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New Year Storm Thread 12/29-01/01


dryslot
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8 minutes ago, radarman said:

Thanks, it is a nice writeup.  As an eyewitness I disagree with their comments about the east slope and the berks.  It was catastrophic there, for sure the equal to pics from N ORH county, albeit with the worst accretion slightly higher up in elevation. (Esp over ~1200')   Single most impactful weather event I've ever observed for sure in parts of Ashfield/Goshen/etc..  Crushed.

Even at Umass there was a significant electrical disturbance and dirty power.  The MA1 radar held up valiantly for a while and we observed strong echoes out on the east slope, pouring, but the UPS batteries only last an hour or two.

Yeah I remember seeing big damage from Berkshires. But as you said, much higher in elevation. I think even MPM at 1000 feet didn't get much ice but at 300 feet in Leominster off to the east side of the ORH hills had catastrophic damage. You had to go much higher off to the west to see the equivalent damage. 

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1 hour ago, mahk_webstah said:

Even if a lot of sleet at least we start the true pack building

It's not building if it's melted within the week following.  :)

1 hour ago, ORH_wxman said:

ORH is an interesting forecast. They have a pretty high max temp in the warm layer...which usually tells me to go ZR...but the cold layer below it is deep and gets to around -6. That's clear sleet there. 

So which method do we give more weight to? Typically when the warm layer gets higher than 3C, you're gonna go ZR...but when the cold layer goes to -6C or colder, it's sleet. But in this case a lot of guidance has both occurring around the ORH area. 

Split the diffference.  A lot of meh.

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1 minute ago, ORH_wxman said:

Yeah I remember seeing big damage from Berkshires. But as you said, much higher in elevation. I think even MPM at 1000 feet didn't get much ice but at 300 feet in Leominster off to the east side of the ORH hills had catastrophic damage. You had to go much higher off to the west to see the equivalent damage. 

The difference between my place at 1000' and a mile away at 1200' was staggering.

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3 minutes ago, moneypitmike said:

 

Split the diffference.  A lot of meh.

I could see ORH getting IP/ZR in enough of a split to minimize the impact. Like they end up with quarter inch or less of accretion with an inch of sleet...and maybe even some cold rain for a while early on. 

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4 minutes ago, ORH_wxman said:

I could see ORH getting IP/ZR in enough of a split to minimize the impact. Like they end up with quarter inch or less of accretion with an inch of sleet...and maybe even some cold rain for a while early on. 

The wind speed component is a factor.  As Ryan as pointed out wind increases accretion rates. Complex formulas involved but Utilities especially need all parameters to prepare. 

Once the occurrence of freezing rain was determined by one of the above methods, estimates of ice accretion thickness on surface objects were calculated at each model grid point using the simple ice accretion model (Jones 1998). The uniform radial ice thickness on a cylinder, accumulated over the duration of a storm, is calculated by

Fig thumbnail _i10

where Req is the uniform radial ice thickness (mm), N is the number of hours of freezing precipitation, ρi is the density of ice (=0.9 g cm−3), ρ0 is the density of water (=1.0 g cm−3), P is the precipitation rate (mm h−1), V is the wind speed (m s−1), and W is the liquid water content (Wj = 0.067P0.846j

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4 minutes ago, ORH_wxman said:

I could see ORH getting IP/ZR in enough of a split to minimize the impact. Like they end up with quarter inch or less of accretion with an inch of sleet...and maybe even some cold rain for a while early on. 

The RGEM surface temps would argue for a fair amount of plain rain unless there's a colder layer above it.  This is going to go down as 40-page event discussion that will be pedestrian outside of 4 posters in SNE.  :lol:

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Just now, Ginx snewx said:

The wind speed component is a factor.  As Ryan as pointed out wind increases accretion rates. Complex formulas involved but Utilities especially need all parameters to prepare. 

Once the occurrence of freezing rain was determined by one of the above methods, estimates of ice accretion thickness on surface objects were calculated at each model grid point using the simple ice accretion model (Jones 1998). The uniform radial ice thickness on a cylinder, accumulated over the duration of a storm, is calculated by

Fig thumbnail _i10

where Req is the uniform radial ice thickness (mm), N is the number of hours of freezing precipitation, ρi is the density of ice (=0.9 g cm−3), ρ0 is the density of water (=1.0 g cm−3), P is the precipitation rate (mm h−1), V is the wind speed (m s−1), and W is the liquid water content (Wj = 0.067P0.846j

Yea, just give me an ice-clown map...thanks lol

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1 minute ago, moneypitmike said:

The RGEM surface temps would argue for a fair amount of plain rain unless there's a colder layer above it.  This is going to go down as 40-page event discussion that will be pedestrian outside of 4 posters in SNE.  :lol:

Wouldn't be the first time and won't be the last.

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6 minutes ago, Ginx snewx said:

The wind speed component is a factor.  As Ryan as pointed out wind increases accretion rates. Complex formulas involved but Utilities especially need all parameters to prepare. 

Once the occurrence of freezing rain was determined by one of the above methods, estimates of ice accretion thickness on surface objects were calculated at each model grid point using the simple ice accretion model (Jones 1998). The uniform radial ice thickness on a cylinder, accumulated over the duration of a storm, is calculated by

Fig thumbnail _i10

where Req is the uniform radial ice thickness (mm), N is the number of hours of freezing precipitation, ρi is the density of ice (=0.9 g cm−3), ρ0 is the density of water (=1.0 g cm−3), P is the precipitation rate (mm h−1), V is the wind speed (m s−1), and W is the liquid water content (Wj = 0.067P0.846j

image.png.eed82861f9574e3d35630aa3e305da4b.png  * 0 = MeH

image.png

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Just now, PaulyFromPlattsburgh said:

I am highly concerned that many local weather stations are undermining icing threat. mesoscales really starting to point to a confined but solid area of significant icing

Given how confined it is, a simple mention of that fact that could a case in a small area should be enough.  This will not be a wide-spread area of significant (damaging/disrupting) icing.

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