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Central PA - February 2017


MAG5035

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11 minutes ago, MAG5035 said:

Now that we're pretty close in I've been starting to look at some of the finer details. I think snow could really pile up fast if we get heavy rates and once we start accumulating. This seems like one of those events where snow ratios will be improving as the event wears on with the low and mid levels cooling throughout the event. First off, look at the NAM 700mb VV at 30 and 33 (!!!)

nam-vvelprs-700-usne-30-B-000.png

nam-vvelprs-700-usne-33-B-000.png

 

That coincides with temps at the 700mb layer at h30 and 33 being:

 

nam---usne-30-B-700rh_tmp_hgt_wdb2.png

nam---usne-33-B-700rh_tmp_hgt_wdb2.png

One can see the 700mb temp will be falling as the low gets to the coast. While not directly in the ideal DGZ, temps of -5 to -8ºC should allow for some relatively decent ratios from a dynamic standpoint (perhaps 12-15:1ish). Even 850 temps in PA aren't all that bad once the event is in full swing, with a very tight gradient ending up between DC and the mason dixon. At hour 33 the -4ºC 850 line is pretty much running the mason-dixon line in the eastern half of PA. I'd be curious to see some of the full BUFKIT data, I guess if there's some good lift a bit higher than 700mb you might have even better snow growth. I'm sure heavy_wx could really elaborate on this subject. 

Here is a BUFKIT profile for KLNS from the 00z 4K NAM. The white line shows negative omega (upward vertical motion) from 900 mb and up. The model actually has ice supersatured conditions and significant upward motion between 750-450 mb. Those conditions, especially at colder temperatures favor the nucleation of new ice crystals. Therefore, we would expect a large number of ice particles in supersatured conditions to grow as the fall from the coldest temperatures where they were nucleated to the warmer temperatures where the will continue to grow.

klns.png
 

With the above type of profile, ice crystals will experience a fair amount of growth between -20 and -10 degrees C; you can see that the maximum in vertical motion happens to be between 650-550 mb, where temperatures are within this range. This temperature range favors plate-like/dendritic crystal growth, and these crystals tend to collect into low-density aggregates, increasing the snow-liquid ratio. However, ice crystal growth below 650 mb may be more columnar, which could increase the density of the snow aggregates and decreases the snow-liquid ratio. Also, I would probably expect at least some riming with this degree of saturation between 800-650 mb and that may also increase the density of snow at the ground.

You can also see that temperatures near 750 mb are only a few degrees C below freezing, favoring increased sticking of aggregates together and maybe also higher snowflakes. Overall, I think we should see some pretty large aggregates with both some dendritic growth aloft and efficient collection of ice crystals into aggregates. Of course the high density paste will generally stick around longer...

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7 minutes ago, heavy_wx said:

Here is a BUFKIT profile for KLNS from the 00z 4K NAM. The white line shows negative omega (upward vertical motion) from 900 mb and up. The model actually has ice supersatured conditions and significant upward motion between 750-450 mb. Those conditions, especially at colder temperatures favor the nucleation of new ice crystals. Therefore, we would expect a large number of ice particles in supersatured conditions to grow as the fall from the coldest temperatures where they were nucleated to the warmer temperatures where the will continue to grow.

With the above type of profile, ice crystals will experience a fair amount of growth between -20 and -10 degrees C; you can see that the maximum in vertical motion happens to be between 650-550 mb, where temperatures are within this range. This temperature range favors plate-like/dendritic crystal growth, and these crystals tend to collect into low-density aggregates, increasing the snow-liquid ratio. However, ice crystal growth below 650 mb may be more columnar, which could increase the density of the snow aggregates and decreases the snow-liquid ratio. Also, I would probably expect at least some riming with this degree of saturation between 800-650 mb and that may also increase the density of snow at the ground.

You can also see that temperatures near 750 mb are only a few degrees C below freezing, favoring increased sticking of aggregates together and maybe also higher snowflakes. Overall, I think we should see some pretty large aggregates with both some dendritic growth aloft and efficient collection of ice crystals into aggregates. Of course the high density paste will generally stick around longer...

Yup that's what I was looking for, great explanation. 

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11 minutes ago, heavy_wx said:

Here is a BUFKIT profile for KLNS from the 00z 4K NAM. The white line shows negative omega (upward vertical motion) from 900 mb and up. The model actually has ice supersatured conditions and significant upward motion between 750-450 mb. Those conditions, especially at colder temperatures favor the nucleation of new ice crystals. Therefore, we would expect a large number of ice particles in supersatured conditions to grow as the fall from the coldest temperatures where they were nucleated to the warmer temperatures where the will continue to grow.

klns.png
 

With the above type of profile, ice crystals will experience a fair amount of growth between -20 and -10 degrees C; you can see that the maximum in vertical motion happens to be between 650-550 mb, where temperatures are within this range. This temperature range favors plate-like/dendritic crystal growth, and these crystals tend to collect into low-density aggregates, increasing the snow-liquid ratio. However, ice crystal growth below 650 mb may be more columnar, which could increase the density of the snow aggregates and decreases the snow-liquid ratio. Also, I would probably expect at least some riming with this degree of saturation between 800-650 mb and that may also increase the density of snow at the ground.

You can also see that temperatures near 750 mb are only a few degrees C below freezing, favoring increased sticking of aggregates together and maybe also higher snowflakes. Overall, I think we should see some pretty large aggregates with both some dendritic growth aloft and efficient collection of ice crystals into aggregates. Of course the high density paste will generally stick around longer...

This is such a great forum. Good stuff heavy 

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9 minutes ago, MillvilleWx said:

Well, I start a string of overnights tomorrow night into Thursday morning, so I'll certainly be staying up for the Euro. Anyone joining the party?

I wish, but my old bones need rest.  I MAY peek in around 2 or 3 cause I can set a clock in my brain when I've got something of interest.  If you dont see me....bring this one home for us.  

Nut

 

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16 minutes ago, MillvilleWx said:

This is such a great forum. Good stuff heavy 

Its like Christmas came.....really late for me.

I'd like to thank you all for the great evening.  Fun and informative, and potentially snowy.  Red taggers...yall just are a great group and offer much to learn from.

Its nice to see the activity in here.  

While not afraid, I'm glad to not be "down" in the MA forum, as they are a grumbly bunch after the first half of the 0z's came in, and while I think they still have a play in this hand...I'm not interested in getting jammed up for trying to help, so I'll let them sort out things themselves.  Good group with lots of contributions, but they really need to lay off the "northern" crap as were all a big weather community, and were all often in search of the same things.  

Gnight all.  Here's to hopefully a great day tomorrow.

Nut

 

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Euro held serve with regard to slightly cooler temps and track compared to other guidance. QPF into PA not as prolific compared to all other models as well, so it could be under doing the QPF to the NW of the low. It did that during Blizzard last year and it's been doing it recently with the latest update as I've noticed out in the SW US where I forecast. Overall, the depiction is clear that the state will see a wide spread snowfall and some people will have a very solid snowfall of warning criteria. The southern tier has a bit more concern as the thermal layer initially starts a bit warm, but rapid cyclogenesis advecting cold air on the NW side of the low will lead to crashing temps over the entire boundary layer. Definitely not a terrible run and one many in here will still be happy with. I think it's 100% official ladies and gentleman! We will actually see a solid snowfall this winter. Pop the cork

 

Edit: Will add that the Euro and other guidance is indicating some snow showers/squalls across western and central PA developing in response to strong PVA on the backside of the trough. Low level lapse rates are pretty decent over the PA high country and we could see some bonus snow in spots as a result. Nothing beats snow on snow. 

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30 minutes ago, Voyager said:

Why couldn't this come on a Saturday???

It would be better for me, and everyone would still be happy we're getting a snow storm.

Yea and I'd be happy because I would be on OT plowing. With all of our accounts I will still probably end up with some OT but not as much as I would if it were a weekend storm. Plus there's too many people out thinking they know how to drive in snow and ice when we're trying to work and it just makes things more difficult. Weekend storms are easier to manage. Timing of this one couldn't be more worse either. Can't wait for tonight though, first plow of the year!

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22 minutes ago, Superstorm said:

Thinking around 4 to 6 for Lancaster, unless we can get in that CCB.


Sent from my iPhone using Tapatalk

Great write ups last night by the boys in RED as to how we may have great snow growth opps down here.  I think it was Heavy and Mag.  check it out.  Fantastic read.

Nut

 

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3 minutes ago, sauss06 said:

i had 44 this morning, now 46

but the sun is just starting to come out here

You in da valley...

He up high.....

boy if that cold press could be a little quicker, I'd definalely lean towards 8" round here.  Just scared that we lose while column cools down here.

Nut

 

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8 minutes ago, Voyager said:

MASSIVE temperature spike the last hour here in Tamaqua. A short time ago, it was 42 degrees. Now we are up to 58, with a 3 degree rise in just the past 5 minutes... :o

Add one more. Up to 59 now...

My station is a fan aspirated Acu-rite setup which is quite accurate.

 

20170208_6692.JPG

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Just now, kdskidoo said:

we need this to reach a little further to the north to include Potter and Tioga, they need snow up there.

Yeah, cams dont look so good.  Just hoping the base made by last weeks riding hold up.  Longer range looking like frequent opps to freshen up/start over ;(.

Saw that you got some midweek riding in.  we got 158 in on saturday.  was awesome.  Back for Presidents Day weekend w/ family, so save me some snow up there bud.

Nut

 

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2 minutes ago, pasnownut said:

Yeah, cams dont look so good.  Just hoping the base made by last weeks riding hold up.  Longer range looking like frequent opps to freshen up/start over ;(.

Saw that you got some midweek riding in.  we got 158 in on saturday.  was awesome.  Back for Presidents Day weekend w/ family, so save me some snow up there bud.

Nut

 

glad you got some good riding in.  we ended up with 160 miles thursday afternoon and part of friday.  we wanted to stay and ride saturday, but had water issues at the cabin, so had to cut the weekend short. :(  the canyon area was beautiful.  it's not looking too good to hold onto what we had.  looks warm over the weekend, so although the longer range has promise, I think we'll basically be starting over.

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5 minutes ago, kdskidoo said:

glad you got some good riding in.  we ended up with 160 miles thursday afternoon and part of friday.  we wanted to stay and ride saturday, but had water issues at the cabin, so had to cut the weekend short. :(  the canyon area was beautiful.  it's not looking too good to hold onto what we had.  looks warm over the weekend, so although the longer range has promise, I think we'll basically be starting over.

Yeah I figured we start over, but lets hope the long range holds and some of these storms deliver.

Sorry about the water.  Hope it wasnt major.  I didnt turn mine on...roughed it for the weekend. :)

Nut

 

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14 minutes ago, pasnownut said:

Yeah I figured we start over, but lets hope the long range holds and some of these storms deliver.

Sorry about the water.  Hope it wasnt major.  I didnt turn mine on...roughed it for the weekend. :)

Nut

 

not sure what's going on with the water.  we had a plumber from Lock Haven there friday afternoon and he thinks we need a new well pump.  hopefully it's not the other option, low water level in the well.  I'll probably be heading up next week one day to get the repair work done, I'll see what's left up there at that time.  I really hope the longer range holds and we get a few more good storms this season, we need to make up for last year and the first part of this year.

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No major changes to what I'm thinking over the area with regard to accumulations. 12z runs still pretty solid for the subforum. I'll try to give Final Call Outlook later today. Start overnights tonight, so I'm going to be off and sleeping today. We have more Mets and great analysis by many on here than ever before. Reel it in boys. 

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Just broke through the 60-degree mark (1st time this year? ... I think...), hitting 61 degrees about 15 minutes ago.  Now back down to 59.

Boy what a shocker this is going to be to people not in-the-know...although there is a winter storm warning in effect so that should help.  I love dramatic turns in the weather from one extreme to the other.  Just wish all the fun wasn't going to be overnight.  Might make it hard to go to bed since the action is expected to ramp up dramatically around midnight.  Good write-up in the disco from NWS this morning.

Looks like my sisters back in north Jersey might be looking at close to a foot with this one.  I better go give them a call...

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