Potential vorticity streamers (PVSs) are elongated filaments of high PV air that frequently occur in the subtropical Atlantic basin, and occur in conjunction with anticyclonic wave breaking (AWB), when low PV air folds over high PV air. PVSs modify the nearby tropospheric environment by enhancing vertical wind shear (VWS) and moisture anomalies in their vicinity. These environmental changes in VWS and moisture often impact tropical cyclone (TC) activity in the Atlantic basin. This research is motivated by knowledge that PVS climatologies have not examined how these environmental variables change as PVSs fluctuate in intensity during the TC season, which then affects seasonal TC activity in the Atlantic basin.
   This study investigates PVSs in the Atlantic basin using the CFSR and ERA-Interim reanalysis from 1979–2015. PVSs are identified using an algorithm from June–November on the 350-K isentropic surface bounded by the 2-PVU contour, where PVSs are identified as the high PV trough downstream of the AWB axis. PVSs are then sorted into strong and weak intensity cases using their standardized PV anomaly averaged within the PVS area. Before formation, strong PVSs possess stronger upstream ridge growth, while after formation strong PVSs have higher VWS anomalies and lower precipitable water anomalies compared to weak PVSs. To assess the impact PVSs intensity has on TC activity, a seasonal PVS activity metric is computed, which combines PVS size, intensity, and duration during the TC season. In general, seasons with larger and stronger PVSs are negatively correlated with TC activity, while seasons with more cases of weak PVSs are positively correlated with TC activity. These factors are likely attributed to environmental differences in VWS and moisture that occur between strong and weak PVSs.

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I recently gave a seminar presentation related to this particular topic at the National Hurricane Center in March 2017. You can view a video of the presentation below:
Abstract:[link]

Seminar Presentation given at National Hurricane Center

(April 2017)

(Click the image to view PDF presentation)

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I also presented a poster related to this topic at the 18th Cyclone Workshop in Sainte Adele Quebec, Canada in October 2017. In this poster, I focus on intensity variations in PV streamer activity, focusing on their seasonal role in impacting tropical cyclone activity. In summary, there is a significant negative correlation between PV streamer activity in the Atlantic basin and tropical cyclone (TC) activity, which in linked to a reduction in non-baroclinic type TCG pathways.
Abstract:[link]

Poster Presentation given at the 32nd Conference on Hurricanes and Tropical Meteorology

(October 2017)

(Click the image to enlarge)

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   The track of Tropical Cyclone (TC) Joaquin in September-October 2015 was exceptionally difficult to forecast due to the large uncertainty in forecast tracks. The forecast uncertainty was attributed to competing synoptic-scale features that were expected to impact the steering motion of TC Joaquin. These steering features would ultimately guide Joaquin out to sea, east of the forecast model guidance majority, and result in large left of track errors operationally by the National Hurricane Center. This presentation is motivated in part by these large errors in the initial operational track forecast, and also by the need to clarify which synoptic-scale features were responsible for steering TC Joaquin out to sea. This study will employ piecewise vorticity inversion and apply it to reanalysis and ensemble based forecast datasets of TC Joaquin to analyze the synoptic features responsible for track errors and steering of TC Joaquin. The role of errors in these synoptic features on Joaquin's track forecasts are further investigated using the European Center for Medium-Range Weather Forecasts (ECMWF) ensemble, available through the THORPEX Interactive Grand Global Ensemble (TIGGE) dataset.

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I gave a oral presentation related to this particular topic at the 32nd Conference on Hurricanes and Tropical Meteorology in San Juan, PR in April 2016. You can check out the presentation below.
Abstract:[link]

PowerPoint Presentation given at the 32nd Conference on Hurricanes and Tropical Meteorology

(April 2016)

(Click the image to view PowerPoint)

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   On 13 August 2014, a new all-time New York State 24-h precipitation record was set when 345 mm (13.57") of rain fell at Islip, New York on Long Island (LI). This record-breaking rainfall induced high-impact flooding over parts of LI. This flooding was a direct result of the persistent “training” of precipitation cells in a mesoscale band of intense convection. Prior to this event, heavy rainfall was forecasted across the northeastern United States in conjunction with an amplified upper-level trough that established poleward flux of deep moisture and provided synoptic-scale forcing for widespread rainfall. However, the location and magnitude of the heaviest rainfall over LI was poorly predicted, even at short forecast lead times. One hypothesis for this low predictability is linked to mesoscale factors governing the organization of the convective band associated with the LI flooding. Lower-resolution, convection-parameterized models often poorly represent these mesoscale features, which often limit the predictability of extreme precipitation events such as the LI flash flood.

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I gave a oral presentation related to this particular topic at the 27th Conference on Weather Analysis and Forecasting/23rd Conference on Numerical Weather Prediction in Chicago, IL in June 2015. You can check out the presentation below.
Abstract:[link]

PowerPoint Presentation given at the 27th Conference on Weather Analysis and Forecasting/23rd Conference on Numerical Weather Prediction

(June 2015)

(Click the image to view PowerPoint)

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