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Model Discussion for April

Quincy

By Quincy,
in New England

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40/70 Benchmark

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Pretty amazing given the snow water equivalent across New England in mid-late March. If we had like a rainy week with 2-4" on top of the snow, along with warmth, could've been big flooding.

 

 

it's funny, I was thinking the same thing. Amazing actually if you think about. Mother Nature could have and statistically should have put the hurt on us but didn't. Lots of folks counting their lucky stars on how this came down gently.

Sent from my iPhone

Had this season pulled a '96 at the end of that 2 month mini ice age, we'd still be searching for belongings.

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It was impressive to put up 8 - 10' seasonal totals, 90% of which fell in 5 weeks, then lose it all; much over, lose it all with area hydro concerns pretty much none existent.   But I think that's a skin deep analysis..  

 

Quick recall, most of that 90% fell in temperature less than 20 F.  That in its self is a remarkable statistic.  But the point is, ...the actual quantifiable water stowed in a snow, dictates a great deal of said hydro concerns.  In this case, that was about as bone dry a 9' snow total as physically possible.  If that 9' of snow came by way of the more typical 40th parallel 31 F affairs, we'd be talking 10 and 12:1 ratio glacier, and that would have been 10" of water!!   

 

But we put down an impressive 9' of 20:1 talcum powder.   ...Obviously this varies up or down, community to community, WX Net station to station... By and large, the actual amount of water taken in was not that impressive guys.  In fact, to put it into perspective, the one single December 1992 event ~ put down the same liquid equivalent amount in many interior SE zones, that had 2-4" of rain, followed by 12-18" of pure blue when the changeover came and they choked on 32 F suffocation rates.

 

Not trying to debase the significance of our history winter here.  Obviously ...it was.  The combination of cold and snow alone was really a silent achievement there.  But anytime one can boast a 40" pack, powder or not, that's impressive.  There were roof and construction failures to go along ... obviously it wasn't no water in the pack.  But it cannot be argued that if we got 9' of 10:1, that would have been an entirely different ball game compared to gossamer fluff that was too susceptible to elevating sun angles, dry air sublimation, and compaction.  By the time the 'real' seasonal thawing warm arrived, meh, the whole thing was easily manageable.

 

The best hydro years are when you drill a lot in the autumn, then freeze the top soil.  Put a snow pack over that, then spring rain, and there you go - 

Well, if it had come with more marginal air masses, portions of the region would not have fared as well....especially the south shore.

 

I'ts difficult to keep succeeding under marginal conditions on the cp of sne, which is why most of our epic periods are usually very cold.

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Typhoon Tip

Typhoon Tip

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Even with the fluffy nature of a lot of the snow events....we still put a solid 7"+ inches of water in that pack. That would have been ugly if it all melted very quickly.

 

The cold/dry March was perfect for the slow release.

 

All I am saying is that repeating 20:1 events is not going to be as problematic as repeating 10:1 events.   Ray brings up a good point though, and that is it's kind of hard to get PWAT into air mass supporting snow, required to get 9' 10 or 12:1 types of snow around here. Hahaha.  Man, this isn't the Sierra Nevada.  

 

I hope there's no resistance to accepting that 20:1 snow is not as problematic?   The counter point is absurd -

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ORH_wxman

ORH_wxman

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All I am saying is that repeating 20:1 events is not going to be as problematic as repeating 10:1 events.   Ray brings up a good point though, and that is it's kind of hard to get PWAT into air mass supporting snow, required to get 9' 10 or 12:1 types of snow around here. Hahaha.  Man, this isn't the Sierra Nevada.  

 

I hope there's no resistance to accepting that 20:1 snow is not as problematic?   The counter point is absurd -

 

 

Well yes...you could also say that we could have been worse off if they were 6 to 1 cement jobs too...but the chances of getting 100" of snow in 3 weeks on cements jobs is almost zero for our area. It was low enough to get them using 15 to 1 and 20 to 1 storms.

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powderfreak

powderfreak

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Even with the fluffy nature of a lot of the snow events....we still put a solid 7"+ inches of water in that pack. That would have been ugly if it all melted very quickly.

The cold/dry March was perfect for the slow release.

Yeah there were still sat estimated SWE of 5-10" region wide towards the end of March.

Tippy's right to a point but that snow also soaked up some rainers and other events before it finally melted...so the SWE was higher than just those snow storms would indicate. All those minor 0.3" QPF'ers add up over a month like in March.

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Ginx snewx

Ginx snewx

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Yeah there were still sat estimated SWE of 5-10" region wide towards the end of March.

Tippy's right to a point but that snow also soaked up some rainers and other events before it finally melted...so the SWE was higher than just those snow storms would indicate. All those minor 0.3" QPF'ers add up over a month like in March.

I maxed at 5.92 w/e, that is probably close to a record for my area. The non melting long winter was a huge factor. Great way to melt out. 

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Yeah there were still sat estimated SWE of 5-10" region wide towards the end of March.

Tippy's right to a point but that snow also soaked up some rainers and other events before it finally melted...so the SWE was higher than just those snow storms would indicate. All those minor 0.3" QPF'ers add up over a month like in March.

Which is why worm holing your way to a 3' pack in one major event is not as ominous....no time to build up the WE.

We also need a cold pattern, so as to not destroy too much of it.

 

Fine line....this year treaded it.

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Typhoon Tip

Typhoon Tip

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Well yes...you could also say that we could have been worse off if they were 6 to 1 cement jobs too...but the chances of getting 100" of snow in 3 weeks on cements jobs is almost zero for our area. It was low enough to get them using 15 to 1 and 20 to 1 storms.

 

Yeah, this is more the argument to go for, and I agree... I wonder what the "physical boundary", so to speak, where it 'can't' happen more??  I mean, it takes ridiculous energy to convert higher PWAT into phase changing -- the Earth's atmosphere is only capable of so much. 

 

Kinda like that upper bound of hurricane energy potential.  The earth only spins so fast, and at our atmospheric density, the available mechanics are only able to sink so much dynamical power and that's going to be it.  You can't create a "red-spot" on Earth... 

 

Interesting.   

 

One thing that I thought was also interesting, to get 9' of snow and have almost no melting ... fail to register deeper than a 40" pack at any given time ... I mean, how did those colonial annuls get their 6' ers again? 

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tamarack

tamarack

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I maxed at 5.92 w/e, that is probably close to a record for my area. The non melting long winter was a huge factor. Great way to melt out. 

 

Tops here was 7.16" on 4/6.  Last year I measured 11.25" on 4/5, probably 2nd only to 2008 since I've lived in the foothills.  2013 peaked at 6.63" on 3/23.  I don't have SWE records for 07-08, but tracking temps and precip suggests a peak of 12-13" in early March.  We probably had over 10" in the 48" pack on 3/31/2001, and I doubt any other winters closely approach double digits.  March 2005 probably got to 8-9", as did 2009 after the Feb. 22-23 dump brought the depth to 49".

 

All time max was about 16" SWE in 65" snowpack in Ft. Kent, March 1984.  That pack included a 3-inch layer from the Dec ZR/IP event that by itself held 1.9" LE.  Once there was a snowfall atop that layer, it was strong enough to support adult moose.  Thanks to near-perfect April-May wx, there wasn't even a hint of flooding that spring.

 

Edit: 

My experience is that new snow compacts to much more dense than 10:1.  One example is the 24" snowfall (with 1.9" LE) in Feb. 2009, noted above.  That boosted snow depth from a solid 27" pack to 49" (was actually up to 51" about 10 AM but settled a bit by my 9P TOBS.)  Two mostly sunny days with highs 25, 30 and the depth was 41", meaning that big dump's ratio after 3 days was about half the 13:1 it had been when fresh.  Even in cold temps, snowpack seems to assume a ratio in the 4:1 to 6:1 range after a week or so.

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Snowpack to me will often settle out to 10:1 pretty quickly even with sub-freezing temps...so I know even if I get 18" of 18:1 snow, in a few days that'll be 10-12".

So if say 9 feet fell and depths maxed around 40", probably a good 4-5" of QPF.

Good rule-of-thumb.

 

Never thought of that.

 

I have also noted that for every 10" that falls, settling will increase in increments of roughly 1"....for instance, 10" roughly 1", 20" 2", 30" 3", etc...

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ORH_wxman

ORH_wxman

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Man, April '75 keeps showing up on the GFS. Pretty much destroys MA Pike N ON D10 with a tree branch bender. Kev/Rev may have to flee the area for a few days as Scott gets the last laugh. Either way, definitely going to be cold again especially during the nights during that time period.

 

 

The pattern showing up is obscene on both OP and ensembles...huge blocking. If there was ever a pattern to get another snow event this late in April, then this is it.

 

Either way, we will be waiting a while for any true warmth...this past weekend was a teaser.

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Ginx snewx

Ginx snewx

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The pattern showing up is obscene on both OP and ensembles...huge blocking. If there was ever a pattern to get another snow event this late in April, then this is it.

 

Either way, we will be waiting a while for any true warmth...this past weekend was a teaser.

When I spoke of NAO last week it was met with a meh. Its real and its spectacular, what it produces is the question

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tamarack

tamarack

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Yea I'm thinking uh no but it is fodder for a early summer like call, lol

 

Cool.  Kev gets buried while Jeff and I get bypassed once again.  The winter than never quits quitting...

 

I liked the 1975 talk more - Farmington got 20" from that event, tied for their biggest April snowfall.  12z gfs looked more like 36 hr of 38F RA, then repeat the following week.

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