Warm sectors - always milder than forecast

Nqp15hhu · 31-12-2020 9:06pm #1

I don’t know what causes this. But in a given warm sector I always notice:

1. It is very windy where I live. Warm sectors are rarely calm here.
2. Temperatures are a lot milder than forecast.

For example, today we were forecast 5c and the temp rose to 6.7c which is warmer than predicted.

Any particular reason for this? Wind?

Any other day, the temps are close to those progged.

31-12-2020 9:17pm

Sun I'd say
My Davis gets good exposure south facing to the sun and can spike at this time of the year for a half hour or that
That said, today's max in the sun here in SE wicklow was only 4.5c

Nqp15hhu · 31-12-2020 9:21pm

AuntySnow wrote: »

Sun I'd say
My Davis gets good exposure south facing to the sun and can spike at this time of the year for a half hour or that
That said, today's max in the sun here in SE wicklow was only 4.5c

We had plenty of sun yesterday and only had a 2c high so that’s not the case.

Danno · 31-12-2020 9:24pm

Any higher ground of say 350m or higher? If the high ground is between you and the prevailing wind, chances are you're getting a local fohn effect.

Nqp15hhu · 31-12-2020 9:26pm

Danno wrote: »

Any higher ground of say 350m or higher? If the high ground is between you and the prevailing wind, chances are you're getting a local fohn effect.

Slightly to my north.

31-12-2020 9:28pm

Nqp15hhu wrote: »

We had plenty of sun yesterday and only had a 2c high so that’s not the case.

Ah yeah but sun can have different effects at different times of the day
As you have a Davis, can you post a graph of today and yesterday temperatures so we can see the ebbs and flows on both days
The environment your station is in too eg a small garden can effect it
Steam from a boiler that's blowing its way for instance

Nqp15hhu · 31-12-2020 10:15pm

AuntySnow wrote: »

Ah yeah but sun can have different effects at different times of the day
As you have a Davis, can you post a graph of today and yesterday temperatures so we can see the ebbs and flows on both days
The environment your station is in too eg a small garden can effect it
Steam from a boiler that's blowing its way for instance

Not really the fan works well.

Oneiric 3 · 31-12-2020 10:31pm

Nqp15hhu wrote: »

For example, today we were forecast 5c and the temp rose to 6.7c which is warmer than predicted.
.

Models are really only there to give you a rough guide. Rarely if ever are they ever spot on. Harmonie model (met eireann)for example has me down for 2c currently, but the actual temp is 4c.

Nqp15hhu · 31-12-2020 10:34pm

Just wondering if my station is over reading or if the hill behind my house is contributing to it.

The two nearest stations say 5.5c

31-12-2020 10:35pm

Nqp15hhu wrote: »

Not really the fan works well.

The fan will only mix in the boiler steam, it won't restore temp it will still rise
Regardless, I think oneiric has given you the best answer

Kermit.de.frog · 31-12-2020 10:35pm

The temperature modelling these days in typical short range 1 - 3 day forecasts I find to be exceptionally accurate through all layers. However, you can't legislate for every local effect that may be subject to more mesoscale variables distinctive to the location whether it's nestled against hills, in a valley, beside the sea etc...

Oneiric 3 · 31-12-2020 10:36pm

Nqp15hhu wrote: »

Just wondering if my station is over reading or if the hill behind my house is contributing to it.

The two nearest stations say 5.5c

Malin Hd, not far from you, is currently reading a rounded 7.0c, so pretty much same as your reading going from your attached pic.

Nqp15hhu · 31-12-2020 10:52pm

Oneiric 3 wrote: »

Malin Hd, not far from you, is currently reading a rounded 7.0c, so pretty much same as your reading going from your attached pic.

It’s about 50 miles away and my temps are usually lower.

31-12-2020 11:06pm

Nqp15hhu wrote: »

It’s about 50 miles away and my temps are usually lower.

Same Ocean though at same latitude
Yours is a half degree lower
(I think we can rule out the boiler)
Aswell as that,a Met Eireann station will be located in a more exposed location than a cold garden
In better conditions than in an enclosed small garden say, where the ground mightnt have had as much of a chance to warm up after a frost

Oneiric 3 · 31-12-2020 11:14pm

AuntySnow wrote: »

Same Ocean though at same latitude
Yours is a half degree lower
(I think we can rule out the boiler)
Aswell as that,a Met Eireann station will be located in a more exposed location than a cold garden
In better conditions than in an enclosed small garden say, where the ground mightnt have had as much of a chance to warm up after a frost

Temps look pretty much uniform along that general northwest/north coast region at the moment on the met eireann map:

31-12-2020 11:53pm

Oneiric 3 wrote: »

Temps look pretty much uniform along that general northwest/north coast region at the moment on the met eireann map:

Indeed!
I see the Bushmills one on that wow.met.ie maxed out at 4.7c yesterday with a dewpoint of 1.2c
McGilligan maxed at 3c further inland
Neither of them had a sub zero dew point at any point in their hourly yesterday so their wet bulbs must have been 1 or 2 c aswell
Just shows how big the Atlantic mixing effect/marine layer is along the north coast on whats a weak enough cold flow anyway

Nqp15hhu · 01-01-2021 12:18am

That bushmills station is very mild. It records 5c when it was 0.5c here at 6am this morning! Odd

Gaoth Laidir · 01-01-2021 2:00am

Nqp15hhu wrote: »

It’s about 50 miles away and my temps are usually lower.

Malin Head is only 27 miles (44 km) as the crow flies from Limavady. Magilligan No. 2 is 14 km from you and Derry Eglington airport 15 km.

Midnight readings from the first two (Eglington airport is closed)

Malin Head 6.7
Magilligan 6.3

Nqp15hhu · 01-01-2021 6:22am

And yet often they have rain whilst I have snow a prime example of this was the other night, heavy rain the whole way down the road, which then turned to snow on my road.

polarhullar · 01-01-2021 7:16am

Gaoth Laidir wrote: »

Malin Head is only 27 miles (44 km) as the crow flies from Limavady. Magilligan No. 2 is 14 km from you and Derry Eglington airport 15 km.

Midnight readings from the first two (Eglington airport is closed)

Malin Head 6.7
Magilligan 6.3

Eglinton**

Nqp15hhu · 01-01-2021 8:20am

So the Malin Head station is 29 miles from me. I did not realise it was that close as it is 90 minute drive and further than Belfast by car.

I am equidistant with that and the ballypatrick forest station.

I would say my weather is more of a mix of magilligan and lough fea. There have definitely been times when we have a covering here and it is raining at magilligan.

I also notice Malin head is a lot warmer on crisp winter days.

Nqp15hhu · 01-01-2021 8:22am

On the 30th Malin heads high was 3c warmer than here.

https://www.ogimet.com/cgi-bin/gsynres?lang=en&ind=03980&decoded=yes&ndays=2&ano=2020&mes=12&day=30&hora=18

Gaoth Laidir · 01-01-2021 10:54am

Nqp15hhu wrote: »

On the 30th Malin heads high was 3c warmer than here.

https://www.ogimet.com/cgi-bin/gsynres?lang=en&ind=03980&decoded=yes&ndays=2&ano=2020&mes=12&day=30&hora=18

Malin Head is practically surrounded by sea on 3 sides, so it'll not get the lows that your location would get.

Lough Fea is at 225 m amsl, so it may be colder than you in some situations but actually warmer in others (e.g. flat calm frosty nights, when the cold air pools down at lower altitudes and it's up in an inversion).

Nqp15hhu · 01-01-2021 11:03am

Gaoth Laidir wrote: »

Malin Head is practically surrounded by sea on 3 sides, so it'll not get the lows that your location would get.

Lough Fea is at 225 m amsl, so it may be colder than you in some situations but actually warmer in others (e.g. flat calm frosty nights, when the cold air pools down at lower altitudes and it's up in an inversion).

The point is that it’s not as mild.

01-01-2021 11:38am

Nqp15hhu wrote: »

The point is that it’s not as mild.

Welcome to the vagaries of weather
On the evening of December 30th,I drove an approximate 12 mile round trip inland from home 2kms from the coast to a point about 10kms inland at the other side of croghan mountain under clear skies
The road rises to about 1100ft and my destination was at about 600ft asl
I'm at 162 ft asl
Minus 1.9 at home
Driving further inland the temp rose to 2c under the same clear skies
A long stretch of the road was around 1c and dipped to -1c at my destination at the other side of the mountain
Varying temperatures of varying pockets of air,that bear NO relation to the weather in precipitation because the precipitation type depends on the temperature of the air from the cloud base to the ground and how saturated it is
If the precipitation is falling for too long through air above freezing even if the last 1000ft is freezing or below after an inversion frost that hasn't warmed up yet, you'll have rain,freezing rain
I guess my point/advice is to not be stressing about ground level location temp
Looking at the current pattern, I've never seen anything similar and we've no idea what is going to happen to the pv yet ,where if anywhere its daughter lobes go if displaced/split BUT my hunch is settling snow in the next month is coming
It has to if the current pattern continues long enough because our weather is coming from areas less impacted by the warm NAD and partly for example next week not at all impacted by it
Thats continental climate territory

Oneiric 3 · 01-01-2021 11:42am

Nqp15hhu wrote: »

The point is that it’s not as mild.

Temps can vary from mile to mile and place to place, even over a small area. You have a great weather station that is very accurate and will read accurately for whatever place you have it located. It doesn't matter your garden temp is reading colder or warmer than another nearby station, it is still reading correct temperature for your garden so enjoy it for what it is.

Meteorite58 · 01-01-2021 12:09pm

Yeah I have no doubt the bottom of my garden which is at the bottom of a slight decline is colder than the middle or the top of the garden . Cold air definitely pools down there that bit more in cold settled weather, you can even feel it when you walk down there and more so behind the ditch where the sunlight is slow to reach and will hold the frost the longest. My car is usually parked on the N side of the house and would normally frost over quicker then if on the S side. My weather station is sited about middle of the garden but my trees have grown a lot over the years and would be recording slightly higher now more so in Summer than if on open land. Being away from concrete footpaths and walls and having near the correct height is a must though to keep the temp readings somewhat more naturally accurate for a site. I have taken my sensor out and put it into a homemade Stephenson's screen for more accuracy.

My site here in North Kerry occasionally gets higher readings than official stations in Kerry and Shannon as I benefit from a noticeable fohn effect when the winds are from the SE and humid and rise over the Slieve Mish Mts, often getting 1 or close to 2 degrees more, such is the nature of local weather.

You have a great station , very interesting to be able to see over time how weather patterns can effect an area differently even over short distances.

pauldry · 01-01-2021 1:15pm

In the park less than 1k from here night time temperatures are a couple of degrees colder and in the park itself the far side is a degree colder than the near side at night

Nqp15hhu · 01-01-2021 1:23pm

Why are you all calling me a liar? It’s obviously going to be much less maritime here than Malin Head or Magilligan.

I have photos on my computer looking down on the Magilligan area and you can see how the snow coverage starts as you head inland from there.

01-01-2021 1:34pm

We're just talking basic meteorology and geography
You asked a question
We answered
As I said don't stress over opinions different to yours
Life's too short

Mount Vesuvius · 01-01-2021 2:29pm

Nqp15hhu wrote: »

Why are you all calling me a liar? It’s obviously going to be much less maritime here than Malin Head or Magilligan.

I have photos on my computer looking down on the Magilligan area and you can see how the snow coverage starts as you head inland from there.

Nobody is calling you anything. You wanted proper meteorological debate, well this is it. These good people are simply sharing their own personal experiences in relation to how quickly temperature can change at such short distances.
Engage the conversation politely because believe it or not, Nobody is out to make you look bad.

Warm sectors - always milder than forecast

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