NCEP/EMC: Extratropical cyclones

NCEP Tropical and Extratropical Cylone Tracks and Verification

Operational extratropical cyclone tracks

NCEP currently runs storm tracker over model forecast grid data from NWP centers around the world to track storms in both tropical and extratropical regions. Real time forecast storm tracks are then plotted and imported to this page for monitoring. It contains track plots from various models, including the NCEP GFS, NCEP NAM, NCEP global ensemble, NCEP short range ensemble (SREF), as well as UKMET and NOGAPS models, Canadian high resolution model and ensemble, and ECMWF model and ensemble. Most recent 45 day's tracks can be displayed.

For forecast tracks in hemispheric plot:

For forecast tracks in different regions:

For ECMWF forecast tracks in hemispheric plot:

For forecast tracks in different regions:

Analysis cyclone tracks

In order to measure the accuracy of the model forecast tracks, a "truth" has to be established for verification. In the tropical storm cases, Hurricane Prediction Center issues "observed" tracks as the "truth". But no such luxuries are available for extratropical storms. The next best thing would be analysis cyclone tracks that are embedded in the forecast track files. By linking these analysis storm centers sequentially, storm tracks are identified.

For analysis tracks in hemispheric perspective:

For analysis tracks in different regions:

For EMC NAM parallel runs, go to

Link: Hurricane FAQs

Atlantic Oceanographic and Meteorological Laboratory has a good FAQs page about Hurricanes.

Link: Tropical cyclone facts

Who decides what the next name is going to be? What's the difference between a hurricane and a typhoon? Is climate change affecting tropical cyclones? UK MET Office has the answer.

Extratropical cyclone forecast verification

Now there are model forecast cyclone tracks and analysis tracks available. Absent of real track observations similar to hurricane tracks, the analysis tracks can be used as the truth for the forecast tracks verification. More detailed description about the verification processes can be found at "NCEP Operational Global Cyclone Tracking and Verification System." and

"Operational Extra-Tropical Cyclone Tracks Verification System."

Operational cyclone track errors

Following table provides model forecast cyclone track errors in unit of KM from NCEP operational models and from other centers. Each plot displays past 10 days verification against analysis tracks.

For forecast track errors:

Operational cyclone track biases

Mean biases between forecast and anlysis tracks in X and Y directions are also computed. Following links show most recent 10 days mean track biases from different models.

For forecast track X-bias and Y-bias:

For forecast along and cross track errors:

For forecast intensity and absolute intensity errors:

For forecast absolute along and absolute cross track errors:

For cyclone track monthly, yearly verification, go to

For cyclone track seasonal, yearly verification, see below:


Seasonal cyclone track errors
	Spring	Summer	Fall	Winter
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019

Yearly cyclone track errors
2010	2011	2012	2013	2014	2015	2016	2017	2018	2019

Time series and errors at 84hr and 120hr
84hr	120hr	84hr	120hr

For queries on the EMC/MMB involvement in cyclone tracks, email Guang.Ping.Lou@noaa.gov