Spring 2021 General Discussion

Donegal Storm

Mostly cloudy here again after a sunny morning :rolleyes: Finally cleared up the late evening but the sun was already low in the sky by that point. Hopefully better tomorrow

Gaoth Laidir

compsys wrote: »

I'd report anything within 20km as coastal or at least being affected by the sea breeze. So yes PP too - which is not surprising as I think most Dubliners would agree they live 'close to the sea' - though maybe not ON it.

I'm saying PP, DA and Johnstown Castle (and Cork Airport maybe) will ALL be a few degrees cooler than the West this week during the day due to the sea breeze but DA will be the only one with the very cool nights.

I actually thought JC was right ON the sea. I didn't realise is was almost the same distance inland...

But as you've mentioned it - let's take 15th April - DA got down to -3º - that's a heavy frost. JC went to 2.3º only while Cork got to 3º. All relative similar distances from the sea.

Mainly on calm nights only though.

Quite often I've seen nights in summer where you have had 8º to 10º 850 temps over the country - temps widely over 20º during the day - a 13º sea - every station will have a relatively warm and sultry night and DA will stick out as having gone close to the freezer.

I would like to see actual data to statistically back this up because I've been keeping an eye on it for years and I've not found anything out of the ordinary. Oneiric's Met.ie data show 29 air frosts per year versus Casement's 39. Both have 82 ground frosts (noting the relocation of the DA station within that climate period).

Many nights DA will go under zero when frost won't have been mentioned at all on the forecast.

BTW I agree that PP has its own issues too probably. Though nothing like Shannon.

Perhaps it's in a perfect location. My main point is that it's unusual for a station to be so heavily influenced by the sea during the day and to lose that influence during the night. Out of all the stations within 20km of the sea, I'd imagine DA experiences the highest number of frosts?

There is a sweetspot of X km inland where a location is affected by both sea breeze during the day AND a land breeze during the night. DA could be in this location. Both Dunsany and Casement may be too far inland to be greatly affected by the sea breeze during the day, meaning they will start the night off warmer and hence won't as easily cool to the level of Dublin Airport, which will have been cooler during the day.

There have been some comments here down through the last few years claiming that the DA station has to be reading incorrectly, along the same lines of the complaints about the bad radar coverage in some areas of the country. I've never accepted these claims as I know both the station and area well. I'd have more of an issue with other stations around the country, such as Shannon Airport, which we've seen reads high in easterly wind regimes due to the huge 21,000 m² carpark surrounding its station. This is therefore feeding erroneous data into the weather models. These models take into account the local topography and soil properties, but to have the artificial effect of a manmade influence like that can only lead to model error. Garbage in, garbage out.

Oscar Bravo

Max today:

Shannon airport 17.8 degrees
Valentia 17.2
Athenry 16.9
Gurteen 16.8
Mount Dillon 16.7

compsys

Gaoth Laidir wrote: »

I would like to see actual data to statistically back this up because I've been keeping an eye on it for years and I've not found anything out of the ordinary. Oneiric's Met.ie data show 29 air frosts per year versus Casement's 39. Both have 82 ground frosts (noting the relocation of the DA station within that climate period).



There is a sweetspot of X km inland where a location is affected by both sea breeze during the day AND a land breeze during the night. DA could be in this location. Both Dunsany and Casement may be too far inland to be greatly affected by the sea breeze during the day, meaning they will start the night off warmer and hence won't as easily cool to the level of Dublin Airport, which will have been cooler during the day.

There have been some comments here down through the last few years claiming that the DA station has to be reading incorrectly, along the same lines of the complaints about the bad radar coverage in some areas of the country. I've never accepted these claims as I know both the station and area well. I'd have more of an issue with other stations around the country, such as Shannon Airport, which we've seen reads high in easterly wind regimes due to the huge 21,000 m² carpark surrounding its station. This is therefore feeding erroneous data into the weather models. These models take into account the local topography and soil properties, but to have the artificial effect of a manmade influence like that can only lead to model error. Garbage in, garbage out.

I think in that case DA has definitely hit the sweet spot.

For example this morning DA fell to -0.3º between 3 and 4am or so. The coldest in the country apart from MT Dillion.

This compares to lows of 8 degrees or so for JC and Cork. Even Dunsany, which is more inland, held warmer.

Last April and May are good examples of what happens during settled weather. They were both very sunny, warm and very settled months. Here are the temp stats against LTAs for Dublin.

April
Casement +1.4º
PP +1.5º
DA +0.4º (coldest location in the country)

May
Casement +1.3º
PP +1.5º (warmest location in the country!)
DA +0.2º (coldest location in the country - its average max for May was actually a good bit above its LTA but its average min was below average).

I know the station has been moved to a 'colder' location making comparisons difficult but given the huge LTA anomalies posted for the other Dublin stations you'd have expected something a bit warmer.

Again it only happens on clear, calm nights which is part of the reason I find it interesting - it means DA is often a 'warmer' location during wet, and cloudy months when the weather is poor than it is during dry, sunny and settled months as the temp usually drops like a stone in these conditions after dark.

KanyeSouthEast

It’s a beautiful dry sunny blue sky day here but Jesus that f-ing wind!

Graces7

KanyeSouthEast wrote: »

It’s a beautiful dry sunny blue sky day here but Jesus that f-ing wind!

Ah it muted to a gentler warm breeze. At the front anyway! My place lies north to south as many very ocean-exposed houses tend to do so I can have two different weathers

Sheerly lovely out there now. The roof is ticking. which means the sun is strong! Not heard that much this year.

West Mayo offshore

OldRio

Stunning morning here but it clouded over at 11.00am and a cool wind replaced the Sun. Dissapointing.
Leitrim.

US2

Sun just out here now. Think we will hit the 18c mark today.

Thelonious Monk

Beautiful in Howth now, feels warm, no wind.

Tyrone212

Two more air frosts at Castlederg since I last posted. Bringing the total to 12 for this month. Almost 3 times the average of 4.4. Currently 16c and -1 to -2 expected tonight.

Tyrone212

Belmullet 18c at 3pm.

Tyrone212

Tyrone212 wrote: »

Belmullet 18c at 3pm.

9.6c down here on the east coast thanks to the marine layer
Little to no breeze but that layer of air is getting in a few km's
Not a cloud in the sky
Sat pic's today will be nice

pad199207

Humidity down to 27% here

pad199207

pad199207 wrote: »

Humidity down to 27% here

Thats the SE flow coming over the mountains to you really drying out the air
Its 55% here on the opposite side of them

pad199207

Marine Layer wrote: »

Thats the SE flow coming over the mountains to you really drying out the air
Its 55% here on the opposite side of them

Phew! I thought another humidity sensor is after failing on me

pad199207

pad199207 wrote: »

Phew! I thought another humidity sensor is after failing on me

No you're safe enough in that department
A station nestled near knockananna near Lug is at 36%
Dryer still by the time the flow gets fully across

pad199207

Marine Layer wrote: »

No you're safe enough in that department
A station nestled near knockananna near Lug is at 36%
Dryer still by the time the flow gets fully across

Nivea time!!

Gaoth Laidir

The air inland is probably no drier than your air, Marine Layer. It's just that your temperature is lower, making your r.h. higher. I bet both dewpoints are around the same. The mountains can't dry the air out if it's not raining on the windward side.

Gaoth Laidir

compsys wrote: »

I think in that case DA has definitely hit the sweet spot.

For example this morning DA fell to -0.3º between 3 and 4am or so. The coldest in the country apart from MT Dillion.

This compares to lows of 8 degrees or so for JC and Cork. Even Dunsany, which is more inland, held warmer.

Last April and May are good examples of what happens during settled weather. They were both very sunny, warm and very settled months. Here are the temp stats against LTAs for Dublin.

April
Casement +1.4º
PP +1.5º
DA +0.4º (coldest location in the country)

May
Casement +1.3º
PP +1.5º (warmest location in the country!)
DA +0.2º (coldest location in the country - its average max for May was actually a good bit above its LTA but its average min was below average).

I know the station has been moved to a 'colder' location making comparisons difficult but given the huge LTA anomalies posted for the other Dublin stations you'd have expected something a bit warmer.

Again it only happens on clear, calm nights which is part of the reason I find it interesting - it means DA is often a 'warmer' location during wet, and cloudy months when the weather is poor than it is during dry, sunny and settled months as the temp usually drops like a stone in these conditions after dark.

Dublin Airport was almost cloud-free overnight and this morning while Johnstown Castle was reporting 5-7 okta, hence the higher minimum. Grass minimum there was +2 °C while it was -3 °C at D.A. Cork Airport had 4 okta throughout the night. Unfortunately Dunsany doesn't report cloud cover.

Looking at the Met.ie monthly temperature curves for April last year there was a notable northeasterly sea-breeze effect at Dublin in the last week of the month, which was much less pronounced at Casement, given the much longer land and urban track from that direction. This affected both maxima and minima at Dublin. Had this been more of an easterly I reckon the difference between the two would have been less pronounced.

Gaoth Laidir

Gaoth Laidir wrote: »

The air inland is probably no drier than your air, Marine Layer. It's just that your temperature is lower, making your r.h. higher. I bet both dewpoints are around the same. The mountains can't dry the air out if it's not raining on the windward side.

My dp is 0.8c
Pads is -1.8c
Nearly 3c of a difference
Both of us are at opposite ends of the mountain range
Rh does drop a lot if your air flows over the mountains in my experience especially if its northerly or northwesterly cyclonic variable here
I'm assuming the same dynamics working in reverse direction

Graces7

Lovely to have it light so blessedly early. I " call home" to Canada early and can now go for a walk afterwards watching the light waken ang grow over the ocean as the birds shout their song melodiously.


The sky so changeable as it wakes. Today, striated horizontal gray and rose.. ripening then to gray and white..

And calm and serene. A gently day. Kindly.

UPDATE! it has morphed into a chilling shivery morning.. Pften is like that when lovely so early. There used to be a saying, " Sun before seven, rain by 11"...

Often early beauty is misleading But it WAS lovely

West Mayo offshore.

KanyeSouthEast

Breezy slightly overcast temp 4 degrees real feel 1 degree at 8am. Disappointing really was hoping to see the blue skies and sun today. Hopefully picks up during the day that east wind is cold.

pauldry

Cloudy here too. Not much mention of cloud on forecast but Met might change it to something like some cloudy spells likely on Atlantic coasts

c/o Met Eireann
Today will be dry and bright with spells of hazy sunshine. Mild and pleasant with highest temperatures of 12 to 18 degrees, mildest in the west, with slightly cooler temperatures along eastern and southern coasts owing to onshore breezes. East to southeast breezes will be mostly moderate in strength, stronger at times along Munster coasts.

Oneiric 3

Looking at this 7 day temperature trend forecast map, it looks as if it could be a case of 'make the most out this current shallow warmth while you can!'

Supercell

Gaoth Laidir wrote: »

The air inland is probably no drier than your air, Marine Layer. It's just that your temperature is lower, making your r.h. higher. I bet both dewpoints are around the same. The mountains can't dry the air out if it's not raining on the windward side.

Would there not also be an element of condensation against cooler mountain surfaces higher up drying out air also at play too? (assuming the dew point temperature is reached on these surfaces).

OldRio

Cloudy day which after watching and reading the forecast, I'm surprised at.
I forgot to mention the wind. Biting.
Leitrim.

Tyrone212

Mt Dillon and Dublin airport were 0c when I checked last night.

Castlederg got down to -2. Monaghan and Kilygordon -2 last I saw but no way to get the lowest temperature for them on NRA weather.

Gaoth Laidir

pauldry wrote: »

Cloudy here too. Not much mention of cloud on forecast but Met might change it to something like some cloudy spells likely on Atlantic coasts

c/o Met Eireann
Today will be dry and bright with spells of hazy sunshine. Mild and pleasant with highest temperatures of 12 to 18 degrees, mildest in the west, with slightly cooler temperatures along eastern and southern coasts owing to onshore breezes. East to southeast breezes will be mostly moderate in strength, stronger at times along Munster coasts.

The word "spells" would indicate the presence of cloud.

pauldry

Yes cloudy here too but sun visible under the cloud. Very high cloud I guess.

Tomorrow will be the best day in the West.

It's a Saturday. Sundays are never as good.

Gaoth Laidir

Supercell wrote: »

Would there not also be an element of condensation against cooler mountain surfaces higher up drying out air also at play too? (assuming the dew point temperature is reached on these surfaces).

Well that would be in the form of cloud, which I'm not sure was there yesterday. There'd be no condensation on surfaces during the day in sunshine like yesterday.

The only other explanation for a reduction in surface dewpoint inland yesterday would be through rising thermals mixing out the boundary layer and forming clouds, which we see did happen from around Kildare west yesterday.