Military TAF Turbulence Codes: The 5-Group Decoded

Military TAF turbulence codes look like a phone number dropped into the middle of a forecast. 520005 carries no letters and no obvious structure, which is why most pilots skip it.

It is one of the more readable groups once you know where to cut it. Six digits, four fields, and the first digit tells you which group you are looking at.

How the 5-group is built

Every turbulence group begins with the digit 5. That is the group marker, not a value, and it is why this is called the 5-group.

The layout after that never changes:

• Digit 1: always 5, marking the turbulence group
• Digit 2: intensity and type, from the table below
• Digits 3 to 5: base of the layer, in hundreds of feet
• Digit 6: thickness of the layer, in thousands of feet

So 520005 splits as 5, 2, 000, 5. The turbulence group, occasional moderate in clear air, based at the surface, five thousand feet thick.

The base is above ground level at the forecast aerodrome. The thickness is added to the base to give the top, so this layer runs from the surface to 5000 feet.

The intensity codes

These come from AFMAN 15-124, Table 1.7, and the wxdecoder parser reads them exactly as written there.

The pattern inside the numbers

The table looks like ten unrelated values. It is really three questions answered in order, and seeing that makes it memorable.

Codes 2 to 5 are all moderate. Codes 6 to 9 are all severe. So the first thing the digit tells you is which half of the ladder you are on.

Within each block of four, the odd number is frequent and the even number is occasional. And the first pair is clear air while the second pair is in cloud.

Read it as: moderate or severe, occasional or frequent, clear air or cloud. Code 7 is severe, frequent, clear air. Code 4 is moderate, occasional, in cloud.

Codes 0 and 1 sit outside the pattern because there is nothing to qualify. X sits outside it at the top for the same reason.

Reading the altitude band

The last four digits are where mistakes happen, because the two fields use different units.

The base uses hundreds of feet, like a cloud group. 080 is 8000 feet.

The thickness uses thousands of feet. A final digit of 3 is 3000 feet, not 300.

So 540803 is the turbulence group, code 4 for occasional moderate in cloud, based at 8000 feet, 3000 feet thick. The layer runs 8000 to 11,000.

A thickness digit of 0 does not mean no layer. It means the layer is under a thousand feet thick, which is common for low-level shear near the surface.

Where the group sits in the forecast

The turbulence group lives in the trailer of the TAF, after the ordinary weather groups, alongside the icing group and the altimeter group.

A military TAF trailer often reads something like 510005 620105 QNH2992INS. Three groups in a row: turbulence, icing, altimeter. The leading digit of each tells you which is which, so you can pick out the one you want without counting positions.

Both hazard groups apply to the change period they sit in. A TEMPO or FM section can carry its own turbulence group, and where it does, it overrides the one before it for that period.

A worked example

Take a trailer reading 570607 and cut it into its four fields.

The leading 5 marks turbulence. The 7 is the intensity, and 7 sits in the severe block as an odd number in the clear-air pair. So it is frequent severe turbulence in clear air.

The 060 is the base, in hundreds of feet, so 6000 feet. The final 7 is the thickness in thousands, so 7000 feet.

Put together: frequent severe clear-air turbulence, from 6000 to 13,000 feet. That is a band to avoid rather than to cross, and the numbers tell you a climb above 13,000 clears it.

Now compare 510005. Same frame, and a far milder forecast: light turbulence from the surface to 5000 feet. The only digit that changed the meaning was the second one.

One quirk worth knowing

The manual is not perfectly consistent with itself, and the wxdecoder parser follows the table rather than the prose.

AFMAN 15-124 gives a worked example at paragraph 1.3.3.1 that narrates code 4 as light to moderate in cloud turbulence. Table 1.7, which is the normative text, says moderate. The table wins.

It is a small thing, but if you have been taught from the worked example you may read code 4 as slightly milder than our decoder reports it.

Verdict on military TAF turbulence codes

Cut the group after the first digit, then after the second, then after the fifth. Marker, intensity, base, thickness.

The intensity digit is the only part you have to learn, and its internal pattern does most of the work. Moderate in the twenties and thirties, severe in the sixties through nineties, odd numbers frequent, and the second pair of each block in cloud.

Last updated August 29, 2026