Elevation observation

[FordHeritageFarm]

Just an observation I noticed today. Of course I was expecting a very large run today with 300 taps, but only collected 150 gallons?. some trees shockingly disappointing with last nights temps. I did observe today that almost of all higher elevation tress ran quite poorly today, but as I worked my way lower in elevation the trees increased in productivity. for example, spot 1 at higher elevation had 84 taps in nice diameter sugar maples, I collected a total of 28 gallons. spot 2 a lowest elevation had 18 taps in nice diameter sugar maples and we collected 26 gallons there. Chance? Desperate for answers for this season? Is there any validity to this observation? Overcast early in the day cause problems? I'll take anything...Thanks.

[WESTVIRGINIAMAPLER]

Yes, your observation is correct. My trees vary 200 to 300 feet in elevation and it makes a lot of difference. The temps are almost always colder at the lower elevations as cold air sinks and I had one run this year where I got as much sap off of 145 taps as I did the other 550 because most of the 145 are lower in elevation than the other 550.

[J. R. Dodge]

I had the exact same results yesterday. The higher elevation was doing poorly but the lower elevation trees were producing 3/4 gpt.

[steve J]

I had terrible day yesterday for this vary reason I am on a high spot with two deep ravines either side of me my low when I woke yesterday was 36 trees did not reset this morning it was 30 I hope they did reset but as I drove to work less than qtr mile from cam but lower elevation it was 28

[happy thoughts]

. The temps are almost always colder at the lower elevations as cold air sinks

That may only be the case if there's snow cover. All things being equal, temps should decrease at higher elevation because of lower barometric pressure at higher altitude.

http://www.onthesnow.com/news/a/15157/ask-a-weatherman--how-does-elevation-affect-temperature-

It should be just as easy to have the opposite of your observed effect when colder night temps at higher elevation could mean sap flow when there is no freeze/thaw cycle at lower elevations. I think you were just lucky to have conditions that gave your lower trees more optimal temps for sap flow than your higher trees at the time of your observation.

[DrTimPerkins]

Is there any validity to this observation?

There are several possible causes for this, but the most likely is that the lower elevation trees froze and the higher elevation trees didn't. This can happen in at least two ways. 1) A warm front approaches creating an inversion layer (warm air over cold air) or 2) a clear night with cold air draining and settling into valleys. The other possible reason would be if the lower elevation trees are much larger than the high elevation trees they could still be thawing out.

[Revi]

That explains why yesterday wasn't as good as the day before. The trees up top of our lot got iced up earlier in the week, while those at the bottom by the sugarhouse weren't iced at all. We go from 400 to 600 feet of elevation, which doesn't sound like a lot, but there are differences that are noticeable. The upper trees might not have as hard a frost.

[FordHeritageFarm]

Thanks for the responses. All trees average around 20" dia. If you were to pull back from my area, say with google earth, the trees that ran well were in the valley, so to speak, of the hills the other ones were on. I would have to lean towards the colder air settling in to the lower elevation. I''ll have to leave a thermometer at higher elevation today just for the data....gotta love data.

[WESTVIRGINIAMAPLER]

From watching it for many years, that has been my experience most of the time. Amazing what difference just 200 to 400 feet in elevation will do on my trees when freeze is marginal.

[FordHeritageFarm]

Just saw this forecast update from the National Weather Service. All trees in all elevations ran really well and relatively equal today. See what happens tomorrow with this.

.NEAR TERM /THROUGH FRIDAY/...
8PM UPDATE... JUST A FEW TWEAKS TO THE TEMPERATURES AND SKY COVER.
SHOULD BE AN INTERESTING NIGHT IN TERMS OF LOW TEMPERATURES. WITH
MOSTLY CLEAR SKIES AND A NICE DRY SOUNDING MOST REGIONS SHOULD
RAPIDLY DECOUPLE SENDING TEMPERATURES DOWN AS FAR AS THE DEW POINT
WILL LET IT GO. A FEW PESKY HIGH CIRRUS CLOUDS ALTHOUGH WITH A BIT
OF A NORTH WIND MAY KEEP SOME LOCATIONS... ESPECIALLY HILL TOPS
... MUCH WARMER THAN THEIR VALLEY NEIGHBORS.

[Revi]

That's really interesting. Since our maples go from near the hilltop to a valley we may have a partial run tomorrow.