados, damaging winds, large hail. (70%) Severe Weather – Thunderstorms, tornados, damaging winds, large hail. (70%) Flooding – Flash floods, and other flooding. (15%) Flooding – Flash floods, and other flooding. (15%) Weather Safety – Basic weather safety rules. (15%) Weather Safety – Basic weather safety rules. (15%) Snow reports – Reporting snow totals (10%) Snow reports – Reporting snow totals (10%)

Terms and Definitions Severe Thunderstorm – Thunderstorm producing winds of at least 58 mph (50 kts), and/or ¾” diameter hail (or greater). Severe Thunderstorm – Thunderstorm producing winds of at least 58 mph (50 kts), and/or ¾” diameter hail (or greater). Tornado – Violently rotating column of air, attached to a thunderstorm base, and in contact with the ground. Tornado – Violently rotating column of air, attached to a thunderstorm base, and in contact with the ground. Funnel Cloud – Rotating funnel-shaped cloud extending downward from a thunderstorm base, but not necessarily in contact with the ground. Funnel Cloud – Rotating funnel-shaped cloud extending downward from a thunderstorm base, but not necessarily in contact with the ground.

Terms and Definitions Downburst – Strong downdraft producing an outrush of damaging winds at or near the ground (Microburst – smaller scale, but wind may be more concentrated) Downburst – Strong downdraft producing an outrush of damaging winds at or near the ground (Microburst – smaller scale, but wind may be more concentrated) Flash Flood – A rapid rise in water, usually occurring in 3 hours or less. Flash Flood – A rapid rise in water, usually occurring in 3 hours or less.

Terms and Definitions Watch – Conditions are favorable for severe weather in and near the watch area. Watch – Conditions are favorable for severe weather in and near the watch area. Warning – Severe weather is imminent or occurring in the warned area. Warning – Severe weather is imminent or occurring in the warned area.

Reporting Criteria Tornado Hail (any size) Funnel Cloud Winds 50 mph or greater Rotating Wall Cloud Rain: 1” an hour or more Flash Flooding Rain: 2” or greater in < 6 hours

We need your photos Many photos from the Great Plains, where the land is flat, the air is clear Many photos from the Great Plains, where the land is flat, the air is clear New England is hills and haze New England is hills and haze Send your photos to: Send your photos to:

Thunderstorms Required for thunderstorm formation: 1.Moisture/Instability 2.Lift

Important Thunderstorm Features MesocycloneMesocyclone Wall CloudWall Cloud Funnel/TornadoFunnel/Tornado HailHail Downburst/MicroburstDownburst/Microburst

Mesocyclone

Remember from earlier?

Wall Cloud in NH

Tornado?

Tornado?

Tornado?

Pulse Storms Most of our severe weather comes from pulse storms. Most of our severe weather comes from pulse storms. Pulse storms are strong thunderstorms, which are briefly severe. Pulse storms are strong thunderstorms, which are briefly severe. –Their core aloft ‘collapses’ resulting in a downburst –Warning lead time will be short, but some lead time can be provided.

What to report We want to hear about what damage storms caused. We want to hear about what damage storms caused. The most common way we verify damaging winds is with a ‘Tree(s) down’ – how many, roughly how large diameter, were they already dead. The most common way we verify damaging winds is with a ‘Tree(s) down’ – how many, roughly how large diameter, were they already dead. We do not need measured wind speeds (although its nice if you have it). We do not need measured wind speeds (although its nice if you have it). Hail, structure damage, tornado, wall cloud, etc. Hail, structure damage, tornado, wall cloud, etc.

What not to report: Lightning Lightning -We have an accurate detection system “Dark Sky,” “It’s starting to rain,” “It’s raining hard,” “The winds are starting to blow,” etc. “Dark Sky,” “It’s starting to rain,” “It’s raining hard,” “The winds are starting to blow,” etc.

Snowstorms (your extra 10%) Planning more a few fall training sessions for more on winter weather spotting. Planning more a few fall training sessions for more on winter weather spotting. Stay tuned on NOAA weather radio, or the web page Stay tuned on NOAA weather radio, or the web page

Measuring Snow Measure snow in a natural, and previously snow- free location if possible (deck, grass, dirt driveway preferable over blacktop) Measure snow in a natural, and previously snow- free location if possible (deck, grass, dirt driveway preferable over blacktop) Take at least 5 representative measurements, then average them. Take at least 5 representative measurements, then average them. We’re interested in a storm total, and roughly every 4 inches (4, 8, 12, 18, 24) We’re interested in a storm total, and roughly every 4 inches (4, 8, 12, 18, 24) Snowfall accumulations of 2 inches per hour Snowfall accumulations of 2 inches per hour Thundersnow Thundersnow

How to report: The best way is to call: The best way is to call: Report to the net Report to the net