EOL Seminar Series: Jonathan Zawislak of NOAA/AOML Hurricane Research Division

Jonathan Zawislak of NOAA / AOML Hurricane Research Division
November 14, 2017  - 3:30 pm to 4:30 pm

What Governs Intensification of Tropical Cyclones Experiencing Moderate Vertical Wind Shear?

While low values (<5 m s-1) of environmental, deep-layer (850–200-hPa) vertical wind shear are generally favorable for tropical cyclone (TC) intensification, and high values (>10 m s-1) detrimental, the response of a TC to moderate shear (5–10 m s-1) is less predictable and is a source of significant forecast uncertainty. Whether or not a TC intensifies in this shear environment depends on internal processes and their interaction with the environment. This presentation will highlight recent and ongoing case studies and composite analyses of observational airborne and satellite data in intensifying and steady state TCs, with an emphasis on TCs within a moderately sheared environment. We focus on the precipitation (deep vs. shallow convection, stratiform precipitation), thermodynamic, and kinematic characteristics in a shear-relative framework. In general, intensification has been associated with a greater azimuthal coverage of precipitation, with an increase in upshear precipitation a critical determinant. This presentation will highlight processes that encourage a more favorable local environment for the increase and maintenance of precipitation upshear; processes such as moistening in the middle troposphere, reduction of vortex tilt, and recovery of lower-tropospheric cooling from downdrafts by surface enthalpy fluxes.


Room Number: 
1022 - Large Auditorium

Type of event:

Will this event be webcast to the public by NCAR|UCAR?: 
Announcement Timing: 
November 8, 2017 to November 14, 2017
Calendar Timing: 
Tuesday, November 14, 2017 - 3:30pm to 4:30pm