Tuesday, March 28, 2017

Tropical Cyclone information graphics changes for the 2017 season.

The National Hurricane Center (NHC) is making several changes to its tropical cyclone graphics.

The 2017 hurricane season will be here before you know it. So I wanted to go over these changes before June 1st.

1)  The NHC will be issuing advisories even before a disturbance becomes a depression or a named storm.  Any potential tropical cyclones that threaten land area with tropical storm or hurricane force winds within 48 hours will be given advisories, with discussions and tracking maps.

2)  The NHC started posting experimental alerts for storm surge last season. For 2017 those alerts will be mandatory. The NHC will be issuing storm surge watches and warnings for the Gulf and Atlantic Coast, for any storm that has the risk for life threatening surge conditions during any stage of a subtropical or tropical cyclone, even potential tropical cyclones.  

3)  For the 2017 hurricane season, the NHC will be issuing approximate arrival times of tropical storm force winds. The new graphic will display the earliest reasonable arrival time of winds of at least 39 mph.  A probability scale will be used along with the arrival time. The scale will show the probability threshold for 39 mph, 58 mph, and 74 mph wind speed will be met in a particular location. 

4)  The size of the Cone Of Uncertainty will be smaller. The cone will be based on the tracking error over the last four hurricane seasons. The cone doesn't represent where impacts like storm surge, wind, flooding, or tornadoes will be felt.
The old Cone of Uncertainty
The updated Cone of Uncertainty

Table showing the circle radii size of the cone

5)  Advisory graphics will be greatly improved.  New bolder colors and easier to read font should make the carts easier to view and understand.  The new graphics will include tropical storm and hurricane force wind fields.

I hope you found this helpful. As always let me know what you think, or post any questions you might have.

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