temperature map

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pokenei
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temperature map

Post by pokenei »

It's been a warm to average start to the Winter season. Check out the temperature map. We have two more months of hard winter to go, but, as long as the pink area stays away from the great lakes, our bamboo is safe.

Notice how the temperature map in North and South Asia is more uniform compared with North America.

http://www.findlocalweather.com/weather ... erica.html
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pokenei
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Re: temperature map

Post by pokenei »

But the windchill map is not looking so good...
We need some southerly wind to push back that pink.
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stevelau1911
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Re: temperature map

Post by stevelau1911 »

It looks like the area of sub-zeros or purple area is pretty small, and may just barely graze the great lakes region through the next 2 months. I think the more important factor is to consider the amount of cold air that has built up as that cold air mass should already be shrinking in about another month.

I think in the winter of 1993/4, the purple area would have been 2 times as big as it is this winter by around this time of the year. Based on the historical data, it seems like there is a pretty good correlation with the extent of snow cover, and extremely cold temperatures. If nearly all of the U.S. is covered by snow, it would cause the ground to reflect a lot more light back into space which leads to the buildup of cold air masses. We just got our first snow yesterday, and there is almost an immediate drop in overall temperatures. This seems to work the other way around too as the lack of snow seems to lead to an early warmup in the spring so I think it would be better if there is plenty of snow cover through early March so plants don't wake up too early for their own good.This correlation may also work the other way around where it may be the cold air that results in extensive snow cover.

So far, the temperature in my greenhouse still hasn't dropped below freezing yet, but that may not last long if this snow sticks around through the winter.
johnw
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Re: temperature map

Post by johnw »

Steve - Watch that pink area on a daily basis, on the Prairies that pink can explode overnight. Calgary can see 80 degree Fahrenheit temp swings in a few hours. That cold bubble can sweep beyond the 49th in a flash. Out here in the far east we worry more about high pressure systems stuck in stationary mode over central Québec. Over the years I can see no correlation between snowcover and cold; 1978 and 1991 were very destructive winters - the former bitterly cold and no snow cover and even dust storms, the latter no precip of any type Dec till March with even peony shoots getting damaged, perennial losses at nurseries were staggering down the eastern seaboard.

johnw - +2c & very grey.
johnw coastal Nova Scotia
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Re: temperature map

Post by johnw »

The pink has already progressed to the 49th parallel.

Our local weather and I wonder about that plunging bottom line on the 7th of January!
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pokenei
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Re: temperature map

Post by pokenei »

Yeah... the big chill is coming. It's projected to be -15 Celsius on Jan 7th in my area, and probably going lower. Let's hope the wind direction changes somehow.
Where has global warming gone...come back!
canadianplant
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Re: temperature map

Post by canadianplant »

pokenei wrote:Yeah... the big chill is coming. It's projected to be -15 Celsius on Jan 7th in my area, and probably going lower. Let's hope the wind direction changes somehow.
Where has global warming gone...come back!
big chill? I win (not willingly)

http://www.theweathernetwork.com/fourteenday/caon0688
pokenei
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Re: temperature map

Post by pokenei »

New forecast is looking better. Phew! Dodged a bullet. Only -12 C is the projected low.

It looks like the coming weeks is going to be very snowy. Snow is a double edge sword as far as bamboo is concerned. It provides insulation for the those covered up, but will reflect more light and reduce heat on the ground, making it colder than otherwise possible.
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stevelau1911
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Re: temperature map

Post by stevelau1911 »

If plants have foliage above the snow line, then it could be bad on sunny days as the light can reflect from the snow back to the plant causing it to be easier to dessicate.

I still think the positives out-weight the negatives when you have snow cover. It provides a lot of insulation. If you dig through a thick layer of snow cover even when the temperatures are in the teens, the soil underneath is typically unfrozen, and it also provides a constant source of moisture as snow prevents moisture loss from the soil, and slowly melts into the soil. As the snow melts in the spring time, and plants come out of dormancy, the snow also provides a good source of nitrogen.

This article also says that snow improves the structure of the soil with the gradual freeze/ thaw cycle.

http://plantpreview.blogspot.com/2011/0 ... lants.html

I think there may be some truth in this as many of my flowering bulb plants performed noticeably worse this last spring following a winter with hardly any snow. For bamboo, a good layer of snow through winter might also make it easier on the shoot buds that are well developed already in the fall.
jd.
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Re: temperature map

Post by jd. »

stevelau1911 wrote: I still think the positives out-weight the negatives when you have snow cover. It provides a lot of insulation.
No doubt! :D
stevelau1911 wrote: This article also says that snow improves the structure of the soil with the gradual freeze/ thaw cycle.
That article writer seems to be confused. The referenced research paper never mentions "gradual" cycles. The paper says:
The results indicate that freezing and thawing significantly reduced the bulk density of plough pan and increased its porosity and hydraulic conductivity. The reduction in the bulk density was closely related to the average daily soil minimum temperature and soil water content.
Using water and freeze-thaw cycles to condition the soil isn't a problem if no crops are planted during the winter.
stevelau1911 wrote: [...] many of my flowering bulb plants performed noticeably worse this last spring following a winter with hardly any snow.
An insulating layer of snow tends to diminish freeze-thaw cycles and the potentially negative effects on plants.
stevelau1911 wrote: For bamboo, a good layer of snow through winter might also make it easier on the shoot buds that are well developed already in the fall.
A deep layer of snow also shelters portions of above ground bamboo from cold dry winds, most useful for young bamboo plants that become buried in snow. :)
stevelau1911
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Re: temperature map

Post by stevelau1911 »

It doesn't look like the purple area has advanced at all after another week, and it should already be getting close to as cold as it will ever get for the winter. On the Accuweather, they are forecasting a 2F low on Thursday night, but I doubt it will reach anywhere close.

It doesn't even look like the bubble of sub-zeros will be making it down into the lower 48. Here's the forecast low for January. This low warmer than a typical day from the winter of 2010/2011, at least across the north.
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Re: temperature map

Post by johnw »

It would be interesting to hear which weeks are typically the coldest of the winter for forumists. Here the coldest are the last week of January and the first week of February, though much damage appears in March if the ground is frozen. It takes so long to thaw here that the combination of low humidity and strong sunshine with deeply frozen soil can be brutal on evergreen foliage.
johnw coastal Nova Scotia
stevelau1911
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Re: temperature map

Post by stevelau1911 »

It's usually 3-4 weeks into January, but on a year like this one where a large area of cold air never takes hold in the northern hemisphere, it could be as early as now for the turning point. If you look on the updated map, instead of increasing, the purple area seems to be shrinking, and daylight will only increase from this point forward.

The snow that is already here might stick around for a few weeks, but I think there will be a noticeable warming trend through the next 2 months. Hopefully it doesn't happen fast enough to produce 60s and 70s for the majority of March like it did last spring. I don't want many of my tree peony seedlings sprouting up by late February, and getting fried later on again. An early warmup might be beneficial to you since your area is less prone to getting very warm in late winter/ early spring.
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Re: temperature map

Post by johnw »

see below
Last edited by johnw on Mon Dec 31, 2012 9:18 pm, edited 1 time in total.
johnw coastal Nova Scotia
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Re: temperature map

Post by johnw »

stevelau1911 wrote: An early warmup might be beneficial to you since your area is less prone to getting very warm in late winter/ early spring.
True we are less prone to getting warm before mid-June, the Labrador Current assures that. However last March we had a two day heat wave on the coast, up to about 27c day and night and the ground was frozen down a foot or more. That kind of heat is rare for here even in mid summer and especially at night. Inland it lasted a couple of more days and that was their undoing. Their Magnolias got a jump start and got frosted in May, something which happens maybe once in 30 years here and rarely if ever on the coast. On the coast we had an extremly close call with that frost, had it been sunny first thing in the morning things would have been clobbered.

So better than an early warm up is unfrozen ground and a very slow warm up. Probably too much to ask for.

Steve - Would your peony seeds actually sprout outdoors in late February?
johnw coastal Nova Scotia
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