Conditions for the occurrence of severe local storms

Carlson, Toby N.; Ludlam, F. H.

doi:10.1111/j.2153-3490.1968.tb00364.x

Cited by 82 publications

(41 citation statements)

References 17 publications

(6 reference statements)

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“…Dry layers are ubiquitous in midlatitude convective environments as air is advected from different source regions under directionally sheared vertical wind profiles (Carlson and Ludlam 1968), such as commonly occurs near the dryline because of advection of the elevated mixed layer, as discussed in GvdH14. Therefore, GvdH14 investigated the impacts of dry layers at three different altitudes and of three different strengths on supercell morphology.…”

Section: Methodsmentioning

confidence: 99%

Cold Pool and Precipitation Responses to Aerosol Loading: Modulation by Dry Layers

Grant

Heever

2015

Journal of the Atmospheric Sciences

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The relative sensitivity of midlatitude deep convective precipitation to aerosols and midlevel dry layers has been investigated in this study using high-resolution cloud-resolving model simulations. Nine simulations, including combinations of three moisture profiles and three aerosol number concentration profiles, were performed. Because of the veering wind profile of the initial sounding, the convection splits into a left-moving storm that is multicellular in nature and a right-moving storm, a supercell, which are analyzed separately.The results demonstrate that while changes to the moisture profile always induce larger changes in precipitation than do variations in aerosol concentrations, multicells are sensitive to aerosol perturbations whereas supercells are less so. The multicellular precipitation sensitivity arises through aerosol impacts on the cold pool forcing. It is shown that the altitude of the dry layer influences whether cold pools are stronger or weaker and hence whether precipitation increases or decreases with increasing aerosol concentrations. When the dry-layer altitude is located near cloud base, cloud droplet evaporation rates and hence latent cooling rates are greater with higher aerosol loading, which results in stronger low-level downdrafts and cold pools. However, when the dry-layer altitude is located higher above cloud base, the low-level downdrafts and cold pools are weaker with higher aerosol loading because of reduced raindrop evaporation rates. The changes to the cold pool strength initiate positive feedbacks that further modify the cold pool strength and subsequent precipitation totals. Aerosol impacts on deep convection are therefore found to be modulated by the altitude of the dry layer and to vary inversely with the storm organization.

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Section: Methodsmentioning

confidence: 99%

Cold Pool and Precipitation Responses to Aerosol Loading: Modulation by Dry Layers

Grant

Heever

2015

Journal of the Atmospheric Sciences

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“…The conditions favorable for the occurrence of severe convective phenomena in mid-latitudes have been described by Newton [28], Ludlam [17], 250 W. Fernandez Carlson and Ludlam [10], and Miller [22]. The significant features are conditional and convective instability, availability of abundant moisture in lower levels, bands of strong winds in lower and upper levels, turning of the wind with height, and some mechanism which can trigger the release of instability.…”

Section: Introductionmentioning

confidence: 97%

Environmental conditions and structure of some types of convective mesosystems observed over Venezuela

Fernández

1980

Arch. Met. Geoph. Biokl. A.

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SummaryA classification of storms in squall lines, thunderstorm clusters, and isolated thunderstorms was made using radar data collected during the second phase of the Venezuelan International Meteorological and Hydrological Experiments (VIMHEX-1972). The nearenvironmental conditions in advance of these types of storms are examined. The modification of the environment, as deduced from the dry static energy, moist static energy, latent heat content and relative winds is also studied, and a conceptual model for the storms is presented. Finally, some aspects of storm movement are described. Zusammenfassung Umgebungsverh/iltnisse und Struktur einiger iiber Venezuela beobachteter Typen yon konvektiven MesosystemenMit Verwendung yon in der zweiten Phase der Venezueler internationalen meteorologischen und hydrologischen Experimente (VIMHEX-1972) gesammelten Radar-Daten wurde eine Klassifikation yon Unwettem in Btenlinien, in Gewittergruppen und in isolierten Gewittern vorgenommen. Die Verh~ltnisse in der nahen Umgebung w~hrend des Vorrtickens dieser Typen yon Unwetter werden untersucht. Die Modifikation der Umgebung wird, abgeleitet aus der trocken-statischen Energie, aus der feucht-statischen Energie, aus dem latenten W~irmegehalt und aus den relafiven Winden, ebenfalls studiert und ein fiir die Unwetter entwickeltes Modell wird vorgelegt. SchlieNich werden einige Aspekte der Bewegung der Unwettergebflde beschrieben.

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“…For example, a stationary convergence line of intense convection over Cornwall influenced flooding in Boscastle on the 16 August 2004 (Golding et al, 2005) while complex frontal structure within a polar low led to devastating flooding in Lynmouth during the 15 August 1952(McGinnigle, 2002. Thunderstorms in warm, moist southerly flows or 'Spanish plumes' (Carlson and Ludlam, 1968) also commonly lead to intense summer thunderstorms.…”

Section: Introductionmentioning

confidence: 99%

Diagnosing links between atmospheric moisture and extreme daily precipitation over the UK

Allan

Lavers

Champion

2015

Intl Journal of Climatology

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Atmospheric moisture characteristics associated with the heaviest 1% of daily rainfall events affecting regions of the British Isles are analysed over the period [1997][1998][1999][2000][2001][2002][2003][2004][2005][2006][2007][2008]. A blended satellite/rain-gauge data set (GPCP-1DD) and regionally averaged daily rain-gauge observations (HadUKP) are combined with the ERA Interim reanalysis. These are compared with simulations from the HadGEM2-A climate model which applied observed sea surface temperature and realistic radiative forcings. Median extreme daily rainfall across the identified events and locations is larger for GPCP (32 mm day −1 ) than HadUKP and the simulations (∼25 mm day −1 ). The heaviest observed and simulated daily rainfall events are associated with increased specific humidity and horizontal transport of moisture (median 850 hPa specific humidity of ∼6 g kg −1 and vapour transport of ∼150 g kg − 1 m s − 1 for both observed and simulated events). Extreme daily rainfall events are less common during spring and summer across much of the British Isles, but in the south east region, they contribute up to 60% of the total number of distinct extreme daily rainfall events during these months. Compared to winter events, the summer events over south east Britain are associated with a greater magnitude and more southerly location of moisture maxima and less spatially extensive regions of enhanced moisture transport. This contrasting dependence of extreme daily rainfall on moisture characteristics implies a range of driving mechanisms that depend upon location and season. Higher spatial and temporal resolution data are required to explore these processes further, which is vital in assessing future projected changes in rainfall and associated flooding.

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Conditions for the occurrence of severe local storms

Cited by 82 publications

References 17 publications

Cold Pool and Precipitation Responses to Aerosol Loading: Modulation by Dry Layers

Cold Pool and Precipitation Responses to Aerosol Loading: Modulation by Dry Layers

Environmental conditions and structure of some types of convective mesosystems observed over Venezuela

Diagnosing links between atmospheric moisture and extreme daily precipitation over the UK

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