A wake low, or wake depression, is a mesoscale

Mesoscale meteorology

Mesoscale meteorology is the study of weather systems smaller than synoptic scale systems but larger than microscale and storm-scale cumulus systems. Horizontal dimensions generally range from around 5 kilometers to several hundred kilometers...

 low-pressure area which trails the mesoscale high following a squall line

Squall line

A squall line is a line of severe thunderstorms that can form along or ahead of a cold front. In the early 20th century, the term was used as a synonym for cold front. It contains heavy precipitation, hail, frequent lightning, strong straight-line winds, and possibly tornadoes and waterspouts....

. Due to the subsiding warm air associated with the systems formation, clearing skies are associated with the wake low. Once difficult to detect in surface weather observation

Surface weather observation

Surface weather observations are the fundamental data used for safety as well as climatological reasons to forecast weather and issue warnings worldwide. They can be taken manually, by a weather observer, by computer through the use of automated weather stations, or in a hybrid scheme using...

s due to their broad spacing, the formation of mesoscale weather station

Weather station

A weather station is a facility, either on land or sea, with instruments and equipment for observing atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include temperature, barometric pressure, humidity, wind speed, wind...

 networks, or mesonets, has increased their detection. Severe weather

Severe weather

Severe weather phenomena are weather conditions that are hazardous to human life and property.- Examples Include :Severe weather can occur under a variety of situations, but three characteristics are generally needed: a temperature or moisture boundary, moisture, and , instability in the...

, in the form of high wind

Wind

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...

s, can be generated by the wake low when the pressure difference between the mesohigh preceding it and the wake low is intense enough. When the squall line is in the process of decay, heat burst

Heat burst

In meteorology, a heat burst is a rare atmospheric phenomenon characterised by gusty winds and a rapid increase in temperature and decrease in dew point...

s can be generated near the wake low. Once new thunderstorm

Thunderstorm

A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...

 activity along the squall line ends, the wake low associated with it weakens in tandem

Tandem

Tandem is an arrangement where a team of machines, animals or people are lined up one behind another, all facing in the same direction....

.

Formation

Wake lows form due to adiabatic

Lapse rate

The lapse rate is defined as the rate of decrease with height for an atmospheric variable. The variable involved is temperature unless specified otherwise. The terminology arises from the word lapse in the sense of a decrease or decline; thus, the lapse rate is the rate of decrease with height and...

 warming in the wake of mature squall lines at the back edge of their rain shields, where evaporative

Evaporation

Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

 cooling is unable to offset warming due to atmospheric subsidence

Subsidence

Subsidence is the motion of a surface as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation...

, or downward motion. They can be caused by gravity wave

Gravity wave

In fluid dynamics, gravity waves are waves generated in a fluid medium or at the interface between two media which has the restoring force of gravity or buoyancy....

s which duct through boundary layers which are deep and cold to the north of a weather front

Weather front

A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front...

. As with mesoscale high-pressure areas behind a squall line, when new thunderstorm

Thunderstorm

A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...

 development stops along the squall line, the wake low will weaken as well. Clearing conditions will accompany the wake low, due to the descending warm air mass associated with the feature. Within the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, these systems have been observed to form in the Mississippi river

Mississippi River

The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

 valley, Southeast, Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

, and Great Plains

Great Plains

The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...

.

Detection

Both direct and indirect ways have been found to indicate the presence of a wake depression. The most direct is through the use of surface observations. Prior to the development of mesoscale weather station networks, or mesonets, it was difficult to find wake lows. With the advent of mesoscale networks, wake lows have become easier to find. On weather satellite

Weather satellite

The weather satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be either polar orbiting, seeing the same swath of the Earth every 12 hours, or geostationary, hovering over the same spot on Earth by orbiting over the equator while...

 and weather radar

Weather radar

Weather radar, also called weather surveillance radar and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, estimate its type . Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the...

 imagery, wake lows and heat bursts normally occur on the back side of a precipitation area. However, within larger precipitation areas, they can be located within the area showing a minimum of returns. When using velocity data from a WSR-88D doppler radar, high winds on the back edge of reflectivity data can give away the location of a wake low.

Association with heat bursts

Heat bursts are rare atmospheric phenomenon characterized by gusty winds and a rapid increase in temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

 and decrease in dew point

Dew point

The dew point is the temperature to which a given parcel of humid air must be cooled, at constant barometric pressure, for water vapor to condense into liquid water. The condensed water is called dew when it forms on a solid surface. The dew point is a saturation temperature.The dew point is...

 (moisture). Heat bursts typically occur during night-time and are associated with decaying thunderstorms. In association with wake lows, heat bursts are caused when rain evaporates (virga

Virga

In meteorology, virga is an observable streak or shaft of precipitation that falls from a cloud but evaporates before reaching the ground. At high altitudes the precipitation falls mainly as ice crystals before melting and finally evaporating; this is usually due to compressional heating, because...

) into a parcel of cold dry air high in the atmosphere making the air denser than its surroundings. The parcel descends rapidly, warming due to compression, overshoots its equilibrium level

Equilibrium level

In meteorology, the equilibrium level , or level of neutral buoyancy , or limit of convection , is the height at which a rising parcel of air is at a temperature of equal warmth to it....

 and reaches the surface, similar to a downburst

Downburst

A downburst is created by an area of significantly rain-cooled air that, after reaching ground level, spreads out in all directions producing strong winds. Unlike winds in a tornado, winds in a downburst are directed outwards from the point where it hits land or water...

.

Recorded temperatures during heat bursts have reached well above 90 °F (32 °C), sometimes rising by 20°F (11°C) or more within only a few minutes. More extreme events have also been documented, where temperatures have been reported to exceed 130 °F (54 °C), although such extreme events have never been officially verified. Heat bursts are also characterised by extremely dry air and are sometimes associated with very strong, even damaging, wind

Wind

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...

s.