tomjnx wrote:
you seem to be the first to cancel a trip days before because of some uncertainty in the forecast. Why?
Well, I got a bit more information than just one model first of all. And no, I don’t cancel that early unless it is perfectly clear (which happens). Usually I would cancel maybe 3 to 4 days ahead unless I need to take a decision wether to buy airline tickets for “must be there” trips. Must and GA don’t play, particularly if it’s VFR and if you have to buy tickets the last day, things get very expensive.
My primary problem, not only weather wise, is a totally unflexible workschedule. I can not ever afford to be stuck somewhere or be late. That in itself is the main reason why I did scale down my flying to more realistic stuff. And subsequently, I did most of what I planned this year. The only thing which I cancelled again was an idea of a flight to BG, which in retrospect was correct to cancel (would not have been flyable on the return days available).
One thing that also needs to be made clear: When I say the models give a false sense of accuracy, I am also talking of people who check weatherpro and think they can predict Tuesday 3 pm in 2 weeks as opposed to 4 pm or 5 pm. You have no idea how many phonecalls I get from people who do take these things as set in stone “because the app sais so”.
I’d say you can get a good trend with those models about a week ahead and an indication of what might be up to 2 weeks. Indication such as yes, it looks pretty stable high pressure, or it looks as if there are fronts moving through in 2 day rythms or no, there is a chance of a cut off so forget any planning at all. If I see a stable high pressure system in Winter for instance, I know that VFR is very unlikely at LSZH due to fog/low stratus, whereas frontal passages are much more optimistic for given situations. As I said, knowing what to read out of models requires a lot of experience which most people can’t have.
(Edited to say, sorry, I think Daniel beat me to it).
Airborne_Again wrote:
ESSA 260750Z 28007KT 9999 BKN013 10/09 Q1016 NOSIG
TAF ESSA 260530Z 2606/2706 25009KT 9999 BKN006 PROB40 2606/2608 BKN010 BECMG 2608/2610 BKN015 TEMPO 2614/2617 SHRA BKN040CBSo we have both low cloud right now and expected convective cloud with rain later today. The clouds are not thin either – the Swedish GA forecast until 13 UTC gives the cloud tops at 3000 ft or higher.
I’m surprised the GFS model is so completely off for a short-time forecast. I saw something similar a few days ago.
The GFS model doesn’t aim for predictions of low cloud. I don’t know exactly what Autorouter GRAMET’s depiction of boundary layer cloud is based on. But in the case of the convective cloud, it does appear that the GFS won, doesn’t it? ;) And after 1200Z, that BKN015 was a long way off.
SA 26/09/2015 19:20→
METAR ESSA 261920Z VRB02KT CAVOK 07/06 Q1021 NOSIG=
SA 26/09/2015 18:50→
METAR ESSA 261850Z 33003KT CAVOK 07/06 Q1021 NOSIG=
SA 26/09/2015 18:20→
METAR ESSA 261820Z 31003KT CAVOK 10/07 Q1021 NOSIG=
SA 26/09/2015 17:50→
METAR ESSA 261750Z 35003KT 9999 FEW037 10/08 Q1020 NOSIG=
SA 26/09/2015 17:20→
METAR ESSA 261720Z 33004KT CAVOK 10/09 Q1020 NOSIG=
SA 26/09/2015 16:50→
METAR ESSA 261650Z 30004KT 9999 FEW036 12/08 Q1020 NOSIG=
SA 26/09/2015 16:20→
METAR ESSA 261620Z 28004KT 9999 FEW036 13/08 Q1019 NOSIG=
SA 26/09/2015 15:50→
METAR ESSA 261550Z 27007KT 9999 FEW035 13/08 Q1019 NOSIG=
SA 26/09/2015 15:20→
METAR ESSA 261520Z 27007KT 9999 FEW027 14/08 Q1019 NOSIG=
SA 26/09/2015 14:50→
METAR ESSA 261450Z 27008KT 9999 FEW027 14/08 Q1018 NOSIG=
SA 26/09/2015 14:20→
METAR ESSA 261420Z 28007KT 9999 FEW027 14/08 Q1018 NOSIG=
SA 26/09/2015 13:50→
METAR ESSA 261350Z 26007KT 9999 NSC 14/08 Q1018 NOSIG=
SA 26/09/2015 13:20→
METAR ESSA 261320Z 27008KT 9999 FEW022 12/07 Q1018 NOSIG=
SA 26/09/2015 12:50→
METAR ESSA 261250Z 30008KT 9999 SCT018 12/08 Q1018 NOSIG=
SA 26/09/2015 12:20→
METAR ESSA 261220Z 26008KT 220V290 9999 SCT018 12/08 Q1018
NOSIG=
SA 26/09/2015 11:50→
METAR ESSA 261150Z 25009KT 9999 BKN018 11/08 Q1017 NOSIG=
SA 26/09/2015 11:20→
METAR ESSA 261120Z 27008KT 9999 BKN016 11/07 Q1017 NOSIG=
SA 26/09/2015 10:50→
METAR ESSA 261050Z 28008KT 9999 BKN018 11/07 Q1017 NOSIG=
SA 26/09/2015 10:20→
METAR ESSA 261020Z 29009KT 9999 BKN017 11/08 Q1017 NOSIG=
SA 26/09/2015 09:50→
METAR ESSA 260950Z 26009KT 9999 FEW014 BKN018 11/07 Q1017
NOSIG=
SA 26/09/2015 09:20→
METAR ESSA 260920Z 28009KT 9999 BKN016 11/08 Q1017 NOSIG=
SA 26/09/2015 08:50→
METAR ESSA 260850Z 28008KT 9999 SCT012 BKN015 10/08 Q1017
NOSIG=
SA 26/09/2015 08:20→
METAR ESSA 260820Z 29007KT 9999 BKN013 BKN018 10/08 Q1016
NOSIG=
SA 26/09/2015 07:50→
METAR ESSA 260750Z 28007KT 9999 BKN013 10/09 Q1016 NOSIG=
SA 26/09/2015 07:20→
METAR ESSA 260720Z 25006KT 9999 BKN012 BKN016 10/09 Q1016
NOSIG=
SA 26/09/2015 06:50→
METAR ESSA 260650Z 24009KT 9999 BKN008 10/09 Q1016 NOSIG=
SA 26/09/2015 06:20→
METAR ESSA 260620Z 25009KT 9999 BKN006 10/09 Q1016 NOSIG=
.
The GRAMET boundary layer top is directly out of GFS, while the bottom is calculated from the spread at ground level.
So does that mean that in the original GRAMET no boundary layer cloud at all was forecast?
