Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
Location: Northern Ireland and temporarily England
7,668 posts, read 5,259,670 times
Reputation: 1392
Advertisements
We have quite high lapse rates in winter. It's not uncommon for it to be 3c at sea level and 0c at 200, the moderation has only occurred at the air near the sea.
Hmm. The comment on that link on snow above freezing said that steep lapse rate wouldn't make much difference; the snow should melt once it passes through above freezing air in about 100 m.
Obviously not unique for that location. But something about it must make it more common in oceanic climates. Was the snow happening in the morning while temperatures much colder than 10°C? Or was it while it was near or at 10°C? If the latter, that's a very warm temperature for water to survive in the frozen form. To get snow to survive in warm temperatures it needs to:
1) Have an extremely steep lapse rate; the warm air is confined close to the surface and it is cold aloft. So there's not enough time for the snow to melt
2) The relative humidity is very low
See this link for (2). Low relative humidity sounds unlikely to be more common in an oceanic climate than a continental, though New Zealand might be an exception given its often high diurnal ranges. Maybe (1) might be more common in an oceanic climate because the moderating effect is limited to the surface. But a lapse rate that steep should spur convection. The length of time over the ocean should moderate the midlevels as well, I would think; such a setup is more common over a sea or lake. A vertical temperature profile would clarify what's going on.
It was snowing around mid afternoon ( a wedding) and had snowed on the previous two days with trace accumulation on one night. Tutiempo records show days around 12-13C, but doesn't indicate even trace snowfall. Convectional cloud is common in NZ during cold frontal rain, which could indicate a steep lapse rate, I've seen fresh snow on the hills here at 1500m, when the temperature here was around 20C. Not common, but could show the degree of the steep rate.
Quote:
Possible here, if it's been milder than average and drier than average. Though not normally. Average date of first snowfall here is November 28, which has an average temperature of 7.5°C/-3.5°C. But that's ignoring trace snowfalls, which are not counted.
Why? If the lower atmosphere is warm enough (because it is moderated) the snow flakes should melt, regardless of polar low. In any case, that's not any different than a continental climate, which would also be exposed to a polar low by late October. The summer-winter difference is gone.
Without recording trace falls, comparisons are difficult.
Continental climates would be exposed to polar lows by October, but could they expect even trace snowfalls at temperatures closer to the November averages of somewhere like the UK?
I didn't expect that Amsterdam was that cold in February 2012. -18,7 C absolute low? Wow! Yes it was a very cold and snowy month for the whole Europe but it is still impressing for me for Amsterdam. Synop report summary
Without recording trace falls, comparisons are difficult.
Continental climates would be exposed to polar lows by October, but could they expect even trace snowfalls at temperatures closer to the November averages of somewhere like the UK?
I can find trace snowfalls recorded if I dig. The issue with comparing a continental climate with similar averages to the UK, is the continental climate (Northeast Americans ones certainly are) has higher temperature variability. So there'll be days much colder than usual when snow is more likely.
Shap in Cumbria fell to -1.6C the other night. No frost yet here, but the way it's going I don't think it will be far away.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
