Saturday weather?

[neilgeddes]

Hi, I’m after advice please.

I’d like to fly into Leeds Bradford lunchtime on Saturday from the South East and return the same day. I’ll be using a capable light single with IFR kit. My concern is the impending warm front so I presume there’ll be significant cloud and some rain, mainly towards Leeds :uhoh: That’s ok provided there’s no risk of ice at around the 3000' I’d like to fly. Of course, Leeds may be snowed in on Friday!

I am IMCR current but I’m not one to plan a deliberate IFR flight expecting to finish with an ILS approach. I’d prefer some en-route IFR if necessary with a hopeful VFR arrival!

The Met Office and other sites, such as WeatherWeb, have given me lots of information but what’s your best guess for the Leeds weather Saturday? Can anyone predict a TAF for me?

Thanks, Neil

[peterh337]

I am not a forecaster but it is likely to be iffy.

The MSLP (http://www.metbrief.com/EGRR.html) suggests a warm front, which tends to be low coud and drizzle, and in these low temps not a lot of convective activity, so the job comes down to the cloudbase and icing conditions / surface temp providing (or not) an escape route from airframe icing.

NOAA (http://ready.arl.noaa.gov/READYcmet.php) for EGNM for the coming 192hrs (http://www.zen74158.zen.co.uk/temp-files-ph/egnm.pdf) suggests temp and DP right on top of each other, cloudbase on the deck, and just for added men v. sheep sorting the 0C level is around ground level also :) And I nearly forgot a bit of precipitation too.

I wouldn't do it unless seriously de-iced, because at practical VFR/IFR levels (a few thousand feet) you will be in freezing temps and also definitely in IMC, and it is a fairly long leg to be doing that enroute.

The south east coast looks OK however.

Anyway that's how it looks right now.

I am IMCR current but I’m not one to plan a deliberate IFR flight expecting to finish with an ILS approach. Why on earth not? If you are current to fly an ILS and you have the kit in the plane, then you should fly an ILS. Phone up the airport beforehand to tell them and off you go. You worked for that bit of paper so use it :)

I’d prefer some en-route IFR if necessary with a hopeful VFR arrival!It's more likely to be the other way round :)

If you need help with using that NOAA site then I can help. It is just one of countless windows into the GFS model, but it's quite a good one.

Can anyone predict a TAF for me?

How about OVC005 to OVC007 with -RA or -SN. At the SE end, looks like SCT020.

[sycamore]

And your diversions are...??

[neilgeddes]

peterh337: that's very good insight and advice, thanks. I was watching the METARS for N.I and Eire today as the front moved across there. 7000 -RA FEW010 SCT020 BKN045 was as bad as it got but Saturday's another day. Thanks also for the NOAA link.

sycamore: I was planning Doncaster Sheffield EGCN as my alternate.

Thanks again, Neil

[BackPacker]

It is just one of countless windows into the GFS model, but it's quite a good one.

Has anybody ever found a (reliable) way into GFS that allows you to retrieve Skew-T/tepigram forecasts?

I know where to get soundings allright, but I think I have once seen a skew-T forecast as well. Can't find it anymore though.

[peterh337]

The NOAA site does forecast soundings, as do other sites, and these are essentially the same as what you get on a skew-t or a tephigram, in terms of temp and DP variation with altitude.

Unfortunately forecast soundings are only forecasts :)

Just noticed the Wyoming (http://weather.uwyo.edu/upperair/sounding.html) site seems to be down, and the other site (http://www.meteo.uni-koeln.de/meteo.php?show=En_We_We) which used to put up the baloon data has been changed and not being a German speaker I cannot find the part of it with the baloon data.

[POBJOY]

Judging by the charts it will very cold on Sat therefore unless you have a machine capable of (flight into known icing conditions) an IMC situation may not be very wise or even considered.

[peterh337]

There is generally no issue (i.e. no significant ice is picked up) with a brief penetration ;) of a thin layer of stratus, e.g. 2000ft thick.

IME, anything which has holes in it so you can see the blue sky above, and given an absence of frontal weather, is not a problem.

But enroute you will pick up ice eventually; no argument there. I always have, though sometimes it took half an hour to see it. Sometimes it is rapid; I have seen 1" in 5 minutes, in a layer of NS.

This is the problem with using the IMCR in the winter. You cannot go into Class A, cannot go into most Class D for long periods, so you end up stuck in icing conditions. Whereas if you had an IR then you just file for FL100 or whatever and climb up straight through it.

The other problem with this kind of wx is that with surface temps around or below 0C you have no escape route if you pick up too much and let it get out of hand. You will have to land with whatever you have picked up - unless you manage to get VMC on top in which case you can let it sublimate away (but that takes ages).

[BackPacker]

if you pick up too much and let it get out of hand.

Just a friendly reminder that Peter is very experienced in these matters, flies his own plane and knows his own and his planes capabilities very intimately.

Mere mortals (;)) should probably get the **** out of icing conditions at the first hint (or forecast) of icing. Because you have no way of knowing when "it gets out of hand".

[peterh337]

You should see what some other pilots write in some other forums about flying in icing conditions. I would look like a shrinking violet :)

BTW, "forecast icing" is a bit of an old chestnut, not least because the UK Met Office forecasts moderate ice in all cloud irrespective of temperature :) :)

[Mariner9]

A pic of aircraft wing after picking up icing in the hold with freezing level on the ground last week...

http://i40.tinypic.com/2rpebnn.jpg

[neilgeddes]

icing in the hold


Eeek :eek:

I've only encountered icing once, at 6000' between two slim cloud layers whilst over the Channel enroute to Alderney last March. Descending to 3500' saw the OAT rise to 2 deg and the wings clear. It was a little embarrasing too (and stupid of me) as we'd just discussed icing and then my female passenger spotted the build up before me. :O

[peterh337]

It probably wasn't between layers that you got ice.

I've never heard of structural icing in VMC.

[ShyTorque]

Hoar frost is possible in VMC flight, just as on your car windows in the morning. Cold airframe, moist air. Not very dangerous from an aerodynamic point of view.

A more dangerous form of icing can occur during taxying and this has a special name.......

[peterh337]

I have never had frost in flight. I wonder why?

The airframe should equalise to the ambient (the local TAT) more or less instantly.

[ShyTorque]

I think how quickly the aircraft reacts to a specific change in OAT depends on the type.

Just think inversion layer. The aircraft can be colder than the OAT on entering it and colder on leaving.

Not a major problem that I could think of, unless you can't clear the windscreens and needed to do so in a hurry.

I've seen it a couple of times in Germany when based out there but we had heated screens on our Pumas so it wasn't a problem. I've also watched it form on the wings of commmercial airliners (cold-soaked fuel tanks).

[peterh337]

OK; I have seen the cold soaked fuel tank effect. Once, following a steep descent from about -15C to about +25C, into Trieste, after landing I saw ice build up on the tanks and then fall off :) Quite amusing.

But during flight the airframe should not be at a different temp for more than a few seconds. Especially the thin sheet metal types of GA hulls/wings.

Windscreens seem to be a different issue. I have had ice form on the inside of the windows when I was flying with some heavy-breathing people :) But this is very rare. Windows can mist up anyway...

Yes it does look better for Saturday. -6C ground temp in the morning :)

[Pace]

Neil

Why Leeds? Doncaster is a much better bet over low ground rather than stuck on the top of a hill with low cloud!
Leeds is always windy and turbulent when everywhere else is calm :E

There seems to have been a lot of ice around recently so tread carefully especially if the freezing level is not well above the MSA.

We like to think that a light piston is a reliable go places aircraft. Especially in winter be very cautious as you can give yourself an unexpected and serious fright or worse.

Pace

[ShyTorque]

Peter337,

If you don't wish to believe someone who has personally experienced it, perhaps some further reading might help?

So here's one article, for a start:

SKYbrary - Hoar Frost (http://www.skybrary.aero/index.php/Hoar_Frost)

Here's another, section 2.3:

http://www.atraircraft.com/media/downloads/coldweatheroperations_2011_20.pdf

Also here:

http://www.bom.gov.au/aviation/data/education/hwp-icing.pdf

[neilgeddes]

Why Leeds?


Pace: I'm hoping to collect my eldest daughter who's up there. (She can always get the train down though.) I don't know the airport but have heard of the wind / runway direction issue and also noted the airfield elevation. Does the airport suffer from being in the shadow of the Pennines? Now I'm showing my ignorance!... :)

P.S. Yes, I'm booked in with Multiflight for handling.

[peterh337]

If you don't wish to believe someone who has personally experienced it

No idea where you got that impression, ShyTorque.

I just said I never got it. I've done ~1400hrs and never seen it. Maybe I fly too slowly?

BTW the last PDF creashes my PDF reader.

[Artistic Intention]

Was that you I heard talking to Coventry this morning? I was practising some approaches for my upcoming IR renewal and heard somebody working Coventry and asking for the Leeds weather.

[neilgeddes]

Was that you I heard talking to Coventry this morning?


Indeed it was! Smashing flight there and back today. 0 deg C at 3000' and no signs of ice. SVFR into and out of Leeds where it was the murkiest (4K vis and coldest).

I was pleased with Multiflight who, though not busy, took interest in me and made a good effort. The scariest part of the whole day was when I noticed the bowser man about to refuel the DA40 with Jet-A1 not Avgas! :=

Thanks everyone for your comments and help! Rgds, Neil

Photos https://skydrive.live.com/?cid=497e16fc7be1a2a3&id=497E16FC7BE1A2A3%21458&sff=1#cid=497E16FC7BE1A2A3