SEMINAR: REMINDER: CIMAS Visiting Scientist Seminar - Prof. Da-Lin Zhang - March 31, 11:45AM, SA103

[mloi@rsmas.miami.edu]

 CIMAS VISITING SCIENTIST SEMINAR

 WHO:     PROFESSOR DA-LIN ZHANG
          Department of Atmospheric and Oceanic Science
          University of Maryland
          College Park, MD

 TITLE:   ON THE RAPID INTENSIFICATION OF HURRICANE WILMA (2005)

 WHEN:    WEDNESDAY, MARCH 31, 2010 AT 10:45 AM

 WHERE:   SLAB SEMINAR ROOM, SA 103
          SCIENCE AND ADMINISTRATION BLDG., RSMAS

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 ABSTRACT

 In this study, a 72-hour cloud-resolving prediction of Hurricane Wilma
(2005), covering its initial 18-h spin up, an 18-h rapid deepening and
the subsequent 36-h weakening period, is performed using the Weather
Research Forecast (WRF) model with the finest grid length of 1 km. The
model initial and lateral boundary conditions, including its bogus
vortex, are taken from the Geophysical Fluid Dynamics Laboratory's then
operational forecast data, but with the specified daily sea-surface
temperatures from satellite observations.

 It is shown that the WRF model prediction compares favorably to the best
track analysis, satellite, radar and reconnaissance flight observations
as well as the vortex message. In particular, the model reproduces
Wilma?s rapid intensity intensification (RI) rate of more than 7 hPa h-1
for a 12-h period, its minimum central pressure of less than 880 hPa, and
the subsequent weakening and reintensification in the surface maximum
wind. Of significance is that the model captures a sequence of important
inner-core structural changes associated with Wilma?s intensity
variations, namely, from a partial eyewall open to the west prior to RI
to a full eyewall at the onset of RI, rapid eyewall contraction during
RI, the formation of double eyewalls at the most intense stage, and the
subsequent eyewall replacement leading to the weakening of Wilma,
followed by another eyewall replacement cycle near the end of the 72-h
prediction. In addition, the model reproduces the polygonal eyewalls, and
the boundary-layer growth up to 750 hPa with an intense inversion layer
above near the eye center.

 Recognizing that a single case does not provide a rigorous test of the
model predictability, our results suggest that it is possible to improve
the forecasts of hurricane intensity and intensity changes if the
inner-core structural changes and storm size could be well predicted
using high-resolution cloud-resolving models with realistic initial
conditions.



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