What is the EF Scale? #
The Enhanced Fujita Scale rates tornadoes EF0–EF5 based on damage assessment, not direct wind measurement. Adopted in 2007, it improved on the original Fujita Scale by tying ratings to engineering-based damage indicators.
Tornado, Hail & EF Scale Terms
Every tornado gets a rating, and every rating comes from a damage survey, not a measurement of the wind. This page covers the EF scale end to end, tornado morphology from ropes to wedges, outbreak terminology, and the hail size ladder that makes a storm severe in the first place. When a tornado is on the ground, XWD’s live coverage in the Discord is where members follow it in real time.
What is an EF0 Tornado? #
EF0 is the weakest tornado rating: 65–85 mph winds. Minor damage — broken tree limbs, signs down, shingles peeled.
What is an EF1 Tornado? #
EF1: 86–110 mph winds. Moderate damage — roof surfaces stripped, mobile homes overturned, exterior doors blown off.
What is an EF2 Tornado? #
EF2: 111–135 mph winds. Considerable damage — roofs torn from well-built homes, mobile homes destroyed, large trees snapped or uprooted. The threshold for significant tornadoes.
What is an EF3 Tornado? #
EF3: 136–165 mph winds. Severe damage — entire stories of well-constructed houses destroyed, trains overturned, structures with weak foundations blown away.
What is an EF4 Tornado? #
EF4: 166–200 mph winds. Devastating damage — well-constructed homes leveled, structures swept off foundations, cars thrown significant distances. Violent tornado tier.
What is an EF5 Tornado? #
EF5: >200 mph winds. The highest rating — incredible damage. Strong-framed homes swept clean off foundations, automobiles thrown 100+ yards, steel-reinforced concrete structures critically damaged.
What is an EFU Tornado? #
EFU (EF-Unknown) is the rating given when a tornado is confirmed but no damage indicators are available to rate it — typically open fields or unsurveyed terrain.
What is a Damage Survey? #
A damage survey is conducted by NWS meteorologists (and sometimes SPC/Engineering teams) in the days following a tornado or damaging wind event. They walk or fly the damage path and use engineering damage indicators to assign the EF rating. Results are published in a PNS. EF ratings come from damage evidence, not direct wind measurement.
What is Storm Data? #
Storm Data is NOAA's official monthly publication documenting all significant U.S. weather events — tornadoes, floods, hail, lightning, wind, winter storms — with location, path info, damage estimates, and fatality/injury counts. It's the definitive historical record for U.S. severe weather events and the source for SPC historical tornado data.
What is a Tornado Track? #
A tornado track is the path of damage on the ground from a tornado, typically trending from southwest to northeast. Track length and width, combined with damage indicators, are used by NWS survey teams to rate tornado intensity (EF-scale) and estimate maximum wind speed. The longest track tornadoes (100+ miles) are typically EF4–EF5.
What is a Rope Tornado? #
A rope tornado is the thin, sinuous tornado form seen during the dissipating stage of a tornado's lifecycle. As the parent mesocyclone occludes and tilts, the tornado stretches into a narrow, contorted rope shape. Despite looking less impressive, rope tornadoes can still be dangerous — some maintain significant intensity in the rope stage before finally lifting.
What is a Stovepipe Tornado? #
A stovepipe tornado is a large, nearly cylindrical, near-vertical tornado with a consistent width from the cloud base to the ground. One of the most recognizable and photogenic tornado shapes — and typically one of the stronger ones. Not an official meteorological classification, but widely used by spotters and the weather community.
What is a Wedge Tornado? #
A wedge tornado is a tornado whose width is greater than or equal to its visible height above the surface — essentially a solid wall of rotation. Nearly always rated EF3+. The 2011 Joplin, 2011 Tuscaloosa-Birmingham, and 1999 Bridge Creek–Moore tornadoes were classic wedges. Spotters sometimes lose reference points for scale, making wedges psychologically as well as physically overwhelming.
What is a Multi-Vortex Tornado? #
A multi-vortex tornado contains two or more sub-vortices orbiting the main circulation. These suction vortices are small (tens of meters) but extremely intense, responsible for the patchwork of catastrophic and minimal damage seen in wide tornado paths. Multi-vortex structure is associated with EF4–EF5 intensity.
What is a Satellite Tornado? #
A satellite tornado is a secondary, smaller tornado that orbits a much larger parent tornado. Unlike suction vortices (inside the main funnel), satellite tornadoes appear as distinct funnels rotating around the primary. They typically occur with violent (EF4+) tornadoes and significantly widen the damage swath.
What is a Rain-Wrapped Tornado? #
A rain-wrapped tornado is a tornado obscured by heavy precipitation — extremely common with HP supercells and QLCS events. You cannot see it coming. This is why sheltering based on warnings (not visual confirmation) is critical. Many tornado fatalities occur in rain-wrapped situations where people didn't shelter because they couldn't see the tornado.
What is a Cyclic Tornado? #
A cyclic tornado is a series of tornadoes produced by the same supercell as it repeatedly cycles through mesocyclone development, tornadogenesis, and occlusion. Each tornado tracks roughly parallel to the previous one but displaced slightly to the right. Some supercells produce 5–10+ tornadoes in a single storm's lifetime.
What is a Tornado Outbreak? #
A tornado outbreak is generally defined as 6 or more tornadoes from the same synoptic system in a 24-hour period. Major outbreaks (e.g. April 27, 2011 with 216 tornadoes in one day) are driven by strongly forced setups with elevated CAPE, strong shear, and a well-defined surface boundary. The SPC issues MDT or HIGH risks before most significant outbreaks.
What is Hail? #
Hail forms when updrafts carry raindrops above the freezing level, where they freeze and accumulate ice layers. Stronger updrafts support larger hail — giant hail (4"+) requires updrafts well over 100 mph.
What is Significant Hail? #
Significant hail is 2 inches in diameter or larger (about hen-egg sized). It's a key SPC threshold and is the entry point for a CIG1 hail outlook.
What is Giant Hail? #
Giant hail is hail 4 inches or larger (softball+). It requires an extreme updraft — typically only the strongest supercells produce it.
Hail Size Reference #
Hail size reference: Pea (0.25"), Marble (0.5"), Dime (0.75"), Quarter (1" — severe threshold), Half Dollar (1.25"), Ping Pong (1.5"), Golf Ball (1.75"), Hen Egg (2" — significant / CIG1), Tennis Ball (2.5"), Baseball (2.75" — destructive), Tea Cup (3"), Softball (4" — giant), Grapefruit (4.5"+).