DWD-COSMO-EU: Geopotential in 300 hPa and Cape (KKN), Time Sequence: 3h, 29 February to 01 March 2008

With this chapter we will consider the potential instability in relation to the vertical motion in 500 hPa. We will use the CAPE. First hints to thunderstorms are CAPE> 300 to 400 (for Middle Europe and summer, no numbers available for other seasons). If we find an area of potential instability superimposed by upward motion convection is likely.

Because the vertical motion fields from the local model are rather difficult to interpretate the fields from the global model is used because they are smoother.

Upward motion (Omega<0) are indicated in yellow to red areas (red means stronger upward motion). Light to dark blue areas means downward motion. Unfortunatley, no suitable legend is available.

That means values of at least 300 in combination of red areas are indications to thunderstorms or strong convection.

The relevant area is west of UK (upper left corner) with CAPE up to 261 and upward motion. We will only concentrate upon this structure. The others will not be discussed.

In this chapter some relations to the significant weather will be considered. Please click upon the link below.

The area of upward motion and potential instability moved to the East. The area of relatively high CAPE moved to Southeast.

The relevant area (CAPE > 500 and lifting) continued moving to Southeast.

The area of relatively high potential instability arrived North Scotland. The model shows upward motion in this region, too.

The area of higher potential instability and lifting covered some parts of the UK and the area west of Scotland. Further to the East (North Sea) we see also upward motion, however, almost no potential instability yielding stratiform rain (according to the corresponding observations)

Outside of our scope: The lee effects of the Scotish mountains leading to a small area of downward motion are very well to be seen.

The field with lifting with stratiform rain moved to the East. The area of potential instability lifting covered entire Ireland and Scotland.

Over the North Sea some indications to convection/thunderstorms (CAPE almost 500 together with lifting) can be found. Some showers and heavy showers were reported.

The critical area moved to the Southeast and arrived over the Central North Sea.

Strongest upward motion can be seen over the southern parts of the North Sea and from Norway to North France. The model analysis exhibits potential instability only at the Danish coast. However, 12h-forecast reveals it also over the southern North Sea. The upward motion might be related to the convective line and the cold front.

Upward motion covered big parts of Germany (according to the observations of rain). This image shows from Netherlands to North Germany an area of potential instability (according to a thunderstorm's report at the Dutch coast).

The models exhibit the stratiform rain (South Germany) and the convective line with many thunderstorms very well (CAPE up to 526 and strong lifting).

The long chain of thunderstorms over Germany is well represented by the model. Further to Southeast stratiform rain (higher levels snow) was reported that fits also well with the model fields.

The convective line (lifting and CAPE up to 282) arrived at the Alps. Very interesting is the Foehn effect (also visible in lower levels, not shown): Intense downward motion and again lifting southeast of it.

The area of lifting became smaller over South Germany. Further to the east-northeast we observe still higher potential instability. Higher CAPE with strong lifting were simulated over Hungary and Romania (in accordance to the weather reports (thunderstorms)).

Whereas over Germany the weather conditions became more quiet the convective line remained still active over Southeast Europe.

No significant changes occured.