The good day - how to see it coming

Wednesday 8 August 2007 provided a fine example of a very good day that was anticipated well in advance; predictions had been made with confidence.
Links are all available from the main weather page


synoptic
sounding forecast
Chart from Hirlam

Sounding archive forecast noon from NOAA


The synoptic chart shows high pressure nearby with the isobars curving round the high - anticylonic curvature.   The winds are very gentle from a northerly point and that is usually the best, although often there is cloud close to the North Sea in northerlies (and maybe also N.Wales).

The sounding forecast (in fact, this is an archive forecast) needs a preliminary check of blue or not blue.  (see soundings tutorial)
The brown moisture content line traced upwards from surface dewpoint comfortably intercepts the red line, so the day won't be blue.

Now by use of the sounding, look at the possible cloud development
Surface maximum temperature will be a little further to the right (of red line) so Tdry / Tdew split could be as much as 14C
That translates to cloud base in excess of 5,500 feet.  See the Bradbury and soundings tutorials

The air around cloud base has low humidity as shown by good split between the green and the blue lines so little liklihood of spreadout or fill-in 

The flying winds are confirmed as being the from north (usually a good direction) at 10 knots or less.

A very important consideration was that the forecast charts and indeed all the data for 8 August had been consistent over  several days.  That gave great confidence.   When each new chart issue for a particular date is different from the previous one, low confidence is indicated.

The day did not disappoint with numerous flights in excess of 500 kms.  

Satpic below courtesy of MODIS Rapid Response Project at NASA/GSFC

satpic-2007-08-08