October CET

[Weather-history]

That said, what is the warmest first half to October on record (i do not expect it to be beaten but there is clearly a chance)?

October 1921 with 15.1C

[Roger J Smith]

I would be glad to produce a summary of forecasts and normals, but was waiting to see if I.F. was going to update his from earlier. So let's say if he doesn't update it today then I will produce said table tonight (your time).

For my own forecast, I really have a strong feeling that this month will turn out like last November, which you may recall started rather mild before turning near-record cold. This may not be as drastic and we are starting from a very high value through 3 days.

The other consideration for me is the "game" aspect of the contest. If you're middle of pack with a couple of forecasts left, then mathematically the only way to move up is to successfully predict an extreme (relative to the other forecasts, 9.7 is hardly extreme in historical terms). So that was part of my motivation to go that low. Have to admit, there is not a lot in reliable or even FI time frames to support a very low second half but, when did we first see reliable modelling signs of the late Novemeber cold spell? Around the 16th perhaps?

[summer blizzard]

Pretty chilly look from the models over the next ten days or so with average/below average isotherms over the UK aside from a breif period around the 10th.

19.2C to the 3rd.

[Thundery wintry showers]

I am already ready to concede that my original prediction is set to be way too low. I was right to envisage the mean trough heading to Scandinavia, but was wrong to discount the possibility of pressure remaining high to the south of the British Isles preventing any change to a northerly type (bar the odd 24-36 hour blast).

[Roger J Smith]

Table of entries for October CET

14.1 .. sparky1972

14.0 .. Craig Evans, ja23

13.9

13.8

13.7

13.6 .. Gavin D

13.5

13.4

13.3 .. Styx, Robbie Garrett ... Warmest on record (2001)

13.2

13.1 .. Scorcher * Paul T **

13.0

12.9

12.8

12.7 .. Backtrack

12.6

12.5

12.4 .. conor123

12.3 .. sunlover

12.2 .. Stormyking, Duncan McAlister

12.1 .. tonyh, Timmy H *

12.0 .. Reef

11.9 .. BreezeInTheEast, Tom D *

11.8 .. davehsug, Corrigan 87 *

11.7 .. Snowstorm1, koldweather

11.6 .. Snowlover2009, Jack Wales

11.5 .. Stargazer, stewfox, DR Hosking

11.4 .. JACKONE

11.3 .. Don, Milhouse *

11.2 .. DAVID SNOW, Harve *

11.1 .. The watcher, Stormmad26, coram **

11.0 .. The Pit, damianslaw, mulzy, GavinP

10.9 .. Isolated Frost, Radiating Dendrite, Mr_Data, fozfoster, SP1986 *

10.8 .. Pete Tattum, Bluebreezer54, Norrance, mullender83 **

10.7 .. summer blizzard, Kentish Man --- MEAN 81-10 ---

10.6 .. Koppite, Ben_Cambs * --- MEAN 61-90 ---

10.5 .. BornFromTheVoid, DeepSnow, AderynCoch

10.4 .. Stationary Front --- MEAN 71-00 ---

10.3

10.2 .. jonboy, sundog, Liam J, Thundery wintry showers

10.1 .. Paul Carter, Terminal Moraine. Mark Bayley, AtlanticFlamethrower * frozencanals**

10.0 .. Polar Gael, BARRY

9.9 ... virtualsphere --- MEAN ALL CET YEARS 1659-2010 ---

9.8 ... SteveB

9.7 ... Roger J Smith

9.6

9.5

9.4

9.3

9.2

9.1

9.0 .. Optimus Prime

8.9 .. joggs

7.8 .. Coldest recent (1974, 1992)

5.3 .. Coldest on record 1740

* day late ; ** 2d late

_________________________________________________________________

I see we now have three Craig Evans(es), perhaps a top 3 grouping if this hot start is not matched by later cold spells. If first four days averaged 17.5, then rest of month would have to average as follows to produce CET values predicted:

14.0 ... rest of month 13.5

13.0 ... rest of month 12.3

12.0 ... rest of month 11.2

11.0 ... rest of month 10.0

10.0 ... rest of month 8.9

9.0 ..... rest of month 7.7

[Aaron]

I cannot believe some people are going for the warmest on record.

[BornFromTheVoid]

18.0C to the 4th

http://www.metoffice..._info_mean.html

Yesterday was 14.2C. Today's minimum is 13.1C while maxima look like averaging around 19C, so a drop back to 17.6C tomorrow looks likely.

After that, the 06z GFS will have the CET at

16.5C to the 6th (11.2)

15.9C to the 7th (11.9)

15.5C to the 8th (12.6)

15.6C to the 9th (16.3)

15.4C to the 10th (13.8]

15.0C to the 11th (11.0)

14.9C to the 12th (13.8]

I'd say low to mid 14s most likely by the 15th.

Edited October 5, 2011 by BornFromTheVoid

[reef]

I cannot believe some people are going for the warmest on record.

Its not actually as difficult to attain now as you might imagine. It would only require the remaining days of the month to average 12.7C.

[Isolated Frost]

I'd imagine with at least the first half of the month in a set pattern then the CET will be extremely different to the Scotland/NI/UK average - tropical maritime air is most likely to affect the south the most while polar maritime incursions mainly for the north - this will mean much cooler air on average in Northern parts, I know that the south will also see some polar maritime air and the north will see tropical airstreams, but looking at the gfs, this looks like the set pattern.

Also, many parts of Scotland and NI didn't have the heatwave practically at all, just a warm stream of Tm air - with cool maxima (mid to high teens) and mild minima (low teens) - this could take about 1/2c off the cet figure if it had endured Belfast's first 3 days of October.

What I'm trying to say basically is, the cet may not really reflect the nation's weather/temperatures this month as much as it usually would. I'd expect the October cet to be fairly above average but would not be shocked if the Scotland, NI and even possibly UK as a whole average temperature to be average or slightly below.

[Roger J Smith]

To give some idea of what can happen later in the month, last three days of October 1836 averaged 0.7 C, and even as recently as 2008 we have seen a CET day close to 2 deg C in October.

Just scrolling through the years, you get the impression that most of the days before the 15th are usually above 10 C and most of the days after the 15th are below 10 C. But in 1974 there was only one day above 10 C and that was near the end.

[damianslaw]

To give some idea of what can happen later in the month, last three days of October 1836 averaged 0.7 C, and even as recently as 2008 we have seen a CET day close to 2 deg C in October.

Just scrolling through the years, you get the impression that most of the days before the 15th are usually above 10 C and most of the days after the 15th are below 10 C. But in 1974 there was only one day above 10 C and that was near the end.

Yes on average there is a marked difference in the CET values for the first half of the month compared to the second. Of the 12 months of the year, October sees the greatest degree of cooling from start to finish. Far too early to be predicting with confidence a significantly above average month, though a below average month does appear to be a tall order (could still happen if we see a prolonged blast of polar conditions or cold anticyclonic conditions).

[Weather-history]

To give some idea of what can happen later in the month, last three days of October 1836 averaged 0.7 C, and even as recently as 2008 we have seen a CET day close to 2 deg C in October.

The last day of October 1934, alone was enough to knock 0.3C off the CET

[reef]

Hadley is 17.6C to the 5th. Yesterday was very warm again at 16.1C.

For the remaining 26 days:

9.4C is required to reach the 1981-2010 average

12.5C is required for the warmest October in the CET series.

[TonyH]

Above average but not a record breaker then, I would hazard a guess at this early stage!

[BornFromTheVoid]

Should see a large drop on tomorrows update, down to 16.5 or 16.6C.

[summer blizzard]

Hadley is 17.6C to the 5th. Yesterday was very warm again at 16.1C.

For the remaining 26 days:

9.4C is required to reach the 1981-2010 average

12.5C is required for the warmest October in the CET series.

We may get scupered near the end of the month like September, but current modeling for the next ten days would suggest average/below for the time of year. The warmest on record is very unlikely in my opinion as that still requires us to average 2C above average when modeling suggests a pretty complete absence of warmth away from the far south.

[Milhouse]

Not sure there will be a complete absence of warmth when we have the 10c 850hpa line making it into southern England on Sunday and then Tuesday-Thursday going by the GFS. The GFS 12z has 21c in the south on Sunday so that is warm for the time of year even if it may feel cooler in the wind. However the ECM is making more of the cooler period early next week so further falls are guaranteed but there will be warmer days mixed in too which will limit the fall. The decline could be a lot greater is what i'm saying but still looks to be falling enough to keep my hopes up come the end of the month.

Edited October 6, 2011 by Milhouse

[BornFromTheVoid]

16.6C to the 6th

http://www.metoffice.gov.uk/hadobs/hadcet/cet_info_mean.html

Yesterday was 11.3C, coolest since June 12th. Minimum today is 8.5C and maxima are around 15C, so we should see a drop to around 15.9C tomorrow.

[Paul T]

Very cold spell from late Oct into early Nov will bring the CET in the high 12's.

Largely Mild otherwise

[Isolated Frost]

Something like 14c/14.5c to the 15th imo - may have some cool spells but they generally won't affect the cet zone and high pressure and extremely warm uppers (8c-12c) often move into S England on the 12z GFS.

My 10.9c guess is looking way off the mark - but my rule is once i've made a guess i don't change it, and I always guess early - because that's all it is - a guess! I'd warrant a non-accurate estimate that with some slow falls through the mid-end of the month, as thermal maxima and minima naturally drop - about 12.5c/13c to halloween, so 12c/12.5c after adjustments. I'm going for 12.4c currently (+1.7c), very, very warm month.

[Isolated Frost]

15.9c to the 7th (can't copy and paste link as on mobile currently), 3.7c above the average for the first 7 days of October.

[BornFromTheVoid]

15.5C to the 8th

http://www.metoffice.gov.uk/hadobs/hadcet/cet_info_mean.html

[TonyH]

Most likely to be above 15c mid month given the warm week ahead.

[Isolated Frost]

Record warm October well on the cards now.

[summer blizzard]

Most likely to be above 15c mid month given the warm week ahead.

Most likely to be above 15c mid month given the warm week ahead.

I find that very unlikely, while above average we are still at a warm point and thus even if we see above average temperatures, i struggle to see daily means above 15C.