"Graham" wrote in message
...
Yesterday (19th) we had 21.9 mm from 09.00 to 21.00 after patchy light
rain mostly in the East Midlands was forecast.
Today Penny Tranter was the culprit. While doing the Midlands forecast
she said some light patchy rain here and there becoming drier from the
west.
We've had another 17.5mm today (20th) up to 18.00 and it's still
raining!!

Graham, the mechanism which delivered your persistent rain is an
interesting one ... but it is one I would have expected the mesoscale
model to have picked out, which should have prompted the
presenter to mention it in your regional forecast.

The heaviest rain appears to have been localised over the rising
ground which might be called a southwestern extension of the
Peak District around Leek and Stoke with 40mm+ in 48 hours.
By contrast Shawbury had only 7mm in the same period, the
two south Manchester stations at Ringway and Woodford about
25mm, and Buxton also about 25mm. Sadly the Chester
station (at Hawarden) has a rain-gauge problem just now, so
its record is missing -- it would have been useful.

Without being able to do a detailed analysis to confirm it,
I reckon something of a convergence line developed in
the WNW to NW-ly airflow separating air which had crossed
North Wales blowing from the WNW (the wind is always
more 'backed' over the land) from air coming in directly
from the Irish Sea via Liverpool Bay and blowing from the
NW. The convergence line, I guess, would have extended
from near Chester to the Stoke area, and perhaps onward
to Burton-on-Trent, resulting in a narrow zone of enhanced
rainfall which would have been enhanced further around
Stoke and Leek by an orographic contribution.

These convergence lines show up well in unstable and
potentially unstable northwesterlies (this is where we get
the "showers coming through the Cheshire gap" type of
forecast ... at best simplistic, at worst erroneous) ... it is
not so common to find a northwesterly delivering relatively
warm and moist tropical maritime air (returning mT,
I suppose you could call it) as we have had this week.

How far back do your records go? You might be able
to find one or two other examples of a moist NW-ly or
WNW-ly to prove the point.

Philip Eden