Current Weather Conditions: December 2007

Our man in Havana

Widespread Frost forecasted for tonight. 8 degrees out there atm.

Supercell

Wind will need to die down a bit. its 6.5°C for a while now and doesnt look like shifting significantly any time soon

Snowbie

Wind has died down here and temp at 5.6c on the mercury.AWS at 6.4c

Mothman

Could be an air frost by midnight

1.5C atm

I'm kind of expecting a rise any moment, and not decending sub zero till later, with a min of about -1C, but its been a fast drop since 9pm when it was 3C. So a 1.5 drop in 15 minutes

SpitfireIV

Temp at 6.7c here, actually warmer now than it was earlier in the evening.

Supercell

Mothman wrote: »

Could be an air frost by midnight

1.5C atm

I'm kind of expecting a rise any moment, and not decending sub zero till later, with a min of about -1C, but its been a fast drop since 9pm when it was 3C. So a 1.5 drop in 15 minutes

I am amazed by that!
Its getting milder here with a temp of 6.8°C , very interesting local conditions.

Snowbie

Wind has died here now and temp at 4.9c

arctictree

Mothman wrote: »

Could be an air frost by midnight

1.5C atm

I'm kind of expecting a rise any moment, and not decending sub zero till later, with a min of about -1C, but its been a fast drop since 9pm when it was 3C. So a 1.5 drop in 15 minutes

Some big local variations around. I'm at 4.8c, longfield is at 6.7c. Sky seems clear here - I wonder why the temps aren't dropping as quick as you?

A

Supercell

I see arctictree is 4.8 right now, thats a full 2°C cooler than me. He's a bit closer to the coast so it looks like there is a sharp boundary between out relative close locations.

If I hadn't a few drinks on me i'd be tempted to go for a spin in the car and check it out. Great stuff!

Supercell

Just popped outside, its clear and almost still but not cold, interesting stuff.

Snowbie

Longfield wrote: »

I am amazed by that!
Its getting milder here with a temp of 6.8°C , very interesting local conditions.

Yeah agreed. As MM is at sea level and exposed(not too sure if he's is in a hollow) the cold air sinks more rapid.
Where you are the wind would travel down a slope heating as it does so through pressure and friction and a slight fohn wind keeping your temps up there.

Another theory is a Katabatic wind.This would also be generally slight due to little surface heating this time of year.This happens in the early part of the dark hours but should be gone soon and temps should fall much quicker soon.

My temps are lower here due to surface cooling and any heat radiating out to space.Its gone dead calm now.

Check on your wind speed to see if your having wind speeds in excess of 5-6 mph.It is probably why your temps are still up due to mixing of heated air due to friction rather than surface cooling allowed to take place.

Snowbie

It be very interesting to see an thermal image of the mountains to show how the cold pools in the deep valleys(wicklow gap) and the milder air at higher elevations between slopes with a prevailing wind. Air is constantly moving,more so at the higher elevations with all the hollows and valley's have the cold air trapped and progressively gets colder at night.

Opposite during daylight hours especially the summer months when warm air gets trapped in the valleys.Is why sometimes you can see on the graphs,the fluctuations of air temps usually coinciding with slight wind speeds.Cold air moves in followed by a warm pool and vica versa.
Dead calm nights when dewpoints are low,cold air is to heavy,pools,anchored and dry for warm air to mix and therefore temps plummet due to non mixing.

Mothman

Bottomed out at 1.2C, and has risen a little. The wind was 3mph SW has now fallen totally calm. Oddly, the last wind puff registered from the north, and if that were the case, a northerly is usually maritme air for me, and this would explain the rise in DP as well as air temp.

Currently 1.6C and calm.

My site is not in a hollow, but is low enough to be sheltered from the sea. There is a sahllow hollow at one end of field, about 2m lower than weather station and it certainly sees much lower temps.

Wind picked up a little from NW, temp still 1.6C

Snowbie

Mothman wrote: »

My site is not in a hollow, but is low enough to be sheltered from the sea. There is a sahllow hollow at one end of field, about 2m lower than weather station and it certainly sees much lower temps.

Have you ever measured temp difference in that hollow compared to your MET, AWS stations? like on nights you have had recently in the cold spell. Could be some interesting differences.

Temp here starting to fall away again. 4.4c
Wind variable or SW at 1mph

Our man in Havana

8.5C and rising here in south laois atm.

Mothman

Snowbie wrote: »

Have you ever measured temp difference in that hollow compared to your MET, AWS stations? like on nights you have had recently in the cold spell. Could be some interesting differences.

An obvious and something I've been meaning to do, and never got round to it.

I think I'll pop my head into the online stores and see what handheld instruments they've got, because as cold as that little hollow maybe, the farmyard maybe equally warmer It is on top of a small hill only 10m higher, but its much warmer up there on cold nights.

It could be as dramatic as -3C at AWS, near -5C in hollow and -1C up at farmyard. That would be an interesting 5 minute walk

1.8C atm, but its not freezing hard, and I'm doubtful of an air frost tonight

SpitfireIV

7.8c here now:rolleyes:

Weather BOFH

Temp here now up to 6.4C from 3.9C a few hours ago. Light SW breeze around 5km/h.

Snowbie

Mothman wrote: »

An obvious and something I've been meaning to do, and never got round to it.

I think I'll pop my head into the online stores and see what handheld instruments they've got, because as cold as that little hollow maybe, the farmyard maybe equally warmer It is on top of a small hill only 10m higher, but its much warmer up there on cold nights.

It could be as dramatic as -3C at AWS, near -5C in hollow and -1C up at farmyard. That would be an interesting 5 minute walk

1.8C atm, but its not freezing hard, and I'm doubtful of an air frost tonight

Defo interesting in such a local area.


Temp on the up here 5c with wind Sw at 5mph

Mothman

On the rise again after being down to +0.7C

Supercell

Its 6.2°C here and windy, yet 200 meters lower down and about 9 miles east of here its roughly 1.5°C

Unusual weather conditions for sure.

Supercell

Arctictree is showing 6.3°C too. MM are you sure your AWS isnt locked up or something?

Black Briar , whats your station reading?

rc28

3.2c here.

Mothman

Longfield wrote: »

Arctictree is showing 6.3°C too. MM are you sure your AWS isnt locked up or something?

You mean I shouldn't have it in the fridge

1.2C

Snowbie

Now 7.1c and cloudy

Mothman

Turned cloudy here as well with light drizzle an hour ago.

Overnight mins
Air +0.7C
Grass -3.8C

Took opportunity of light wind and lack of freezing to run moth traps.
7 species which is not too bad for this time fo year.

Partly cloudy atm, 7C

Snowbie

Stuck at 7.2c most of the night,wait 7.3c now.
Stratus......

mike65

Still, warm and sunny (for December)

Mike.

SpitfireIV

Slightly overcast and temp of 7.1c. Light S'ly breeze

Trogdor

Lovely clear night here, currently 6.9C