The forecast used today by the traffic management stakeholders is the CDM Convective Forecast Planning Guidance (CCFP), where CDM stands for Collaborative Decision Making. The CCFP consists of four broadly-defined probabilistic contour maps created every 2 hours, showing likely regions of thunderstorms at 2, 4, 6, and 8 hours in the future. The contour regions are either low or high confidence (grey or blue color), and they indicate expected storm coverage via a progressively more dense fill pattern for sparse, medium or solid coverage.
The CCFP probabilistic contours do not resemble typical radar-map thunderstorm depictions; instead they depict likely regions where convective weather is expected. The broader the CCFP probability contours, the more spread (disagreement) between the various numerical weather prediction models that contribute to the CCFP.
In the image, an example of a 6-hour CCFP issued at 1500 UTC on October 15, 2014 shows a long oval region of high confidence, sparse coverage stretching from New York to the Atlantic Ocean east of Florida. Within this large region are two small regions of high confidence, medium coverage. The northern of these over Pennsylvania indicates storm tops of 25-29 thousand feet (labeled '290' on map), while the southern region offshore from South Carolina indicates storm tops of 30-34 thousand feet ('340'). A low confidence, sparse coverage region with tops of 35-39 thousand ('390') feet is shown in southern Florida.
In addition to the machine-generated CCFP, NOAA also offers the human-generated Collaborative Aviation Weather Statement (CAWS), issued only when the CCFP forecast is incorrect.
In contrast to CCFP, the NextGen Weather Processor (NWP) provides deterministic "radar-forward" predictions of storms from the current time out to 8 hours in the future. "Radar-forward" means that the future storm pattern, storm intensity and vertical extent, new storm growth and storm decay, are all portrayed in a similar format to the presentation of current weather on radar maps. FAA enroute and terminal users are accustomed to viewing weather radar returns to indicate thunderstorm flight hazards, and they are familiar with interpreting storm-imposed constraints on their airspace via these radar displays.
To illustrate the NextGen "radar-forward" predictions, the NWP Precipitation product issued at 1300 UTC on September 11, 2013, was selected. In the figure below, the Precipitation product is shown on the left, and the "truth" — the actual radar map that was eventually measured for each valid time — is shown on the right. The animation loops from 1 to 8 hours into the future in 1-hour steps, revealing the evolution of storms over the northeast US. Notice how the NWP product conveys the overall storm pattern, including multiple parallel lines of storms with gaps in between, the intensity of the storms, and the timing of storm growth in the region. The NWP product strongly resembles at every time step the actual storms that eventually occurred.
NWP also provides a "radar-forward" Echo Tops prediction that indicates the vertical extent of storms. An example of the 8-hour Echo Tops product for the same case is shown. As with the Precipitation product, the overall pattern of storms is conveyed in high resolution. The storm tops in central and eastern New York state, northeastern Pennsylvania, and southeastern Ohio are predicted to be over 40,000 feet tall, blocking jet routes and reducing capacity in those areas. (An animation for this same day displaying flight paths around the weather-impacted airspace is shown in the FAQ "What happens when enroute flights encounter thunderstorms?".)
NWP provides predictions up to 5 minutes apart out to 2 hours, and 15 minutes apart out to 8 hours. The format for the 2-8 hour strategic predictions is identical to the 0-2 hour predictions, providing a seamless capability for strategic and tactical impact assessment. The NOAA operational High Resolution Rapid Refresh (HRRR) numerical model contributes most heavily to the NWP results, while other NOAA models provide additional utility within the greater NWP domains and contribute to forecast confidence metrics.
NWP's predictive products, with their associated Translation Products and Confidence Metrics, pave the way for the generation of quantitative, objective capacity impact predictions needed to support collaborative strategic traffic flow management.
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