Model Output Discussion - 3rd May Onwards 00z--->

[Summer Sun]

looking at this morning's UKMO, ECM was onto something yesterday morning when it shifted the high west that's exactly what UKMO has done 24 hours later whilst the extreme west could hold onto some drier weather the further east you are the greater risk you have of catching some rain / showers.

 

After a warmer few days temperatures would heading back down if it came off maybe struggling to get into the teens for some

 

[mushymanrob]

Interestingly, the anomaly charts dont look like being spot on, neither do the ops, as theres unlikely to be a northen low as per the anoms, nor a high centred over us as per the most progressive ops.

 

yeah well... i spoke too soon, starting to let my preferences for the dry and warmth the ops had been championing recently , influence my thinking.

this morning the ops are now in line with what the anomaly (noaa) charts have been telling us will happen.... no (lasting) pressure build over the uk with the high being anchored to our west/southwest, upper trough to our north/northeast, with a mean upper flow from the northwest... so cool, rather unsettled at times with and settling down/calm being rather transitory.

Edited May 20, 2015 by mushymanrob

[Summer Sun]

For the same period as UKMO, ECM has the high further east, still the risk of some rain / showers for some northern and eastern parts but more ares would see some better weather compared with UKMO, whats looking fairly likely is this high will be centered west of the UK, what is uncertain is what influence it would have on the UK

 

[Polar Maritime]

The GFS this morning shows the weekend settling down a little as High Pressure skirts the UK, Before the flow turns N/W once again for the working week.

 

[bluearmy]

The Azores ridge is unable to encourage a euro height rise

we seem to be stuck in this pattern and hope that the less settled spells are the ones which are short lived.

No likelihood of late spring/early summer temps.

Of course, the old adage that stuff equals itself out could promise some very plumey summer conditions

[knocker]

I have no particular astute meteorological reasoning for saying this but I can't help wondering whether the reluctance to shift this blaster upper trough is not somehow tied in with this seemingly permanent vortex over N. Canada that keeps feeding cooler air across the pond  south of Greenland thus forcing the jet into a very uncompromising position.

Edited May 20, 2015 by knocker

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON WEDNESDAY MAY 20TH 2015.

 

THE CURRENT GENERAL SITUATION A cool West or NW flow will weaken across the UK over the next 24 hours or so as a ridge affects the South tomorrow and a front affects the far NW by the same time.

 

http://www.wetterzentrale.de/pics/Rtavn001.gif 

 

MODELS-2 WEEK HEADLINE Slowly becoming drier and brighter especially towards the SW but still rather cool with a little rain at times towards the North and NE.

 

http://www.netweather.tv/index.cgi?action=jetstream 

 

GFS OPERATIONAL The GFS Operational's main theme this morning is for High pressure to lie out to the WSW of the UK for some considerable time, never close enough to guarantee full influence over the UK with the ridge over the Uk from it collapsing at times to allow weak troughs SE across Britain with cloud and a little rain. then in the second half of the run low pressure again comes down from the cool North giving rise to a sustained cool and showery period as the Low pressure swirling around the UK out to the end of the run.

 

http://www.wetterzentrale.de/pics/Rtavn1441.gif

 

http://www.wetterzentrale.de/pics/Rtavn3841.gif 

 

THE GFS CONTROL The GFS Control run without going into specific detail is in good support of the operational run with Low pressure becoming the main player again over the second half of the run after a period of benign NW winds in association with High pressure down to the SW in the first half of the period. 

 

THE GFS CLUSTERS The GFS Clusters today still show a more restricted bias towards a High pressure ridge affecting the UK from the SW but with more support today for Low pressure to be a player too later in the period with a variety of options meaning a greater chance of rain at times late in the period.

 

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

 

UKMO UKMO this morning shows a weakening ridge of High pressure giving way to  a straight Northerly flow by Bank Holiday Monday with some showers likely epecially in the East and South following a little rain on Sunday

 

http://www.wetterzentrale.de/pics/Rukm1441.gif 

 

THE FAX CHARTS The Fax Charts show a series of weak troughs moving SE across the Uk through the period with some light rain at times as they pass though with some drier and bright spells too with conditions a little less cold than recently.

 

http://www.weathercharts.org/ukmomslp.htm#t120.

 

GEM GEM this morning shows a High pressure ridge affecting the UK for much of the next week with a light and cool drift of wind at times from the North and variable cloud cover. late in the run as with GFS it shows Low pressure moving down towards Northern Britain with a greater threat of rain for all by the end of the run.

 

http://www.wetterzentrale.de/pics/Rgem2401.gif 

 

NAVGEM NAVGEM also shows a Northerly or NW flow across the UK through the start of next week though with High pressure out to the SW extending a ridge at times towards the UK only scattered showers affecting the far East for a time should be the only annoying weather factor in an otherwise benign period of weather.

 

http://www.wetterzentrale.de/pics/Rnvg1681.gif.

 

ECM ECM today shows a lot of benign conditions too over the weekend and start to next week as a NW flow remains weak with a lot of cloud at times and the odd shower too. later in the period it looks like pressure will fall as the High to the SW declines and allows slack Low pressure to take control in a more showery theme nationwide by the end of the run.

 

http://www.wetterzentrale.de/pics/Recm2401.gif

 

ECM 10 DAY MEAN The ECM 10 Day Mean Chart from last night continues to show High pressure out to the WSW with a slack North or NW flow across the UK.

 

http://www.wetterzentrale.de/pics/Reem2401.gif 

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The model continue to oscillate between quiet and benign NW or North winds together with fair weather and Low pressure re-establishing later next week with rain at times.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 96.7 pts followed by UKM at 95.8 pts and GFS at 95.1. At 5 days ECM  leads UKMO with 86.2 over UKMO's 83.3pts with GFS at 81.9. At 8 days ECM clocks in ahead of GFS at 51.8 over 51.6. Then at Day 10 ECM remains slightly ahead of GFS at 33.6pts to 33.5pts

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png 

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.prig

 

 

MY THOUGHTS Things still look undecided in where we go with the UK synoptic pattern in the second half of the outputs forecasts this morning. As of yesterday there is still some models who think that the gradual shift will be back towards more unsettled and showery conditions in the latter stages of next week and beyond. In the shorter term things are a little more agreed in that the likely pattern will be one of NW or North winds blowing down over the UK over the Bank Holiday period. The timing of weak fronts crossing South in the flow will be instrumental in determining day to day conditions in any one place but what can be said is that it will probaly feel less chilly when the sun shines with temperatures close to average though still rather chilly feeling under the cloudier spells of which there will be quite a few and any light rain or showers that fall from these clouds. Then as we move deeper into next week it looks likely that there will be some deterioration in conditions as Low pressure reignites from the NW to bring an increased risk of showers among the continuing drier phases. Overall though things look rather drier than what we have seen through May so far with some pleasant sunshine making it feel warmer too than recently but confidence in any one solution as we move into June looks lower than usual.

 

Next update from 08:00 Thursday May 21st 2015

[len]

The Azores ridge is unable to encourage a euro height rise

we seem to be stuck in this pattern and hope that the less settled spells are the ones which are short lived.

No likelihood of late spring/early summer temps.

Of course, the old adage that stuff equals itself out could promise some very plumey summer conditions

.

Seems to be the exact opposite of the idea of the North Pacific warm "blob" causing a High.

We have a stubborn Mid-Atlantic cold SST anomaly. And the Mid-Atlantic High seems unable to leave it?

[Captain Shortwave]

The pattern looks similar to March in a sense that lower than normal heights over central Europe are proving very stubborn and hence attract further low heights in the Atlantic to dig south east down the north sea. That said if we saw a pattern flip like we did for April then June would turn out pretty nice indeed. That said no more than hope and a few CFS 4 week runs as back up. Most long rangers are showing a pretty poor summer overall. Still the question will be whether the developing el-Nino will play a part? Scientific evidence suggests a negligible impact at the moment.

[knocker]

.

Seems to be the exact opposite of the idea of the North Pacific warm "blob" causing a High.

We have a stubborn Mid-Atlantic cold SST anomaly. And the Mid-Atlantic High seems unable to leave it?

 

I still don't agree that the recent paper on the blob says that it causes the anomalous HP. Rather it's the other way around unless I'm misreading it.

 

 

Final Remarks

A prominent mass of positive temperature anomalies developed in the NE Pacific Ocean during winter of 2013–2014. This development can be attributed to strongly positive anomalies in SLP, which served to suppress the loss of heat from the ocean to the atmosphere, and leads to a lack of the usual cold advection in the upper ocean. The extra mixed layer heat persisted through the summer of 2014 and may have represented a significant contribution to the unusually warm summer (in some locations record high temperatures) observed in the continental Pacific Northwest. The linkage between the upper ocean temperature and downstream temperatures over the coastal region of the Pacific Northwest may provide a secondary source of predictability for seasonal weather forecasts. In particular, it suggests that coupled atmosphere-ocean models such as NCEP's Coupled Forecast System model may need to properly handle the evolution of the upper ocean in the NE Pacific because of its regional influences.

The present analysis does not focus on the cause(s) of the anomalous atmospheric forcing. A broad region extending from the North Pacific across North America is known to be subject to the effects of teleconnections from the tropical Pacific in association with El Niño–Southern Oscillation (ENSO) events, i.e., the “atmospheric bridge†[e.g., Alexander et al., 2002; Lau and Nath, 1996]. But such an explanation fails to account for the winter of 2013–2014 since ENSO was in a neutral phase. On the other hand, SST anomalies in the far western tropical Pacific, and accompanying deep cumulus convection, appear to account for a significant portion of the anomalous circulation [Seager et al., 2014; Hartmann, 2015; Lee et al., 2015] that occurred in the winters of both 2012–2013 and 2013–2014, with intrinsic atmospheric variability probably an additional important factor.

 

Causes and impacts of the 2014 warm anomaly in the NE Pacific

http://onlinelibrary.wiley.com/doi/10.1002/2015GL063306/full

Edited May 20, 2015 by knocker

[coldcomfort]

The Azores ridge is unable to encourage a euro height rise

we seem to be stuck in this pattern and hope that the less settled spells are the ones which are short lived.

No likelihood of late spring/early summer temps.

Of course, the old adage that stuff equals itself out could promise some very plumey summer conditions

It's disappointing enough to be stuck in this pattern, but what is more disappointing to me is the longer range GFS already appears to have picked up a strong signal of what is to follow as we enter June and to be fair it does look like the natural progression.....seen it time and time before.

 

As a result we may in 2-3 weeks time be reflecting on just how good the coming week was in comparison to what we now have, because if the kind of pattern being suggested by the longer range 06 GFS does set up, it could be a very long way back indeed to something even half decent.

[johnholmes]

.

Seems to be the exact opposite of the idea of the North Pacific warm "blob" causing a High.

We have a stubborn Mid-Atlantic cold SST anomaly. And the Mid-Atlantic High seems unable to leave it?

I did try, perhaps not very well, to answer this query some time ago, did it not help Len?

[summer blizzard]

Certainly a turn from the models in recent days. All of them by day 10 have stuck the finger up at the Azores High.

 

[PolarWarsaw]

Cricket season is officially here....expect Flood Warnings, Gales and endless weeks of rain!

[049balt]

What a difference a day makes, gone are the high hopes of Summer and replaced by gloom, I have not given up hope and the models can just as well switch back, it's a tricky one!

[William of Walworth]

Let's have a few more runs shall we? I haven't seen anything futher up-to-date than 00Z yet. And there's been plenty of shifts in the synoptical detail over the last few days, over various runs.

 

I appreciate that most of the very recent anomolies are not so encouraging, but as a more general point of criticism, it does seem to me that one operational run in a less positive, more trough influenced direction is enough to get it very rapidly seized on on this thread as gospel, whereas if any moderate improvement towards a tad more HP influence is hinted at in the next two or three runs, then scepticism is more likely to rule the roost for longer, for many contributors.

 

We are always correctly advised every year to be FI-cautious, but that applies to the trough side of predictions as well as to the HP side, surely.

 

So do stop writing off June before it's started! It's only 20th May today, remember.

[mushymanrob]

Let's have a few more runs shall we? I haven't seen anything futher up-to-date than 00Z yet. And there's been plenty of shifts in the synoptical detail over the last few days, over various runs.

 

I appreciate that most of the very recent anomolies are not so encouraging, but as a more general point of criticism, it does seem to me that one operational run in a less positive, more trough influenced direction is enough to get it very rapidly seized on on this thread as gospel, whereas if any moderate improvement towards a tad more HP influence is hinted at in the next two or three runs, then scepticism is more likely to rule the roost for longer, for many contributors.

 

We are always correctly advised every year to be FI-cautious, but that applies to the trough side of predictions as well as to the HP side, surely.

 

So do stop writing off June before it's started! It's only 20th May today, remember.

 

hi william, it must be summer if youre back!

the anomalies are undeniably pretty accurate, as jh says, (we have just seen what looks like yet another anomaly triumph over the ops) and although they dont make pleasing viewing atm, they only go out to 2 weeks ahead, so hardly touches 'summer' at all. theres loads of time for the longwave pattern to shift (favourably) and tbh, as long as theres positive heights to our west/southwest, itll prevent northern blocking and a southerly tracking jet that started the washout summers of 07, 08, in early june... thats good news!

Edited May 20, 2015 by mushymanrob

[Eugene]

GFS 12Z is absolute shocking in FI, with southerly sourced localised flooding, lets hope it reverts to a drier pattern.

[summer blizzard]

Oh golly.. 12z is pretty much the worst case scenario for summer fans..

 

[Mokidugway]

Indeed yuk ...

[Polar Maritime]

High latitude blocking a plenty as we enter Summer proper shown on this evenings GFS.

 

[East_England_Stormchaser91]

Wow. Those charts are pretty much identical to July 2007. Grim! Thank god it will change! (God willing)!!

[Milhouse]

No point getting hung up over GFS fi charts. Some nice enough days to come in the short term, including tomorrow with temps peaking in the high teens for some. Should feel very different to the cool blustery conditions of late.

[049balt]

Floods in week two.

 

http://wxmaps.org/pix/prec4.html

[Captain Shortwave]

Some rather OTT comments on here, at least the 12z delivers plenty of thundery showers and with south or south westerly winds we would see near normal or slightly above temperatures as opposed to troughing east of the UK which has so far this spring only really delivered if the trough is right over the UK, which has come out from the Midlands south as one day in the entirety of Spring.

 

It's more interesting weather wise than this from the GEM

Mainly dry away from the north east and cool.

 

The UKMO at day 6 is extremely amplified

I would wonder whether we would cut low heights off over Iberia and potentially link the ridges to the west and east of the UK. Looks improbable at the moment as other models are less amplified.

Edited May 20, 2015 by Captain shortwave