Lettucing Gutted
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Posts posted by Lettucing Gutted
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19C for June
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It looks like the only chance of finishing below average is if Philip Eden uses his trademark downward revisions again.
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Re the Atlantic being too active in January for cold weather - an active Atlantic gave us cold and snow in January 1984.
http://www.wetterzentrale.de/archive/ra/19...00119840115.gif
http://www.wetterzentrale.de/archive/ra/19...00119840116.gif
http://www.wetterzentrale.de/archive/ra/19...00119840124.gif
http://www.wetterzentrale.de/archive/ra/19...00119840126.gif
This is the main aspect of the British Weather that is just the pits now at least in may book. I spend winter after winter especially during January whenever a zonal pattern sets in looking for a cold zonal pattern similar to January 1984 that is just totally elusive and never happens. It is just so depressing that we just get mild zonality now and that we never see the likes of January 1984 - it is only the wrong orientation of the zonal flow that keeps us mild.
Another great thing about January 1984 and of course other very snowy months is the very cold adiabatically cooled air at 500HPA over the UK on those charts. This cold 500HPA air is useful in destabilizing the low level cool Maritime Polar airmass allowing for very heavy snow events. This feature of mid level 500HPA cold has been lacking in many of our recent cold spells.
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What are the chances of the CET finishing below 8C?
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What is noticeable there is the trough into the US. and downstream ridge towards Greenland. I take these to be typical la nina signals.
What I am not sure about is the placement of the low over northern Russia. Its been quite cold up there this winter and you might expect high pressure to linger on. What do you think?
It is not unusual for cold locations such as Russia to be overlaid by an upper level low. In addition to adiabatic cooling associated with deep occluding lows the 500HPA surface can also be lowered by a deep cold airmass associated with either cold air advection or radiative cooling associated with a cool high. A similar thing happens over Greenland and Antarctica when the Polar Vortex is strong.
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The main worry must be that another warm Northern hemisphere summer will cause the final breakdown of the remaining multiyear pack.
Ho Hum.....
Unfortunately I doubt many people except scientists and me would be worried since most people would be enjoying another "wonderful" warm summer.
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The highest final April CET achieved with a CET <= 6.8C by the 16th was 8.8C back in 1862.
I think will will probably end up somewhere between 7.5 and 8.0C though.
A final CET like 8C to 8.8C won't do the recent cold weather justice.
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The countryfile forcast says a cloudy anticyclonic returning maritime tropical airmass will set in by Thursday giving mild temperatures by both day and night over the UK (as high as mid double figures). This will certainly dampen chances of a below average April if it lasts too long.
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11.5C for April 2008
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The Atlantic is on the warm side of average particularly the part that affects us and has been for sometime but that is just again a cycle/natural and will change at some stage. A brief response at this time as a bit busy at present with work.
BFTP
The recent toasty than average northeast Atlantic has also tipped the odds from cool zonality in favor of mild zonality. Aside from a volcanic eruption I think the only other way we would see cool zonal winter months comparable with January 1984 would for a mini NAD (North Atlantic Deep Water) shutdown.
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I think it depends on the synoptics that La Nina predisposes us to. In La Ninas that brings warm tropical synoptics in summer (eg summers of '75 and '89) thunderstorms are common in Spanish plume and tropical air moving over warm ground scenarios.
However in La Ninas that brings cool polar synoptics in summer (eg summers of '85 and '88) thunderstorms are common in unstable maritime polar air moving from Greenland and the North Pole over the warm North Atlantic Ocean as well as cool maritime polar air moving over warm land. In cool summers thunderstorms also occur along frontal boundaries between polar and tropical air.
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Those were the days when the daffodils bloomed in March instead of January.
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As fr strong La Nina, I can't say I really know why they nearly always lead to mild winters but the fact that every winter since 1950 including this one tat has been a strong la nina have had a +ve NAO probably suggests the jet stream positioning has a large role to play.
I think strong La Ninas cause the jetstream to go north because La Ninas causes strong upper level warming other the mid latitudes which is caused by adiabatic warming from upper level ridges which are in turn induced by the cooling in the equatorial Northeast and Southeast Pacific Ocean.
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Thanks to the now ever toasty North Atlantic the warmest March C.E.T on record 10C.
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Low sunspot activity = inactive solar magnetic field = higher incidence of cosmic rays on earth -> increase in clouds -> decrease in heat received at the earth's surface.
A complex mechanism that I am not personally fully convinced by just yet - but I believe it warrants further investigation.
Wysi
Yeah complex is a great way of describing the process, especially the part about clouds. We must remember that whilst clouds cool daytime temperatures they have a strong warming effect on nighttime temperatures.
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Does the arrangement of the cool and warm anomalies obey the La Nina signature or has other factors such as Global Warm distort the usual La Nina signature?
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Despite all that it was a pretty average month overall
Min 1.3c
Max 7.4c
Mean 4.4c.
Yeah. It was a quirk that the greatest blizzard of the decade should occur in a mild winter month.About 0.6C above the 1961-1990 CET average for February.
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I wonder how much blame can be put on ozone depletion and stratospheric cooling for our recent hot summers and mild winters etc?
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The scary thing we're supposed to be in cool zonality and we still clocking up well above temps so far. I presume the warm Atlantic isn't helping much here though.
Below is a list of months that reinforces the above quote about how useless westerlies are becoming for achieving cool monthly C.E.Ts:-
Eventhough all of the months below had shortlived cold northerly and warm southerly spells, the vast majority of these months were dominated by westerlies that had a source near Greenland. Yet these months all recorded C.E.Ts above the 1961-1990 C.E.T averages. And all of the months below except for August 1999 and August 2006 even achieved C.E.T means above the 1971-2000 C.E.T averages.
January 1999
February 1999
March 1999
August 1999
December 1999
September 2000
April 2004
April 2006
May 2006
August 2006
May 2007
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I can never recall that in January before in Kent. We are warming folks.
Yeah. To parody "Iceagenow": "The world will end not by ice but by fire"
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In just the same way that one might say 'we haven't had enough evidence to be statistically absolutely certain of excessive warming because not enough years have elapsed' we can also say 'we cannot be sure the trend is reversing because not enough years have elapsed'
Clearly, more warming years have elapsed than cooling ones.
I think human factors (CO2) and natural cooling factors (Sunspots and ENSO) will do battle over the next few years but the cooling factors will ultimately fail to reverse the warming trend.
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What is noticeable in that chart is how the GFS underestimates the temperatures in very mild tropical maritime setups like the last few days. I have a sneaky suspicion that after Thursday's brief cold interlude, we could be seeing temperatures far above what the GFS is currently showing.
Take the T+168 chart for example, its out of the reliable time frame, but looks like a perfect example of how the GFS underestimates.
A mainly south-westerly flow and upper air temperatures approaching 10C. The GFS also goes for cloudless skies:
However, at the surface are temperatures of 9-10C:
In such a setup you'd expect temperatures many degrees above that. The high is not in a suitable position for inversions or fog. I just cant see how a temperature of 10C at the surface in almost 10C upper air could occur when even weak sunshine is in the equation.
It is even feasible that a maximum temperature of 20C could be achieved in London.
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I looked at past weather conditions for New York and compared it what was happening in the UK and there were some similarities
1903
New York: Very mild March, but coolest summer (June-August) on record (1869-Present). 11.63 inches’ rain over 8-9 October.
UK: March mild, very cool summer, wettest October on record
1907
New York: Unseasonably cool mid-May to mid-June.
UK: Also cool in the UK
1916
Warmest January CET wise and also some notably mild weather in New York, March was cold in New York as it was back in the UK. June was cold in New York as it was in the UK and both places had a cold December
1922
New York: Very cool summer after some May heat
UK: Very cool summer after some May heat.
1938
New York: Notably warm March, November warmth during first half
UK: Notably warm March and November warmth during first half
1945
New York: Unseasonably mild February through mid-April, then unseasonably cool through early June
UK: Very mild Feb-May period
1949
New York: Warmest year to date by more than 1 F. June driest calendar month in history (0.02”)
UK: Very warm year
1955
New York: Hot Summer
UK: Warm summer
1961
New York: Warmest September on record
UK: warm
1964
New York: Driest year on record up to this time (32.99”).
UK: Dry year
1973
New York: Late August/Early September heat wave (eight straight days of 90 F or higher temperatures).
UK: Heatwaves in mid August and early September
1977
New York: Cold January; 9.19” rain over 7-8 November
UK: Cold January
1978
New York: Cold January and February; 34 inches’ snowfall in January (record for any calendar month) and 23 inches in February
UK: February cold with huge snowfall in far SW
1979
New York: Cold February, record mild November
UK: Cold Feb, very mild end to Nov
1995
New York: Very warm July and August. Just 0.28” rain from 29 July through 16 September (50 days).
UK: Record breaking July-August period, extremely dry
1995-96
New York: 1995-96 winter snowiest (75.6”) in history; 20.2” on 7-8 January
UK: Some notable snowfalls
1998
New York: Second warmest year in history. Five straight 80 F or higher days in March
UK: Warm March and a warm year
1999
New York: Warmest calendar month (July) in history
UK: Very warm July
2001-02
New York: Mildest winter (December-February) in all history. November 2001 also warmest on record.
UK: Mildest mid Jan-mid Feb period on record
Very well laid out and presented Mr_Data.
I have just been wondering what could have been the cause of most of the "mirrored cold" between the Eastern US and the UK?
Two possible reasons:-
1. Westerlies moving over a colder than average North Atlantic or
2. Maybe a very amplified deep warm ridge over the North Atlantic with deep cold troughs over the British Isles and the Eastern Seaboard of the US?"
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Indeed, I often wonder where that comes from. If anything, cold air pouring out from the east coast of the states (giving them heavy snowfall) tends to power up the jet and encourage cyclogenesis around Newfoundland. In essence, cold there often leads to mild here, the exact opposite.
Very true reef. The only exception to this was January 1977 when it was cold on the East coast of US and still cool in the UK.
June CET
in Spring Weather Discussion
Posted · Edited by Craig Evans
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.