See Section 27.12 for additional information on freezing level forecast graphics.

The NWS produces icing products that are derived from NWS computer model data combined with observations with no forecaster modifications. One of these products is the CIP.

The CIP combines weather satellite, weather radar, METAR, PIREPs and NWS model data to provide an hourly 3D diagnosis of the icing environment. This information is displayed on a suite of graphics available for the CONUS, much of Canada and Mexico, and their respective coastal waters.

The CIP [and its forecast counterpart Forecast Icing Product (FIP) (see Section 27.13)] provide a broad-brush approach to describing icing intensity using estimated liquid water content, drop size, and temperature to depict ice accumulation rate. The intensity of ice accumulation rate varies by aircraft wing shape. Hence, the icing intensity categories depicted in CIPs and FIPs (e.g., none, light, moderate, heavy) is only a broad-brushed indication of ice accumulation rate, and not necessarily of aircraft performance. The icing terms used in SIGMETs and AIRMETs do refer to icing impact on aircraft.

CIPs will continue to evolve over the coming years with increased model resolutions, additional horizontal layers, and improvements to the algorithms and/or data sets used to produce the products. Along with these improvements may come a change in references to the product update version. Users can find additional information on these products and any changes on the AWC’s website.

The CIP suite as it appears on the AWC’s website consists of three graphics, including:

The CIPs are generated for select altitudes from 1,000 ft MSL to FL300.

The CIPs can be viewed at single altitudes and FLs or as a composite of all altitudes from 1,000 ft MSL to FL300, which is referred to as the “maximum” or “max.”

The CIP can be used to identify the latest and forecast 3D probability and intensity of ice accumulation rate. The CIP should be used in conjunction with the report and forecast information contained in an AIRMET and SIGMET.

The Icing Severity plus SLD product can help in determining the threat of SLD, which is particularly hazardous to some aircraft.

Icing PIREPs are plotted on a single-altitude CIP graphic if the PIREP is within 1,000 ft of the selected altitude and has been observed within 75 minutes of the chart’s valid time. Icing PIREPs for all altitudes (i.e., 1,000 ft MSL to FL300) are displayed, except negative reports are omitted to reduce clutter. The PIREP legend is located on the bottom of each graphic.

Finally, while the “C” in CIP stands for “current,” the product does not show the current conditions, rather it depicts the computer’s expected conditions at the valid time shown on the product. This valid time can be an hour old or more depending on when it is received by the user.

See Section 27.13 for additional information on the FIP.

The GTG Nowcast (GTG-N) product has been developed as a tactical aid for aviation. GTG-N provides a nowcast of the current turbulent state of the atmosphere over the CONUS in near real-time, updating every 15 minutes. The basis for the nowcast is the most recently available short-term (one-hour) forecast from the GTG product whose valid time is closest to the current update time. Recent observations of turbulence are then used to update the GTG forecast and create a blended nowcast (expressed as EDR).

Current inputs include PIREPs, automated in situ EDR reports, and EDR estimated from ground-based radar observations via the Next-Generation Radar (NEXRAD) Turbulence Detection Algorithm (NTDA). In future upgrades, lightning, wind/gust observations from METARs, and EDR derived from ADS-B vertical rate data will be assimilated as well.

GTG-N is available at 100 ft MSL, 1000 ft MSL, then every 1000 ft up to FL500.

See Section 27.14 for additional information on the GTG forecast.