January 22, 2021

Weather News – Road Conditions – weather forecast

Paper on the relationship between the amount of ice in clouds and rapid intensification of hurricanes released online in Geophysical Research Letters – Hurricane Research Division

2 min read

Summary:  It is difficult to accurately forecast how strong a tropical cyclone will get, what we call intensity. The biggest problem is in forecasting when the intensity increases dramatically in a short period of time, or rapid intensification (RI).  This study looked at the relationship between how fast a tropical cyclone intensifies and the amount of ice in the clouds that make up the cyclone. Cloud ice can tell us about the strength and organization of thunderstorms in a tropical cyclone, which can be related to the maximum wind speed near the surface.

Artist’s rendition of the CloudSat spacecraft (image credit: NASA)

Two types of cloud ice data were used in this study: 1) observations from NASA’s CloudSat, and 2) forecasts from an experimental version of NOAA’s high-resolution Hurricane Weather Research and Forecasting (HWRF) model. CloudSat uses a special downward-looking radar to measure the amount of energy that is reflected by a cloud that, when combined with temperature data, estimates how much ice is in the cloud. HWRF predicts the amount of ice in the clouds as part of its forecast system.  The two datasets are combined to study the relationship between cloud ice and intensification.

Important Conclusions:

  1. Tropical cyclones with greater amounts of cloud ice are likely to intensify faster than those with less cloud ice. 
  2. Observations of cloud ice may be used to improve hurricane forecast models.

Composites of cloud ice amount for 4 intensification rates in HWRF forecasts.  Higher amounts of cloud ice that surround the center of the storm (0,0 in each panel) are associated with more rapid intensification rates. The number of model snapshots in each composite is provided in parentheses above each panel.

You can read the full study at https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL089669. For more information, contact aoml.communications@noaa.gov.

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