31 OCT 2010 1155 EDT/ 1555 Z
Just like the overall pattern across the northeast US has become rather stormy with intervals of rather tranquil weather in between during OCT 2010… we are seeing a similar sort of pattern over western and central Europe.
We actually end up seeing this sort of thing fairly often. Just like on the West coast where the weather is often the exact opposite is on the east coast… we see the same sort of thing between the East coast of the CONUS and Western / central Europe. There is a specific reason for that – it is not just weather coincidence.
The West coast is 3000- 3300 miles away and that just happens to be most common distance between the wavelenghts of Ridges and troughs at that latitude in the world. This is also the case betwen the East coast and western half of Europe.
Over the past few weeks there have been a number of significant troughs ….some of them quite deep in terms of amplitude over Western Europe which has provided for significant rains. But these longwave troughs have been so deep that the southern end or southern base of the trough have separated from the main flow. This results in a closed 500 MB Low that is ” cutoff” from the main flow. Over the past few weeks this has been happening alot Spain & western Mediterranean. This 500 MB low then meanders across western and central Mediterranean into the southern Balkans and Turkey.
This means that the Ukraine and southwest Russia which is still trying to recover from a deadly heat and drought of the past summer has not been seeing good rains. Indeed that IS the case with this current system. The Sunday weather maps hvae a deep 500 short wave trough with a fairly strong area of low pressure southwest of Cornwall England that is approaching the Bay of Biscay inland at 981 MB. This system over the next two or three days ….will drop through France and and into the central Mediterranean while the northern end the jet stream is carrying in the next strong system well north of Scotland and headed towards Norway.
The Low that moves into the Mediterranean Monday & Tuesday is much weaker than the Low coming into Norway so has a result the Northern Jet stream leaves the southern Low behind . If the Southern System were to continue to move east it could provide some rain into the southern portions of the Ukraine and into sw Russia but the model data clearly shows that does not happen. The weak Mediterranean low meanders over the eastern Mediterranean and then finally falls apart.
Far more important however it is the the depiction of a monster storm for inland and Western Europe NOV 7-8. The 0z Euro has this Low at 953 mb over far southwest England on the evening of the 11/8.
Why does the European model developed this system into a monster North Atlantic storm that reaches category 3 hurricane intensity ?
The KEY appears to be a the development of the coastal storm over the East coast of the CONUS and the monster trough in the Jet stream NOV 5-6-7 and hurricane Tomas. The deep East coast trough causes a strong ridge to form in the western and Central Atlantic Ocean but that ridge is fed or enhanced by the heat from hurricane Tomas as it moves into the western portions of the north Atlantic after day 6-7. This Super powerful ridge in the north Atlantic builds towards the southern tip of Greenland which forces the next piece of energy in the polar jet to drop rapidly the southeast towards Ireland and England as it undergoes rapid intensification.
This results in the European model developing this super Bomb Low for western European UK Low.