Severe Weather Tornado Detection Forecasters and storm spotters have learned to recognize certain thunderstorm features and structure that make tornado formation more likely.
Some of these are visual cues, like the rear-flank downdraft, and others are particular patterns in radar images, like the tornadic vortex signature TVS. Storm spotters have been trained to recognize tornado conditions and report what they see to the National Weather Service.
Storm spotters can be emergency managers or even local people with a keen interest in severe weather who have taken formal storm spotter training in their community. Computer programs, called algorithms, analyze Doppler radar data and display it in ways that make it easier for forecasters to identify dangerous weather.
A storm with a tornado observed by radar has certain distinguishing features and forecasters are trained to recognize them. When a Doppler radar detects a large rotating updraft that occurs inside a supercell, it is called a mesocyclone.
The mesocyclone is usually miles in diameter, and is much larger than the tornado that may develop within it. NSSL developed the WSRD Mesoscale Detection Algorithm to analyze radar data and look for a rotation pattern meeting specific criteria for size, strength, vertical depth, and duration.
A mesocyclone is usually miles in diameter, and is much larger than the tornado that may develop within it.
The TVS appears on radar several kilometers above the ground before a tornado touches ground. It has smaller, tighter rotation than a mesocyclone. While the existence of a TVS does not guarantee a tornado, it does strongly increase the probability of a tornado occurring.
A hook is often associated with a mesocyclone and indicates favorable conditions for tornado formation. The hook is caused by the rear flank downdraft and is the result of precipitation wrapping around the back side of the updraft. Dual-polarization radar technology, installed on NWS radars, can detect the presence of random shaped and sized targets like leaves, insulation or other debris.
This gives meteorologists a high degree of confidence that a damaging tornado is on the ground, and is especially helpful at night when tornadoes are difficult to see with the human eye. NSSL's On-Demand web-based tool helps confirm when and where tornadoes have possibly occurred by mapping circulations on Google Earth satellite images.
NWS forecasters can quickly review warnings and check their accuracy with this system. Emergency responders and damage surveyors have also used On-Demand to produce high-resolution street maps of potentially damaged areas so they can more effectively begin rescue and recovery efforts.
NSSL engineers and scientists have adapted phased array technology, formerly used on Navy ships for surveillance, for use in weather forecasting. Phased array technology can scan an entire storm in less than one minute, allowing forecasters to see signs of developing tornadoes well ahead of current radar technology.
NSSL uses a mobile Doppler radar to position close to tornadic storms to scan the entire lifecycle of a tornado. This helps us understand atmospheric processes to help improve forecasts of significant weather events. NSSL's second generation Warning Decision Support System, WDSS-II, is an advanced algorithm development and visualization platform that accepts data from multiple sources and organizes it in ways that convey critical severe weather information to warning meteorologists.
Tornadic Vortex Signature in radar data. In this display, the circle is a mesocyclone, and the triangle is the TVS. The radars were located about 40 miles from each other and were able to record data on the same storm but from two different perspectives.Intelligence Analysis: Behavioral and Social Scientific Foundations () Chapter: 4 Use of Signal Detection Theory as a Tool for Enhancing Performance and Evaluating Tradecraft in Intelligence Analysis--Gary H.
McClelland. NSSL developed the Tornado Detection Algorithm now used by the National Weather Service in their forecasting operations.
Work continues on the next-generation system which uses Multiple Radars and Multiple Sensors (MRMS) to present critical information to forecasters.
Tornado Alert is a scientific breakthrough based upon over 40 years of research. Unlike existing warning technologies, Tornado Alert constantly monitors the skies in real-time for electrical activity, the scientifically proven cause of tornado formation.
Since the majority of all tornadoes are weak, and because the probability of detection for tornadoes in watches is lowest for weak tornadoes (Leftwich and Anthony ), most of these missed events are weak tornadoes and probably are not associated with supercells.
Galway () has observed that the majority of tornado deaths occur in watches. Tornado Detection and Warnings with Doppler Weather Radar all started with the capture of a tornado NOAA th Top Tens: Tornado Detection and Warnings with Doppler Weather Radar With the NOAA th Celebration coming to a close at the end of , maintenance of this Web site ceased.
principal component methods are used to quantify the correlation between vortex detection attributes and tor- nadoes. The results of this analysis reveal that only a very small percentage (,5%) of.