DDFF

The wind direction (DD) and speed (FF) in the lowest model layer, encoded in the standard manner. Take the first two digits, stick a zero on the end, and you've got the compass heading from which the wind is coming; the speed is given in knots. Usually, the actual wind speed at the surface will be less than this, because the lowest model layer encompasses a lot of air above the ground where friction is weaker and wind speeds are greater. In the example below, the strongest winds occur at hour 18, following a dramatic wind shift (the wind direction has just shifted from 210 degrees, southwest, to 280 degrees, west).

OUTPUT FROM ETA 12Z OCT 30 96

TT PTT R1 R2 R3 VVV LI PSDDFF HH T1 T3 T5

BOS //60 58 60 007 19 131410 56 05 05 04

06 000 81 84 48 042 09 091622 56 08 06 05

12 008 93 51 14 008 02 002126 59 12 12 10

18 000 77 30 14 -18 11 022828 55 12 08 04

24 000 74 35 20 -09 13 092924 49 09 04 00

30 000 64 33 39 -22 16 102818 48 08 03 00

36 000 62 47 49 033 18 112519 47 08 03 00

42 000 61 59 56 -03 18 112621 42 05 02 99

48 000 63 64 54 003 18 132618 40 03 00 97

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