FI Charts (T120+ onwards) Summer/ Autumn 2018 READ MOD NOTE IN FIRST POST

hatrickpatrick wrote: »

Briefly, what are the known biases and caveats of the GEM model? For instance, I do know that where the Atlantic tropics are concerned, it has a reputation for being far more generous in upgrading non-tropical lows to tropical cyclones, which other models don't develop and which ultimately don't end up developing. As in, you can look at a CMC/GEM chart of vorticity in the Atlantic tropics and see two or three tropical storms or hurricanes forming throughout a run, where the GFS and ECM don't see any - and more often than not, the GEM does not verify in these circumstances.

Are there any other known biases with this model which we should look out for in the context of our own part of the world?

I don't know of biases with the GEM but I know that it doesn't have a great verification record.

ECM 12z is a flat zonal westerly and perhaps getting very cool quite quick with the air coming off the cold north Atlantic.

Villain

Jesus FI really is all over the place! ECM flipping and flopping too.

I wouldn’t like to try call beyond +120 which makes The Eagles comments too very strange!

Villain wrote: »

Jesus FI really is all over the place! ECM flipping and flopping too.

I wouldn’t like to try call beyond +120 which makes The Eagles comments too very strange!

I suspect that at least some of the current model uncertainty is related to invest 96-L, a disturbance currently off the US coast which is now formally designated by the nhc to become a tropical depression within the next couple of hours. Models seem to have difficulty with our weather when there's a northward moving subtropical disturbance which is not yet classified as a tropical cyclone and will interact with the jet stream at some stage, so I'd expect them to settle a bit once this system fully develops into a tropical cyclone this evening.

96L denoted by a red X on the left hand side of this image:

Special Message from NHC Issued 6 Jul 2018 20:10 UTC
NHC will initiate advisories at 5 PM EDT on Tropical Depression Three located a couple hundred miles southeast of the North Carolina coast.

Cork Boy 53

Villain wrote: »

Jesus FI really is all over the place! ECM flipping and flopping too.

I wouldn’t like to try call beyond +120 which makes The Eagles comments too very strange!

What did he say?

harr

Cork Boy 53 wrote: »

What did he say?

Well he nearly guaranteed good weather for the next 10 days and to be little in the way of rain for remainder of the month..he sounded fairly certain of it ...

Speak Now

harr wrote: »

Well he nearly guaranteed good weather for the next 10 days and to be little in the way of rain for remainder of the month..he sounded fairly certain of it ...

Just his thoughts, nothing certain in a forecast. Let's hope he's bang on

Yes Tropical Depression Three as it is now known is set to become a Tropical Storm on Saturday. Will be interesting to see it's track and if it interacts with the weather tracking across the Atlantic towards us next weekend as depicted by the ECM.

NHC

The depression is moving toward the north-northwest or 335 degrees
at about 4 knots. The tropical cyclone is currently located on the
southwestern edge of the subtropical ridge, and this weak flow
pattern should keep the depression on the same slow track for the
next 24 hours or so. After that time, the steering currents are
expected to collapse, and the cyclone should begin to meander for a
couple of days well off the coast of North Carolina. Then a
mid-level trough is expected to approach from the west and force
the system on a northeastward track.

I believe you can see it in it's early stage to the SW of Bermuda before it tracks up along the Eastern seaboard of the US before being swept over the Atlantic in one form or another ( as a depression ? a Low Pressure system more than likely ).

What the ECM 12Z is showing this evening for next week end, frontal rain , but away too early to know for certain the timing, strength or if it will verify but it has been trending this for a few days in amongst the jumble of charts that has been coming out. Often a sign though that the models are struggling with a big change after a prolonged spell of similar patterns.

sdanseo

The air between the Eastern Seaboard of the US and us is stupidly warm as compared to averages, and without looking, you'd imagine SSTs would be slightly above normal.

Warmer water fuels hurricanes and other cyclones and will contribute to their remnants as well.

(Note: this is not and cannot be an Ophelia when it reaches us. Forecast to track thousands of km too far north for that)

That's all I'll say for now other than that the last few months have thrown the rulebook away - and the fact that we're openly discussing an Atlantic Hurricane before it has even been named in terms of its impact on Ireland is quite extraordinary.

ECM 0Z Keeping the Ridge firmed up to the end of next week with good summer temperatures I would think with highs to the mid 20's and pushing back ( and holding back ) weather coming in from the Atlantic until later in the weekend. Will be interesting to compare the 12Z run to see if it shows another alternative .

cherryghost

This mornings GFS breaks up precip next Sunday, likely mainly cloudy and still warm then, delays any real fall by a day.

EDIT: Recent GFS pegged it back to Sunday again.

GFS 12Z rolling out and if this was to verify it would produce rainfall from next weekend and could turn quite wet with a large shallow area of LP sinking down over the country ( the remnants of Tropical Depression 3 perhaps ).

GFS 12z is cool, unsettled and cyclonic.

GEM 12z = Summer 2018 lives on.

UKMO starts to turn unsettled at the very end.

Yeah, I definitely think Tropical Depression 3 and Beryl are causing a ruckus in the model output. This is just silly at this stage.

If ECM 12z follows history of previous days, it will be an unsettled run. The ECM 12z runs have had a tendency to be unsettled recently even though the 0z runs tended to be settled.

sryanbruen wrote: »

If ECM 12z follows history of previous days, it will be an unsettled run. The ECM 12z runs have had a tendency to be unsettled recently even though the 0z runs tended to be settled.

It does not follow history, staying settled and warm.

sryanbruen wrote: »

It does not follow history, staying settled and warm.

Well then obviously this is the correct model and all the others are just worthless pieces of junk which we can safely ignore

ECM continues to show the ridge over us by Fri, and then gradually dropping in pressure as areas of Lp ( possible depression ) push in from the W. By no means certain. Models still trying to place now named Tropical Storm Chris ( set to become a hurricane )in the mix. See where the remnants ends up on the latest run. This will take many more days to resolve.

Have not done one of these kinds of posts in quite a while now but this is my update on everything and my thoughts on the outlook which in fairness has proved to be a big headache.

To start off, let's have a look at the latest run of the GFS model. What can I say? Well, it's a very different run compared to pretty much every other GFS run we've seen in the past few days. It keeps high pressure going up to and including Sunday 15th (St. Swithin's Day) with further settled and dry weather although some showers possible Thursday/Friday generated by the heat and slacker gradients for a time in the atmosphere. After Sunday 15th, everything goes slack again with average pressure for the third week of July with nothing definitively unsettled or a washout being indicated on this run, just some light rain bands or showers and sunny spells. Temperatures would be going back down towards average over Ireland but as you can see from Tuesday 17th on this run, the cool 850hPa temperatures over the North Atlantic just don't quite get in to Ireland thanks to a continuously anomalous area of above average heights to the east and over the Azores as well as the jet stream splitting into two.

This is a very different run as I said to what we've seen from the GFS these past few days so it's to be taken in isolation as the overall consensus is for a brief unsettled and cooler period - until we start seeing similar runs to this GFS 12z of course.

UKMO keeps things settled and at the end of its run, the high starts to go to the east pulling in a south to southeasterly flow. On this run, this flow looks stable and high pressure dominated so don't expect convection really if the UKMO 12z were to come off. This is different to yesterday's UKMO 12z which wanted things to turn unsettled by that time frame so again like the GFS 12z to be taken in isolation and not very serious until we see trends of it appear.

What is causing all the ruckus? Simply, Tropical Storm Chris. This is the current expected track of Chris up to Friday. It is expected to become extratropical by either Saturday 14th or Sunday 15th as it comes closer to our shores. The exact track of Chris is uncertain. Previous runs showed it coming through us and bringing us a bout of wet and windy weather but today's UKMO and GFS show it well to the north of us barely having an impact on Ireland.

Chris could be the start of an unsettled spell OR it could even prolong the settled weather again! Let's take a trip back to August 2014 and also April this year.

Both lows; ex-hurricane Cristobal on 31 August 2014 and "Irene" on 16 April 2018; promoted ridging over us. The first one, Cristobal, gave away to one of the driest Septembers on record in our countries with barely any rainfall for a lot of places for much of the month following a very wet end to Summer 2014. Meanwhile, Irene gave away to an exceptional warm spell for the time of year (at least in the UK) and later, a very dry May along with a very dry June with lots and lots of high pressure being the dominant influence. Same could happen with Chris this time in prolonging the settled weather again with it helping to ascend more high pressure from the south (which will be bad news). The Azores High is still very strong and ridgey. Add the fact that the GFS was "toying" onto this idea too yesterday well in FI on some runs. I would not be surprised whatsoever if this was to actually happen given how the Summer has turned out so far and with reasons above given light. You could also consider Hector of mid-June.

GFS ensembles seem to have upgraded the warmer than average temperatures too out to Tuesday 17th but we'll see the whole suite soon.

Uncertainty is a big issue out as early as later this week so taking anything serious beyond that time is a bit pointless.

https://twitter.com/RyanMaue/status/1016039339669803008

https://twitter.com/wxcharts/status/1015944371764637698

https://twitter.com/bbcweather/status/1015933677723897856

On the latest ECM 12Z shows remnants of soon to be named Hurricane Chris become absorbed into an already formed large area of LP and move close to our shores towards the end of next week or start of the following week.. In this run the area of LP seems to become blocked by Hp over Europe. Going to go through a lot of different scenarios in the next few days. We will have the remnants of Hurricane Beryl possibly joining into the mix also! If ever there was a time to take the models in FI with an open mind then this is one.

An example of a large area of LP sending warm humid air up over us on this run anyway. This would probably be cloudy and wet also. the Jet in on the action keeping it spinning and windy. Whatever about getting areas of LP in from the Atlantic we don't want them parking on our doorstep for sure. Again all very much subject to change.

GFS 18Z showing the remnants of Hurricane Chris ( see it moving up along East US before coming across over the ridge ) opening the door to the Atlantic. Not showing up as particularly windy on this run but paving the way for rain if it were to happen.

First, I'll start where I finished off from yesterday. The GFS 12z ensembles were an upgrade on the warmth yesterday in FI (they are similar today but the 16th-19th July is quite cool on today's 12z ensembles). They were showing the unsettled spell in terms of temperatures as a blip than a persistent phase with temperatures warming up again after about a week. Precipitation spikes also seemed to lower in FI. But these are just subtle hints more than anything as it's pointless otherwise because of all the uncertainty again.

Now onto today. This is the latest update of Hurricane/Tropical storm Chris. Chris is expected to become a hurricane tomorrow, back to tropical storm status by Friday as it passes by Newfoundland and then become extratropical as it travels over the North Atlantic. The centre of Chris on the latest run of the GFS is expected to be way to the north of Ireland so wind shouldn't be too much of a concern.

The GFS 12z is a changeable westerly flow with rain from time to time and is quite normal Ireland type conditions, nothing overly wet as well as not very dry. Air masses changing different ways with one having warmer than average temperatures and another having average or relatively cool temperatures. The GFS 0z and 06z had a far more unsettled and zonal pattern with unseasonable strong winds along with some quite heavy rain, the 12z seems to have died that down quite a bit but still changeable. These changes from run to run yet again reveal the uncertainty! Giving Thursday's chart (+66 hrs) on this post to show you where Chris is at that stage and watch how it travels up the North Atlantic and combines with the low pressure over Iceland.

UKMO 12z shows everything slack on Sunday 15th and Chris pushing in from the Atlantic.

GFS ensembles are bringing the NAO into negative territory through next week meaning there is signs of the jet stream heading southwards - at least for a time, bringing depressions with it over Ireland. However, the strength of these depressions whether it's the intensity of the rain or the wind is open up to question. GFS 12z suggested light rain over south and eastern regions whilst the north and west would get the bulk of the rain - as you'd expect in a zonal pattern.

I know there will be people throwing their toys out of the pram - there always is some people that do - that Summer is now over, good luck to us next year. I plotted this graph of the daily NAO data for Summer 1976. As you can see, July 1976 had quite a negative NAO index during much of the month in comparison to a positive NAO June and August that year. July 1976 was actually a rather dull and more unsettled month than June and August even though mean temperature wise, it tended to be the warmest month of that Summer.

Basically, plenty more opportunities for more settled weather sometime this Summer and as you've seen, September (even sometimes October) can be an extension to Summer too.

sunbeam

The ECM 12z builds high pressure back in on day 10.

http://www.meteociel.fr/modeles/ecmwf/runs/2018070912/ECM1-240.GIF

Every model producing different results with each run atm.

Can barely keep up with it. The only thing I can see common is the introduction of fronts over the weekend and following showers, how heavy anyone's guess , atm look light enough.

Could get breezy or a bit windy on coasts over the weekend , but not showing too strong atm.

Sat looks warm especially the Eastern half but noticeably cooler by Sunday especially in the Western half , probably under cloud with rain and drizzle. Not as warm of late going into next week ( high teens perhaps, low 20's at best ) possibly improving if the ridge builds again. Models split on this.

Very divided models into next week.

ECM showing what appears to be the chance of an omega block forming out at + 240

Villain

The battle of US and Europe with ECM going very much against the Atlantic but GFS bringing our more usual influence back.

Interesting model runs ahead in the coming days.

Villain wrote: »

The battle of US and Europe with ECM going very much against the Atlantic but GFS bringing our more usual influence back.

Interesting model runs ahead in the coming days.

Either Sryan or Meteorite mentioned a few weeks ago that the GFS has a bias for returning to a typical jet stream / Atlantic dominated regime in FI, so that's probably something to bear in mind.

Villain

hatrickpatrick wrote: »

Either Sryan or Meteorite mentioned a few weeks ago that the GFS has a bias for returning to a typical jet stream / Atlantic dominated regime in FI, so that's probably something to bear in mind.

Yep it does but it's persisting in the last few runs. TBH they all can overplay the lows in FI but the range between is rather big at present

Latest GFS 6z:
gfs-0-174.png?6

ECM 0Z:

hatrickpatrick wrote: »

Either Sryan or Meteorite mentioned a few weeks ago that the GFS has a bias for returning to a typical jet stream / Atlantic dominated regime in FI, so that's probably something to bear in mind.

Correct, sometimes it can even give some weird northerly charts. Let me give some historical examples from GFS 0z runs, I have plenty more though.

I'd advise to not go beyond Tuesday 17th July with the model runs for now.

GFS 0z for Friday 22nd June on 10th June 2018

Actual 22nd June chart

GFS 0z for Sunday 24th June on 13th June 2018

Actual 24th June chart

GFS 0z for Wednesday 24th July on 12th July 2013

Actual 24th July chart

GFS 0z for Wednesday 25th June on 14th June 2014

Actual 25th June chart