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Straig H T-Line W in Ds Straight Straight-Line Winds Straight-line winds are one of the most common hazards produced by both severe and non-severe thunderstorms. Depending on the organization of the storms, damage can be localized to just a few miles in area or in the case of exceptionally well-organized storms hundreds of miles in area. The - types of thunderstorms that most commonly produce a straight-line wind threat include large Line Winds Mesoscale Convective Systems (MCSs) and supercells. This help page highlights these different storms types, wind shifts, and how to diagnose these features using radar. Thin Lines & Wind Shifts Radar reflectivity is a great tool for diagnosing fronts and wind shifts. Radar can see many different boundaries such as cold fronts, dry lines, and outflow boundaries due to the temperature and moisture differences in the air, which create a radar reflectivity feature known as a “thin line.” In the example to the right, the black ellipse indicates where a thin line is and the red arrows indicate a wind shift associated with a cold front. It is important to keep in mind that thin lines are only visible closer to a radar due to the radar beam overshooting surface fronts at farther distances from the radar. Supercells Even though supercell thunderstorms are often thought of as always producing tornadoes, only 20% of them actually produce tornadoes. Supercells can and do produce straight-line winds more often than tornadoes. In the example below this supercell produced a 70 mph wind gust near Blair, Oklahoma. Base Reflectivity data is on the left and Base Velocity data is on the right. Base Reflectivity Base Velocity Mesoscale Convective Systems Mesoscale Convective Systems (MCSs) are large storm complexes made up of numerous storms. They can be organized in different ways but most commonly contain a line of storms (squall line), multiple lines of storms (line echo wave pattern), or clusters of storms. MCSs tend to form as a severe weather event progresses due to the interaction of multiple storms. The storms work together to produce strong to severe winds as well as very heavy rain. Below is an example of a squall line as viewed in Base Reflectivity (left) and Base Velocity (right). Surface data in the maps include wind barbs and maximum wind gusts (in miles per hour) from the Line Winds Oklahoma Mesonet. Notice how the storms form a continuous region of very heavy rain and strong - winds. Weak tornadoes can sometimes accompany squall lines, though did not occur during this event. Straight Bow Echoes A bow echo is a radar feature that develops during some MCS events and tends to be associated with very strong winds. On radar it can be identified by what looks like a backwards ‘C’ or an archers bow. Winds are typically the strongest towards the center of the bow. Below is an example of a bow echo on radar as viewed with Base Reflectivity (left) and Base Velocity (right). This bow echo had wind gusts as strong as 80 mph and also produced tornadoes in the Tulsa area. .
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