PPRuNe Forums - Unusual SPECI

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mikewil

22nd Dec 2016 22:59

Unusual SPECI

Anyone able to help me figure out why the following AUTO METAR has been designated as a SPECI:

SPECI YPLC 222337Z AUTO 35010KT 340V140 9999 // NCD 35/08 Q1008 RMK
RF00.0/000.0

Which criteria in here would warrant the change to SPECI designation?

fujii

22nd Dec 2016 23:07

There could be a number of things. Wind or temperature change beyond parameters. Can't tell without the previous metar to compare it with. See AIP GEN 3.5 - 9

Dukeunlimited

22nd Dec 2016 23:10

There are a few possible options:

'when mean direction changes by 30 degrees or more, the mean speed before or after the change being 20 kt or more'

'when the QNH altimeter setting changes by 2 hPa or more'

'when the temperature changes by 5 degrees C or more.'

I hope that helps.

mikewil

22nd Dec 2016 23:19

Quote:

'when mean direction changes by 30 degrees or more, the mean speed before or after the change being 20 kt or more'

'when the QNH altimeter setting changes by 2 hPa or more'

'when the temperature changes by 5 degrees C or more.'

Completely overlooked those possibilities, need go to back to AIP me thinks.

By the way, what does the 340V140 mean?

JoelRH

22nd Dec 2016 23:56

Quote:

By the way, what does the 340V140 mean?

Wind direction variation 340 to 140 degrees.

AmarokGTI

23rd Dec 2016 20:46

Quote:

Originally Posted by mikewil (Post 9618123)

There is also often a misconception that a SPECI means the weather is "bad". It can also be the case that, because of an exceedance of the above mentioned parameters, that the weather has changed from "bad" to "good", and a SPECI pops up as a result.

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