Variability of central United States April–May tornado day likelihood by phase of the Madden‐Julian Oscillation

Barrett, Bradford S.; Gensini, Vittorio A.

doi:10.1002/grl.50522

Cited by 67 publications

(63 citation statements)

References 40 publications

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“…e mean and mean rank of the tornado counts was greatest with phase 4 in MAM. Clustering of tornadoes on MJO phase 4 days in MAM is unique because climatological studies [20,23] that aggregated data over a larger number of seasons reported heightened tornado activity with phase 2, 5, and 7 of the MJO in boreal spring months. While only representative of MAM 1982 and 1983, the clustering of tornadoes on MJO phase 4 days in these EN seasons highlights the possibility for a large number of tornadoes when subseasonal climate oscillations are in unfavorable phases.…”

Section: Discussionmentioning

confidence: 99%

“…e MJO is a tropical wave of enhanced convection that propagates the globe from west to east at approximately 5 m·s −1 [29]. It is linked to variability in tornado activity in the midlatitudes through changes in global relative atmospheric angular momentum (AAM), which arise from tropical convective forcing and teleconnected Rossby wave propagation in the midlatitudes [20,23,[30][31][32]. Other factors, such as friction and mountain torque, affect AAM in addition to tropical convection [30][31][32].…”

Section: Methodsmentioning

confidence: 99%

“…Moore [22] also showed this to be true in DJF. Barrett and Gensini [23] reported that tornado days in April are most common on phase 6 and 8 days of the MJO and less common on phase 3, 4, and 7 days. ey also reported that tornado days are most common with phases 5 and 8 and less common with phases 2 and 3 in May.…”

Section: Role Of Gwo and Mjo In The Anomalous Seasonsmentioning

confidence: 99%

“…e states of the Madden-Julian Oscillation (MJO) and Global Wind Oscillation (GWO) are of particular interest here. Both of these oscillations vary over subseasonal timescales (i.e., shorter than the timescale over which ENSO varies) and have been linked to variations in tornado activity [20][21][22][23]. Seasonal and daily composites are also generated to document the synoptic patterns that accompanied the anomalous seasons.…”

Section: Introductionmentioning

confidence: 99%

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An Analysis of Anomalous Winter and Spring Tornado Frequency by Phase of the El Niño/Southern Oscillation, the Global Wind Oscillation, and the Madden-Julian Oscillation

Moore

Clair

DeBoer

2018

Advances in Meteorology

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Winter and spring tornado activity tends to be heightened during the La Niña phase of the El Niño/Southern Oscillation and suppressed during the El Niño phase. Despite these tendencies, some La Niña seasons have fewer tornadoes than expected and some El Niño seasons have more than expected. To gain insight into such anomalous seasons, the two La Niña winters and springs with the fewest tornadoes and the two El Niño winters and springs with the most tornadoes between 1979 and 2016 are identified and analyzed in this study. e relationships between daily tornado count and the Global Wind Oscillation and Madden-Julian Oscillation in these anomalous seasons are also explored. Lastly, seasonal and daily composites of upper-level flow, low-level flow and humidity, and atmospheric instability are generated to describe the environmental conditions in the anomalous seasons. e results of this study highlight the potential for large numbers of tornadoes to occur in a season if favorable conditions emerge in association with individual synoptic-scale events, even during phases of the El Niño/Southern Oscillation, Global Wind Oscillation, and Madden-Julian Oscillation that seem to be unfavorable for tornadoes. ey also highlight the potential for anomalously few tornadoes in a season even when the oscillations are in favorable phases.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Role Of Gwo and Mjo In The Anomalous Seasonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An Analysis of Anomalous Winter and Spring Tornado Frequency by Phase of the El Niño/Southern Oscillation, the Global Wind Oscillation, and the Madden-Julian Oscillation

Moore

Clair

DeBoer

2018

Advances in Meteorology

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“…The index is created such that the MJO generally progresses eastward, from phase 1 to 8 and back to phase 1 again. Days during which the magnitude of the MJO vector was less than one standard deviation from zero were not considered, following the compositing methodology of other recent studies (e.g., Zhou et al 2012;Virts et al 2013;Zhang 2013;Barrett and Gensini 2013). Anomalies in daily DSIC, 500-hPa geopotential height, sea level pressure, 2-m air temperature, and 10-m wind were then found by averaging the day n means for each MJO phase and subtracting them from the overall monthly mean.…”

Section: Methodsmentioning

confidence: 99%

Arctic sea ice and the Madden–Julian Oscillation (MJO)

2014

Self Cite

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Arctic sea ice responds to atmospheric forcing in primarily a top-down manner, whereby near-surface air circulation and temperature govern motion, formation, melting, and accretion. As a result, concentrations of sea ice vary with phases of many of the major modes of atmospheric variability, including the North Atlantic Oscillation, the Arctic Oscillation, and the El Niño-Southern Oscillation. However, until this present study, variability of sea ice by phase of the leading mode of atmospheric intraseasonal variability, the Madden-Julian Oscillation (MJO), which has been found to modify Arctic circulation and temperature, remained largely unstudied. Anomalies in daily change in sea ice concentration were isolated for all phases of the real-time multivariate MJO index during both summer (May-July) and winter (November-January) months. The three principal findings of the current study were as follows. (1) The MJO projects onto the Arctic atmosphere, as evidenced by statistically significant wavy patterns and consistent anomaly sign changes in composites of surface and mid-tropospheric atmospheric fields. (2) The MJO modulates Arctic sea ice in both summer and winter seasons, with the region of greatest variability shifting with the migration of the ice margin poleward (equatorward) during the summer (winter) period. Active regions of coherent ice concentration variability were identified in the Atlantic sector on days when the MJO was in phases 4 and 7 and the Pacific sector on days when the MJO was in phases 2 and 6, all supported by corresponding anomalies in surface wind and temperature. During July, similar variability in sea ice concentration was found in the North Atlantic sector during MJO phases 2 and 6 and Siberian sector during MJO phases 1 and 5, also supported by corresponding anomalies in surface wind. (3) The MJO modulates Arctic sea ice regionally, often resulting in dipole-shaped patterns of variability between anomaly centers. These results provide an important first look at intraseasonal variability of sea ice in the Arctic.

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Importance of the Gulf of Mexico as a climate driver for U.S. severe thunderstorm activity

Molina

Timmer²,

Allen

2016

Geophysical Research Letters

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Different features of the Gulf of Mexico (GOM), such as the Loop Current and warm‐core rings, are found to influence monthly‐to‐seasonal severe weather occurrence in different regions of the United States (U.S.). The warmer (cooler) the GOM sea surface temperatures, the more (less) hail and tornadoes occur during March–May over the southern U.S. This pattern is reflected physically in boundary layer specific humidity and mixed‐layer convective available potential energy, two large‐scale atmospheric conditions favorable for severe weather occurrence. This relationship is complicated by interactions between the GOM and El Niño–Southern Oscillation (ENSO) but persists when analyzing ENSO neutral conditions. This suggests that the GOM can influence hail and tornado occurrence and provides another source of regional predictability for seasonal severe weather.

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Variability of central United States April–May tornado day likelihood by phase of the Madden‐Julian Oscillation

Cited by 67 publications

References 40 publications

An Analysis of Anomalous Winter and Spring Tornado Frequency by Phase of the El Niño/Southern Oscillation, the Global Wind Oscillation, and the Madden-Julian Oscillation

An Analysis of Anomalous Winter and Spring Tornado Frequency by Phase of the El Niño/Southern Oscillation, the Global Wind Oscillation, and the Madden-Julian Oscillation

Arctic sea ice and the Madden–Julian Oscillation (MJO)

Importance of the Gulf of Mexico as a climate driver for U.S. severe thunderstorm activity

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