The April issue of 'Weather' has a fascinating article by W.S. Pike
detailing the history of Biggin Hill meteorological office(s) since
1917.
( For those that don't subscribe, I believe you can get 'one-off' issues
from the RMetSoc: see ..

http://www.rmets.org/membership/subscriptions.php )

As part of this article, there is a facsimile extract from the
Observations Register for August 1940, specifically for the 30th.

This is interesting in several ways:-

1. The code form, and the manner of entry of weather types (using
Beaufort letters) will be familiar to many who have worked in
operational meteorology, and it is interesting to see how things have
changed, and how some things have not. The code form itself was in use
from well before the Second World War (being listed in my copy of the
Admiralty Weather Manual of 1938), and I believe was not superseded
until the 'Washington' code was introduced in the late 1940's. One of
the differences from format we are now familiar with is the manner of
coding wind direction - compass points are used, applying the 32-point
scheme; so north = 32, south = 16, east = 08 etc. Also, the lower 'ww'
figures are significantly different: 08 = mist (now 10), whereas for the
higher numbers (50's upwards) although there are differences, they are
not so great.

2. The economy of space is marked. A single page contains all the
observations for one day, plus extremes, time-marks, additional
information etc. When manuscript entering of observations ended in the
Met Office, the DR for one day covered two over-large pages and took up
a huge expanse of the observer's table: (accidents with tea cups
increased when the code form changed to that now in use!)

3. The day itself was fine; a cold start (grass min 30°F) with a hoar
frost recorded in the Beaufort letters between 04 and 07GMT; this would
not be unusual for this location at the end of August, being some 600ft
asl. Some shallow Cumulus forming between 08 and 15GMT with Cirrus
above. The total cloud amounts never more than 3/10's with good
visibility (after the morning mist). The synoptic situation could be
inferred even without reference to a chart. A gentle northerly wind,
sometimes calm, with a NEPH report made at 06GMT showing a Cirrus motion
from 330deg, with speed 55mph (circa 48 knots, though such accuracy of
conversion wouldn't be justified with the technique). A ridge (surface
and upper) lay to the west of the station, but with a weakening gradient
flow after quite a strong northerly of the previous day (which
presumably brought the chilly, low humidity air across the SE). You can
see the situation by looking at the Re-analysis charts on the
Wetterzentrale site:-
http://www.wetterzentrale.de/topkarten/fsslpeur.html

4. By far the most poignant aspect of this diagram (and the reason why
it is in the article) is that on this day, Biggin Hill was attacked
(twice), along with many other Fighter Command airfields in the
southeast of England .. see:-

http://www.raf.mod.uk/bob1940/august30.html

There were four observers on this airfield, three of them having entries
in the Daily Register for the 30th August, 1940. (They were presumably
working an EMN variant). The last hourly observation on this
near-perfect day was at 1700GMT; the space for the remaining
observations was headed up ready for entry, but the rest of the page is
blank. As Pike notes in the article, all three observers were killed
whilst taking shelter.

The only allusion to this event is the bald statement by the fourth
observer: - " Observations abandoned at 1700. Instruments rendered
useless as a result of enemy action ".


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