Rewriting Aviation Weather


Greetings and Happy Holidays to all!

For those of you with more than a passing interest in the weather side of aviation, I thought I would point out that the National Weather Service has just updated the AC 00-45 (Aviation Weather Service order) to version H. This version is significantly different than its predecessor. The NWS has been rampantly making changes as instrumentation and computer technologies leap forward. They have created a plethora of new weather “products” – charts and graphics relevant to aviation.

The document also indicates that many older type charts will be phased out as the newer ones come online.   For instance, the traditional Weather Depiction Chart and Constant Pressure Analysis updraftcharts are being phased out and replaced with the CVA (Ceiling and Visibility Analysis) and the Upper Air Constant Pressure Level Forecasts

Textual information for AIRMETS and Area Forecasts is being replaced by graphical AIRMETS and Forecasts. The use of graphics has been determined to be more useful to pilots and all the weather products are moving in that direction.

Some of the more interesting highlights include whole new sections devoted to Space Weather analysis and specialized Helicopter weather charts. Extensive revision has been done to sections devoted to Alaska and Hawaii. The order also indicates that a reorganization, and in some cases, re-naming of departments has taken place.

fl180-winds-1-14-13The Radar Section has been gutted and re-written with many new images and descriptions of how radar is depicted and interpreted. It also mentions upcoming radar products still in development. Freezing level graphics are vastly improved and graphical images have been added to show winds aloft information. Radiosonde data and analysis models include SKEW-T diagrams for forecast modeling.

In the past there were many types of textual weather overviews that are now replaced by the Meterological Impact Statement. The various surface analysis charts are now combined into a Unified Surface Analysis Chart that spans the globe. This model will make it easier to predict major storm movements and hurricanes.

Pilots will still see any PIREPS entered into the system by ATC or Flight Service, but the database will also show AIREPs. An AIREP is a PIREP in ICAO format that has been automatically entered by equipment onboard an aircraft. The information gives the lat/long of the aircraft and its flight level along with temperature, wind, and turbulence data. Instead of UA you will see ARP and UUA (urgent reports) will be encoded as ARS.

The Space Weather Prediction Center will be analyzing weather and processes occurring in the Earth’s magnetosphere, ionosphere, and thermosphere. Solar flares, geomagnetic storms and radiation levels can affect GPS navigation and communications. Reports and advisories will describe current ad expected activity and possible impacts on the Earth’s environment.

The Helicopter Emergency Medical Services (HEMS) tool will display weather conditions for short-distance and low-altitude flights. The tool uses radar, wind and satellite data in such a way as to narrow the forecasts to smaller areas

Finally, the NWS has now joined all the other aviation weather briefing sites by allowing a pilot to overlay his flight path on these weather charts using the Flight Path Tool.

Try out the NWS’s new graphical weather charts on their website:

You can find AC 00-45H in PDF format here


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