Heatwave for end of July?

Su Campu · 27-07-2010 8:54am

Yesterday's 12Z Valentia sounding showed a freezing level around 4.1km (~13,500ft), very high for this part of the world. Corresponding 500-1000 thickness 565dm and tropopause height around 13kms (~42,500ft) and -65°C.

2010072612.03953.skewt.gif

M.T. Cranium · 28-07-2010 6:38am

Good morning, the very warm wedge is approaching ... and I continue to think it has been underpredicted although I totally buy into the dense fog and low cloud scenario for the west, that's more or less unavoidable. But I think people will be commenting on the various threads how warm it feels on Thursday, Thursday night and even into Friday, looking at the air mass upstream now between 25 and 35 W out around 50 N the dew points have held near 19 or 20 C (as they were several days ago in this air mass) and of course temperatures out there are not much higher than sea surface values near 21-22 C. This air mass will clearly hit the west coast with a surface layer near 18/18 full of fog and drizzle, but will begin to warm up over land and potentially it could reach 25-27 C if the sun gets through. The warmest part of the wedge is overhead on Friday morning so the morning lows on Friday are likely to feel oppressive (lows of 17-19 C are possible).

Maybe not a heat wave as such, but certainly a warm event of some note, and it stays a bit warmer than average for a few days afterwards, there are hints of a colder turn mid-week but perhaps this will turn out to be rather bland.

lucy2010 · 28-07-2010 10:30am

M.T. Cranium wrote: »

Good morning, the very warm wedge is approaching ... and I continue to think it has been underpredicted although I totally buy into the dense fog and low cloud scenario for the west, that's more or less unavoidable. But I think people will be commenting on the various threads how warm it feels on Thursday, Thursday night and even into Friday, looking at the air mass upstream now between 25 and 35 W out around 50 N the dew points have held near 19 or 20 C (as they were several days ago in this air mass) and of course temperatures out there are not much higher than sea surface values near 21-22 C. This air mass will clearly hit the west coast with a surface layer near 18/18 full of fog and drizzle, but will begin to warm up over land and potentially it could reach 25-27 C if the sun gets through. The warmest part of the wedge is overhead on Friday morning so the morning lows on Friday are likely to feel oppressive (lows of 17-19 C are possible).

Maybe not a heat wave as such, but certainly a warm event of some note, and it stays a bit warmer than average for a few days afterwards, there are hints of a colder turn mid-week but perhaps this will turn out to be rather bland.

MT what happened on Monday that gave us these bizarre temps of 26/27 c just south of Dublin ?

M.T. Cranium · 28-07-2010 6:32pm

Lucy, I think the Monday temps were created by three factors acting together. First of all, there was a widespread warming over the south and east that was reflected in the official temperatures in the 23-24 C range (and as of last night, Dublin A was not reporting its daily max, perhaps they have it on the system today). Secondly, the higher temperatures you're mentioning were not overlapped by official readings, so they could have been consistent with those reports. However, some of these readings are taken at non-standard observing sites. This does not mean that the reports are wrong, probably the temperature was what was reported at those locations. But the official sites in Ireland are all well away from urban effects and therefore these micro or meso scale climate factors are not reflected in the official readings. I won't be too surprised if the same thing happens tomorrow, official stations may reach 24-25 C and some other readings may be reported into the 26-28 C range.

As to the micro or meso-scale climate, sometimes near the sea skies are clear while the air mass supports 70-80 per cent cloud cover inland, and yet the sea breeze is so weak that it fails to cool in that cleared zone, hence you have the optimal conditions for warming, an urban environment getting full sunshine. I suspect that may have been the meso-scale explanation for what happened on Monday. There again, the air mass arriving tomorrow is similar, and could produce a similar result. Could be a great beach day around the east and south coasts.

For those reading with some technical knowledge, note the high thickness values being advected in with this warm wedge, reaching about 567 dm. This can support 28-30 C and that's a likely max temp for Friday in parts of inland southern England. So it would not be physically impossible for temperatures to reach almost that level in one or two places in Ireland later afternoon on Thursday. I think the dynamics are such that the fog on the west coast may start to break up and allow even some west coast holiday areas to enjoy some 22-24 C warmth by late afternoon.

I remain rather bullish on the thunderstorm potential for Friday also -- the dynamics look fairly strong for 12-18z with the east and southeast being the more likely regions to see a thunderstorm.

Su Campu · 28-07-2010 7:10pm

M.T. Cranium wrote: »

As to the micro or meso-scale climate, sometimes near the sea skies are clear while the air mass supports 70-80 per cent cloud cover inland, and yet the sea breeze is so weak that it fails to cool in that cleared zone, hence you have the optimal conditions for warming, an urban environment getting full sunshine. I suspect that may have been the meso-scale explanation for what happened on Monday. There again, the air mass arriving tomorrow is similar, and could produce a similar result. Could be a great beach day around the east and south coasts.

What about Föhn effect warming MT? With plenty of low level stratus covering the Dublin mountains down to a low level recently, it could have drizzled enough moisture to lead to an extra degree or two of adiabatic warming on the leeward side. This may have happened at the Bray airshow on Sunday, where conditions were perfect while further north I was in low cloud and pretty murky conditions. I was actually surprised to hear the airshow went ahead at all!

doccy · 29-07-2010 12:35am

Hmm, I don't know about heat waves and such but one thing I definitely feel is the surface water of the Irish sea feels warmer this year. I've swam every summer since I was a little kid and it definitely feels...less cold

gurramok · 29-07-2010 9:35am

Its about 14C out now, was a little chilly on that breeze on the hands out walking. Hope it gets a bit warmer later as forecasted to the 28C

pauldry · 29-07-2010 10:18am

what country is 28c promised for? England ? No US? Yes

Ireland will reach 23c at best today and only 28c IN THE SUN or more, not in the shade where temperature readings are recorded

Su Campu · 29-07-2010 10:30am

Yes, the wedge of tropical air MT referred to is only reaching the west coast this evening, so it will really be tonight and tomorrow when its effects will be most felt.

lucy2010 · 29-07-2010 11:31am

pauldry wrote: »

what country is 28c promised for? England ? No US? Yes

Ireland will reach 23c at best today and only 28c IN THE SUN or more, not in the shade where temperature readings are recorded

Good to see what we get today remember Trogs weatherstation hit 26.9c on Monday & im a bit up from the sea from him. Im not too bothered on excessive temps just enjoyin the " dryness" for change

delw · 29-07-2010 1:23pm

ME forcast after 1 o'clock news has ireland with a max of 20c for today

Mobhi1 · 29-07-2010 1:25pm

Yea, can't see us reaching high temps today. Still below 18C in most of the country. The warmest is only 18C in Valentia, nearest the "warm wedge".

Mobhi1 · 29-07-2010 3:16pm

Think we'll be doing well to reach 20C here, anyway!

Domscard · 29-07-2010 3:34pm

Grey and dull here in east Donegal. The only heatwave I'm getting is when I stand close to the fire

M.T. Cranium · 29-07-2010 4:25pm

This warm wedge has been underperforming so far, I do notice on satellite imagery that clearing skies have begun to spread further east so it may turn out fairly warm for the evening in the south and possibly the east, but basically the inversion seems to have remained fairly strong despite the high sun angle of July, and given a result more like perhaps November with the thickness pattern. Note, the wedge may be centered further west at present but the 564 dm thickness contour has crossed Ireland with the 570 dm thickness forming a ridge just to the southwest of Kerry now (from the 12z chart just in).

I'll have to see if I can find a logical explanation of the disconnect that took place between thickness and surface temperature, other than marine layer dynamics, because it seems that the temperature has not responded very well over the UK either. It's probably just one of those things where there were two possible outcomes and not enough energy was available to shift the inertial outcome to the dynamic outcome. That may have consequences for tomorrow's forecast, will have to see how the next model run handles that situation.

delw · 29-07-2010 4:33pm

like you say MT hopefully we get a nice evening however with only a couple of days left in july fingers are crossed for sunny weather in august

gurramok · 29-07-2010 10:08pm

pauldry wrote: »

what country is 28c promised for? England ? No US? Yes

Ireland will reach 23c at best today and only 28c IN THE SUN or more, not in the shade where temperature readings are recorded

Smart are we?

I've always been lead to believe temp recordings from forecasts are based on been recorded in the shade not in the sun.

Read MT's post of explanation for todays unexpected temp readings.

Had to close the window, its a little cool outside now, no muggy night in store so far!

adamski8 · 29-07-2010 10:31pm

owenc wrote: »

Don't beleive me then you mustn't be too good a geography because it is!

http://en.wikipedia.org/wiki/British_Isles

owenc wrote: »

Yes he is hes trying to deny it because it has the word "british" in it:rolleyes:.... its 9.5c here!:eek:

owenc wrote: »

Hes being sarcastic.:rolleyes::rolleyes:

no i wasn't being sarcastic! hahaha you made me laugh though!
i dont have any problem with the word british.

Su Campu · 29-07-2010 10:44pm

M.T. Cranium wrote: »

This warm wedge has been underperforming so far, I do notice on satellite imagery that clearing skies have begun to spread further east so it may turn out fairly warm for the evening in the south and possibly the east, but basically the inversion seems to have remained fairly strong despite the high sun angle of July, and given a result more like perhaps November with the thickness pattern. Note, the wedge may be centered further west at present but the 564 dm thickness contour has crossed Ireland with the 570 dm thickness forming a ridge just to the southwest of Kerry now (from the 12z chart just in).

I'll have to see if I can find a logical explanation of the disconnect that took place between thickness and surface temperature, other than marine layer dynamics, because it seems that the temperature has not responded very well over the UK either. It's probably just one of those things where there were two possible outcomes and not enough energy was available to shift the inertial outcome to the dynamic outcome. That may have consequences for tomorrow's forecast, will have to see how the next model run handles that situation.

I don't know but I think it was just too much boundary layer modification as it slowed down over the Atlantic. The 06Z and 12Z FAX charts depict warm frontolysis in a slack flow, which would back this theory up. The 18Z Valentia sounding shows the strong inversion above around 900hPa, capping a well mixed boundary layer containing a 1500ft thick cloud deck. Without this cloud the sounding would suggest a Tmax around mid-high 20s, but the cloud deck ruined it on us. I think it was just too much marine track for it to hold onto its heat

12_UKMet_Boden+00.gif

pauldry · 29-07-2010 10:59pm

gurramok wrote: »

Smart are we?

I've always been lead to believe temp recordings from forecasts are based on been recorded in the shade not in the sun.

Read MT's post of explanation for todays unexpected temp readings.

Had to close the window, its a little cool outside now, no muggy night in store so far!

Not being smart at all. Just giving my opinion. It didnt get at all warm today did it? Yes MT explains it well. Maybe we'll get the 23c tomorrow or even the 28c which would be better again.

It seems to be quite difficult to predict conditions in July in Ireland. One of my friends said .... no its not its just 18 or 19c every day and 12 or 13 at night. Hes right most of the time for Sligo anyways.

M.T. Cranium · 29-07-2010 11:54pm

Thanks for posting that SC, I noted the Valentia sounding had a tight cap on the inversion from 500 to about 1200 metres, when this breaks up tomorrow morning it could become rather unstable so we'll have to watch carefully how the cold front develops moving into this stable (not so) warm wedge. This may also under-perform or it might just decide to go off with a bang someplace.

ch750536 · 30-07-2010 1:42am

MT, I mentioned a week ago that it felt like the grey muck was here to stay, perhaps that's just from living here. It still feels like grey muck is here to stay. You have to be here to appreciate just true grey muckeyness, is very hard to forecast as nowhere on earth can be that dull for that long.

gurramok · 30-07-2010 7:10am

Its like a winters morning outside except for the temp. Its raining and very dull, temp about 15C. No breeze at all though.

Plug · 30-07-2010 8:31am

Its the end of July, so no heatwave. Typical crap, I suppose we will have to wait till the end of August then:rolleyes:

Graces7 · 30-07-2010 8:34am

ch750536 wrote: »

MT, I mentioned a week ago that it felt like the grey muck was here to stay, perhaps that's just from living here. It still feels like grey muck is here to stay. You have to be here to appreciate just true grey muckeyness, is very hard to forecast as nowhere on earth can be that dull for that long.

Echoing this; Ireland is very... experiential. And very atmospheric. Things that go beyond science.

"grey muck" is indeed the phrase to be used these days. Deluges and thick, heavy cloud cover that deadens all senses.

Time to hibernate!

ciaran67 · 30-07-2010 8:41am

Plug wrote: »

Its the end of July, so no heatwave. Typical crap, I suppose we will have to wait till the end of August then:rolleyes:

Im moving to Toronto. I think next summer will be rather 'auntie Betty'

Mobhi1 · 30-07-2010 11:31am

Just looking at GFS FI. It's got HP over us from 7th to 15th August and 10-15 850hpa temps and has us in 564 dam air for most of the time.:eek: And we might get continental air rather than Atlantic air. What are the chances of that coming off? And I'm on holiday that week too! New thread for mid-August heatwave anyone?

Gonzo · 30-07-2010 12:49pm

I wouldnt get excited yet about a heatwave, this weeks heatwave turned out to be nothing more than cloudy weather with barely a glimse of sunshine and temperatures around 18C for most of the week and now it's pouring rain, we've had just another crap July with struggling temperatures and mostly cloudy and wet conditions and the outlook into the beginning of August is cool, wet and miserable. Im just about to give up hope for the rest of this summer.

lucy2010 · 30-07-2010 12:57pm

Its been a mucher better end to July here than other years. We had a few drops this mornin but there has been no rain here in over a week which is what I call a miracle..Its grey between the sun but for the first summer in years the kids are out playing which has created many a happy mammmy. ive tons of ironing of do as got so mch dry rather than using the dryer so im pleased enough. Its been very warm too here - 20's most days ... When I think back to the last few summers - yuck !

Domscard · 30-07-2010 2:21pm

Another damp squib summer here in Donegal - looking at the long term forecast for my area on Yr.no and there's rain forecast for every single day for the foreseeable - very little sun showing in any of the icons. This grey muck is just headache weather

I'm giving up now ... hello winter :mad:

Graces7 · 30-07-2010 3:04pm

lucy2010 wrote: »

Its been a mucher better end to July here than other years. We had a few drops this mornin but there has been no rain here in over a week which is what I call a miracle..Its grey between the sun but for the first summer in years the kids are out playing which has created many a happy mammmy. ive tons of ironing of do as got so mch dry rather than using the dryer so im pleased enough. Its been very warm too here - 20's most days ... When I think back to the last few summers - yuck !

Where are you? Sounds.. heaven! Not even daring to do washing as cannot afford to run a drier and no way of hanging it out in this weather..

Graces7 · 30-07-2010 3:07pm

Please correct me on this by all means.. But in my early years in Ireland we had a heatwave in I think August? Temps into the 80s.

I am here nearly ten years now so that narrows the scope...

mike65 · 30-07-2010 3:09pm

1995 was the last real stinker, just a few periods of warm summer since then like 2006.

goat2 · 30-07-2010 3:12pm

Domscard wrote: »

Another damp squib summer here in Donegal - looking at the long term forecast for my area on Yr.no and there's rain forecast for every single day for the foreseeable - very little sun showing in any of the icons. This grey muck is just headache weather I'm giving up now ... hello winter :mad:

i am also looking forward to winter
we have nothing but drizzle fog and rain here and there seem to be no end to it, hard to get lawn cut, or clothese line dried,
have better chance in the winter, may be a few degrees cooler, but it is a lot more days dry,

Mobhi1 · 30-07-2010 3:39pm

The weather was good here from April to the beginning of July and the last week has been relatively OK. So instead of heading back to winter we really need to head back to May/June!

It's got very warm and humid here near Dublin city centre in the last while, since the rain stopped. Must be in the warm wedge of air now - I see DP for Dublin is 18C! All we need now is some sunshine.

Danno · 30-07-2010 3:57pm

2003 was a great summer.

lucy2010 · 30-07-2010 7:25pm

Graces7 wrote: »

Where are you? Sounds.. heaven! Not even daring to do washing as cannot afford to run a drier and no way of hanging it out in this weather..

Grace you really dont get the best of weather do you. Like you though I was housebound in the snow - I have a steep driveway & had solid ice for 2 weeks ... Eventually we had to winch the car out.... Im just south of Dublin by the sea.. It is possibly the best summer in many years.... beautiful & not even the sea breeze is cooling us like it should be. I did however attach the sun brolley to the clothes line thee a few weeks ago as was fed up with non-drying - it worked a treat but ive now had the pleasure of removing .. beautiful evening.. Ive been sitting out in the sun since about 5 having a good read ... Listening to all the kiddies out playing ....very hot between clouds.. Trog's station hit 22.4 down on the beach there just after 5 so would imagine a bit warmer up here with me... Very relaxing weather. Im not bragging but I honestly havent found myself this chilled out in a long long time.

Domscard · 31-07-2010 2:54am

lucy2010 wrote: »

It is possibly the best summer in many years.... beautiful & not even the sea breeze is cooling us like it should be. I did however attach the sun brolley to the clothes line thee a few weeks ago as was fed up with non-drying - it worked a treat but ive now had the pleasure of removing .. beautiful evening.. Ive been sitting out in the sun since about 5 having a good read ... Listening to all the kiddies out playing ....very hot between clouds.. Trog's station hit 22.4 down on the beach there just after 5 so would imagine a bit warmer up here with me... Very relaxing weather. Im not bragging but I honestly havent found myself this chilled out in a long long time.

JEALOUS

alentejo · 31-07-2010 3:55pm

I think the heat wave is a non-runner??

Seems that the end of July was a matter of some over ambitious forecasts, which never materialised. Ireland has very difficult weather to forecast for any time span, which is over 2/3 days.

Gonzo · 31-07-2010 7:12pm

this summer is like chasing cold snaps in the winter, the good weather always seems to be close by but never makes it to Ireland.

thetonynator · 31-07-2010 9:08pm

Gonzo wrote: »

this summer is like chasing cold snaps in the winter, the good weather always seems to be close by but never makes it to Ireland.

except we had a lot more success chasing cold snaps than we had chasing sun. .

Heatwave for end of July?

Comments