Storm Station 247

The Field Book/Vol. III, The Sky/Cloud classification/FB-SKY-042

Overshooting top and above anvil plume

An overshooting top is a dome of cloud pushed above a thunderstorm's anvil by an updraft strong enough to carry air past the tropopause. Downwind of it, ice thrown higher still can stream away above the anvil as a plume. Both mark the strongest storms, and both are watched from space.

Plate FB-SKY-042Storm cloudsRevision 1, 2026-09-24Status draftAlso called overshooting top, overshooting dome, above anvil cirrus plume, anvil plume, enhanced V, cold U, penetrating top

A painted section of a strong thunderstorm over a prairie, heights to scale from the ground to 59,000 feet (18 kilometres): a billowing tower with an updraft arrow rising through it and past the tropopause near 39,000 feet (12 kilometres), into a dome above the anvil dimensioned as a few thousand feet above it; the thin anvil spread along the tropopause; a streaked plume of ice thrown downwind above the anvil under an arrow of the wind at anvil level; and a note that the dome is the coldest cloud top on the map.
Fig. A The top of a strong storm. The dome over the anvil, and the plume thrown downwind above it.MaximizeThe drawing, to scale

What it is

An overshooting top is a dome of cloud standing above a thunderstorm's anvil, directly over its updraft. The anvil spreads out flat along the tropopause, near 39,000 ft (12 km) in the middle latitudes in summer, because that is where rising air stops being lighter than the air around it. An updraft strong enough is still rising fast when it gets there, and its momentum carries it on, a few thousand feet higher, before it slows and sinks back. Fig. A draws the dome, the anvil and the updraft beneath them.

Downwind of the dome, ice thrown higher still can be caught by the wind above the anvil and stream away from it as a plume, the above anvil plume. Both mark the strongest storms, and both are watched from space.

What it is not

It is not the anvil itself, which is flat and spreads along the tropopause; the dome stands above it, over the updraft. It is not the cauliflower top of a growing cumulus, Cumulus FB-SKY-018, which lies below the tropopause. And it is not permanent: a single dome rises and collapses in minutes, and a storm with a strong, lasting updraft sends up one after another.

Lookalikes

Anvil
Flat, spreading along the tropopause; the dome stands above it
Cumulus congestus top
A cauliflower top below the tropopause, not a dome above an anvil
Gravity wave ripples
Waves on the anvil top that move away from the dome; the dome itself stands over the updraft

The machine

Above the tropopause the air grows warmer with height, Atmosphere in section FB-ENG-001. A parcel carried up into it by the updraft keeps cooling as it rises, so it is soon much colder than the air around it, and heavier. It slows, stops and falls back. That is why the dome is the coldest cloud top on the map: it is the one place where cloud has been pushed up into air it cannot stay in, still carrying the cold of its rise.

How high the dome rises measures how strongly the updraft is still rising at the tropopause. A few thousand feet is usual; much more than about 10,000 ft (3 km) is rare. A storm whose tops repeatedly overshoot has an updraft strong enough to hold large hail aloft and to feed a mesocyclone, Supercell FB-EVT-007, and such storms bring most of the damaging hail, wind and tornadoes.

The plume forms where the dome's ice is thrown into the stratosphere and the wind there, strong and often from a different direction than the wind at anvil level, carries it downwind above the anvil. Because the stratosphere is warmer than the anvil top, the plume can look warmer than the anvil beneath it on an infrared image.

A painted plan of a thunderstorm seen from above, as a schematic of an infrared image: the anvil as a long oval spread downwind to the right over grey brown ground, pale blue at its edge, deeper blue within and violet at its colder core; a small bright bubble of overshooting top near its upwind end; a pale plume streaming downwind from it above the anvil; an arrow of the wind at anvil level; and a key from warmer to colder.
Fig. B The same storm from above, in the infrared. Looking down on the anvil: the colder the cloud top, the deeper the colour.MaximizeThe drawing, to scale

The drawings

Each figure drawn as an engineering sheet, its parts numbered, to print at 11 by 17.

Section of a thunderstorm from the ground to 59,000 feet (18 kilometres): the updraft rising through the tower and past the tropopause near 39,000 feet (12 kilometres) into a dome above the anvil, dimensioned as a few thousand feet above it; the anvil spread along the tropopause; a plume of ice streaming downwind above the anvil with the wind at anvil level; and a note that the dome is the coldest cloud top on the map.1122334455667788AABBCCDDEESTORM STATION 247THE FIELD BOOKPLATE FB-SKY-042-ATHE UPDRAFT CARRIED PAST THE TROPOPAUSE INTO A DOME ABOVE THE ANVIL, AND A PLUME OF ICE THROWN DOWNWIND ABOVE IT; HEIGHTS TYPICALFIG. A THE TOP OF A STRONG STORM010203040500246810121416kft(km)LOWMIDDLEHIGHTROPOPAUSE, NEAR 39,000 ft (12 km)WIND AT ANVIL LEVELTHE DOME IS THE COLDESTCLOUD TOP ON THE MAPA FEWTHOUSAND FEETKEYIce crystalsUpdraft12345TITLEOvershooting top and above anvil plume, the top of a strong stormVOL. III THE SKY · STORM CLOUDSTYPESECTIONSCALEHEIGHT TO SCALE, WIDTH NTSREVREV 1 DRAFT SHEET 1 of 2DATE2026-09-24IDFB-SKY-042-ADRAWN AS linework on paperSOURCES AMS, Markowski, Wallace
Fig. A, the drawing The top of a strong storm. The updraft carried past the tropopause into a dome above the anvil, and a plume of ice thrown downwind above it; heights typical HEIGHT TO SCALE, WIDTH NTSMaximizeThe sheet, SVG, 11 by 17The painting
  1. The overshooting top
  2. The anvil
  3. The above anvil plume
  4. The updraft
  5. The tropopause
Plan of the storm seen from above as a schematic of an infrared image: the anvil as a long oval spread downwind to the right, its colder core ruled closer, the overshooting top as a small cold bubble near its upwind end, and the plume streaming downwind from it above the anvil.1122334455667788AABBCCDDEESTORM STATION 247THE FIELD BOOKPLATE FB-SKY-042-BTHE STORM SEEN FROM SPACE IN THE INFRARED, AS A SCHEMATIC: CLOSER RULING IS COLDER CLOUD TOPFIG. B THE SAME STORM FROM ABOVE, IN THE INFRAREDWIND AT ANVIL LEVELDRAWN AS A SCHEMATIC OF AN INFRARED IMAGE: CLOSER RULING IS COLDER CLOUD TOP. NOT TO SCALE.KEYThe anvilIts colder core1234TITLEOvershooting top and above anvil plume, the same storm from above, in the infraredVOL. III THE SKY · STORM CLOUDSTYPEPLANSCALENOT TO SCALEREVREV 1 DRAFT SHEET 2 of 2DATE2026-09-24IDFB-SKY-042-BDRAWN AS linework on paperSOURCES AMS, Markowski, Wallace
Fig. B, the drawing The same storm from above, in the infrared. The storm seen from space in the infrared, as a schematic: closer ruling is colder cloud top NOT TO SCALEMaximizeThe sheet, SVG, 11 by 17The painting
  1. The overshooting top, the coldest cloud top on the map
  2. The above anvil plume, carried downwind
  3. The anvil
  4. The anvil's downwind edge

Ingredients

  • An updraft strong enough that its air, reaching the tropopause, is still rising fast
  • Its momentum, which carries the air past the level where it stops being buoyant
  • Strong wind above the anvil, which carries ice from the dome downwind as a plume

Scales

time
minutes for one dome; they pulse and collapse and rise again while the updraft lasts
horizontal
a dome a mile or a few miles (a few km) across; a plume can stream 100 mi (160 km) downwind
vertical
a few thousand feet above the anvil
orlanski
meso gamma

Signatures

satellite
the coldest cloud tops on the infrared image, often in a V or U shaped ring of cold cloud; bubbling texture and shadows in the visible
radar
a strong, tall echo reaching above the tropopause
surface
none directly: it stands far above any station, though the storm beneath it often brings hail and damaging wind

The numbers

QuantityValue, and the kind of number it is
Overshooting topA dome of cloud above the anvil, made by an updraft that carries air past the tropopauseStandard, Glossary of Meteorology
Height above the anvilTypically a few thousand feet, rarely more than about 10,000 ft (3 km)Typical, Markowski 2010
TemperatureColder than the anvil around it, because the rising air keeps cooling as it overshootsTextbook, Wallace 2006
Tropopause36,000 ft (11 km) in the standard atmosphere; near 39,000 ft (12 km) above summer stormsStandard, U.S. Standard Atmosphere
Above anvil plumeIce thrown into the lower stratosphere above the anvil and carried downwindTextbook, Markowski 2010
Severe thunderstormHail of 1 inch (2.5 cm) or more, a gust of 58 mph (50 knots, 26 m/s) or more, or a tornadoStandard, Directive 10-511

How the station sees it

No station on the ground sees it: the dome stands far above every instrument. Satellites see it best. In the infrared, Fig. B, it is the coldest spot on the storm's top, often at the upwind end of a V or U shaped ring of cold cloud, with the plume spreading downwind from it. In the visible, the dome casts a shadow on the anvil in the low sun of morning and evening, and its top bubbles as each new pulse arrives. Radar sees the storm's echo reaching unusually high.

How it is warned

The dome is not warned; the storm beneath it is. Forecasters use overshooting tops, and above anvil plumes, as signs that a storm's updraft is strong enough to be severe, and they watch for them on the satellite loop while the radar shows what is happening lower down. The warnings that follow are Severe Thunderstorm and Tornado Warnings, Thunderstorm FB-EVT-001.

See also

Sources

  1. American Meteorological Society. Glossary of Meteorology.
  2. Markowski, P. and Y. Richardson. Mesoscale Meteorology in Midlatitudes (2010).
  3. Wallace, J. M. and P. V. Hobbs. Atmospheric Science, An Introductory Survey, 2nd ed. (2006).
  4. NOAA, NASA and the U.S. Air Force. U.S. Standard Atmosphere, 1976.
  5. National Weather Service. Directive 10-511, WFO Severe Weather Products Specification.

Definition after the International Cloud Atlas. Plate FB-SKY-042, revision 1, 2026-09-24. The number is permanent; cite it.