Archives For October

2015-11-21_14-40-20

Quick October weather summary for Reigate 2015.

Summary stats for October in Reigate, Surrey, England

  • T average 11.6C
  • Tmax 19.33 C
  • Tmin 3.2C
  • Rainfall total 61mm (CoCoRaHs)
  • Sunshine 95.3 hours
  • Max gust 24mph (24 Oct)

October CET temperature came out just above average at +0.4C. Significantly, globally, October 2015 was the warmest October ever on record for this month by a significant margin, probably due in part to a strong El Nino.  In fact every month of 2015 so far has been record-breakingly warm and each month has been the warmest recorded anomaly… since 1880.

2015-11-21_14-55-43

October global temperature anomaly 2015

Due to anomalously high pressure for much of the month, South East England rainfall was lower than average at some 76% of the long term average.  In Reigate this amounted to 61mm of rain.

Despite the high pressure sunshine amounts were average or slightly below in the south east with Reigate totting up 95.3 hours of sunshine in the month.

October is sometimes correlated with winter outcomes. Anomalously high pressure in October has sometimes been correlated with cold winter patterns, though this is highly experimental.  In addition, October Siberian snow cover expanded rapidly and beyond the 2014 cover for the same period.  This got winter forecasters further interested in the possibility of high pressure, northern blocking and the increased potential for a cold late winter in the UK.  However, seasonal forecasts have a habit of going awry, as was illustrated by the ill-fated “October Pattern Index” much heralded in the run-up to winter 2014 when it predicted a cold one. The OPI, as far as I can tell, has now disappeared off the seasonal forecasting scene completely.

http://www.metoffice.gov.uk/climate/uk/summaries/2015/october

October 2014 rain and temperature

October 2014 rain and temperature

sunshine hours October 2014

sunshine hours October 2014

Reigate weather summary for October 2014

Tmax 22.6C

Tmin 2.4C

Taverage 13.1C

Total rainfall 112.3mm (CoCoRahs)

Despite memories of big storms like St Jude last year, October 2014 has turned out more than twice as wet with 112.3mm.  For the UK as a whole October 2014 was a warm month and broke records with the warmest “Halloween” on record.  At an average of 13.1C it was warm in Reigate as well, but oddly did not exceed the 2013 average of 14C. So 2014 was wetter but not quite as warm in Reigate as last year.  It was a quieter month with lower wind speeds and less widespread stormy conditions and it looks like Autumn 2014 will continue in this mild wet style but without the threat of big trains of countless Atlantic storms like last year.  Blocking HIGHS over Russia / Scandinavia and to the North look set to slow down the train of Atlantic weather and send it south into the Mediterranean where wet and stormy conditions have already been experienced (“Medicane” Mediterranean hurricane November Malta 2014)

In the UK as a whole October 2014 was the equal-tenth warmest October for the UK in a series since 1910 according to Central England temperatures (CET).  Globally, unconfirmed data suggests that October might be the warmest on record.

In Reigate much of the heaviest rain came in the first half of October in big convective downpours that were hit and miss.  Some tornadoes were reported across the UK and these were quite damaging in places further North.  We have yet to record a tornado in Reigate.  Tornados are extremely tricky to forecast but several agencies try it.. usually the MetOffice do not mention tornadoes in their forecasts because they are so hit and miss, even when potential is there.  Estofex, UKWW and SkywarnUK are agencies that have an eye on tornadic and severe weather conditions in the UK that RGSweather follows carefully.

MetOffice winter prediction 2014-15 as follows: It states “For November-December-January above-average UK-mean temperatures are more likely than below-average” and “Latest predictions for UK-mean precipitation favour near- or above-average rainfall for November-December-January”.  In contrast, other weather agencies and some seasonal model predictions are suggesting the possibility of a colder winter as various early indicators seem to suggest the possibility of incursions of cold air at times.  In particular, early October extensive Siberian snow cover, cooler than average temps over Siberia and a negative OPI index leading to an amplified jetstream (which seems to be occuring now) seem to suggest the possibility cold blasts at times this winter.  In addition, an Easterly phase of the Quasi-Biennial Oscillation (QBO) in the stratosphere favours a weaker flow of upper westerly winds that shut out cold air for the UK and W Europe.  An easterly QBO phase favours colder winters for us, but not always.  Whilst a strong El Nino has not transpired, there are indications that sea surface temperatures in the Pacific (especially central Pacific) are rising, albeit modestly: El Nino tends to link with cooler Euro winters.  These immediate measurable indicators correlating more or less with cold UK winters are interesting but not necessarily enough on their own to drive the atmopshere toward cold conditions.  They might, however, couple with other connections in the Stratosphere to cause stratospheric warming which, some weeks after, can cause downwelling of cold air into the troposphere and further disruption of the westerly flowing jetstream.  This is especially the case if warming is sudden (SST).  IF this all happens and IF surface pressure patterns play ball then the UK could see some cold snowy conditions! Charts below show some of these connections:

October quick summary

Nationally, October 2013 was one of the warmest Octobers since UKMO records began in 1910!

In Reigate October 2013 will be remembered as a wet and windy month in Reigate with 94mm of rainfall, much of this fell in two spells of very wet weather 11-13 Oct and then at the end 27-28 Oct with the strongest storm for decades, St Jude / Christian.

BUT… last year October 2012 was even wetter here with 122mm!

October this year was also warmer than 2012 by over 2c and recorded a Tmax of 20c which was significantly warmer than the Tmax last year.

  • Tmax  20.6c (13.6c 2012)
  • Tmin 1.1c  (7c 2012)
  • Temp average  12.3c (10c 2012)

October will also be remembered for the high winds experienced during St Jude storm, a maximum gust was recorded in Reigate of 48mph.  This is well documented in the detailed summary found here…