Spring 2018 Weather
Spring 2018 Forecast Verification
Created on 21st June 2018 this is the verification for the Spring 2018 forecast from GWV.
The forecast which was created on 25th February predicted temperatures close to average for Spring 2018. We thought there was a chance of a slightly warmer or slightly cooler than average Spring but either way we didn't expect a big deviation. Precipitation-wise we thought Spring 2018 would be another drier than average season.
Using the climate average summary pages from the UK Met Office we see that Spring 2018 was average to slightly warmer than average when set against the 81-10 thirty year average but when set against 61-90 we see the Spring was a significantly warmer than average season.
As predicted we started off with a cold and "blocked" month in March before seeing a reversion to proper Spring weather in April - Which was both a significantly warmer and wetter than average month. May also came out warmer than average and had more variable rainfall.
As far as rainfall is concerned we saw quite a wet season for England and Wales but a direr season for Scotland and Northern Ireland. Overall the driest anomalies to average were in the north-west and the wettest anomalies to average were in the southern part of England and Wales.
The GWV Spring forecast was incorrect for rainfall but closer when it came to temperature and the overall patterns that occurred through the Spring. So there-fore we think was somewhere between a "hit" and a "miss" but we are pleased with how the analogues in particular played out.
Spring 2018 Forecast
Created on 25th February 2018 this is the final and official Spring 2018 forecast from GWV. The forecast combine's the analogues that we've been looking at through our season of updates (scroll down page to see out Spring 2018 analogues updates) with the long range, seasonal model updates.
We also briefly look at some new analogues for the Easterly QBO (Quasi-Biennial-Oscillation) which largely back up the signal from our previous analogues and the long range seasonal models.
We're predicting temperatures to be largely close to average this Spring. We anticipate temperature anomalies might be slightly below or slightly above average but a large temperature deviation is not expected either way.
We think Spring 2018 will have a notably cold start with a strong blocking signal indicated for March which could have quite a cold/blocked start before the blocking pattern maybe relaxes somewhat later in the month. Although a cold month is expected with above average snow as well, we don't expect a month as severe as March 2013.
April is anticipated to be when Spring 2018 properly gets going. Although we do expect some unsettled weather at times and there's the possibility the blocking pattern from March may still occasionally show it's hand we think overall April should be a reasonably nice month.
May poses a problem and turns out to be more of a "wild card" month - Some of our analogues are pointing to a dismal, cold and wet month but other analogues point to a month that might not to be too bad. GWV generally expects another reasonable month following on from April (but confidence is very low)
Precipitation-wise we're looking at another average to slightly drier than average season... Although should May take a turn for the worse a very wet month looks possible (but even in this scenario it probably won't be enough to give us a wetter than average season)
This forecast will be evaluated at the end of the season as always. Long range updates now move on to Summer 2018
Keep checking back for more.
Third And Final Spring 2018 Seasonal Model Round-Up
Created on 24th February 2018 this is the third and final seasonal model round-up for Spring 2018 - Looking at 13 long range seasonal models to see what they are all showing for Spring one last time.
We begin with the probability charts from the long range Russian model. This model is forecasting increased probability of average to cooler than average temperatures across north-west Europe.
Looking at the long range JMA model we see that temperatures are forecast to be slightly above average this Spring with above average rainfall too - A rather Atlantic-driven, mild and unsettled Spring can there-fore be expected.
The Brazilian model looks rather cool and unsettled (for this model) while CANSIPS as usual shows slightly milder than average temperatures with near normal rainfall.
Peitao Peng's analogues still look very nice (as they have done consistently throughout these updates) with milder than average temperatures and average to drier than average precipitation anomalies predicted - The height anomaly suggests ridging to the east which should deliver us a very pleasant "southerly Spring"
CFS V2 shows an anomalous blocking feature over Greenland with a tough underneath it. This would give us a cool and unsettled Spring with a southerly tracking jet stream. Temperature anomalies are coming out average to possibly even colder than average (which is unusual for CFS) while rainfall anomalies are close to average (but drier than average to out north and wetter than average to our south which indicates a blocking pattern and subsequent southerly tracking jet stream.
Out interpretation of the POAMA model indicates quite an unsettled, Atlantic-driven Spring with near normal temperatures and above average rainfall.
EC seasonal model forecasts an anomalous trough of low pressure to the north-east of the north-east of the UK which would leave us with a chilly north-westerly flow. Temperature anomalies are close to or possibly slightly colder than average with precipitation anomalies near normal.
Meanwhile Meteo France looks more unsettled with it's MSLP (Mean-Sea-Level-Pressure) anomalies showing lots of low pressure over and to the north of the UK. Temperature anomalies are slightly above average with rainfall anomalies again coming out near normal.
The Beijing Climate Center (BCC) 500z height anomaly has an anomalous ridge to the north-west of the UK. This would give us relatively cool north-westerly winds. Temperature anomalies are near or slightly milder than average and precipitation is on the drier side.
Jamstec continues to be colder than average (as it has been all season) with rainfall perhaps on the slightly drier than average side - What's interesting here is that we haven't had the usual cold > mild flip that we tend to see from Jamstec across the three seasonal model round-ups and so instead of going from cold (in update one) to mild (in update three) it's just generally stayed cooler than average throughout.
Finally the UKMO GloSea5 MSLP is showing an area of high pressure near Greenland this Spring which forces low pressure and the jet stream further south into the central Atlantic. This gives us an appreciably wetter than average Spring (has been a strong signal from GloSea) with temperatures average or slightly milder than average (this GloSea update is cooler compared to recent GloSea5 updates even if its still slightly above avewrage)
So a mixed bag - But what we can say is that many of these seasonal models are now cooler (not cold) compared to earlier updates with many of them now near normal with the temperatures for Spring 2018.
The pattern that delivers these average temperatures is variable and so there is no clear signal for precipitation but a rather unsettled Spring is probably favoured across the model suites.
Tomorrow we'll put the long range models with the analogues and we'll release the GWV Spring 2018 Forecast. Keep checking back for more.
Spring 2018 Analogues (Part Three)
Created on 18th February 2018 this is the third and final part of our Spring 2018 Analogues - For this batch of analogues we're focusing on this Winters weather patterns and specifically February's weather patterns.
We begin looking at colder than average February's and the Springs that follow them. This has posed some challenges as it's quite difficult to "pitch" where the CET for February 2018 is going to come in. We expect a colder than average CET for February 2018 but we're unsure whether that will just be slightly colder than average (CET between 3-4C) or significantly colder than average (CET between 2-3C)
So we split the two analogues packages. The first batch is for Springs following slightly colder than average February's. These Springs show a blocking signal with high pressure centered over Greenland and below average heights to the south of the country. This looks to be a cold Spring signal overall.
March with these Springs shows the strongest blocking signal with a large block centered over Greenland and below average heights (low pressure) through the Atlantic and into Europe. In April we lose the blocking signal and revert to a milder, Atlantic-driven scenario. May shows a deterioration in the pattern with below average heights (low pressure) over the UK.
Then we look at Springs which follow more significantly colder than average February's. These Spring's again have very blocked and cold looking patterns for March. As far as April is concerned we tend to see the blocking signal continue (so unlike with the slightly colder than average Feb's where April goes milder and more Atlantic-driven these significantly colder than average Feb's see the blocking signal persist to April too) May also looks generally cool ad unsettled.
We also look at Springs that follow a cold February but also a mild January (like we've had in 2018) and we see a very similar scenario unfolding overall. These Springs overall continue with a blocking pattern and below average heights underneath it, telling us a potentially cold and unsettled Spring could be expected - It seems mild January's have less bearing on the Spring compared to cold February's which do seem t be quite important.
Trying to find a match to February 2018 synoptic pattern has proved challenging but overall we think February 1951 and 1981 could be closest to February 2018. Out of the two February 1951 looks the most compelling match. The Spring of 1951 was generally a cool and unsettled Spring. All three Spring months in 1951 were unsettled and cool overall with an especially cool and unsettled pattern during May 1951.
1951 is an interesting comparison for another reason as Winter 1950/51 was one of the Winters that showed up a LOT in the GWV Winter 2017/18 analogues which we used for our Winter forecast. It seems the patterns that showed up a lot leading up to Winter 17/18 are continuing through to Spring so Spring 50/51 seems to be a useful analogue for Spring 2018.
Looking at the analogues we used for the Winter 17/18 Forecast and following them through to Spring we see a very similar pattern to that which we started off with the Springs following cold Feb's. March comes out cold and blocked, April sees relaxation of the blocking pattern with a rather milder, Atlantic driven pattern developing while May looks very unsettled with low pressure parked over the top of the UK.
The Springs overall are very cool and unsettled when we follow through from the analogues we used for our Winter forecast.
The third and final Spring 2018 seasonal model round-up will be released next Saturday (24th February) and the GWV Spring 2018 Forecast will be released on Sunday 25th February - Just one week's time!
Keep checking back for more.
Spring 2018 Analogues (Part Two)
Created on 4th February 2018 this is the second part of our Spring 2018 Analogues - For this batch of analogues we're specifically focusing on ENSO - So Springs that follow La Nina Winters and either return to ENSO neutral conditions or keep La Nina going through the Spring.
The batch of analogues we look at are Nina to Neutral Springs. These analogues are quite a mixed bag with Springs as diverse as 1917 (very cold) and 2017 (very mild) included. If we combine all the years together we find that overall these Nina to Neutral Springs are unsettled with an anomalous trough centered over the UK and western Europe.
Although some of these Springs are cold, generally this isn't an especially cold temperature signal... But it is a signal for unsettled Spring (although there are notable exceptions such as the aforementioned 2017)
If we narrow down the Spring to just those that are ENSO neutral following weak La Nina (so excuding moderator or strong Nina's_ we see a slightly colder signal with more of these Spring tending to have above average heights (high pressure) towards Greenland, albeit it's a relatively weak signal.
Looking at La Nina's Spring (so these are Springs that has Nina through the Winter and continue that Winter through the Spring) we again see a lot of diverse years such as 1909 (cold) and 2011 (very warm) however looking at the "all years combined" charts we do see a much strong signal for blocking to be centered towards Greenland and Iceland so consequently these are on average colder Springs (and that's also true looking at the "all years combined" charts for weak La Nina Spring (so taking out all the moderate or strong La Nina years)
So if we return to Nina to ENSO neutral we favour an unsettled but probably not overly cold Spring. But if we see La Nina continuing through the Spring we probably favour something rather colder.
However, given the rather extreme divergence we see in several of years we need to question just how useful a guide these analogues actually are... Similar to the first batch of Spring 2018 analogues (which focused on Springs before solar minimum) these analogues are quite inconclusive and possible raise more questions than they answer.
That said all these analogues will be combined with the seasonal models when we come to issue the GWV Spring 2018 forecast on 25th February... So keep checking back for more.
Second Spring 2018 Seasonal Model Round-Up
Created on 28th January 2018 this is the second seasonal model round-up for Spring 2018
We begin by looking at the three models that only cover the early Spring (Feb-Apr) period - Which are the Russian, APEC and JMA models.
The probability forecast from the Russian model suggests the possibility of quire a cool early Spring with temperature probability average or even cooler than average for northern Europe and the north Atlantic. APEC looks milder than average and slightly wetter than average too, while the JMA looks relatively cool and unsettled With temperature anomalies from Feb-Apr not too far from average while precipitation anomalies are above average.
All other models in this second Spring 2018 seasonal model round-up are covering the full Spring 2018 period. Looking at the America's first week see that most of the seasonal models are going for a miler than average Spring.
The Brazilian model is slightly milder average with no signal for rainfall, the CANSIPS model is also going for a milder than average Spring and this one looks fair dry too. Peitao Peng's analogues continue last months trend with a very mild but also a very dry Spring being favoured while CFS V2 looks generally Atlantic driven for the Spring with temperature anomalies coming out slightly milder than average and also a signal for above average rainfall - Especially in the north and wets of the UK and Ireland (Note as with last month we don't have the experimental seasonal model from NASA)
Coming back closer to home the ECMWF model forecasts a warmer than average Spring but also hints at rainfall being close to normal meanwhile the long range model from Meteo France looks rather cool with temperature anomalies (average to slightly cooler than average) and we also see a rather wetter than average signal predicted the mean sea level pressure (MSLP) anomaly depicts high pressure to our south and low pressure to our north with a classic westerly Spring.
The Beijing Climate Center (BCC) show above average heights (high pressure) over the UK as an anomalous ridge. This brings us near normal to slightly cooler than average temperature anomalies with a much drier than signal for the Spring as well.
JAMSTEC shows a colder than average Spring (a continuation of what we saw last week) with drier than average anomalies to our north and wetter than average anomalies to out south - This seems to be a negative NAO signal and so this is what's bringing us those colder than average temperatures.
Finally the UKMO GloSea 5 model shows a very unsettled Spring with low pressure dominating the MSLP signal. Temperatures are significantly above average but so too is rainfall - So a mild and wet Spring forecast by UKMO.
The third and final Spring 2018 seasonal model round-up for Spring 2018 will be released on 24th February with the Spring 2018 forecast issued on February 25th - In the meantime we'll have more analogues for you next week (Sunday 4th February)
Keep checking back for more.
Spring 2018 Analogues (Part One)
Created on 21st January 2018 this is part one of GWV Spring 2018 analogues
The Spring 2018 analogues update focuses on Springs that are within two and one year of solar minimum of their respective solar cycles going back to Solar Cycle 10 (1855 to 1867) - This is a direct follow on from the Eleventh Winter 2017/18 Update which explored Winters within one and two years of solar minimum within their respective solar cycles back to SC10.
The first batch of analogues we look at are Springs that are within two years of solar minimum - These analogues are more relevant to the current situation we're in within the current solar cycle - SC24 - As we're probably around eighteen months or so away from solar minimum.
What we see for these first analogues is that many of the Springs though the early solar cycles (10-18) seem to have considerable northern blocking signals and are there-fore frequently cold and unsettled Springs.
The later solar cycles (19-23) show much more variability within these Springs. Some of them do still demonstrate a northern blocking signature but others have little or no northern blocking with no clear signal overall.
The the second batch of analogues shows a similar situation - The Springs that are within a year of solar minimum of their various solar cycles (so essentially these are the true solar minimum Springs) show a blocking signal for the early Solar Cycles but then the signal becomes rather more variable in the later solar cycles.
If we combine all years from batch one (Springs within two years of solar minimum) we see a strong blocking signal overall and a signal for below average heights to our south and east. This is an indication that many of these Springs are cold with winds frequently from northerly or easterly directions - Althoguh we must keep in mind that the Springs become far more variable from the middle and later 20th Century onwards.
It's a very similar story for batch two - Again we see quite a strong blocking signal but these true solar minimum Springs also look more unsettled with the all years combined chart showing a deep areas of below average heights over and to the west of the UK - This implies that batch one Springs tend to be cold and not overly unsettled while batch two Spring can be cold but are more reliably very wet.
Again we do need to factor in the variability that see with many of these Spring from mid-20th Century on.
Further Spring 2018 Analogues updates will follow in the weeks ahead with two more seasonal model round-up's for Spring 2018 as well.
GWV Spring 2018 Forecast will be released on Sunday 25th February. Keep checking back for more.
First Spring 2018 Seasonal Model Round-Up
Created on 31st December 2017 this is the first seasonal model round-up for Spring 2018 - Looking at several long range seasonal models from various international met agencies to see what the consensus is for the weather in the UK during Spring 2018.
We begin looking at at the long range Brazilian model. This model is showing an unsettled February to April with a trough of low pressure within the 500z flow sitting over the top of the UK. Temperature anomalies are warmer than average with precipitation suggested to be above average as well.
CANSIPS shows no real signal for the mean sea level pressure (MSLP) but temperature anomalies come out earmer than average with rainfall on the drier side. Similarly Peitao Peng's analogues are showing quite a nice Spring with above average heights (high pressure) just to out east and below average heights (low pressure) to our west. A warmer and drier than average Spring is anticipated in the scenario.
CFS v2 700z height anomaly for Spring 2018 is weak. Much of Europe is suggested to have a much warmer than average season although the UK and Ireland come out closer to normal. Precipitation-wise we see a rather wetter than average season is anticipated in north and west Europe (UK included)
The Beijing Climate Center (BCC) shows above average heights to our west and below average heights to our east for Spring 2018. This leaves us to a north-west to south-east jet stream with temperature anomalies close to average (so cooler than some other models) with rainfall anomalies rather above average. A fairly cool and unsettled Spring predicted from the BCC.
Jamstec is forecasting a colder than average Spring and also wetter than average too. This model often forecast colder than average temperature anomalies at this range only to modify them later so caution is needed here.
ECMWF MSLP probability forecast suggests an increase probability of low pressure close to the UK and north Atlantic this Spring. Temperature probability suggests near normal temperatures for the UK (although much of Europe is coming out warmer than average) with rainfall probability greater than average - So again we see a suggestion for a relatively cool and unsettled Spring from EC's System 5 model.
Meteo France long range model has high pressure to our south with low pressure to the north. Temperature anomalies are average to slightly cooler than average for north-west Europe with rainfall near normal.
Finally the UK Met Office GloSea5 model shows low pressure close to the UK and much of northern Europe this Spring. Temperature anomalies are significantly warmer average with this model but a wetter than average Spring is expected.
So fairly good agreement for an unsettled season. Many of these models seem to be picking up on a trend for quite a wet Spring although there are differences in the exact pattern that's delivering this unsettled weather. There-fore we see differences in temperature forecasts with some models going for a very mild Spring while other models see average to rather cool temperatures this Spring.
Only Jamstec is actually forecasting a colder than average Spring at this early stage though.
Next month we'll have more long range models to add to the mix for Januaries second seasonal model round-up. We'll also start bringing in some analogues for the Spring as well with the GWV Spring 2018 forecast released on 25th February 2018.