The road back from Cherbourg should be a belter

[LadyInBed]

Re: its also for Monday and at altitude

The chart says - Mean sea level pressure, wind speed at 850 hPa and geopotential 500 hPa
What altitude are you looking at?

PS Monday chart is now looking better but Tuesday is siht!

 

[tome]

Re: its also for Monday and at altitude

You trust a forecast almost a week ahead?

 

[DJE]

Re: its also for Monday and at altitude

The blurb that comes with these says:

On this page you can visualise the meteorological forecast of pressure reduced at sea level (Mean Sea Level Pressure, black contours labelled in hPa), wind speed at low levels (850-hPa isobaric surface - nearly 1500m - yellow/green shading labelled in m/s) and height of the 500-hPa isobaric surface (blue contours labelled in dam).

1500m = approx. 5000 ft.

 

[zefender]

It's from the remedial guide to wevver it rains or shines. Anyway, Tome's yer man for this stuff. He, sensibly is probably waiting or tomorrow's forecast. He even managed to steer Ian right into the path of a F8 in Biscay (for a bit of offshore testing) when all I managed was wallowing about in a F3, wondering whether to put another fishing line out!

 

[LadyInBed]

Re: Trust

Tis a bit like tides - a prediction /forums/images/graemlins/wink.gif

 

[tome]

You don't worry too much about skirting a gale in an HR42, especially from the comfort of an armchair ashore!

 

[Peppermint]

Re: Top up on Diesel

Or you'll all be late for work.

 

[BlueSkyNick]

Re: its also for Monday and at altitude

thanks Dave, I knew there was something about altitude in there, but didn't have time to investigate it!

it is still a good image, nonetheless.

Just hoping the strong wind stays north of Bristol until at least Sunday night.

 

[StugeronSteve]

Re: its also for Monday and at altitude

Windguru and metcheck are showing f3-4 poss north, or west, or a bit of s. west, for Friday night. <f3 for Sunday and Monday. "Theyr" haven't updated since yesterday, but they were giving f3 west for friday.

 

[snowleopard]

Re: its also for Monday and at altitude

XCWeather is now showing westerlies till Friday, then turning Easterly /forums/images/graemlins/grin.gif

However, since we're not going this year.....

Ye're a' doomed....DOOOOOOOOOMED!

 

[peterb]

Re: its also for Monday and at altitude

[ QUOTE ]
The blurb that comes with these says:

On this page you can visualise the meteorological forecast of pressure reduced at sea level (Mean Sea Level Pressure, black contours labelled in hPa), wind speed at low levels (850-hPa isobaric surface - nearly 1500m - yellow/green shading labelled in m/s) and height of the 500-hPa isobaric surface (blue contours labelled in dam).

1500m = approx. 5000 ft.

[/ QUOTE ]

The Met Office book "Meteorology for Mariners" says:-

"Over the sea, it is found that the surface wind speed is usually about two-thirds that of the geostrophic wind [i.e. the wind shown on the ECMWF chart]"

The speed in m/s needs to be doubled to get the speed in knots. So the bottom limit of the yellow (15 m/s) gives a speed at altitude of 30 knots, which gives a sea level speed of 20 knots, almost the top of F5 (21 knots). The bottom limit of the green (20 m/s) translates to 26 knots at sea level, almost the top of F6 (27 knots). The line between the light and dark greens (25 m/s) translates to the top of F7.

Beyond that I prefer to think that it's to far in the future to be reliable, and with any luck it might calm down a bit. If it doesn't, there's always some maintenance that needs doing, and anyway the local pub could do with a bit more custom! /forums/images/graemlins/shocked.gif

 

[ChrisE]

Re: its also for Monday and at altitude

Peter,
Thanks for the post, I'd forgotten this and had long thought the ECMWF chart was overegging the winds, now I can recalibrate the forecast.
Chris