Lettucing Gutted

8C February 2009 CET

So could this "global temperature inversion" be a very cold polar troposphere and very warm polar stratosphere combination extending well into the mid latitudes?

My favourite weather event of 2008 is the closing cold spell of October 2008. B)

Hi Roger B) I foresee a very warm second half of January to rival May giving a final CET of 8C.

Business as usual for 2009 11C

It would be very nice to hear Tamara's thoughts on this remarkable sustained cold spell.

8.5C

Do hurricanes "throw up" upper level ridges due to latent heat release in the upper troposphere?

I think there is more than cloud cover at work there with regards to the high minimas this August. I think those warm SST anomalies in the North Atlantic that never seem to go away have been putting a lot heat back into what could have been an unseasonaly cold maritime polar airmass. So a potentially unseasonaly cold August has been turned into an average one. Augusts like 1912, 1956 and 1986 managed far cooler CETs despite having a lot of cloud and similar westerly synoptics to this month.

The minima are surprisingly high considering were in cold sectors in the westerly airstream. They must be well modified by the nearby warm SST anomalies.

Indeed that is a feature that other winter months like January 1978 and January 1984 use to have known as Cool Zonality.

Another advantage of the early figures is that we can see clearly which factor is driving the August CET upwards. Currently it is the minima since they are well above the 1961-1990 average whilst the maxima are bang on average.

It looks like July 2008 is yet another that promised to finish below the 1961-1990 and yet it has failed to thanks to another insane warm spell.

20C. The warmest August on record.

It looks like this could be the first "8" July to record a CET above the 1961-1990 average for July.

And a bit more east as well. The problem with cold Atlantic troughs is that they build downstream Euro/Bartlett ridges over the continent which actually draws up warm air or shallow inversion cold at best. A better position for the displaced upper cold low would be over us like so on 13/01/87:- http://www.wetterzentrale.de/archive/ra/19...00119870113.gif

I think the indirect effect is that the northerly tracking lows build compensating deep warm highs over Europe which enhances warm air advection into the UK (an enhanced Ferrel Cell).

Continental winds in summer usually mean heatwaves but here is an example of a freak event... Here is a cold continental flow on 3rd August 1912. http://www.wetterzentrale.de/archive/slp/1...slp19120803.gif This brought one of the coldest CET daily means on record for August. The 3rd August 1912 recorded a daily CET mean of only 10.5C. http://hadobs.metoffice.com/hadcet/cetdl1772on.dat This was due to a very cool daily CET maximum of 15.7C on the 3rd August 1912 http://hadobs.metoffice.com/hadcet/cetmaxd...8on_urbadj4.dat offset by a very cool daily CET minimum of 5.2C on the 3rd August 1912 http://hadobs.metoffice.com/hadcet/cetmind...8on_urbadj4.dat It was very apt indeed that August 1912 was the coldest on record in the CET zone with a CET of only 12.9C.

Once again this will be yet another June without any particular cool monthly minima. Infact a lot of Junes since 2000 have been warm due to warm nights.

With Arctic Sea Ice once again approaching record lows expect temperatures to go through the roof... 20C

I think it is unlikely this June will be below average. For that we need a slow northern jet to allow cool troughs to buckle over us combined with a negative AO and a negative NAO to unleash the cool air from the north.

That must be pretty rare. Thundersnow on Spanish mountains in June!

Oh not another moderate El Nino...

Could your cold but sunny May be down to frequent low level highs combined with upper level cool troughs to allow maximum radiative cooling?

I am surprised that a "tropical" storm of all things would have brought those low temperatures. Usually they bring very warm temperatures. Tropical storms are usually deep tropospheric warm cores of maritime tropical air.