METAR RMKs

[charley varrick]

Boning up on my METARS, and I can't for the life of me find out where it states what the second digit in these pressure trends means. Anything I read only says that it states the "character" of the trend.

KBOS 261154Z 28006KT 10SM FEW160 SCT250 21/14 A3001 RMK AO2 SLP160 T02060144 10211 20183 51018

KMSP 261153Z 00000KT 10SM FEW055 BKN250 19/17 A3006 RMK AO2 SLP175 ACC DSNT SW-NW T01940172 10211 20183 53003

KSFO 261156Z 26004KT 10SM FEW008 13/11 A3006 RMK AO2 SLP180 T01280111 10139 20128 58007

I'm referring to the last bit on each of the above, the 5(number)nnn . . . anybody got the rosetta stone for this one?

Thanks!

 

[A Squared]

The first digit after the 5 indicates what the atmospheric pressure has done in the last 3 hours

0= increasing, then decreasing

1 = Increasing, then steady, or increasing then increasing more slowly.

2= Increasing steadily or unsteadily.

3= Decreasing or steady, then increasing; or increasing then increasing more rapidly.

4= Steady

5=Decreasing then increasing.

6= Decreasing, then steady, or decreasing then decreasing more slowly.

7=Decreasing steadily or unsteadily

8=Steady or increasing, then decreasing; or decreasing then decreasing more rapidly.

the last 3 digits are the amount of change in the last 3 hours, in tenths of a hectopascal. ie: 012 means the pressure has changed 1.2 hectopascals in the last 3 hours

hope this helps

 

[charley varrick]

Thanks, A.--no wonder I never knew that! Nice and unambiguous, huh? Next time I fly, I'm gonna ask the controller if the hectopascals have been increasing then steady, or increasing then increasing more slowly. No matter their reply, I'll immediately declare an emergency.

By the way, what'd you locate this info?

 

[A Squared]

Federal Meteorological Handbook No. 1

http://205.156.54.206/oso/oso1/oso12/fmh1/fmh1toc.htm

Chapter 12, near the end.

I would recommend declaring an emergency before you start to read this

regards

 

[charley varrick]

What a read! The ending was kinda of a disappointment, though. Maybe Book No. 2 will be more action-packed.

 

[A Squared]

>>>The ending was kinda of a disappointment

yeah, I got the feeling they were just setting hte stage for a sequel

 

[Rank&File]

Surely no one would expect pilots to know what those numbers on the bottom of the report are. I've been told that they're only there to help the actual weather forcaster do his job. Aren't they only found on automated reports?

 

[charley varrick]

Rank&File,

Are you insinuating that knowing the three-hour pressure trend in hectopascals is not going assist you in your day-to-day flying? I, for one, think that limiting this invaluable info to mere tenths is far too restrictive. I have a petition with three signatures (okay, they are all my family) which requests that the NWS immediately begin releasing this data in hundrenths, preferably thousandths--then we, as dedicated, safety-minded aviators would really be able to assess the true trend in the weather.

If you would like to contribute to my lobbying effort, please send a cash donation to:

Pressure Trend Augmentation Fund
Hollowed-out Tree Stump Near My Garage
Hectopascal, MN 54405