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Graphical Airman's Meteorological Advisory (G-AIRMET)
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All Forecast Regions
The graphical Airman's Meteorological Advisory (G-AIRMET) is a BUFRformatted time-series depiction of aviation hazards occurring with occasional or greater frequency throughout the conterminous U.S. and adjacent coastal waters (NWS, 2005a). The aviation hazards depicted in the G-AIRMET are: • Instrument Flight Rule conditions (IFR): Areas of cloud ceilings with bases less than 1000 feet above ground level (AGL) and/or areas of surface visibilities below 3 statute miles, including the weather causing the visibility restriction. The cause of the visibility restriction includes only PCPN, FU, HZ, BR, FG, and BLSN. • Mountain Obscuration: Areas of widespread mountain obscuration where Visual Meteorological Conditions (VMC) cannot be maintained, including the weather causing the obscuration. The weather causing the obscuration includes only CLDS, PCPN, FU, HZ, BR, and FG. • Icing: Areas of moderate airframe icing, other than convectively induced, including the areal extent. • Freezing level information is included after AIRMETs for moderate icing or statements indicating that no significant icing is expected. Freezing level is defined as the lowest freezing level above the ground or at the SFC as appropriate. Freezing levels are delineated using high altitude VOR locations describing the location of the lowest freezing level above the ground or SFC as appropriate. Freezing levels above the ground are delineated at 4000 feet intervals above mean sea level (AMSL). Multiple freezing levels above the ground are delineated using "BOUNDED BY" followed by high altitude VOR locations. The range of freezing levels across the forecast area is also included. • Turbulence: Areas of moderate turbulence, other than convectively induced, including the vertical extent. • Low Level Wind Shear (LLWS): LLWS is defined as wind shear below 2000 feet AGL, other than convectively induced, exceeding 10 knots per 100 feet (vector difference between two points in space). LLWS potential information is included after AIRMETs for moderate turbulence and/or sustained surface winds greater than 30 knots or statements indicating no significant turbulence is expected. LLWS Potential information includes the list of affected states, and the phrase "BOUNDED BY" followed by high altitude VOR locations to delineate the area affected. • Strong Surface Winds: Areas of sustained surface winds greater than 30 knots. The direction and speed of winds are not be depicted; only the area where sustained surface winds greater than 30 knots will occur.
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0000-00-00 Comment End Date: 0000-00-00
Last edit date to this meta-data: 2019-07-02