News of rumoured extreme low pressure. 940mb.
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Quote from Chris Scott:
COR is automatically inserted into all METARs that are re-broadcast with a Trend appended. If for some reason the Trend doesn't get added the METAR should appear without it. Most online sources appear to strip out the COR anyway. Hope that helps.
Think what probably happens sometimes is that the METAR is broadcast before the system has tacked the TREND on to the end of it. When the omission comes to someone’s attention, the METAR has to be reissued as a “COR!”.
Time wasting on the Volmet/ Reams of paper...
Hi FCUK12,
What you say makes sense, and does not contradict my main point. [Only applies to airfields that qualify for TREND forecasts.]
But your theory that the word "corrected" is removed (from the amended version of the METAR) - by whatever agency broadcasts the METARS - is not what seems to be happening in practice. This definitely applies to some agencies that present METARS on the web, and ls_jet2's comment about the London Volmet is correct (pun not intended).
It is all time-consuming, when you are desperate for an Actual. Whatever fireflybob says, you can't always get the destination ATIS in time for your descent brief, and not all our colleagues have data links like ACARS. And the ATIS rarely includes a TREND forecast, unless things have changed in the last 6 years.
Here is an up-to-the-minute example from AvBrief:
METAR EGLL 121450Z 28019KT CAVOK 11/M03 Q1005=
METAR COR EGLL 121450Z 28019KT CAVOK 11/M03 Q1005 TEMPO 28020G30KT=
METAR COR EGLL 121420Z 28023KT 9999 FEW049 11/M02 Q1005 TEMPO 28025G35KT=
METAR COR EGLL 121350Z 27024G35KT 9999 SCT049 11/M01 Q1004 NOSIG=
METAR EGLL 121320Z 28022G32KT 9999 FEW049 10/M01 Q1004=
COR EGLL 121320Z 28022G32KT 9999 FEW049 10/M01 Q1004 NOSIG=
METAR EGLL 121250Z 28022G34KT 9999 FEW049 10/M01 Q1003=
COR EGLL 121250Z 28022G34KT 9999 FEW049 10/M01 Q1003 NOSIG=
On the other hand, here are the same group of METARS from ADDS (Aviation Data Digital Service [USA]):
EGLL 121450Z 28019KT CAVOK 11/M03 Q1005 TEMPO 28020G30KT
EGLL 121420Z 28023KT 9999 FEW049 11/M02 Q1005 TEMPO 28025G35KT
EGLL 121350Z 27024G35KT 9999 SCT049 11/M01 Q1004 NOSIG
EGLL 121320Z 28022G32KT 9999 FEW049 10/M01 Q1004
EGLL 121250Z 28022G34KT 9999 FEW049 10/M01 Q1003
You will note that for the 1250 and 1320 METARS, the TRENDs are missing; they have tried to avoid clutter, perhaps; but have either failed to receive the "CORs", or failed to use them when they became available.
The 1450z, however, has come out well.
Now, the UK MetOffice website:
EGLL 121450Z 28019KT CAVOK 11/M03 Q1005 TEMPO 28020G30KT
So the UK Met Office seems to be interpreting its own output of METARs correctly - hardly surprising?
Just copied the LHR 1450z METAR on "London Volmet Main" (135.375MHz):
"London heathrow at 1450 corrected, Wind two-eight-zero degrees one-niner knots, CAV-O-K, Temperature one-one, Dew-point minus three, Q-N-H one-zero-zero-fife; Tempo- Wind two-eight-zero degrees two-zero knots maximum three-zero knots."
[Sorry, everyone, but the gales now seem to be dying out...]
What you say makes sense, and does not contradict my main point. [Only applies to airfields that qualify for TREND forecasts.]
But your theory that the word "corrected" is removed (from the amended version of the METAR) - by whatever agency broadcasts the METARS - is not what seems to be happening in practice. This definitely applies to some agencies that present METARS on the web, and ls_jet2's comment about the London Volmet is correct (pun not intended).
It is all time-consuming, when you are desperate for an Actual. Whatever fireflybob says, you can't always get the destination ATIS in time for your descent brief, and not all our colleagues have data links like ACARS. And the ATIS rarely includes a TREND forecast, unless things have changed in the last 6 years.
Here is an up-to-the-minute example from AvBrief:
METAR EGLL 121450Z 28019KT CAVOK 11/M03 Q1005=
METAR COR EGLL 121450Z 28019KT CAVOK 11/M03 Q1005 TEMPO 28020G30KT=
METAR COR EGLL 121420Z 28023KT 9999 FEW049 11/M02 Q1005 TEMPO 28025G35KT=
METAR COR EGLL 121350Z 27024G35KT 9999 SCT049 11/M01 Q1004 NOSIG=
METAR EGLL 121320Z 28022G32KT 9999 FEW049 10/M01 Q1004=
COR EGLL 121320Z 28022G32KT 9999 FEW049 10/M01 Q1004 NOSIG=
METAR EGLL 121250Z 28022G34KT 9999 FEW049 10/M01 Q1003=
COR EGLL 121250Z 28022G34KT 9999 FEW049 10/M01 Q1003 NOSIG=
On the other hand, here are the same group of METARS from ADDS (Aviation Data Digital Service [USA]):
EGLL 121450Z 28019KT CAVOK 11/M03 Q1005 TEMPO 28020G30KT
EGLL 121420Z 28023KT 9999 FEW049 11/M02 Q1005 TEMPO 28025G35KT
EGLL 121350Z 27024G35KT 9999 SCT049 11/M01 Q1004 NOSIG
EGLL 121320Z 28022G32KT 9999 FEW049 10/M01 Q1004
EGLL 121250Z 28022G34KT 9999 FEW049 10/M01 Q1003
You will note that for the 1250 and 1320 METARS, the TRENDs are missing; they have tried to avoid clutter, perhaps; but have either failed to receive the "CORs", or failed to use them when they became available.
The 1450z, however, has come out well.
Now, the UK MetOffice website:
EGLL 121450Z 28019KT CAVOK 11/M03 Q1005 TEMPO 28020G30KT
So the UK Met Office seems to be interpreting its own output of METARs correctly - hardly surprising?
Just copied the LHR 1450z METAR on "London Volmet Main" (135.375MHz):
"London heathrow at 1450 corrected, Wind two-eight-zero degrees one-niner knots, CAV-O-K, Temperature one-one, Dew-point minus three, Q-N-H one-zero-zero-fife; Tempo- Wind two-eight-zero degrees two-zero knots maximum three-zero knots."
[Sorry, everyone, but the gales now seem to be dying out...]
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[Sorry, everyone, but the gales now seem to be dying out...]
1 - the budget will now grab the headlines
2 - all this is going on North of Watford
Still 270-280 gusting 40kts at MAN with windshear reported and a couple of recent g/a which got in at the second attempt. Similar speeds at present at LPL and LBA
MAN TAF shows winds likely to decrease from 2300......
Suzeman
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Regarding the LPL closure - I might be responsible for the start of that rumour, after telling FCA ops that Servisair were about to run for cover and not despatch any more aircraft.
Servisair decision was fine by me because I did not want to depart for BHX with winds gusting up to 60kts across the runway. Landing at Liverpool was bad enough with the wind just 10 or 20 degrees off the runway.
And Atcham Tower if that was you on the radio my I say thank you because without your string of wind reports in the last few hundred feet we would of gone round. Cheers.
Servisair decision was fine by me because I did not want to depart for BHX with winds gusting up to 60kts across the runway. Landing at Liverpool was bad enough with the wind just 10 or 20 degrees off the runway.
And Atcham Tower if that was you on the radio my I say thank you because without your string of wind reports in the last few hundred feet we would of gone round. Cheers.
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Guzzler, don't blame you for staying there as things were starting to move around and I wasn't looking forward to going out to see what it was!! The turbulence coming off the hangers was making landing sporting at best, saw one baby arrival that looked very close to being No 1 engine first from where I was on stand 50.
Jonty were you in the ATR? On the RT it sounded like they landed in those conditions every leg.
Jonty were you in the ATR? On the RT it sounded like they landed in those conditions every leg.
Chris,
it depends a bit with the US data on foreign airports. First of all, they often are quite late and secondly, it depends strongly if they get properly propagated by the GTS system. Not always the case. I know of some applications which run off the US data, their METARS are always 1 behind due to the way the GTS input gets distributed into their cycle files of which ADDS and other applications are feeding. That way it can happen very well that COR's are not present.
Some other applications have the same problem. I've been fighting this end for e.g. GTS mauled messages to be still shown, particularly African TAF's which sometimes have whole sections in gobbledegook due to lousy datalines, but I'd rather have this TAF than none at all. But quite a few databases simply kill anything missing a character or two.
Best regards
AN2
On the other hand, here are the same group of METARS from ADDS (Aviation Data Digital Service [USA]):
Some other applications have the same problem. I've been fighting this end for e.g. GTS mauled messages to be still shown, particularly African TAF's which sometimes have whole sections in gobbledegook due to lousy datalines, but I'd rather have this TAF than none at all. But quite a few databases simply kill anything missing a character or two.
Best regards
AN2
Whatever fireflybob says, you can't always get the destination ATIS in time for your descent brief, and not all our colleagues have data links like ACARS.
One of the challenges with ATIS is co channel interference, one of the most classic ones is the EMA ATIS which is blasted out by CDG (I think) such that you cannot realistically copy same until the Luton area when approaching from the south. Apparently the DOC of arrival ATIS is only around 60 nm. But the same happened at MAN some time ago and when crews started filing reports with CHIRP they eventually changed the ATIS freq!! The weather isn't the only issue, it's the runway in use which if you second guess the wrong way requires a change of set up and brief whilst descending in some of the busiest airspace in Europe - a recipe for an altitude bust maybe?
Of course in the "olden days" on first contact with LATCC as well as the inbound routing STAR etc one was passed the Runway in use at destination. Presumably this was dropped due to issues of RT congestion and controller workload etc.
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Lowest pressure this week?
Think Super VC-10 probably wanted the lowest QFF (okay, QNH will do) in the Thread episode, hellsbrink.
Or are you being deliberately facetious?
During my limited researches, the lowest reported by METARs was about 950 hPa (millibars) at Shannon on Mar10/0600z-0630z. See my post#194:
EINN 100800Z 31010KT 9999 FEW010 SCT018CB BKN025 04/04 Q0954 NOSIG
EINN 100730Z 36004KT 9999 FEW014 SCT018CB BKN030 04/03 Q0952 NOSIG
EINN 100700Z 10005KT 9999 FEW014 SCT018CB BKN038 04/03 Q0951 NOSIG
EINN 100630Z 12008KT 9999 -SHRA FEW014 SCT018CB BKN036 04/03 Q0950 WS RWY06 NOSIG
EINN 100600Z 14017KT 9999 -SHRA FEW014 SCT018CB BKN033 04/03 Q0950 WS RWY06 NOSIG
EINN 100530Z 12021KT 8000 -SHRA FEW014 BKN018CB BKN023 04/03 Q0950 NOSIG
EINN 100500Z 12018KT 8000 -SHRA FEW014 BKN018CB BKN034 04/02 Q0951 NOSIG
The above observations seem to show one of the eyes (do you agree. FCUK12 and PKPF68-77?) of the complex depression moving eastwards in transit just south of Shannon aerodrome. Note the steep rise of pressure afterwards, and the reversal of wind direction during the couple of hours' passage. For further info, including an explanation of wind speeds near deep depressions, see PKPF68-77's Post #163.
[Strictly speaking, of course, a QNH does not represent the precise notional sea-level pressure at a station ("QFF"). This is because a QNH is merely a device to ensure that an ICAN-calibrated altimeter, situated at the station, reads the correct elevation amsl if the QNH is set on its sub-scale. In a deep/cool depression, it is unlikely that the local pressure lapse-rate would conform to the ICAN (standard atmosphere).]
No need to worry, though (what do you mean; you weren't?).
In the case of Shannon, the station elevation is about 45 ft amsl, so the "error" is negligible.
Another point to bear in mind is that 950 could represent a pressure as high as 950×5, because decimal-5s of pressure are always rounded down, for safety reasons.
Hope this helps. Did anyone get a lower one?
Or are you being deliberately facetious?
During my limited researches, the lowest reported by METARs was about 950 hPa (millibars) at Shannon on Mar10/0600z-0630z. See my post#194:
EINN 100800Z 31010KT 9999 FEW010 SCT018CB BKN025 04/04 Q0954 NOSIG
EINN 100730Z 36004KT 9999 FEW014 SCT018CB BKN030 04/03 Q0952 NOSIG
EINN 100700Z 10005KT 9999 FEW014 SCT018CB BKN038 04/03 Q0951 NOSIG
EINN 100630Z 12008KT 9999 -SHRA FEW014 SCT018CB BKN036 04/03 Q0950 WS RWY06 NOSIG
EINN 100600Z 14017KT 9999 -SHRA FEW014 SCT018CB BKN033 04/03 Q0950 WS RWY06 NOSIG
EINN 100530Z 12021KT 8000 -SHRA FEW014 BKN018CB BKN023 04/03 Q0950 NOSIG
EINN 100500Z 12018KT 8000 -SHRA FEW014 BKN018CB BKN034 04/02 Q0951 NOSIG
The above observations seem to show one of the eyes (do you agree. FCUK12 and PKPF68-77?) of the complex depression moving eastwards in transit just south of Shannon aerodrome. Note the steep rise of pressure afterwards, and the reversal of wind direction during the couple of hours' passage. For further info, including an explanation of wind speeds near deep depressions, see PKPF68-77's Post #163.
[Strictly speaking, of course, a QNH does not represent the precise notional sea-level pressure at a station ("QFF"). This is because a QNH is merely a device to ensure that an ICAN-calibrated altimeter, situated at the station, reads the correct elevation amsl if the QNH is set on its sub-scale. In a deep/cool depression, it is unlikely that the local pressure lapse-rate would conform to the ICAN (standard atmosphere).]
No need to worry, though (what do you mean; you weren't?).
In the case of Shannon, the station elevation is about 45 ft amsl, so the "error" is negligible. Another point to bear in mind is that 950 could represent a pressure as high as 950×5, because decimal-5s of pressure are always rounded down, for safety reasons.
Hope this helps. Did anyone get a lower one?
Last edited by Chris Scott; 14th Mar 2008 at 13:03. Reason: Blast, if the server hadn't erased all my original work, I'd have got in before PKPF68-77... Typos.
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Or are you being deliberately facetious?
As far as the lowest that day, I've seen assorted figures ranging from 950 but nothing below that.
Forecasting in our youth
Quote from PKPF68-77:
Pretty awesome forecasting if you know what the skills were like over 30 years ago.
[Unquote]
How true. In his day, the mid and upper-air forecasting (on which all this hinges?) was fairly hit and miss. Was once crossing Holland en-route to to Germany in a Dakota (1968), and none of our planned drifts or ETAs were making much sense at FL070. The forecat W/V in the area was about 260/30. So we used the optical drift sight to confirm the actual drift (starb'd); and stopwatch for ground-speed (TAS was 140). On that basis, we estimated the actual wind was about 310/45.
As for the (westerly) sub-tropical jet, SNAKING over North Africa in winter, the direction in the 1970s was fequently 30 or 40 degrees out. This made an enormous difference to your drift and/or GS when it was blowing at 150 kts... And the strength was equally unreliable in those days.
This may have been contributory to the shooting down of a Libyan B727 by the Israelis in about 1978. The A/C was going from Tripoli to Cairo, and completely overshot its destination, finding itself over Israeli-occupied Sinai, where the Israelis assumed it was hostile.
By the 1990s, the computer-forecast en-route winds had become uncannily accurate...
Pretty awesome forecasting if you know what the skills were like over 30 years ago.
[Unquote]
How true. In his day, the mid and upper-air forecasting (on which all this hinges?) was fairly hit and miss. Was once crossing Holland en-route to to Germany in a Dakota (1968), and none of our planned drifts or ETAs were making much sense at FL070. The forecat W/V in the area was about 260/30. So we used the optical drift sight to confirm the actual drift (starb'd); and stopwatch for ground-speed (TAS was 140). On that basis, we estimated the actual wind was about 310/45.
As for the (westerly) sub-tropical jet, SNAKING over North Africa in winter, the direction in the 1970s was fequently 30 or 40 degrees out. This made an enormous difference to your drift and/or GS when it was blowing at 150 kts... And the strength was equally unreliable in those days.
This may have been contributory to the shooting down of a Libyan B727 by the Israelis in about 1978. The A/C was going from Tripoli to Cairo, and completely overshot its destination, finding itself over Israeli-occupied Sinai, where the Israelis assumed it was hostile.
By the 1990s, the computer-forecast en-route winds had become uncannily accurate...
Last edited by Chris Scott; 14th Mar 2008 at 12:58. Reason: For PKPF68-77 and others: YES! We must REMEMBER ALWAYS to create our posts in a word-processor...
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"Blast, if the server hadn't erased all my original work**, I'd have got in before PKPF68-77... "
[ ... ]
**I have lost one or two long posts that way.
[ ... ]
**I have lost one or two long posts that way.
