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6yjjk
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Hurricane Metar - Strange Wind Block

Mon Aug 20, 2007 9:17 am

Just got this METAR for Kingston, Jamaica:

MKJP 192300Z E11099OO180KT 0KM BKN008 BKN010CB OVC080 24/24 Q0998

Naturally, with a hurricane nearby, it's pretty nasty, but what exactly is that wind block saying? 180kt looks too high, given that the forecast intensity isn't meant to hit 140kt for a while yet, and I've never seen "E" or "OO". Can someone familiar with the more arcane intricacies of the METAR format help me out?
 
OPNLguy
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RE: Hurricane Metar - Strange Wind Block

Mon Aug 20, 2007 9:51 am

Over at wunderground.com, they're showing (as of 40 something minutes ago)"

Updated: 43 min 10 sec ago
» Disable Rapid Fire — About Rapid Fire
Observed at: Kingston / Norman Manley, Jamaica
Elevation: 10 ft / 3 m

77 °F / 25 °C
Overcast
Humidity: 92%
Dew Point: 75 °F / 24 °C
Wind: 173 mph / 278 km/h / from the ESE
Wind Gust: -
Pressure: 29.58 in / 1002 hPa
Visibility: 0.0 miles / 0.1 kilometers
UV: 0 out of 16
Raw METAR Aviation
AAXX 20003 78397 31300 81199 00150 10249 20239 30001 40017 6////

That wind pretty much syncs with the "E11099OO180KT", and the "E" looks to be "estimated" (Don't think there's any human observer insane enough to go out and take readings). The "110" is the direction of the wind (from 110 degrees, or ESE). I'm not sure about the "99" and "OO" codes, but I'm researching that one now...
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N908AW
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RE: Hurricane Metar - Strange Wind Block

Mon Aug 20, 2007 9:57 am

Quoting OPNLguy (Reply 1):
I'm not sure about the "99" and "OO" codes, but I'm researching that one now...

Well. I'm fairly certain the 99kt refers to sustained winds, whilst 180 is, then, the gust.

And the OO refers to how big the guy's eyes looked when he first got that wind readout.
'Cause you're on ATA again, and on ATA, you're on vacation!
 
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asuflyer05
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RE: Hurricane Metar - Strange Wind Block

Mon Aug 20, 2007 1:27 pm

I have never seen OO used in a METAR. I just looked it up in the FAR/AIM and it is not listed there either.
 
OPNLguy
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RE: Hurricane Metar - Strange Wind Block

Mon Aug 20, 2007 2:04 pm

Quoting Asuflyer05 (Reply 3):
I have never seen OO used in a METAR. I just looked it up in the FAR/AIM and it is not listed there either.

The US uses a slightly different METAR format, and I'm looking at WMO stuff to see if I can figure it out....
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Indy
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RE: Hurricane Metar - Strange Wind Block

Mon Aug 20, 2007 3:05 pm

I'd like to see that wind speed validated. At the same time the pressure was listed as 1002 mb. So with that pressure it would seem the wind speed was likely incorrect. I know some anemometers will give bad wind readings if not properly grounded.
Indy = Indianapolis and not Independence Air
 
OPNLguy
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RE: Hurricane Metar - Strange Wind Block

Mon Aug 20, 2007 3:10 pm

Quoting Indy (Reply 5):
I know some anemometers will give bad wind readings if not properly grounded.

They've also been known to give bad readings if the sensors have been blown away....  Wink

Kinda reminds when Hurricane Andrew took out one of the local VORTACs in the Miami area, as well as the weather radar at the National Hurricane Center....
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Indy
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RE: Hurricane Metar - Strange Wind Block

Mon Aug 20, 2007 3:13 pm

It could have been the moment the anemometer met a live power line  Smile
Indy = Indianapolis and not Independence Air
 
6yjjk
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RE: Hurricane Metar - Strange Wind Block

Tue Aug 21, 2007 1:41 am

It's certainly an odd one. OPNLguy, have you had any luck? I haven't found anything.

Wild-ass guess: since the wind speed is usually two digits, they put 99 in there, and the "OO" is some sort of separator between that and the real speed. So the whole thing is "estimated 110 at 180kt"... though that estimate still looks too high,and I do like N908AW's idea better:

Quoting N908AW (Reply 2):
OO refers to how big the guy's eyes looked when he first got that wind readout

 Smile

Quoting Indy (Reply 5):
I'd like to see that wind speed validated. At the same time the pressure was listed as 1002 mb. So with that pressure it would seem the wind speed was likely incorrect.

I thought it was the pressure gradient that governed the windspeed, not the pressure itself - if it's 1002mb here and 950mb 20 miles down the road, it's going to be a bit breezy(!). Have I misunderstood you? I did check what Montego Bay was giving, but it seems they had the good sense to go home long before Kingston put this out.  Smile
 
Indy
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RE: Hurricane Metar - Strange Wind Block

Tue Aug 21, 2007 2:40 am

Quoting 6YJJK (Reply 8):
I thought it was the pressure gradient that governed the windspeed, not the pressure itself - if it's 1002mb here and 950mb 20 miles down the road, it's going to be a bit breezy(!). Have I misunderstood you?

It is certainly a product of pressure gradient. However if the pressure is 1002mb it is certain that 1005 and 1010 mb are not too far away. That isn't a very big pressure gradient. Certainly enough for a bit of a breeze but not enough for 100+ mph winds. At 1002 mb you will be at the outer edge of the pressure drop. You aren't embedded in it where you'd expect to get the higher winds.
Indy = Indianapolis and not Independence Air
 
6yjjk
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RE: Hurricane Metar - Strange Wind Block

Tue Aug 21, 2007 8:58 pm

Quoting Indy (Reply 9):
At 1002 mb you will be at the outer edge of the pressure drop. You aren't embedded in it where you'd expect to get the higher winds.

That'd fit with every chart I've seen, with the isobars more tightly packed toward the middle. I see what you're saying, now.

Anyone had any luck with that "OO"?
 
OPNLguy
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RE: Hurricane Metar - Strange Wind Block

Tue Aug 21, 2007 10:39 pm

Quoting 6YJJK (Reply 8):
OPNLguy, have you had any luck? I haven't found anything.



Quoting 6YJJK (Reply 10):
Anyone had any luck with that "OO"?

No luck here...
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sphealey
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RE: Hurricane Metar - Strange Wind Block

Tue Aug 21, 2007 11:03 pm

Per Weather Underground, Kingston's official wind speed gauge was destroyed early on in the event.

sPh
 
6yjjk
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RE: Hurricane Metar - Strange Wind Block

Tue Aug 21, 2007 11:24 pm

Quoting Sphealey (Reply 12):
Per Weather Underground, Kingston's official wind speed gauge was destroyed early on in the event.

I'm not surprised! I wish I were an anemometer salesman in the Caribbean  Smile

Quoting OPNLguy (Reply 11):
No luck here...

No worries. I've just asked the Jamaican met office what it was all about, though their site crashed when I submitted the form and I'm sure they have better things to be doing right now anyway. If I get an answer, I'll let you know.
 
OPNLguy
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RE: Hurricane Metar - Strange Wind Block

Wed Aug 22, 2007 2:08 am

Quoting Sphealey (Reply 12):
Per Weather Underground, Kingston's official wind speed gauge was destroyed early on in the event.



Quoting OPNLguy (Reply 6):
They've also been known to give bad readings if the sensors have been blown away....

Looks like I wasn't too far off..  Wink

Wonder how far from KIN the equipment got blown.......
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graphic
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RE: Hurricane Metar - Strange Wind Block

Wed Aug 22, 2007 2:37 am

Quoting OPNLguy (Reply 14):

Wonder how far from KIN the equipment got blown.......

...A poor family in Havana just got a new set of drinking cups...
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CaptSkibi
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RE: Hurricane Metar - Strange Wind Block

Wed Aug 22, 2007 2:58 am

I haven't seen anything on the E or the OO in the wind block in the US FMH (Federal Meteorological Handbook) No. 1 nor in WMO No. 36 Manual On Codes Volume I.1 Part A. In WMO No. 36 Vol I.1, I was looking in FM 15, and under Vol. II, I was looking under Region IV coding practices (as Kingston is part of WMO Region IV).

One thing it did mention, however, is that if the wind speed is in excess of 99 (MPS, KT, or KMH), the three digit wind speed is simply reported. This is not the form that a variable wind direction (maximum CCW or CW direction) is reported, either, so it is not due to the rotating winds of the hurricane. Unfortunately, the ADDS only goes back 36 hours, as well, so you can't use it's "translated METAR" function, either.

EDIT:
On a good note, however, my upper-air station at Kingston has survived! It has reported data throughout the storm!

[Edited 2007-08-21 20:00:22]
Private Pilot, Airplane Single Engine Land / former frequent flyer with 9 straight years being elite on NW/DL
 
InnocuousFox
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RE: Hurricane Metar - Strange Wind Block

Thu Aug 23, 2007 3:36 am

Quoting OPNLguy (Reply 6):
They've also been known to give bad readings if the sensors have been blown away....

To quote Ron White... "It's not THAT the wind is blowin... it's WHAT the wind is blowin'."
Dave Mark - Intrinsic Algorithm - Reducing the world to mathematical equations!
 
6yjjk
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RE: Hurricane Metar - Strange Wind Block

Thu Aug 23, 2007 4:35 am

Quoting CaptSkibi (Reply 16):
I haven't seen anything on the E or the OO in the wind block in the US FMH (Federal Meteorological Handbook) No. 1 nor in WMO No. 36 Manual On Codes Volume I.1 Part A. In WMO No. 36 Vol I.1, I was looking in FM 15, and under Vol. II, I was looking under Region IV coding practices (as Kingston is part of WMO Region IV).

Wow. See, this is why I come to a.net.  Smile
 
InnocuousFox
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RE: Hurricane Metar - Strange Wind Block

Thu Aug 23, 2007 6:45 am

It probably has something to do with the fact that the METAR or the equipment won't read/display over 99. I agree that "E" means estimated.
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