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Central PA & The Fringes - February 2014 Pt. VI

2001kx

By 2001kx,
in Upstate New York/Pennsylvania

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Superstorm93

Superstorm93

Posted
Posted 
Contact: Evan Kuchera
0.5 degree isobaric GFS GRIB data from NCEP. 
The snowfall accumulation algorithm used on these charts is as follows:
1) Find the maximum temperature in the lowest 500 hPa in degrees K (MAXTMP)
2) If MAXTMP is greater than 271.16K, then the liquid equivalent ratio (RATIO) is 12.0 + 2.0*(271.16-MAXTMP)
3) If MAXTMP is less than 271.16K, then the liquid equivalent ratio (RATIO) is 12.0 + (271.16-MAXTMP)
The 3-hourly snowfall (SNOW) is RATIO multiplied by the three hour liquid precipitation total. The accumulated snowfall (ACCUM_SNOW) is the sum of all the SNOW values up to that projection time.
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paweather

paweather

Posted
Posted 
Contact: Evan Kuchera
0.5 degree isobaric GFS GRIB data from NCEP. 
The snowfall accumulation algorithm used on these charts is as follows:
1) Find the maximum temperature in the lowest 500 hPa in degrees K (MAXTMP)
2) If MAXTMP is greater than 271.16K, then the liquid equivalent ratio (RATIO) is 12.0 + 2.0*(271.16-MAXTMP)
3) If MAXTMP is less than 271.16K, then the liquid equivalent ratio (RATIO) is 12.0 + (271.16-MAXTMP)
The 3-hourly snowfall (SNOW) is RATIO multiplied by the three hour liquid precipitation total. The accumulated snowfall (ACCUM_SNOW) is the sum of all the SNOW values up to that projection time.
attachicon.gifWINTER_GFS0P5_SFC_ACCUM-SNOW_111HR (1).gif 
Contact: Evan Kuchera
0.5 degree isobaric GFS GRIB data from NCEP. 
The snowfall accumulation algorithm used on these charts is as follows:
1) Find the maximum temperature in the lowest 500 hPa in degrees K (MAXTMP)
2) If MAXTMP is greater than 271.16K, then the liquid equivalent ratio (RATIO) is 12.0 + 2.0*(271.16-MAXTMP)
3) If MAXTMP is less than 271.16K, then the liquid equivalent ratio (RATIO) is 12.0 + (271.16-MAXTMP)
The 3-hourly snowfall (SNOW) is RATIO multiplied by the three hour liquid precipitation total. The accumulated snowfall (ACCUM_SNOW) is the sum of all the SNOW values up to that projection time.
attachicon.gifWINTER_GFS0P5_SFC_ACCUM-SNOW_111HR (1).gif
is that the euro?
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MillvilleWx

MillvilleWx

Posted
Posted

6z gfs and gefs look awful unless you love sleet. Hopefully not a trend.

 

That run was a little warmer in the mid levels overall giving its extension of sleet a little further north than 0z. Today will be a big day to watch the progression of the models into tonight's 0z runs. Our "little" storm should be coming on shore today and we'll start getting a much better picture on its overall makeup due to better sampling. Unfortunately, I've got classes and an ODE exam today to end my week from hell at school. I appreciate any and all updates on here. Keep up the good work everyone

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Voyager

Voyager

Posted
Posted

6z gfs gets a warm layer all the way to 80. Gefs is even worse and prob implies mixing all the way into the northern tier but its just one run of an off hour gfs and the least accurate of the 4 gfs runs statistically also. Have to wait for 12z to see if it was onto something.

 

Gotcha. I was looking at Plymouth State's GFS soundings, and they were all below 0c, but they haven't updated and they were from the 0z run.

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NeffsvilleWx

NeffsvilleWx

Posted
Posted

Straight from the horse's mouth:

 

 

For nearly a week I've been talking about the pattern being right for a significant storm in the east...sometime around the end of Feb or beginning of March. While a touch of light snow is possible Saturday morning (with returning warm air aloft), it's a complex storm system setting up for Sunday into Monday that concerns me. It will be a classic battle of seasons as a massive temperature gradient develops over the eastern half of the country (nearly a 100 degree temp difference between the Gulf Coast and Upper Midwest!). It's a classic late Winter/early Spring setup that we see every couple of years, and the result will be a large swath of snow, ice and cold rain from the Midwest to the OH Valley to the Mid-Atlantic and Northeast. Just where the battle front sets up is critical to the outcome here--it's much too early to dial in details, but Lancaster will likely see a significant amount of precip....and quite likely some of each form (rain, ice, snow). Time frame is later Sunday into Monday night. Has anyone said "uncle" yet on this winter thing we've got going????

 

 

(Horst)

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psuhoffman

psuhoffman

Posted
Posted

I just hate being in the bullseye 100 hours out. Needing the models to hold serve that long is torture and rarely works out. Usually I want to be a little north of the target on guidance at 3-5 days out. We're down to 60 hours now and still in the bullseye on most guidance but my gut says be cautious it's rare not to see any shifts from 5 days out. Nothing scientific to support this just my own experience of being let down too many times when it looked perfect at day 5. Id rather a good setup but flawed result at day 5 morph into a perfect track at day 2.

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psuhoffman

psuhoffman

Posted
Posted

Gotcha. I was looking at Plymouth State's GFS soundings, and they were all below 0c, but they haven't updated and they were from the 0z run.

. 6z was a big shift north and warmer from 0z and the gefs did support it as well. Doesn't make it right but a little concerning. 0z was prob a 14-18" snow for us. 6z prob 8" of snow/sleet mix. Even more noticeable down near mason Dixon line where some spots went from over a foot to mostly sleet
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MillvilleWx

MillvilleWx

Posted
Posted

Straight from the horse's mouth:

(Horst)

That's a really nice write up from Eric. He's right. The timing is usually always a key with these types of systems. The plume of moisture over taking the cold air on the north side of the arctic boundary will be very impressive. The flow of WAA will be pronounced in a big way. The question now is the strength between the 2 features and who ultimately wins out (WAA vs arctic boundary). Another note is exactly where is this storm going to exit off east coast? These types of large systems rolling into the west love to exit on the same latitude they are brought in at. I'd watch for that very closely. This isn't a situation where we see a phase and hope everything goes correctly. We got a classic overrunning event on our hands with anomalous pwat indices moving into a favorable drilling air mass. It'll be interesting to see how this all plays out. Eric told me yesterday he's not biting on anything till that storm is better sampled. I agree with him completely. Today is the day we'll get a better depiction on what might happen. Just my 2cents
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paweather

paweather

Posted
Posted

I just hate being in the bullseye 100 hours out. Needing the models to hold serve that long is torture and rarely works out. Usually I want to be a little north of the target on guidance at 3-5 days out. We're down to 60 hours now and still in the bullseye on most guidance but my gut says be cautious it's rare not to see any shifts from 5 days out. Nothing scientific to support this just my own experience of being let down too many times when it looked perfect at day 5. Id rather a good setup but flawed result at day 5 morph into a perfect track at day 2.

I am no expert but 6z GFS looks fine for most of PA again. Very consistent. I'll go back and look at 0z again and compare but first sight this is still a heavy snowstorm for almost all of PA.

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heavy_wx

heavy_wx

Posted
Posted

That run was a little warmer in the mid levels overall giving its extension of sleet a little further north than 0z. Today will be a big day to watch the progression of the models into tonight's 0z runs. Our "little" storm should be coming on shore today and we'll start getting a much better picture on its overall makeup due to better sampling. Unfortunately, I've got classes and an ODE exam today to end my week from hell at school. I appreciate any and all updates on here. Keep up the good work everyone

 

Why do the snow threats always seem to happen when there's a test coming up?

 

I think the position of the 250 mb jet streak will be important in determining where the best forcing will set up. This is dependent upon the strength and position of the mid-level confluence from the PV lobe in southeast Canada as well as the SE ridge strength. Like we've seen with several storms this year, convection resulting from solid Gulf moisture transport can strengthen this ridge, sometimes more than the model guidance suggests.

 

Both the GFS and Euro briefly develop a 925 mb low, though the GFS sustains and even strengthens this low by Monday morning. The stronger low on the GFS produces a more southerly component to the flow, giving southeast areas precip type issues. This feature is more developed on the GFS likely due to the slightly more amplified 500 mb trough. This is supported by the higher QPF forecasts over the MS valley region on the GFS, which may help amplify the downstream SE ridge a bit more.

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psuhoffman

psuhoffman

Posted
Posted

I am no expert but 6z GFS looks fine for most of PA again. Very consistent. I'll go back and look at 0z again and compare but first sight this is still a heavy snowstorm for almost all of PA.

its not a disaster but there is a lot of mixing south of 80 on 6z gfs but more importantly to me is if its the start of a bad trend. Gefs went way north at 6z compared to previous runs.
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MillvilleWx

MillvilleWx

Posted
Posted

Why do the snow threats always seem to happen when there's a test coming up?

I think the position of the 250 mb jet streak will be important in determining where the best forcing will set up. This is dependent upon the strength and position of the mid-level confluence from the PV lobe in southeast Canada as well as the SE ridge strength. Like we've seen with several storms this year, convection resulting from solid Gulf moisture transport can strengthen this ridge, sometimes more than the model guidance suggests.

Both the GFS and Euro briefly develop a 925 mb low, though the GFS sustains and even strengthens this low by Monday morning. The stronger low on the GFS produces a more southerly component to the flow, giving southeast areas precip type issues. This feature is more developed on the GFS likely due to the slightly more amplified 500 mb trough. This is supported by the higher QPF forecasts over the MS valley region on the GFS, which may help amplify the downstream SE ridge a bit more.

You know I said that same thing about storms and exams yesterday haha

That's a pretty good observation of how this could play out. I really haven't had any time to look in depth at anything like I would want. So far this season it has over performed religiously in the same areas and it's hard to go against the grain. I do think southern tier will be hit with a mix early on, but change to snow. On can not deny the consistent favorable frontogen that keeps popping up over our southern counties towards the MD/Pa line. My gut says that even with sleet mixing in, those areas will still get belted. I think the winners will be along a line around true CPA around the turnpike towards NJ. Those areas I think can see all snow with the setup and lots of it. Of course, 83 Blizzard will probably walk with 20" to maintain his mini ice age ha

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paweather

paweather

Posted
Posted

its not a disaster but there is a lot of mixing south of 80 on 6z gfs but more importantly to me is if its the start of a bad trend. Gefs went way north at 6z compared to previous runs.

It is a tad warmer. Hopefully today trends don't continue that way, good for now but we still have a zillion runs to go.

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Superstorm

Superstorm

Posted
Posted

I am leaning more towards a solution of this being strung out and coming out in pieces.

I could see a scenario where we get light rain (LSV) from the first piece of energy then we get fringed or flurries from the main wave with MD/VA receiving heavy snow.

Although way out of its range, the NAM has that look.

Sent from my iPhone using Tapatalk

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paweather

paweather

Posted
Posted

I am leaning more towards a solution of this being strung out and coming out in pieces.

I could see a scenario where we get light rain (LSV) from the first piece of energy then we get fringed or flurries from the main wave with MD/VA receiving heavy snow.

Although way out of its range, the NAM has that look.

Sent from my iPhone

EURO and GFS has been the most consistent. They could be wrong but to go from over an 1" of liquid to flurries I don't see that happening.

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