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powderfreak

NNE Fall Thread

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13 hours ago, wxeyeNH said:

Great work thanks.  This event up near Mt Washington was acerbated by the fact that the area got 4ish of rainfall just a few days before.  So the ground was saturated and the streams were still running high.  The Whites  probably got 10" of rain in a week.  Your research shows that this was a rare event.  What can make big rainfall events worse also is snowmelt happening at the same time.  So a 5" storm coming at spring thaw could probably equal something much bigger!  So snowmelt and how much rain has fallen within a say week before the big events are wildcards...

Thank you.  Nice to be able to offer potentially useful info out of the time I've spent with the Farmington records.  (Also nice to have a 125-year co-op 6 miles from my home.)

Addendum:  Farmington measured 4.10" last Wed-Fri, so now 24 events 4-4.94".  The double trouble can be a thing.  In Oct. 2005, their 2nd wettest month after Dec. 1969 and part of Maine's wettest year on record, the co-op had 5.68" 7-9 then 4.02" 14-16.  Not 10 in a week but not far off.  And snowmelt is usually (not always) a factor in NNE's biggest floods, though in my experience, snowmelt alone produces only minor flooding at worst on significant watercourses.  Farmington's biggest non-snowmelt-augmented peak flow (and 5th overall) came from that June '98 storm o0f 7.89", but was barely over half the volume of April 1987, when 5.12" of warm rain finished melting a dense pack after a week of high temps 50s-60s.  That pushed the Sandy up to 51,100 cfs, 12,500 higher than #2 in March 1936, and the Kennebec above Augusta rose to 233,000, greatest flow on record for any river in the state.  (2nd is 175,000 on the St.John at Ft. Kent in 2008.)  K'bec records date back only to 1979, but in that span the next greatest flow was a comparatively puny 113,000 cfs.


On another topic, October mildness:

Avg temp:  51.1  That's 6.1 AN and 2.4F milder than the previous max in 2007.  We all know what followed THAT October...
Avg max:  62.7   7.4 AN and the first of my 20 Octobers here that had no sub-50 maxima.  2007 had only 2, other Octs no lower than 4.
Avg min:  39.5   4.9 AN
Warmest day:  74 on the 4th, mean:  62 on the 5th, mildest min:  58 on the 25th
Coolest day:  23 on the 17th, mean:  39.5 on the 17th, cool max:  51 on the 31st.  (Of note:  My avg mean for 10/31 is 39.4.)

Precip:  8.32"  That's 2.67" above my wettest month's avg, though only 4th highest of 20. 
Largest one day:  2.17" on the 30th.  Also had 2.10" 5 days earlier.  first month with 2 deuces since Oct 2006.  (Oct 2005 had 4, including 2 with 3"+.)

Snow:  Not a trace.  That's been the case in 8 of 20 Octs.

 

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2 hours ago, tamarack said:

Thank you.  Nice to be able to offer potentially useful info out of the time I've spent with the Farmington records.  (Also nice to have a 125-year co-op 6 miles from my home.)

Addendum:  Farmington measured 4.10" last Wed-Fri, so now 24 events 4-4.94".  The double trouble can be a thing.  In Oct. 2005, their 2nd wettest month after Dec. 1969 and part of Maine's wettest year on record, the co-op had 5.68" 7-9 then 4.02" 14-16.  Not 10 in a week but not far off.  And snowmelt is usually (not always) a factor in NNE's biggest floods, though in my experience, snowmelt alone produces only minor flooding at worst on significant watercourses.  Farmington's biggest non-snowmelt-augmented peak flow (and 5th overall) came from that June '98 storm o0f 7.89", but was barely over half the volume of April 1987, when 5.12" of warm rain finished melting a dense pack after a week of high temps 50s-60s.  That pushed the Sandy up to 51,100 cfs, 12,500 higher than #2 in March 1936, and the Kennebec above Augusta rose to 233,000, greatest flow on record for any river in the state.  (2nd is 175,000 on the St.John at Ft. Kent in 2008.)  K'bec records date back only to 1979, but in that span the next greatest flow was a comparatively puny 113,000 cfs.


On another topic, October mildness:

Avg temp:  51.1  That's 6.1 AN and 2.4F milder than the previous max in 2007.  We all know what followed THAT October...
Avg max:  62.7   7.4 AN and the first of my 20 Octobers here that had no sub-50 maxima.  2007 had only 2, other Octs no lower than 4.
Avg min:  39.5   4.9 AN
Warmest day:  74 on the 4th, mean:  62 on the 5th, mildest min:  58 on the 25th
Coolest day:  23 on the 17th, mean:  39.5 on the 17th, cool max:  51 on the 31st.  (Of note:  My avg mean for 10/31 is 39.4.)

Precip:  8.32"  That's 2.67" above my wettest month's avg, though only 4th highest of 20. 
Largest one day:  2.17" on the 30th.  Also had 2.10" 5 days earlier.  first month with 2 deuces since Oct 2006.  (Oct 2005 had 4, including 2 with 3"+.)

Snow:  Not a trace.  That's been the case in 8 of 20 Octs.

 

Thanks for the great info.  Speaking of these 2 rainfall events I had saved the Oct 21rst GFS,  four days before the first storm.  Saw that bullseye around the N Whites and thought that was obviously way overdone and wouldn't happen.  Well I'm sure that 12" was not far off.  Kinds of reminds me of Harvey with the 50" rain totals. So sometimes the crazy model stuff can be right...

Untitled.jpg

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6 minutes ago, wxeyeNH said:

Thanks for the great info.  Speaking of these 2 rainfall events I had saved the Oct 21rst GFS,  four days before the first storm.  Saw that bullseye around the N Whites and thought that was obviously way overdone and wouldn't happen.  Well I'm sure that 12" was not far off.  Kinds of reminds me of Harvey with the 50" rain totals. So sometimes the crazy model stuff can be right...

Untitled.jpg

Had 7.97" for the week here. Northfield 2.8E had 7.78" so similar ballpark.

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24 minutes ago, tamarack said:

Near drought here, only 6.81".

Tamarack,  I keep thinking about your post and the potential floods in your area and in Alex's area.  Trying to come up with a realistic return rate.  He said that he understood that he was in a 100 year flood zone but that seems way to long considering this happened to the property he bought during Irene in 2011.

The Ammonoosuc River is a small river that feeds of the brooks and streams on the west side of Mount Washington and the South  Presidentials and the north side of Crawford Notch.  So I guess it is very susceptible to rapid water rises.  Like you suggested it's complicated to figure out a potential flood situation because you have to look at what has previously happened just before the current storm event and then take into account potential snowmelt.  This past week shows that even without snowmelt you can still have very rare, high flash flood events.

So if you had to guess,  and I know  its only a guess putting all the factors above what would you say would be the return rate?  Once in 10 years, 25 years, 100 years?  I'm just curious as to your guess if you were advising a friend who was thinking of buying a home site near that river that just had 5 feet of flooding.    If this happened in Irene in 2011 and now again 2017 this would suggest to me it has happened more frequently over the years.

Thoughts?    Thanks  Gene

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3 hours ago, dendrite said:

Had 7.97" for the week here. Northfield 2.8E had 7.78" so similar ballpark.

Not sure what I got at the cabin, but it was the first time I got water in my basement. Only about a couple gallons, but figured it was due to my road being paved (for the first time). 

 

Radar estimates put me at about 7-8" over the past 10 days. 

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47 minutes ago, wxeyeNH said:

Tamarack,  I keep thinking about your post and the potential floods in your area and in Alex's area.  Trying to come up with a realistic return rate.  He said that he understood that he was in a 100 year flood zone but that seems way to long considering this happened to the property he bought during Irene in 2011.

The Ammonoosuc River is a small river that feeds of the brooks and streams on the west side of Mount Washington and the South  Presidentials and the north side of Crawford Notch.  So I guess it is very susceptible to rapid water rises.  Like you suggested it's complicated to figure out a potential flood situation because you have to look at what has previously happened just before the current storm event and then take into account potential snowmelt.  This past week shows that even without snowmelt you can still have very rare, high flash flood events.

So if you had to guess,  and I know  its only a guess putting all the factors above what would you say would be the return rate?  Once in 10 years, 25 years, 100 years?  I'm just curious as to your guess if you were advising a friend who was thinking of buying a home site near that river that just had 5 feet of flooding.    If this happened in Irene in 2011 and now again 2017 this would suggest to me it has happened more frequently over the years.

Thoughts?    Thanks  Gene

My hydrology "education" dealt with how trees respond to different drainage classes of soil, so anything I offer beyond that should be taken with year's supply of road salt.

20 years ago I'd have said 25 year return.  The increase in bigger precip events is clearly shown in the obs data, not just bigger events but combos like the past week.  So I'd call it a 10-year return, at least for localized effects.  The steepness of a watershed and amount of "delaying" areas like lakes and bogs are also important.  The Ammonoosuc has little of either, the Wild Ammonoosuc almost none.  I can see the contrast locally with the Carrabasset and Sandy Rivers.  The Sandy has a watershed 50% larger than the Carrabasset, but Irene's downpours gave the Carrabasset a peak flow above 31,000 cfs while the Sandy barely got over 20,000.  Their peaks from this latest deluge were closer, 22k to 20, while the snowmelt+rain events that hold most of the top flows for the two rivers usually have the Sandy slightly greater.  the more concentrated the rainfall, the more important those upstream catchment acres become.

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22 minutes ago, tamarack said:

My hydrology "education" dealt with how trees respond to different drainage classes of soil, so anything I offer beyond that should be taken with year's supply of road salt.

20 years ago I'd have said 25 year return.  The increase in bigger precip events is clearly shown in the obs data, not just bigger events but combos like the past week.  So I'd call it a 10-year return, at least for localized effects.  The steepness of a watershed and amount of "delaying" areas like lakes and bogs are also important.  The Ammonoosuc has little of either, the Wild Ammonoosuc almost none.  I can see the contrast locally with the Carrabasset and Sandy Rivers.  The Sandy has a watershed 50% larger than the Carrabasset, but Irene's downpours gave the Carrabasset a peak flow above 31,000 cfs while the Sandy barely got over 20,000.  Their peaks from this latest deluge were closer, 22k to 20, while the snowmelt+rain events that hold most of the top flows for the two rivers usually have the Sandy slightly greater.  the more concentrated the rainfall, the more important those upstream catchment acres become.

Thanks so much.   You know much more about this than me but my gut was saying something between 10 and 25 years.  Definitely less than a 100-year type of flood.  Extreme events definitely seem to be increasing around the world in general.  Fun for us weather freaks but not for the victims of climate change!

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I was surprised to see some leaves hanging on by Snake Mountain outside of Middlebury on my return today. Obviously in most areas stick season has arrived. 

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3 hours ago, MarkO said:

Not sure what I got at the cabin, but it was the first time I got water in my basement. Only about a couple gallons, but figured it was due to my road being paved (for the first time). 

 

Radar estimates put me at about 7-8" over the past 10 days. 

I believe radar ran a little low for me. Have you checked to see if there's anyone close to you on cocorahs?

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3 hours ago, tamarack said:

My hydrology "education" dealt with how trees respond to different drainage classes of soil, so anything I offer beyond that should be taken with year's supply of road salt.

20 years ago I'd have said 25 year return.  The increase in bigger precip events is clearly shown in the obs data, not just bigger events but combos like the past week.  So I'd call it a 10-year return, at least for localized effects.  The steepness of a watershed and amount of "delaying" areas like lakes and bogs are also important.  The Ammonoosuc has little of either, the Wild Ammonoosuc almost none.  I can see the contrast locally with the Carrabasset and Sandy Rivers.  The Sandy has a watershed 50% larger than the Carrabasset, but Irene's downpours gave the Carrabasset a peak flow above 31,000 cfs while the Sandy barely got over 20,000.  Their peaks from this latest deluge were closer, 22k to 20, while the snowmelt+rain events that hold most of the top flows for the two rivers usually have the Sandy slightly greater.  the more concentrated the rainfall, the more important those upstream catchment acres become.

Thanks for the info. This was a good teaching moment for us - don't underestimate the Ammo, and don't build at ground level! 

Now the next question for me is - I know how high the water got in this last event. I wasn't here for Irene and the previous owner lied about it so I have no data to go by, but I wonder how much higher could the water go? Not sure there's any way to know that... but certainly would be really helpful to know!

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11 hours ago, alex said:

Thanks for the info. This was a good teaching moment for us - don't underestimate the Ammo, and don't build at ground level! 

Now the next question for me is - I know how high the water got in this last event. I wasn't here for Irene and the previous owner lied about it so I have no data to go by, but I wonder how much higher could the water go? Not sure there's any way to know that... but certainly would be really helpful to know!

Alex,  my guess is that it takes an exponential amount of rain as rivers like yours rise higher and higher.  I been to your house several times and  it seems the "flood plain"  is wide so that the river can spread out at least right at your location.  So to get a couple more feet of water right at your property the river would have to get really wide.  Just a complete guess.  The other thing I suggested to you on the phone is to call the Mt Washington.  They must have long time employees or locals that can judge how this flood on the Ammo compared to others.  They can tell by how high the water came over the access road to the resort...

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On ‎10‎/‎31‎/‎2017 at 9:46 PM, powderfreak said:

Love the dedication J.

Tree down blocking your drive to work so you biked to Waterbury and got the GMTA shuttle to BTV.  Props!

 

Well, that’s how we do it around here - VT Strong!

 

Actually, during my morning class yesterday I was letting the students know why I might be looking a bit scruffier than usual this week, showed them the pics, and told them about the Monday morning rude awakening.  We’d managed to have class on Monday of course, so we all LOLed when one of the students asked “So, what does actually have to happen for you to cancel class?”  I told them I wasn’t sure, but something more than that!

 

We just got power back yesterday (and even cable/internet, which I was worried might take quite a while) so that’s been a nice upgrade in terms of heat and web access.  There are still 8,000 homes in the state without power though based on what I heard on VPR this morning, so keep up the good vibes for those folks!

 

VermontStrong.jpg

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I am lucky I was away as it looks like a tree here fell into our driveway during the storm. Anyway here are some more from my return to home drone flight near snake mountain off 22A in VT:
23032725_10104864802139429_5183543765123

23213298_10104864802134439_9125408304623

23157336_10104864802463779_2816368025504

23116889_10104864802493719_2501780597322

23116722_10104864802129449_2189595624762

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47 minutes ago, eyewall said:

I am lucky I was away as it looks like a tree here fell into our driveway during the storm. Anyway here are some more from my return to home drone flight near snake mountain off 22A in VT:
23032725_10104864802139429_5183543765123

23213298_10104864802134439_9125408304623

23157336_10104864802463779_2816368025504

23116889_10104864802493719_2501780597322

23116722_10104864802129449_2189595624762

When did you take these?

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1 minute ago, eyewall said:

Yesterday

Sent from my VS995 using Tapatalk
 

That's surprising.  I drove past Snake Mountain this morning and from the road, it didn't look nearly as vibrant or with as many leaves.  Perspective matters.

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That's surprising.  I drove past Snake Mountain this morning and from the road, it didn't look nearly as vibrant or with as many leaves.  Perspective matters.

Yeah I didn't boost saturation but dehaze can make it look a little more saturated than in real life. I am sure the leaf drop is happening rapidly today with these winds.

Sent from my VS995 using Tapatalk

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I’ve got my precipitation numbers for October:

 

October totals: Trace snow/5.35” L.E.

 

With just a trace of snowfall it was of course below average (~1”), but we know how variable October can be with respect to snowfall, and getting only a trace or zero is actually not much beyond 1 S.D. from the mean.

 

Liquid was right around average (5.28”), so after a couple of below average months that was good to see as we head into the colder season.  Calendar year water is at 48.72”, which is still holding a few inches ahead of average pace.

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4 hours ago, Hitman said:

new and improved snow stake at lincoln peak.

 

 

snowstake.jpg

Nice where's that one located?

I still don't like the close trees but looks like it's at a lower elevation by the size of the vegetation?

Also if I'm seeing that right, they have the measuring stake in the middle of the board?  That's fantastic if the case.  Nice work SB.

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On 11/1/2017 at 8:35 PM, alex said:

Thanks for the info. This was a good teaching moment for us - don't underestimate the Ammo, and don't build at ground level! 

Now the next question for me is - I know how high the water got in this last event. I wasn't here for Irene and the previous owner lied about it so I have no data to go by, but I wonder how much higher could the water go? Not sure there's any way to know that... but certainly would be really helpful to know!

Well there are a couple ways you can look at it. Probably the best is to use streamflow downstream at Bethlehem, where we have a gauge.

Unfortunately our gauge crapped the bed as the river crested, so we'll have to do some post-analysis to ultimately estimate that (unless they had a back up crest gauge).

2017-11-02_20-49-36.png.16dd046159c02e67fe4cd48d08190d3f.png

Safe to say that flow was over 9,000 cfs though, but probably not much over.

Compare that to historic high flow events and you can start to put this event into context. Now not every event will be the same experience at your location vs. the gauge, but I find it pretty hard to believe the comparison will be wildly different given how close you are to the gauge. Our gauge is just upstream of where 302 crosses the Ammonoosuc, so maybe 3ish miles from you.

2017-11-02_20-47-06.png.5dfe4c09ecab441cb982c6df056fd141.png

It really looks like this flow was higher than Irene, with four floods higher than this. We have 77 years of gauge data there, and probably 9 (including this one) similar flood events over 10.5 feet (8,000 cfs). So ballpark 1 in 10 year return period. 

But the stream bed may have changed significantly in that time. You see 4 floods in the 50s, and two in '73 alone. There may have been something about those years that made the river more prone to high flow flood events. 

That's about the best I can do. But flooding events on these flashy rivers are tough, because these big floods alter the flood plain and can actually change the flood stage (a la the Saco at Conway in Irene).

 

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2 hours ago, powderfreak said:

Nice where's that one located?

I still don't like the close trees but looks like it's at a lower elevation by the size of the vegetation?

Also if I'm seeing that right, they have the measuring stake in the middle of the board?  That's fantastic if the case.  Nice work SB.

Don’t know where it’s located.  I wouldn’t assume where it’s pictured is where it’s going to reside.  But if all goes well, I’ll be up next weekend and will do a litttle recon.  Also Need new ski boots which is a tough thing for me to shop for.

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18 minutes ago, Hitman said:

Don’t know where it’s located.  I wouldn’t assume where it’s pictured is where it’s going to reside.  But if all goes well, I’ll be up next weekend and will do a litttle recon.  Also Need new ski boots which is a tough thing for me to shop for.

This is the only place to get ski boots:  http://innerbootworks.com/

Plan on spending at least a couple hours there

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12 minutes ago, dendrite said:

As usual we're the place where warm fronts go to die. Highs today...

ASH 70
MHT 67
CON 65
LCI 58
Here 55.8
1P1 54

Real good damming signature to our hourly temp obs dumps today. Tis the season.

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1 hour ago, j24vt said:

This is the only place to get ski boots:  http://innerbootworks.com/

Plan on spending at least a couple hours there

I go to alpine options in Warren.  They’re great.  Already done the couple hours of fitting, but can’t decide which boot I want to go with.  

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On 11/1/2017 at 8:35 PM, alex said:

Thanks for the info. This was a good teaching moment for us - don't underestimate the Ammo, and don't build at ground level! 

Now the next question for me is - I know how high the water got in this last event. I wasn't here for Irene and the previous owner lied about it so I have no data to go by, but I wonder how much higher could the water go? Not sure there's any way to know that... but certainly would be really helpful to know!

FEMA may have elevation profiles of the river you're on. If so, and if it was me, I'd build above the 500 year flood elevation. If not, I'd go 3 feet above the previous flood. 

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