Weather Advisories

Question 1

Airmen’s

Answer 1

AIRMETs over the CONUS depict the following en route aviation weather hazards:
• IFR conditions (ceiling <1,000 ft and/or surface visibility <3 mi).
• Widespread mountain obscuration.
• Moderate icing.
• Freezing levels.
• Moderate turbulence.
• Non-convective LLWS potential below 2,000 ft AGL.
• Sustained surface winds greater than 30 kt.

AIRMET Sierra describes IFR conditions and/or extensive mountain obscurations.
• AIRMET Tango describes moderate turbulence, sustained surface winds of 30 kt or greater,
and/or non-convective LLWS.
• AIRMET Zulu describes moderate icing and provides freezing level heights.

Question 2

Sigmet

Answer 2

Severe or greater turbulence (SEV TURB).
• Severe icing (SEV ICE).
• Widespread dust storm (WDSPR DS).
• Widespread sandstorm (WDSPR SS).
• Volcanic ash (VA).

Question 3

Convective Sigmet

Answer 3

Tornado, hail greater than or equal to ¾ in (at the surface), or wind gusts greater than or equal to
50 kt (at the surface) are reported.
• Indications of rapidly changing conditions if, in the forecaster’s judgment, they are not sufficiently
described in existing Convective SIGMETs.

Question 4

Center Weather Advisory (Notice
of significant changes)

Answer 4

CWAs may be issued for the following situations:
• There is no existing AWC or AAWU advisory in effect or any of the following conditions occur:
o Conditions meeting Convective SIGMET criteria;
o Icing—moderate or greater;
o Turbulence—moderate or greater;
o Heavy and extreme precipitation;
o Freezing precipitation;
o Conditions at or approaching LIFR;
o Surface wind gust at or above 30 kt;
o LLWS (surface–2,000 ft); or
o Volcanic ash, dust storms, or sandstorms.