FI Charts (T120+ onwards) Spring 2018 **READ MOD NOTE IN FIRST POST**

sryanbruen

Chilly next weekend. GFS shows a northwesterly regime bringing in polar maritime air but ECM shows a northerly. Subzero temperatures at night? With the ECM solution, yes it is possible but grass frost for certain if it comes off. GFS not so much. Snow on higher ground? Yes, again on the ECM it is possible and GFS not so much.

Daytime temperatures below average for the time of year with 9-12c generally on both of these models though the GFS temperature maps show them as only 7-9c widely.

Do you prefer me labelling the high and low pressures along with the jet stream on these charts?





At the end of the ECM run at +240 hrs, the weather starts to become nicer with a transient ridge being sent up from the Azores and the jet stream going northwards.

Meteorite58

Yea looks a bit cool next weekend, ECM atm showing temps around 10C during the day and getting down around 1 to 4C at night hopefully that ridge shown to build after +196 will materialize . Will see.

sryanbruen

Awful ECM 12z run with some very wet and cool weather for 29/30 April.

sryanbruen

Deluge in England and Wales on Sunday with the GFS whilst the ECM shows it for Saturday. Very cool otherwise. The awful runs continue.



Funny how the same day 6 years ago (Sunday 29th April 2012), there was another deluge. In fact, strikingly similar charts.

Neddyusa

Any sign of a settled period of high pressure on the FI horizon?

I honestly can't remember a run of months (since last September) with such a scarcity of high pressure spells!

Even the couple of good days here last week were accompanied by strong and blustery southerly winds.

jdcv94

Neddyusa wrote: »

Any sign of a settled period of high pressure on the FI horizon?

I honestly can't remember a run of months (since last September) with such a scarcity of high pressure spells!

Even the couple of good days here last week were accompanied by strong and blustery southerly winds.

Going to be cool over the next week, there's signs of improvement in the first week of May however, nothing to ride home about yet but that Azores high is certainly trying to make inroads. Promising for the week/days after.

hatrickpatrick

Very far out GFS shows massive improvements from the 8th of May on, with the Azores high pushing North over us:



Meanwhile, the ECM shows it arriving earlier, by the 3rd of May - slipping back a bit to the south subsequently, but still enough to bring mostly dry weather by the 5th:





The ECM forecast for high and high-ish pressure is inching closer to the reliable timeframe, so fingers crossed for the next few days of model runs I guess. As always, don't get excited quiet yet, but remain cautiously optimistic.

Comhrá

I never trust that Azores High until I see it marching ashore on the beaches of West Cork & Kerry.

Artane2002

Comhra wrote: »

I never trust that Azores High until I see it marching ashore on the beaches of West Cork & Kerry.

Unless it's winter when it readily ridges in

jdcv94

Looks like a little bit of an upgrade compared to yesterday. With the ECM showing a high settling just off our east coast for the 5th.









A long way off still, but could be quite nice conditions here, similar to the spell we just had but perhaps warmer for the east this time.

jdcv94

Just noticed that those 850hPa are values for 2am in the morning, and a birdie once told me to add rougly 10-15 degrees onto those values for sea level temps, so would that mean we're looking at 18c+ at night? I'm still learning this stuff https://www.ecmwf.int/en/forecasts/charts/catalogue/medium-z500-t850-public?facets=undefined&time=2018042600,0,2018042600&projection=classical_europe

sryanbruen

jdcv94 wrote: »

Just noticed that those 850hPa are values for 2am in the morning, and a birdie once told me to add rougly 10-15 degrees onto those values for sea level temps, so would that mean we're looking at 18c+ at night? I'm still learning this stuff https://www.ecmwf.int/en/forecasts/charts/catalogue/medium-z500-t850-public?facets=undefined&time=2018042600,0,2018042600&projection=classical_europe

Temperatures we would likely be seeing in that kind of setup is perhaps high teens and low 20s though really depending on the sunshine during the day dropping to around the low to mid teens during the night which is very warm for May especially so early in the month. I don't add a certain amount to 850hPa temperatures to estimate what they are on the surface personally, I look at things like cloud cover, exact position of heights and pressure and historical occurrences.

I remember last May's very warm spell towards the end featured 850hPa temperatures of around 11 or 12c which brought daytime temperatures up to 23-26c and nightime temperatures not getting much below the mid teens.

GFS 0z does not show what the ECM shows here, just a flat zonal westerly regime with low pressure to the northwest and high pressure to the southeast before going into a northwesterly again way into FI.

JCX BXC

jdcv94 wrote: »

Just noticed that those 850hPa are values for 2am in the morning, and a birdie once told me to add rougly 10-15 degrees onto those values for sea level temps, so would that mean we're looking at 18c+ at night? I'm still learning this stuff https://www.ecmwf.int/en/forecasts/charts/catalogue/medium-z500-t850-public?facets=undefined&time=2018042600,0,2018042600&projection=classical_europe

You add 10-15c in the daytime.

sryanbruen

UKMO 12z has the low for Monday very close to the east of Ireland with a northeasterly airstream. Uncertainty on the exact track of the low for now.

England and Wales will certainly have a washout on Monday with a lot of heavy rain and very cool for the time of year with gusty northeasterly winds making it feel very miserable. More like November weather here.

ARPEGE 12z even shows the chance of snow for parts of England within this low.





If Ireland isn't going to get hit by that low, the end of the ARPEGE run brings a band of heavy rain down from the northwest anyway.

Artane2002

If that ARPEGE verifies then England is going to go crazy!

sryanbruen

ECM 12z was a downgrade on the 0z of the high ridging up to us. A zonal westerly wins over. Anyway, it's FI so not to worry. Plenty of time to change again and again and again.

jdcv94

The ECM and GFS have totally flipped on each other overnight. Now the GFS is indicating at a warm spell on the dates where the ECM 0z was yesterday, which as sryanbruen has posted above, has downgraded.

Ultimate Seduction

jdcv94 wrote: »

The ECM and GFS have totally flipped on each other overnight. Now the GFS is indicating at a warm spell on the dates where the ECM 0z was yesterday, which as sryanbruen has posted above, has downgraded.

Downgraded alright but still doesn't look too bad does it?

sryanbruen

ECM 0z is still good with it being quite similar to last week. Perhaps cloudy out to the west though.

SleetAndSnow

Looks nice for the bank holiday weekend anyway! Orange is back



(courtesy summersun on netweather)

sryanbruen

12z runs are pretty meh, especially in comparison to 0z.

UKMO shows a very unsettled pattern out to the 3rd May (+144 hrs) as far as it can go. There is a big block to the northeast of Europe causing the jet stream to just barely split. The Azores High needs to get itself together to put us in a good scenario here on the UKMO run because a split jet is not good.



GFS shows a reasonable Sunday 6th May with some nice sunny skies to the south dragging up temperatures in the high teens and maybe touching 20c or a bit higher in one or two spots. Much cloudier up to the north though close to low pressure and the jet stream which eventually by mid-week then wins over.



ECM is similar to its 0z run but the upper airs are cooler and low pressure is closer on the 12z meaning more cloud around perhaps with some rain not too far away from western coasts. Although we have quite a good combination of the Azores High and the Scandinavian High here so it would be a bit difficult to push the lows through against them. ECM is not far off a very good pattern for warmth and sun.

sryanbruen

ECM 0z delays the high pressure ridging over Ireland but still gets there in the end with lots of dry weather setting up. Quite warm too. Sunshine is hard to say how much there would be.





GFS 0z meanwhile shows an easterly. Don't think it would be particularly sunny though. Nevertheless, it brings quite warm air from the continent.





Artane2002 asked me to look at the GEM 12z from yesterday and my god, what a stonker of a run that was. High pressure sets up slap bang over top of the country.





So, different solutions are still being thrown at for the May Bank Holiday Weekend but the general theme is for some dry and warm weather from the models for the past few days. Let's hope it continues.

Artane2002

The GEM is a gem

Meteorite58

ECM showing a bit better Temperature wise next weekend but nothing stand out as yet.






Would be great if the jet takes this Northerly route as shown in the GFS away out in F1

sryanbruen

Meteorite58 wrote: »

Would be great if the jet takes this Northerly route as shown in the GFS away out in FI

That would be fantastic if it were to be a thing. This has been a crazy Spring that I will certainly not forget any time soon.

Will report on 12z runs later when they have all released. Looking briefly at the GFS 12z, it's seemingly very good so far in terms of dry weather but not all that warm.

sryanbruen

UKMO 12z shows the high pressure ridging up from the south on Friday 4th May with the jet stream going to the north!



GFS 12z shows completely anticyclonic conditions throughout from the 5th May onwards.







ECM 12z shows two attempts of ridging for 5th and 7th May. The first one goes too far to the south and east to affect Ireland. The second one stays to the south and a zonal regime takes over.

sryanbruen

GFS 0z brings in two ridges from the Azores for the Bank Holiday Weekend on the 4th and 7th but then a northwesterly quickly takes over and breaks down the pattern. With strong high pressures including a combination over Scandinavia with the Azores, I'm surprised how quickly the GFS breaks it down.





ECM 0z shows pretty much what the GFS 12z yesterday was showing with anticyclonic conditions.

Artane2002

The models tend to break down high pressure far too quickly. The GFS particularly does this. We should ignore the breakdown until the potential fine spell happens.

cameramonkey

What sort of temperatures would this give to the south west during this set up?

sryanbruen

cameramonkey wrote: »

What sort of temperatures would this give to the south west during this set up?

Mid-teens around 15 or 16c are the average temperatures you should expect here in a pattern of such at this time of year but sunshine or a slight change in wind direction can make all the difference and you could get up to the high teens or even over 20c.

The temperatures on the model runs aren't overly exciting but it is not as simple to forecast temperatures now as it was in Winter because like I said, you can vary quite significantly from region to region with wind direction and the amount of cloud or sunshine.

This is all FI for now which means it is to be taken with a pinch of salt and just used to look at possible solutions we could have for the Bank Holiday Weekend.

It would be nice to get a dry and sunny spell for a change because this Spring badly needs it after what has been a very dull season so far, possibly the dullest start to Spring since 1992.

Good thing is the NAO is continuing to be very positive for the near future on the GFS ensembles.