Geopotential height, Temperature and Wind at 500 hPa
18 September 2007, 00 UTC
A deep upper-level trough, presented by the isolines of 500hPa height in black, is located over the west coasts of Europe. There is
a low
forming west of Portugal over the Atlantic. From the western
Mediterranean towards the central Europe there is strong southwesterly
stream in the upper levels. Notice the wind barbs over northern Italy -
the wind speed at 500 hPa is above 50 knots.
Cold air is penetrating
from the north within the trough, as seen from the temperature field presented by blue and violet lines.
18 September 2007, 06 UTC
A low over the Atlantic has cut off.
The cold air penetrates even more to the south. Wind over Slovenia
increases.
18 September 2007, 12 UTC
The low southwest of the Iberian
penninsula deepens. The cold air is reaching central Europe. Strong
southwesterly wind can be noticed in the region where pre-frontal
convection occurs and also on the rear side of the front.
18 September 2007, 18 UTC
A pool of very cold air is reaching
the northern and central parts of the Alps behind the front. Convective
activity ahead of
the front moves now to the east.
19 September 2007, 00 UTC
Slightly warmer air is coming from the west
as the system moves to eastern Europe.
