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The Aviation Weather Center (AWC) has the responsibility, as part of the
World Area Forecast Center, Washington, to provide global weather
forecasts of significant weather phenomena. Presently, the AWC produces
High Level Significant Weather charts covering two thirds of the globe,
both northern and southern hemispheres that are issued four times per
More recently the Aviation Weather Center has accepted the
responsibility for routinely providing a Mid Level Significant Weather
chart, between FL100 and FL450, for the North Atlantic Ocean Region
(NAT). The NAT chart implementation is scheduled for Sept 15, 2003 with
The presentation of significant weather on the mid level significant
weather chart is similar in many respects to that on High Level
Significant Weather charts. The detail required however is more
extensive because the bottom of the chart is now at FL100 instead of
FL250. Aircraft flying at these lower levels in the atmosphere, below
FL250, will more likely encounter larger areas of icing and turbulence.
The North Atlantic Mid Level Significant Weather chart will be
transmitted along with the High Level Significant Weather charts.
Transmission times for forecast packages are:
|24 hour forecast package valid at 00Z
|24 hour forecast package valid at 06Z
|24 hour forecast package valid at 12Z
|24 hour forecast package valid at 18Z
The information placed on the Mid Level Significant Weather chart will
be the combination of information imported from the corresponding High
Level Significant Weather chart and additional information generated by
the meteorologist specifically for the Mid Level chart.
WAFS Significant Weather (SIGWX) Data in BUFR
This document has been prepared by the World Area Forecast Centres
(WAFCs) for the purpose of providing guidance to software developers who
have the task of constructing WAFS SIGWX BUFR visualisation software.
The document is designed to assist developers in the construction of
compliant visualisation software that receives its data input from text
files obtained from BUFR decoding software.
The Mid Level chart will include the following information:
|| a) Thunderstorms and
Surface frontal positions and movement;
| b) Jet streams;
|* Jet Depth: The vertical
depths to the 80 knot wind field above and below the jet steam using
flight levels. Jet stream vertical depth forecasts are included when
the maximum speed is 120 knots or more. More
|| c) Tropopause heights;
| d) Tropical Cyclones;
| e) Moderate or Severe
f) Moderate or Severe Turbulence
(in cloud or in
|| g) Volcanic Eruptions;
| h) Widespread Sand
| i) Release of
To Receive the North Atlantic Mid Level Chart
The Aviation Weather Center provides dissemination via its International
Flight Folder Documentation Program. To receive this chart via automated
facsimile service call 877-280-2811 and request document number 2135.
You may also provide comments on this sample chart. Send comments to:
|Click on MAP to enlarge