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Explosive cyclogenesis

Explosive cyclogenesis, commonly referred to as a "meteorological bomb" or "bomb cyclone"—a term popularized in media during the 2010s—, is the rapid deepening of an extratropical cyclone, defined by a central sea-level pressure decrease of at least 24 hectopascals over 24 hours when normalized to 60° latitude.^[1] This criterion, equivalent to a pressure fall rate of 1 hectopascal per hour, distinguishes these events from typical cyclogenesis by their extreme intensity and speed of development.^[2] The phenomenon was first systematically described in a 1980 study analyzing Northern Hemisphere cyclones from 1976 to 1979, highlighting its role in producing severe weather.^[1] These storms predominantly form in maritime environments during the cold season, favoring regions of enhanced baroclinicity such as the western North Atlantic (near the Gulf Stream) and North Pacific (near the Kuroshio Current) oceans.^[2] Key characteristics include strong upper-level forcing from cyclonic vorticity advection and divergence, combined with low static stability and latent heat release from condensation, often amplified by the presence of atmospheric rivers—narrow corridors of intense water vapor transport.^[3] Atmospheric rivers coincide with approximately 80% of explosive cyclogenesis events, peaking near the maximum deepening point and contributing to heavier precipitation through enhanced moisture influx.^[3] Explosive events are statistically separable from non-explosive cyclones by stronger upper-tropospheric wave influences and kinematic vertical velocities, though low-level baroclinity shows less distinction.^[4] The impacts of explosive cyclogenesis are significant, generating strong winds often exceeding 90 km/h (56 mph), heavy rainfall leading to flooding, and dangerous marine conditions like high waves and storm surges that threaten coastal areas.^[5] A study from 1979 to 2008 found no long-term global trend in frequency, remaining within natural variability, with higher occurrence in the Northern Hemisphere winter compared to the Southern Hemisphere; however, more recent analyses indicate increasing trends in certain regions, such as approximately 40% in the Atlantic basin from 1980 to 2020 and 2.3 per decade in the Southern Ocean.^[2]^[6]^[7] Improved detection methods, such as normalized deepening rates relative to both central pressure and climatological gradients, help exclude artificial intensifications in reanalysis data, ensuring accurate climatological assessments.^[2]

Definition and Characteristics

Definition

Explosive cyclogenesis refers to the rapid deepening of an extratropical low-pressure cyclone, characterized by a significant decrease in central sea-level pressure over a short period. Specifically, it is classified as explosive when the central pressure falls by at least 24 hectopascals (hPa) in 24 hours when normalized to 60° latitude.^[1] This threshold is adjusted for lower latitudes to account for variations in the Coriolis parameter, using the formula \Delta p \geq 24 \times \frac{\sin \phi}{\sin 60^\circ} hPa over 24 hours, where \phi is the latitude of the cyclone's center. For instance, the required pressure drop increases to approximately 28 hPa near the poles (\phi = 90^\circ) and decreases to about 12 hPa at 25° latitude. This scaling ensures the criterion reflects the dynamical constraints on cyclone intensification at different latitudes.^[1] The phenomenon is also known by alternative terms such as "meteorological bomb," "weather bomb," or "bomb cyclone"; these were formalized by Sanders and Gyakum in 1980, drawing an analogy to the explosive rapidity of development, with informal use of "bomb" for intense storms dating to the 1940s Bergen School.^[1]^[8] In contrast to regular cyclogenesis, which involves gradual intensification of extratropical cyclones typically at rates below these thresholds, explosive cyclogenesis highlights an accelerated phase driven by enhanced baroclinic instability.^[1]

Key Characteristics

Explosive cyclones during their intensification phase display a distinctive structural evolution, most notably the development of a comma-shaped cloud pattern visible in satellite imagery, where the "head" of the comma corresponds to the occluded warm front and the "tail" to the trailing cold front.^[9] This pattern reflects the cyclone's rapid organization, featuring a tight central pressure gradient that enhances surface winds and a potential warm seclusion, in which a mass of relatively warm air becomes wrapped around the low-pressure center and isolated from surrounding colder air.^[9] These systems generate severe associated weather, including hurricane-force winds exceeding 64 knots (74 mph or 119 km/h), which can cause widespread damage, along with heavy precipitation leading to flooding or blizzards, and storm surges that threaten coastal areas.^[10] The typical deepening rate averages 1–2 hPa per hour during the explosive phase, far surpassing ordinary extratropical cyclone development and amplifying the intensity of these features.^[1] Explosive cyclogenesis events are primarily winter phenomena in both hemispheres, aligning with peak baroclinicity and cooler sea surface temperatures that support rapid intensification.^[1] On average, around 70 such events occur globally each year (based on 1979–2008 reanalysis data), with approximately 45 in the Northern Hemisphere and 26 in the Southern Hemisphere; recent regional analyses indicate variability, with some areas showing increases.^[2] In contrast to tropical cyclones, which feature a symmetric warm core powered by convective heat release without distinct fronts, explosive cyclogenesis pertains to extratropical systems marked by prominent frontal boundaries and driven by mid-latitude baroclinic instabilities.^[1]

Historical Development

Early Observations

Early weather observations of rapid cyclone deepening date back to the late 19th and early 20th centuries, when mariners in the North Atlantic and North Pacific frequently recorded sudden intensifications of storms in ship logs and journals. These anecdotal accounts described abrupt pressure drops and escalating winds that caught vessels unprepared, often leading to significant maritime hazards; for instance, reports from transatlantic crossings highlighted storms emerging rapidly from weaker lows, transforming into intense systems within hours. Such observations contributed to the foundational data used by early meteorologists to map storm patterns, though systematic analysis was limited by sparse instrumentation.^[11] In the 1920s and 1930s, the Bergen School of Meteorology in Norway advanced the understanding of these phenomena through the development of the Norwegian cyclone model, which incorporated surface weather reports—including ship-based data—to describe the lifecycle of extratropical cyclones. Led by figures like Vilhelm Bjerknes and Halvor Solberg, the school emphasized the role of frontal boundaries in cyclone evolution, noting instances of accelerated deepening associated with interactions between polar and tropical air masses. This conceptual framework linked early observational evidence of sudden storms to broader atmospheric dynamics, laying groundwork for recognizing rapid intensification without yet formalizing it as a distinct process.^[12] During the 1940s and 1950s, Norwegian meteorologists, including Tor Bergeron, further elaborated on these patterns through studies of polar outbreaks—large-scale incursions of cold Arctic air that triggered rapid cyclone development. Bergeron's work on the occlusion process, a key stage in cyclone maturation, highlighted how frontal occlusions could lead to intensified lows, drawing from surface and upper-air data. These insights were particularly applied during World War II aviation weather forecasting efforts, where accurate prediction of sudden storm intensifications was critical for Allied operations, such as D-Day planning under Sverre Petterssen's guidance using Bergen School methods. Observations from aircraft reconnaissance and enhanced surface networks during this period revealed the explosive nature of some deepenings, often over oceanic regions.^[13]^[14] The informal terminology for these events emerged in the 1940s and 1950s among Bergen School meteorologists, who analogized the dramatic pressure falls—sometimes exceeding 20 hPa in 24 hours—to exploding bombs, evoking the storms' sudden and destructive power over the sea. This "bomb" descriptor captured the rapid energy release in maritime cyclones, predating quantitative thresholds and reflecting practical forecaster language based on observed pressure traces from weather stations and ships. U.S. weather services later adopted similar phrasing in reports, influenced by transatlantic exchanges of meteorological knowledge post-war.^[8]

Formal Definition and Evolution

The formal definition of explosive cyclogenesis, often termed a "bomb," was established by Sanders and Gyakum in their seminal 1980 study published in Monthly Weather Review. They defined it as an extratropical surface cyclone exhibiting a central sea-level pressure decrease of at least 1 bergeron unit, equivalent to 24 hPa over 24 hours when referenced to 60° latitude, to account for latitudinal variations in the Coriolis parameter. This threshold was derived from a climatological analysis of 33 explosive events in the Northern Hemisphere during the cold seasons from September 1976 to May 1979, highlighting the phenomenon's synoptic-dynamic characteristics and frequency during winter months.^[1] Following this foundational work, the definition gained widespread adoption within the meteorological community. The American Meteorological Society incorporated it into its Glossary of Meteorology in the 1990s, standardizing the term for use in research and operational forecasting as a rapid deepening of extratropical cyclones with the specified pressure criterion. In the 2000s, numerical weather prediction models evolved to better integrate diabatic processes, such as latent heat release from condensation, which enhance cyclone intensification beyond purely adiabatic dynamics. Recent refinements, informed by climate modeling, have adjusted projections to emphasize compound events where explosive cyclogenesis coincides with atmospheric rivers, projecting increased frequency and duration under future warming scenarios; a 2025 study using CMIP6 models examined such dynamics in the North Atlantic.^[15]

Formation Mechanisms

Baroclinic Processes

Explosive cyclogenesis is primarily driven by baroclinic instability, a dynamic process in which horizontal temperature contrasts, such as those between cold polar air masses and warm subtropical air, release available potential energy, converting it into kinetic energy that fuels cyclone intensification.^[16] This instability arises in regions of strong baroclinicity, where sloping isopycnals allow for the efficient transfer of energy through ageostrophic circulations that tilt perturbations with height.^[17] The process is adiabatic and relies on the mean thermal wind shear to sustain growth, distinguishing it from other influences in cyclone development. Key dynamics involve upper-level divergence ahead of a 500-hPa trough, which promotes ascent and enhances surface low-pressure formation.^[18] Frontogenesis further amplifies this by sharpening temperature gradients, leading to increased surface convergence and vorticity accumulation at the cyclone center.^[19] Subsequent geostrophic adjustment restores balance between the mass and wind fields, resulting in rapid central pressure falls as the cyclone adjusts to the altered thermal structure.^[20] Synoptic-scale Rossby waves play a crucial role in amplifying baroclinic instability by providing the initial perturbations that resonate with the mean flow, enhancing wave growth through constructive interference.^[21] The growth rate of these instabilities can be approximated by the Eady formula \sigma \approx 0.31 \frac{f}{N} \left| \frac{\partial u}{\partial z} \right|, where f is the Coriolis parameter, N is the Brunt-Väisälä frequency, and \frac{\partial u}{\partial z} is the vertical wind shear related to the meridional temperature gradient \frac{\partial T}{\partial y} by thermal wind balance \left| \frac{\partial u}{\partial z} \right| \approx \frac{g}{f \bar{T}} \left| \frac{\partial T}{\partial y} \right|, with g the gravitational acceleration and \bar{T} the mean temperature.^[22] This expression highlights how stronger temperature gradients and weaker static stability promote faster development of explosive systems. Climatological studies indicate that explosive cyclones, or "bombs," frequently initiate near maxima in the jet stream, where baroclinicity is maximized and upper-level support is optimal.^[1] These locations facilitate the necessary divergence and shear for rapid deepening, as documented in comprehensive analyses of Northern Hemisphere events.^[1]

Diabatic Influences

Diabatic influences play a crucial role in accelerating the deepening of extratropical cyclones beyond baroclinic dynamics alone, primarily through the release of latent heat during condensation processes in the warm conveyor belt. Latent heat release occurs as moist air ascends and condenses, generating positive potential vorticity anomalies that enhance cyclone intensity. In intense cases of explosive cyclogenesis, such as storms Lothar, Klaus, and Xynthia, latent heat release contributes approximately 40-60% to the total surface pressure tendency during the explosive deepening phase.^[23]^[24] Air-sea interactions further amplify instability by providing sensible and latent heat fluxes, particularly over warm ocean currents like the Gulf Stream. During cold air outbreaks, these fluxes heat and moisten the lower troposphere, with sensible heat increasing potential temperature by up to 21 K over three days along affected trajectories. Latent heat fluxes account for 80-90% of moisture uptake in these regions, fueling subsequent condensation and cyclone development.^[25] For instance, in North Atlantic explosive cyclones, interactions over the Gulf Stream sustain baroclinicity and contribute to rapid intensification by enhancing low-level moisture availability.^[26] Other diabatic factors, including evaporation of precipitation and cloud microphysics, modulate the overall heating profile but play secondary roles compared to latent heat release and surface fluxes. Evaporation from underlying ocean surfaces during marine explosive events can sustain moisture supply, while microphysical processes like autoconversion and accretion influence precipitation efficiency and associated heating. Recent studies highlight an ongoing debate regarding the relative importance of these diabatic elements versus baroclinic forcing, with analyses from 2018 to 2025 indicating increased diabatic contributions in warmer climates due to enhanced moisture availability.^[27] Numerical models demonstrate that diabatic processes can substantially boost deepening rates, with sensitivity experiments showing that their inclusion leads to intensification rates up to twice those of purely adiabatic simulations in marginal explosive cases. For example, in a super explosive cyclone over the northwestern Pacific, diabatic heating from latent heat release was the dominant factor in early development, effectively doubling the cyclone's growth compared to baroclinic-only scenarios.^[28]^[29]

Geographical Distribution and Motion

Primary Regions

Explosive cyclogenesis exhibits distinct regional hotspots, primarily concentrated in the mid-latitudes of both hemispheres where baroclinic zones and maritime influences are pronounced. In the Northern Hemisphere, the Northwest Pacific and North Atlantic are the most active areas, driven by the region's strong temperature gradients and frequent synoptic setups conducive to rapid intensification. The cyclones often develop along the downstream extension of the jet stream. Activity is notably lower in the Mediterranean, with only 5–6 events per year, though this basin contributes occasional intense systems due to its semi-enclosed geography and variable sea surface temperatures.^[2]^[30] In the Southern Hemisphere, explosive cyclogenesis is less frequent overall but shows concentration in the Southwest Pacific near New Zealand and eastern Australia, with approximately 2–3 events per year, facilitated by the interaction between subtropical highs and polar air masses. The South Atlantic experiences sparse activity, with fewer documented cases attributed to limited observational coverage and weaker baroclinicity compared to northern counterparts. Total Southern Hemisphere events average around 26 per year (1979–1999), though recent analyses indicate approximately 50 events annually over the Southern Ocean (50°S–70°S) from 1980–2020, with an increasing trend of 2.3 events per decade. These hemispheric differences arise partly from disparities in land-ocean distribution and data availability, as reanalysis datasets reveal higher confidence in Northern Hemisphere statistics.^[2]^[31]^[32]^[7] Climatologically, these events peak during the winter seasons of each hemisphere—November through March in the Northern Hemisphere and May through September in the Southern Hemisphere—aligning with maximum baroclinicity and storm track intensity. Ocean currents play a critical role in fueling development; the warm Kuroshio Current in the Northwest Pacific and the Gulf Stream in the North Atlantic supply essential heat and moisture to the lower troposphere, enhancing latent heat release and deepening rates. In the Southern Hemisphere, analogous influences from the East Australian Current contribute to Southwest Pacific activity.^[2]^[33] Globally, these cyclones show no long-term trend in frequency from 1979 to 2008, remaining within natural variability, with higher occurrence in the Northern Hemisphere winter compared to the Southern Hemisphere.^[2]

Typical Trajectories

Explosive cyclones in the Northern Hemisphere typically follow poleward trajectories, moving northeastward across the Atlantic and northward over the Pacific Ocean, primarily steered by the upper-level westerlies that guide their motion along the mid-latitude jet stream.^[18] These systems often initiate near warm ocean currents such as the Gulf Stream or Kuroshio, where enhanced baroclinicity supports early development, before undergoing rapid intensification in offshore regions and eventually decaying upon encountering landmasses.^[34] Their average propagation speeds range from 30 to 50 km/h, allowing them to traverse significant distances during their lifecycle, which typically spans 48 to 72 hours from formation to dissipation.^[35] Key dynamical influences include vorticity advection by the upper-level flow, which reinforces the cyclone's track, and the beta-effect from the planetary vorticity gradient, which can induce slight recurvature in their paths.^[36] In the Southern Hemisphere, explosive cyclones more frequently exhibit equatorward motion south of 50°S, particularly southeastward over the Pacific, influenced by the blocking effects of subtropical high-pressure systems that divert their paths away from the poles.^[31] These storms often form and intensify near the Antarctic Circumpolar Current or east of southern landmasses like South America, mirroring the offshore rapid deepening seen in the north but with trajectories that spiral around the Antarctic continent before weakening over cooler continental interiors. Most follow southeastward trajectories, undergoing net cyclogenesis in mid-latitudes and cyclolysis closer to Antarctica.^[37]^[7] Propagation speeds in this hemisphere tend to be slightly faster, reaching up to 40 km/h on average, contributing to their shorter effective traversal times compared to Northern Hemisphere counterparts.^[37] The lifecycle phases align closely with those in the north—initiation over warm marine areas, explosive growth offshore, and inland decay—lasting approximately 48 to 72 hours overall.^[38]

Notable Events

Historical Cases

One of the earliest documented cases of explosive cyclogenesis in the North Atlantic was the Presidents' Day Storm of February 18–19, 1979, which affected the U.S. East Coast. This extratropical cyclone underwent rapid intensification, with a central pressure drop of approximately 24 hPa over 12 hours, exemplifying the phenomenon shortly after its formal definition by Sanders and Gyakum in 1980. The storm produced record-breaking snowfall accumulations exceeding 35 inches (89 cm) in parts of Maryland and Virginia, accompanied by sustained winds up to 70 knots (130 km/h) and gusts over 90 knots (170 km/h) along the coast.^[39] Early analyses by Sanders highlighted the role of baroclinic instability and upper-level divergence in driving the explosive deepening, contributing to foundational studies on the synoptic patterns of such events.^[40] The Braer Storm of January 10, 1993, stands as a benchmark for explosive cyclogenesis in the North Atlantic, rapidly deepening by 78 hPa over 24 hours to a record minimum central pressure of 914 hPa south of the Shetland Islands.^[41] Observed winds reached sustained speeds of 105 knots (192 km/h) at Ocean Weather Ship Cumulus and North Rona, with gusts likely exceeding 120 knots (222 km/h) in the core.^[42] The storm's track passed just west of Scotland, leading to severe disruptions including downed power cables in the Lothian region and widespread structural damage; its name derives from the earlier grounding of the MV Braer oil tanker on January 5 amid precursor gales, which spilled 84,700 tonnes of crude oil near the Shetlands.^[43] This event underscored the potential for extreme intensification over oceanic regions, with reanalysis confirming latent heat release as a key driver. Earlier 20th-century examples, such as the Bar Harbor cyclone of October 1884 along the U.S. Northeast coast and the North Sea storm of January 31, 1953, illustrate the challenges in documenting explosive cyclogenesis before widespread satellite observations. The 1884 event produced gale-force winds and coastal flooding in Maine, with anecdotal reports suggesting rapid pressure falls, but sparse ship-based measurements limited quantitative assessment.^[44] Similarly, the 1953 storm deepened to around 960 hPa while generating a catastrophic surge that inundated the Netherlands and UK, killing over 2,400 people, yet pre-satellite data relied heavily on surface stations and buoys, hindering precise tracking of deepening rates.^[45] These cases highlight how data scarcity in the pre-1970s era often obscured the full extent of explosive development, relying on retrospective synoptic reconstructions to identify patterns akin to modern criteria.^[9]

Recent Examples

In November 2024, a powerful bomb cyclone combined with an atmospheric river struck the U.S. West Coast, particularly affecting California and Oregon from November 19 to 23. This event featured rapid intensification, qualifying as explosive cyclogenesis with a central pressure decrease exceeding 30 hPa over 24 hours, driven by enhanced baroclinicity and moisture transport. It resulted in at least two deaths, widespread power outages affecting hundreds of thousands, and severe flooding from over a month's worth of rainfall in some areas, leading to flash floods, debris flows, and hurricane-force winds up to 100 mph. Satellite observations from NOAA's GOES-West highlighted the storm's evolution, underscoring the compound nature of the event that amplified precipitation and wind impacts across the Pacific Northwest.^[46] During the 2024/25 North Atlantic season, Storm Éowyn underwent explosive cyclogenesis on January 23, 2025, rapidly deepening by 50 hPa in 24 hours from 991 hPa to 941 hPa as it crossed the jet stream, an ideal pathway for such intensification. The storm brought record-breaking winds, with gusts reaching 114 mph in Ireland and 100 mph in the UK, causing one death from a fallen tree in County Donegal and power outages for over a million people across the British Isles. This event was linked to disruptions in the polar vortex, contributing to its extreme development and subsequent impacts on Europe, including structural damage and transport disruptions. Modern reanalysis data revealed the role of upper-level divergence in sustaining the cyclone's ferocity during landfall.^[47] In December 2024, a bomb cyclone developed off the U.S. East Coast on December 11, fueled by an atmospheric river that brought chaotic winter weather to the Northeast, including rapid snowmelt combined with heavy rain. The storm produced record daily rainfall in nine locations, such as 4.6 inches in Providence, Rhode Island—nearly double the previous record—and winds gusting over 60 mph, leading to flash flooding, over 100 damage reports from North Carolina to Maine, and power outages for 90,000 customers in Maine alone. This potential bomb event highlighted the risks of warm, moist air overriding recent snow cover, exacerbating runoff and urban flooding in densely populated areas.^[48] A 2023 study identified an extreme explosive cyclone over the Kuroshio Extension that achieved the most rapid intensification recorded in the region over 42 years (1979–2020) during the cold season. This event was characterized by enhanced low-level baroclinicity and mid-level cyclonic vorticity advection, with diabatic heating playing a key role in the initial stages, leading to unprecedented deepening rates and associated marine hazards. Diagnostic studies using reanalysis data emphasized the cyclone's departure from typical patterns, driven by strong water vapor convergence and upper-tropospheric warm-air advection.^[49] Recent analyses indicate an increasing frequency of compound events involving explosive cyclogenesis and atmospheric rivers, particularly in the North Atlantic, where 72% of such cyclones are now associated with ARs at their maximum deepening point. A 2025 study using ERA5 reanalysis and CMIP6 models projects further rises in their concurrence under future warming scenarios, with AR intensity exceeding 1250 kg m⁻¹ s⁻¹ for prolonged durations, potentially amplifying impacts over western Europe. These trends reflect broader shifts in extratropical dynamics, including stronger jet streams and moisture availability, as observed in post-2000 events.^[15]

Impacts and Forecasting

Meteorological and Societal Impacts

Explosive cyclogenesis generates severe meteorological phenomena, including hurricane-force winds exceeding 74 miles per hour (119 km/h), which can damage infrastructure such as buildings, power lines, and coastal structures.^[50] These storms also produce heavy precipitation in the form of rain or snow, leading to widespread flooding, landslides, and avalanches in affected regions. Additionally, storm surges from these events contribute to coastal erosion and inundation, while oceanic cases often generate significant waves reaching heights of 10 meters or more, posing risks to maritime navigation and offshore installations.^[3]^[51] The societal consequences of explosive cyclogenesis are profound, frequently causing power outages that affect hundreds of thousands of households due to wind-damaged grids.^[52] Transportation systems experience major disruptions, including road closures, flight cancellations, and port shutdowns, halting commerce and emergency responses.^[53] Major events result in economic losses ranging from $1 billion to $10 billion, encompassing repair costs for infrastructure, agricultural damage, and business interruptions.^[54] Fatalities often occur from high winds toppling trees onto vehicles or homes, as seen in the 2024 West Coast bomb cyclone where at least two deaths were reported from such incidents.^[55] Coastal populations are particularly vulnerable due to their proximity to storm tracks, exacerbating risks from surges and flooding in densely settled areas.^[56] Aging infrastructure in many regions amplifies damage potential, as outdated power and transportation networks fail under extreme loads. Climate change contributes to heightened vulnerability by amplifying moisture availability in the atmosphere, leading to 10-20% more precipitation per event through enhanced evaporation and warmer air capacities.^[57] Effective mitigation relies on early warning systems, which can reduce overall impacts by up to 30% in developed regions by enabling evacuations, preparations, and resource allocation before peak intensity.^[58] These systems, when integrated with real-time monitoring, have proven instrumental in minimizing loss of life and property damage during rapid-onset storms.

Prediction and Modeling

Ensemble prediction systems, such as the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System and the National Centers for Environmental Prediction's Global Forecast System (GFS), are primary tools for forecasting explosive cyclogenesis. These models utilize high-resolution horizontal grids of approximately 9 km for ECMWF and 13 km for GFS, which allow for the representation of mesoscale features critical to rapid cyclone deepening, including baroclinic instability and frontogenesis.^[59]^[60] Satellite-based detection complements these models by identifying precursor cloud patterns, such as the distinctive comma-head structure in water vapor imagery, and rapid intensification indices based on cloud-top temperature gradients and convective signatures.^[61] Challenges in predicting explosive cyclogenesis often stem from the underrepresentation of diabatic processes, particularly latent heat release from condensation and convection, which can account for up to 50% of cyclone deepening in simulations lacking moist physics.^[62] This leads to systematic underprediction, with dry model runs capturing only half the observed pressure falls in many cases, resulting in missed or underestimated events.^[62] Enhanced data assimilation from observational platforms, including ocean buoys for sea surface temperature, aircraft reconnaissance for upper-air profiles, and satellite radiances, is essential to refine initial conditions and reduce forecast errors by incorporating real-time moist dynamics.^[62] Projections from Coupled Model Intercomparison Project Phase 6 (CMIP6) ensembles indicate that explosive cyclogenesis will feature greater intensity and central pressure depth by 2100 under high-emission scenarios, driven by amplified baroclinicity and warmer sea surfaces.^[15] Compound events involving explosive cyclones and atmospheric rivers (ARs) are expected to increase, with ARs enhancing moisture transport and latent heating to prolong and deepen cyclones by 2.5–10 hPa.^[15] These applications integrate baroclinic and diabatic mechanisms to better capture rapid development, though uncertainties persist in extreme cases.^[63]

References

[1]
Synoptic-Dynamic Climatology of the “Bomb” in - AMS Journals
Oct 1980. Download PDF · © Get Permissions. Full access ... explosive cyclogenesis in the Northern Hemisphere during the period September 1976–May 1979.
[2]
Explosive Cyclogenesis: A Global Climatology Comparing Multiple ...
Explosive cyclone development has been traditionally defined by a central pressure fall of 24 hPa over a 24-h period relative to 60° of latitude (Sanders and ...
[3]
The concurrence of atmospheric rivers and explosive cyclogenesis ...
Jan 22, 2018 · The explosive cyclogenesis of extratropical cyclones and the occurrence of atmospheric rivers are characteristic features of a baroclinic ...
[4]
[PDF] Study of Explosive and Nonexplosive Cyclogenesis During ... - DTIC
These explosive cyclogenesis events are defined as low pressure systems with a deepening rate of one mb per hour for a 12 h period or longer. They are ...<|control11|><|separator|>
[5]
Why We Call Winter Storms 'Weather Bombs' - Atlas Obscura
Jan 3, 2018 · Back then, a sea “bomb” didn't have a formal definition, but the meteorologists used it to refer to destructive sea storms.Missing: etymology | Show results with:etymology<|control11|><|separator|>
[6]
A Composite Study of Explosive Cyclogenesis in Different Sectors of ...
Throughout the period the system is accompanied by increasing clouds, which display a distinct “comma” shape from t0 onward (Figs. 4d–f). In the NEA sector (Fig ...
[7]
[PDF] A Climatological Study of Hurricane Force Extratropical Cyclones
Mar 6, 2012 · For example, a storm system is determined to have reached hurricane status once sustained winds reach 64 knots (Category One on the Saffir-.
[8]
[PDF] Tropical Cyclones of the North Atlantic Ocean
Jun 13, 1978 · The first operational radio weather report from a ship underway was received December 3, 1905; the first message reporting a hurricane was sent ...
[9]
A review of extratropical cyclones: observations and conceptual ...
Jan 2, 2020 · The Bergen meteorologists in Norway set out to understand and describe the structure and evolution of extratropical cyclones.Missing: sudden | Show results with:sudden
[10]
Antecedents for the Shapiro–Keyser Cyclone Model in the Bergen ...
Feb 26, 2021 · Thus, it may have been during 1927–28 that Bergeron first recognized the existence of bent-back fronts in extratropical cyclones. After 1930, ...
[11]
[PDF] 8. Sverre Petterssen, the Bergen School, and the Forecasts for D-Day
They were aided by the brilliant Norwegian theoretician Sverre Petterssen (1898-1974), a giant in the field of weather analysis and forecasting and an ...
[12]
East Coast storm born from 'bombogenesis'. It's less scary than it ...
Jan 3, 2018 · A big winter storm is hitting the East Coast this week, spanning from the Carolinas through New England and into Nova Scotia.
[13]
Future changes in compound explosive cyclones and atmospheric ...
Jan 21, 2025 · We find that explosive cyclones associated with atmospheric rivers tend to be longer lasting and deeper than those without.
[14]
On the Local Available Potential Energy Perspective of Baroclinic ...
The heat transport is organized in baroclinic waves, which convert potential energy (PE) into kinetic energy (KE). Margules (1903) recognized that the PE which ...
[15]
[PDF] Instability, Cyclogenesis, and Anticyclogenesis
proportional to γ, baroclinic instability increases with meridional temperature gradient, and decreases with static stability ! This makes sense since the ...
[16]
Characteristics of Explosive Cyclones over the Northern Pacific in
Dec 1, 2017 · In addition, the diabatic process was also taken as an important factor favoring the rapid development of ECs (Ahmadi-Givi et al. 2004 ...Missing: inclusion | Show results with:inclusion
[17]
Baroclinic Instability in a Two-Layer Model with Parameterized ...
These results suggest a sequence of events involved in some explosive cyclogenesis: Convection leads to rapid frontogenesis and the formation of a bent-back ...
[18]
The Role of Antecedent Surface Vorticity Development as a ...
All 24-h pressure falls are adjusted geostrophically to 45°N, so that. AP45. = Арф sin45° sino. (3) where Ap45 is the adjusted pressure change, Ap, is the.
[19]
Rossby Wave Breaking Morphologies on the Southern Hemisphere ...
Rossby waves grow in amplitude through baroclinic instability, which can be thought of as resonating low-level and upper-level Rossby waves. Their life cycle ...
[20]
Estimating the Lowest Latitude of Baroclinic Growth in - AMS Journals
Using the Eady growth rate, defined as λEady=(f/N)(∂u/∂z) , to estimate the lowest latitude of baroclinic growth assumes that the mean flow is baroclinically ...Introduction · Vertical decay rate of the... · Estimates for the lowest... · Results
[21]
Diagnosing the influence of diabatic processes on the explosive ...
Apr 12, 2012 · For Xynthia, Klaus and Lothar diabatic processes contribute more to the observed surface pressure fall than horizontal temperature advection ...Missing: 2000s | Show results with:2000s
[22]
[PDF] THE EFFECTS OF DIABATIC HEATING ON UPPER
It has been shown that 40-50% of the deepening during explosive cyclogenesis occurs through latent heating. (Reed et al. 1988). This process would likely ...
[23]
Linking Gulf Stream air–sea interactions to the exceptional blocking ...
Feb 8, 2024 · We establish that more than one-fifth of these air masses interact with the Gulf Stream in the lower troposphere, experiencing intense heating and moistening ...
[24]
Air–Sea Fluxes over the Gulf Stream Region - AMS Journals
This circulation is consistent with the intense cold air outbreak and explosive cyclogenesis that has been documented over the north and west flanks of the ...
[25]
j. mailhot and c. chouinard - American Meteorological Society
However, a critical factor for simulating marine explosive cyclogenesis is identified as evaporation from the ... distributions of cloud and precipitation ...
[26]
Changes of Intense Extratropical Cyclone Deepening Mechanisms ...
To sum up, while a notable and quick enhancement of diabatic heating emerges in response to a warmer and moister climate (which may indirectly contribute to an ...
[27]
Physical Process Contributions to the Development of a ... - Frontiers
Oct 17, 2021 · The combination of the diabatic heating, warm-air advection and cyclonic-vorticity advection forced the most explosive development at tmax, and ...
[28]
Heat Budgets of Analyses and Forecasts of an Explosively ...
Diabatic heating (latent heat release) at 600-700 mb is the primary process to maintain strong vertical motion during the most rapid deepening period.
[29]
Mediterranean cyclones: current knowledge and open questions on ...
Feb 14, 2022 · A large number of intense cyclones occur every year in the Mediterranean basin, one of the climate change hotspots.
[30]
Explosive Cyclone Development in the Southern Hemisphere and a ...
The authors' analysis detects, on average, 45 explosive cyclones per year in that hemisphere. It is found that over the last 21 yr the number of these systems ...
[31]
Development mechanisms of an explosive cyclone over East Sea on ...
These previous studies have indicated that explosive cyclones are dominantly driven by baroclinic instability due to strong sea surface temperature (SST) ...<|control11|><|separator|>
[32]
Diagnostics of Mediterranean Explosive Cyclogenesis Using ... - MDPI
Aug 31, 2023 · The results demonstrate that the interaction between the upper level baroclinic and low-level diabatic processes triggered the development of ...
[33]
Distribution and trend of explosive cyclones over the Southern ...
Aug 22, 2024 · On average, approximately 50 ECs are generated annually over the Southern Ocean, with a significant increasing trend of 2.3 per decade during the studying ...
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[PDF] a methodology for modulating the intensification rates of forecast ...
Explosive cyclogenesis events typically occur during the cold season along the warm, western boundary currents of the Atlantic (The Gulf Stream) and Pacific.
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13.1: Cyclone Characteristics - Geosciences LibreTexts
Dec 9, 2022 · If cyclogenesis is rapid enough (central pressures dropping 2.4 kPa or more over a 24-hour period), the process is called explosive cyclogenesis ...
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[PDF] Chapter 16 Extratropical Cyclones - the NOAA Institutional Repository
Operational forecast systems frequently failed to predict rapidly developing cyclones (Sanders and Gyakum 1980; Bosart. 1981; Gyakum 1983a,b; Anthes et al. 1983) ...
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Explosive Cyclone Development in the Southern Hemisphere and a ...
On average, 26 explosive cyclones occur per year in the SH. They are more prevalent in winter although their seasonality is more modest than that seen in the ...3. ``explosive Development''... · 5. Sh Bomb Characteristics · A. Explosive Cyclone Density...
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A Global Climatology of Explosive Cyclones using a Multi-Tracking ...
May 24, 2019 · Over the last 40 years, studies on ECs have been focused on deriving a climatology in Northern/Southern Hemisphere (hereafter NH/SH; e.g. ...
[39]
Explosive Cyclogenesis in the Southeast Australian Region
Explosive cyclogenesis over the Australian region occurs predominantly over southern and eastern parts of the continent and adjacent waters during the late ...
[40]
The intensification of the strongest nor'easters - PNAS
Jul 14, 2025 · Polar amplification reduces the pole-equator temperature gradient, in turn reducing the baroclinic energy available for ETC formation (4). In ...
[41]
The Presidents' Day Snowstorm of 18–19 February 1979
On 18–19 February 1979 a major east coast cyclone deposited a record-breaking snowfall on the Middle Atlantic States.Missing: drop | Show results with:drop
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Fred Sanders' Roles in the Transformation of Synoptic Meteorology ...
Download book PDF · Synoptic—Dynamic Meteorology and Weather Analysis and ... -, and J. R. Gyakum, 1980: Synoptic-dynamic climatology of the “bomb.” Mon ...<|control11|><|separator|>
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The Braer storm revisited - Odell - 2013 - Weather - Wiley Online ...
Mar 27, 2013 · The Braer storm of January 1993 was the deepest ever recorded cyclone ... A composite study of explosive cyclogenesis in different sectors ...
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[PDF] Braer Storm 10 January 1993 - Met Office
Jan 10, 1993 · The whole of the United Kingdom started wet and windy with heavy rain in places and winds gusting over 60 knots on.
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BRAER, UK, 1993 - ITOPF
Jan 5, 1993 · Following engine failure, BRAER ran aground in severe weather conditions on Garth's Ness, Shetland on 5th January 1993.
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[PDF] 1884
Encountered a cyclone in lat. 22° N., long. 57° W., September 7, 1884 ... At 4 p. m., the vessel was in the harbor of. Santiago, and from that time ...
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The North Sea Flood of 1953 | Environment & Society Portal
The North Sea flood of 1953 caused widespread damage and approximately 2400 fatalities in the UK, the Netherlands, and Belgium. As devastating as it was, ...Missing: explosive | Show results with:explosive
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GOES West Monitors Atmospheric River and "Bomb Cyclone"
Nov 20, 2024 · NOAA's GOES West satellite captured enhanced color imagery of a powerful mid-latitude cyclone and accompanying atmospheric river impacting northern California.
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Storm Éowyn: One dead and more than a million without power - BBC
Jan 24, 2025 · 'Stingjet'. While crossing the Atlantic, Storm Éowyn underwent a process known as "explosive cyclogenesis" – sometimes called a "weather bomb".
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Bomb cyclone's record rain, high winds followed by frigid air and snow
A rare East Coast atmospheric river led to flash flooding in some areas while snow accumulated in others on Dec. 11. A powerful storm that met the definition of ...
[51]
Diagnostic Study of an Extreme Explosive Cyclone over the ...
Nov 9, 2023 · The relative contribution of the diabatic heating decreased from the initial explosive-developing stage to the maximum-deepening-rate stage ...
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Explainer: What are bomb cyclones and how do they form? - Reuters
Nov 29, 2024 · A bomb cyclone, also referred to as explosive cyclogenesis or bombogenesis, is a mid-latitude cyclone that has rapidly intensified. A cyclone is ...
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Increasing risks of the explosive extratropical cyclones over the ...
Apr 12, 2024 · In cold seasons, winter storms are the most dangerous weather systems due to their huge societal and economic impacts (Hewson and Neu 2015).
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Explosive Cyclone Impact on the Power Distribution Grid in Rio ...
Feb 24, 2024 · These cyclones cause high-impact weather, such as heavy precipitation, strong winds, and abrupt temperature changes [9]. The momentum exchange ...
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Deadly 'bomb cyclone' lashes US Northwest – DW – 11/21/2024
Nov 21, 2024 · A bomb cyclone has hit the western coast of United States, disrupting transport, knocking out power for half a million people and causing at least two deaths.Missing: cyclogenesis fatalities
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Billion-Dollar Weather and Climate Disasters
The US sustained 403 weather and climate disasters from 1980–2024 where overall damages/costs reached or exceeded $1 billion (including CPI adjustment to 2024).Events · Summary Stats · Time Series · Disaster Mapping
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Bomb cyclone hammers West Coast, 2 dead in Washington state
Two people were killed by falling trees in Washington state as a powerful storm hammered the Pacific Northwest. In Bellevue, a tree fell into a home, ...Missing: cyclogenesis | Show results with:cyclogenesis
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Mediterranean Cyclones in a Changing Climate: A Review on Their ...
May 5, 2025 · In conclusion, Medcyclones are key drivers of weather variability in the region, leading to extreme events such as heavy precipitation, ...
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Chapter 11: Weather and Climate Extreme Events in a Changing ...
This chapter assesses changes in weather and climate extremes on regional and global scales, including observed changes and their attribution, as well as ...
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Cuts to Early Warning Systems Are Leaving the U.S. Unprepared for ...
Jul 22, 2025 · The Global Commission on Adaptation has found that just twenty-four hours of advance warning can reduce damage by 30 percent. It estimates that ...
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[PDF] Sensitivity of extratropical cyclone characteristics to horizontal ...
It is shown that many of the key-characteristics of extratropical cyclones in the ECMWF model are highly sensitive to horizontal resolution, with the low- ...
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Documentation - GFS - Virtual Lab - NOAA VLab
The current operational horizontal resolution is T1534 (T574), or approximately 13 km (34km) at the equator for days 0-10 (days 10-16) forecasts. In the ...<|control11|><|separator|>
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[PDF] Satellite signatures of rapid cyclogenesis. - CORE
Dec 14, 1988 · forecasting explosive development. The cloud pattern evolution of oceanic cyclogenesis is further discussed by Weldon. (1977). He refers to ...
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The importance of diabatic processes for the dynamics of synoptic ...
Oct 24, 2024 · Diabatic processes, once considered secondary, now strongly affect extratropical cyclone and Rossby wave dynamics, impacting their structure ...
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Predictability of Explosive Cyclogenesis over the Northwestern ...
Abstract. The predictability of explosive cyclones over the northwestern Pacific region is investigated using an ensemble reanalysis dataset.Missing: inclusion | Show results with:inclusion