My SKYWARN PAGE

HOW TO BECOME AN OFFICIAL NATIONAL WEATHER SERVICE SPOTTER

SKYWARN is the National Weather Service's (NWS) nationwide program of trained volunteer severe weather spotters. SKYWARN volunteers support their local community and government by providing the NWS with timely and accurate severe weather reports. These reports, when integrated with NWS Doppler Radar signatures and other data, can be critical in the issuance of severe weather warnings. This can save lives and protect property, which is the main mission of the NWS. SKYWARN was formed in the early 1970's as a nationwide program after major tornado outbreaks ravaged many areas. However, each NWS Forecast Office runs its own SKYWARN program. In southern New England, approximately 1,500 spotters have become official spotters for the NWS Forecast Office located in Taunton, Massachusetts. But we still can use many more, since severe storms can strike anywhere. The Taunton office is responsible for issuing severe weather warnings for all of Massachusetts except Berkshire County (Albany NWS); all of Rhode Island; Hartford, Windham, and Tolland Counties in Connecticut; and Cheshire and Hillsborough Counties in New Hampshire. In order to become an official NWS spotter, one needs to attend a training session conducted by the NWS. It is about a 3 hour slide and video presentation about the cloud features associated with severe thunderstorms and tornadoes. Being able to accurately identify these features is essential, so that roll clouds are not mistaken for funnel clouds or so that a true wall cloud does not go unrecognized. Criteria and procedures for reporting hail, wind, and other damage to the NWS are discussed. All SKYWARN spotters receive a newsletter at least once per year. Approximately one-third of NWS-Taunton's spotters also are amateur radio operators. This dual role can be helpful, especially during a major storm such as a hurricane, when phone and power lines are downed and amateur radio may become the primary means of communications. SKYWARN volunteers also help the NWS by reporting winter weather, flash flooding, coastal flooding, etc., according to the established criteria. It must be stressed that we are looking for reliable and objective reports. When snowfall reports are inflated or hail sizes are exaggerated, for example, it can do more harm than good. While not a requirement, it is preferred that our SKYWARN volunteers would be available to receive a call from the NWS, in the event we feel that something suspicious is happening in their area. A questionnaire form handed out at the training sessions allows one to give additional information, such as hours of availability, access to rivers/streams, type of weather equipment owned (if applicable), etc. Training sessions are held throughout southern New England typically in the late spring and early summer months. To keep informed of the latest training dates and locations, one can listen for announcements on NOAA Weather Radio or, with access to the Internet, one can type: http://www.nws.noaa.gov/er/box (the Taunton NWS Home Page) and click on "Skywarn" in the Education section.

SEVERE WEATHER DEFINITIONS

Severe weather, definitions and terminology The National Weather Service defines a severe thunderstorm as having large hail, at least 3/4 inches (0.75 inches) in diameter, and/or damaging winds, at least 58 mph, or 50 knots. Lightning, no matter how frequently it is striking, is not a criterion for determining whether a storm is severe by national weather service definitions. A severe thunderstorm watch is issued when severe thunderstorms are possible. It generally covers a large area, perhaps several states. A severe thunderstorm warning is issued when a severe thunderstorm is occurring or expected to occur within a matter of minutes. It takes a special set of atmospheric conditions to provide an environment favorable for the development of tornadoes. If these exist, then a tornado watch will be issued instead of a severe thunderstorm watch. A tornado watch means that conditions are favorable for severe thunderstorms, a few of which could produce tornadoes. A tornado warning means that a tornado has been sighted or is imminent based on radar indications. Tornadoes can form suddenly, and there may only be a severe thunderstorm warning in effect. Thus, you should pay very close attention to the weather whenever any severe weather threat exists and watches and warnings have been issued. All severe thunderstorm or tornado watches are issued by the storm prediction center in Kansas City missouri. All severe thunderstorm or tornado warnings are issued by local National Weather Service offices. The following are the hail sizes that the national weather service equates with various terminology, Pea..............1/4 inch, not severe Marble...........1/2 inch, not severe Mothball.........1/2 inch, not severe Dime.............3/4 inch, severe Penny............3/4 inch, severe Nickel...........7/8 inch, severe Quarter..........1 inch, severe Half dollar......1 1/4 inches, severe Walnut...........1 1/2 inches, severe Ping pong ball.. 1 1/2 inches, severe Golf ball........1 3/4 inches, severe Hen egg..........2 inches, severe Tennis ball......2 1/2 inches, severe Baseball.........2 3/4 inches, severe Tea cup..........3 inches, severe Grapefruit.......4 inches, severe Softball.........4 1/2 inches, severe Some other definitions, Funnel cloud: a funnel shaped cloud extending downward from a thunderstorm. It is associated with a rotating column of air that has condensed to form a cloud. It is not in contact with the ground. Tornado: a violently rotating column of air in contact with the ground and extending to the thunderstorm base. It can be a few yards across to a mile wide. Downburst: a sudden rush of cool air toward the ground that can impact with speeds greater than 70 mph and produce damage similar to that of a tornado. Viewing the damage from the air does not reveal evidence of a twisting motion or convergence toward a central track, like it would for a tornado.

SEVERE WEATHER WATCHES VS. WARNINGS

Do you know the difference between a severe thunderstorm watch and a severe thunderstorm warning? A severe thunderstorm watch means that the potential exists for the development of thunderstorms which may produce large hail or damaging winds. When a watch is issued, you should go about your normal activities, but keep an eye to the sky and an ear to the National Weather Service's weather radio or local radio and television stations for further updates and possible warnings. A severe thunderstorm warning, on the other hand, means that a severe thunderstorm is occurring or is imminent based on doppler radar information. You should move indoors to a place of safety. Schools should think about delaying departure of buses, and should take quick action to delay outdoor sports activities, etc. The term severe refers to hail that is dime size, 0.75 inches in diameter or larger, and/or wind gusts to 58 mph or more. Although lightning can be deadly it is not a criterion for what the National Weather Service defines as severe since any ordinary thunderstorm can produce a lot of lightning. Also, excessive rainfall may lead to flash flooding, but heavy rain is not a criterion for the term severe. Severe strictly refers to hail at least 3/4 of an inch in diameter or wind gusts of at least 58 mph. If hail golfball size or larger is falling, it indicates that a storm is very well organized and likely has a rotating updraft. Any storm producing giant hail should be watched closely for signs of a possible tornado. A tornado watch, like a severe thunderstorm watch, means that conditions are favorable for severe thunderstorms to form, but it also means that a few storms may be capable of producing a tornado. A tornado warning is the ultimate in severe warnings, it means that a tornado is either occurring or imminent based on radar. You should take cover immediately.

SEVERE WEATHER WATCHES VS. WARNINGS

A downburst is a strong downrush of air from a thunderstorm. It is also referred to as strong straight Line winds. Downburst wind speeds can be phenomenal, with 158 mph measured from a downburst at andrews air force base in maryland in 1986. As viewed from the air, downbursts have a damage pattern that gets wider along its path, as opposed to that of a tornado which exhibits a pattern that converges toward one central track. A small downburst, with a damage swath less than 2.5 miles across, is called a microburst. These are extremely dangerous to aviation. A large downburst is called a macroburst. Strong downbursts will definitely cause roaring sounds and people may often refer to a Sound like a freight train, terms typically associated with tornadoes. Although downbursts are not tornadoes, they can cause damage equivalent to that of a small to medium tornado. After all, wind is wind. A major downburst occurred late in the afternoon on may 21 1996 in Plymouth county in eastern Massachusetts. Earlier in the day, downbursts swept across southern portions of Hartford, Tolland and Windham counties in Connecticut with gusts to 70 mph reported and trees knocked down. But the storm that moved across Plymouth county had a measured gust to 104 mph in Whitman and caused 60 injuries in the City of Brockton and a total of about 4 million dollars in damage. Thousands of trees and tree limbs were blown down from northwest to southeast across a wide area, some striking homes and automobiles. Several thousand electric customers remained without power for several days. A number of cemeteries were severely damaged when large trees were uprooted. Golf ball size hail accompanied this storm. When unusually large hail is present, you should always take immediate precautions because the storm could be capable of producing a downburst or even a tornado.