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The Madden-Julian Oscillation and Gulf of Mexico Extratropical Cyclogenesis

Authors: Robert V. Rohli*, Louisiana State University, Stephen P. Caparotta, Louisiana State University, Philip Klotzbach, Colorado State University
Topics: Climatology and Meteorology, Coastal and Marine, Hazards, Risks, and Disasters
Keywords: Severe Weather, Gulf of Mexico, Gulf Coast Cyclone, Madden-Julian Oscillation
Session Type: Paper
Day: 4/6/2020
Start / End Time: 4:40 PM / 5:55 PM
Room: Virtual Track 1
Presentation File: No File Uploaded

Intra-seasonal weather variability is important, especially in areas such as the Gulf of Mexico, where large coastal populations and valuable fisheries and energy-extractive industries exist. Previous research has linked a form of high-frequency, intra-seasonal variability in eastward-propagating tropical convective pulses, known as the Madden-Julian Oscillation (MJO), to variations in intra-seasonal tropical cyclogenesis, extratropical nor’easters, Gulf Coast severe weather, and North American extreme precipitation, temperature, tornadoes, and atmospheric rivers. But to date, little research has focused on the cyclogenesis itself in this region in which cool-season conditions frequently support rapid cyclone intensification near the coast. October-March cyclogenesis events were identified for the 1979-2014 period, for the area bounded by 19-33°N and 100-80°W, using data obtained from the National Snow and Ice Data Center (NSIDC), which in turn were compiled using 3-hourly sea-level pressure data available from Modern-Era Retrospective analysis for Research and Applications (MERRA). After filtering the NSIDC dataset to remove 12 tropical events and the extratropical events that passed through without originating within the study area, 136 of the 272 cyclones remained. Results of Monte Carlo simulations reveal significant associations between the MJO and cyclogenesis. Analysis suggests a link to modified synoptic-scale Rossby waves by the MJO-related convective clusters. In particular, anomaly plots show that measures of atmospheric pressure, moisture, and instability favor (oppose) the development of convection in the study region during Phases 7 and 8 (4, 5, and 6). These results may be useful for forecasters as they seek additional guidance on the likelihood of cyclogenesis.

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