Central PA - March 2013

[Jns2183]

THe 06Z NAM went south a tiny bit from what I hear, but S Central Pa QPF output looks improved with purples sneaking into western Cumberland county. It seems like we get under some stronger forcing.

The first picture is the 72 hr QPF from the Oz NAM while the second is from the 6z.

6Z

[Yorkpa25]

Ouch 6zGFS cuts back more from 0z run. Not even close to the 6z NAM total qpf. Really looking like a 3-5 inch storm at most. Early march,battling sun angle and the main models beginning to cut QPF. Don't get upset but the bar was set at 8 inches for me, and that's not happening. NWS should downgrade this to a WWA for York,PA. Bright side is come Thursday this winter will be all but over and spring so so close. Better luck 2013-2014 winter I hope

[Jns2183]

We shall see. HPC is leaning to a NAM/ECMWF blend the first 48 hours as of 1:30 am. Also the NAM could be showing some of the QPF associated with the banding better then the GFS. The SERFS mean snowfall plumes for south central Pa are also high and remarkably consistent across the board. If there was ever going to be a storm with a big upside bust potential it could this one. I'm leaving my expectations at 3-5" In Camp Hill while acknowledging that double that or more could easily sneak up on us without much warning.

[Wmsptwx]

Lol sne found a way to get pounded while me and others fight for a tenth. Confluence cant be that terrible if sne is getting a good hit.

[djr5001]

Ouch 6zGFS cuts back more from 0z run. Not even close to the 6z NAM total qpf. Really looking like a 3-5 inch storm at most. Early march,battling sun angle and the main models beginning to cut QPF. Don't get upset but the bar was set at 8 inches for me, and that's not happening. NWS should downgrade this to a WWA for York,PA. Bright side is come Thursday this winter will be all but over and spring so so close. Better luck 2013-2014 winter I hope

sun angle will be an issue only if it does not start accumulating before sunrise or if falling too light... moderate to heavy snow that is accumulating will be enough to counter the sun... this will still likely be the biggest snow our region sees this winter

[Jns2183]

Old vs New snowfall map from CTP. Cumberland County looks fun. Going from 4 inches in Mechanicsburg to 10 Inches in Shippensburg, a mere 25 miles away. God Bless any the TV Mets who are have to make a call where that gradient sets up. It's the equivalent of leaving Hershey with 4 in and The west shore with 8-10 in.

OLD Map

New Map

[Wmsptwx]

1 to 2 woot lol. highest theyve had s. lycoming county

[pawatch]

Wow!! another storm where the models are having a hard time agreeing about the storm.

I have been wondering about temps. Is this going to be all snow or is there more of a chance for a mix?

 

Been following all of the posts, thanks to all the contributors with their analysis !! PSUhoffman good to see you posting over here.

Good to see the folks south of us is gonna get some snow.

 

 

Edit:Wmsptwx at least we will be adding to our yearly total. Which is still down.

[Wmsptwx]

Hey pawatch...if we get precip it will def be all snow. Gfs was a hair south last runs...just getting closer to a consensus.

[Paweatherguy1]

sun angle will be an issue only if it does not start accumulating before sunrise or if falling too light... moderate to heavy snow that is accumulating will be enough to counter the sun... this will still likely be the biggest snow our region sees this winter

 

Again though, other than the NAM, the models aren't really supporting moderate to heavy snow outside of the border counties. I don't know the specifics of the Euro however.

[sauss06]

put the women and children to bed it's about time to get serious fella's........looks like i fell asleep to early last night and left you guys hard at it. Not only could this be our biggest snowfall of this season, there is a small chance we could go back to 2011-12. my notes show the biggest then was 5.25" on 1/21/12..

 

not only  will i win a bottle of crown royal black.........Our brother across the mighty susky may owe us all a beer! cough cough Canderson cough cough

[djr5001]

Again though, other than the NAM, the models aren't really supporting moderate to heavy snow outside of the border counties. I don't know the specifics of the Euro however.

Correct in a post earlier I was agreeing with your concern last night.  While the NAM and SREFs are showing periods of heavy snow, we can't be ruling out the possibility that the moderate to heavy snow does not push north into PA or far north into PA.  There are things that are favorable for southern PA to see a good hit, and there are things that say otherwise.  Today will be key in looking at current obs to see how real conditions compare to the model runs from the past few days.  Also will be interesting to see how far the precip shield expands from the center of the system.  This thing could go either way and what makes it so interesting is that it could do it a few miles from another location.  I really think we will see a mix of high totals and low totals not too far apart from one another.  Where exactly that occurs and if it will occur north enough in PA only time will tell. 

[Wmsptwx]

12z is very very important.

[djr5001]

Wow!! another storm where the models are having a hard time agreeing about the storm.

I have been wondering about temps. Is this going to be all snow or is there more of a chance for a mix?

 

Been following all of the posts, thanks to all the contributors with their analysis !! PSUhoffman good to see you posting over here.

Good to see the folks south of us is gonna get some snow.

 

 

Edit:Wmsptwx at least we will be adding to our yearly total. Which is still down.

from all skew-ts I have looked at there are only temperatures above 0C near the surface.  Moderate to heavy snowfall rates will saturate this layer enough that temperatures will be cold enough to be all snow and accumulate.  Lighter snowfall will accumulate, but at a much much slower rate and will not amount to much in the end.

[sauss06]

Correct in a post earlier I was agreeing with your concern last night.  While the NAM and SREFs are showing periods of heavy snow, we can't be ruling out the possibility that the moderate to heavy snow does not push north into PA or far north into PA.  There are things that are favorable for southern PA to see a good hit, and there are things that say otherwise.  Today will be key in looking at current obs to see how real conditions compare to the model runs from the past few days.  Also will be interesting to see how far the precip shield expands from the center of the system.  This thing could go either way and what makes it so interesting is that it could do it a few miles from another location.  I really think we will see a mix of high totals and low totals not too far apart from one another.  Where exactly that occurs and if it will occur north enough in PA only time will tell. 

I'm going to start looking to see what this storm is doing on its way here.

[JamieOber]

Again though, other than the NAM, the models aren't really supporting moderate to heavy snow outside of the border counties. I don't know the specifics of the Euro however.

Here's why I disagree and it's based solely on logic.

 

I guarantee you that even with light snow, it will accumulate until about 9 or so. Our ground here is frozen pretty solid from overnight temps that were quite cold and we've remained cold. Low in State College was 22, it got to 19 at my house 12 miles west. Our forecasted high is 39. Currently we're cloudy and based on the latest AFD we may remain cloudier than expected. So, there should be minimal ground melt. We are supposed to fall back to the upper 20s, which would at least re-freeze the ground. (Although if I had to pick one claim people here make that I see disproved over and over and over again, it's warm ground will prevent any accumulations...our April and October snows destroy that assertion).

 

So, and I know you said it doesn't matter when it snows, but if it starts early enough then it should accumulate, even as light snow. 

[Paweatherguy1]

Well, I'm not saying it wont accumulate, I just think people that are seeing totals of .3-.5 inches of qpf over a 24 hour period need to temper their expectations. With the warmer air temps, I think that places will see 1-3, and not the 3-6 they seem to be expecting.

Here's why I disagree and it's based solely on logic.

I guarantee you that even with light snow, it will accumulate until about 9 or so. Our ground here is frozen pretty solid from overnight temps that were quite cold and we've remained cold. Low in State College was 22, it got to 19 at my house 12 miles west. Our forecasted high is 39. Currently we're cloudy and based on the latest AFD we may remain cloudier than expected. So, there should be minimal ground melt. We are supposed to fall back to the upper 20s, which would at least re-freeze the ground. (Although if I had to pick one claim people here make that I see disproved over and over and over again, it's warm ground will prevent any accumulations...our April and October snows destroy that assertion).

So, and I know you said it doesn't matter when it snows, but if it starts early enough then it should accumulate, even as light snow.

[JamieOber]

Well, I'm not saying it wont accumulate, I just think people that are seeing totals of .3-.5 inches of qpf over a 24 hour period need to temper their expectations. With the warmer air temps, I think that places will see 1-3, and not the 3-6 they seem to be expecting.

 

Hard to say. I've seen storms like this get written off before. I think we see 1-3 here. Banding with this one is going to be huge. 

[Wmsptwx]

Here are my thoughts then I will see what you guys think. It basically breaks down into three categories. No snow zone: IPT, FIG. Models will continue to tighten up and dry air will likely eat up anything that falls. On the edge: UNV, SEG abd AVP. In this area you are right on the edge of meaningful precip. A bump south, high and dry. A bump north solid low end advisory snows. And the It Will but How Much crew: MDT,.LNS, AOO, JST, THV. At least a solid advisory snow if a bump north very nice warning event.

[djr5001]

I'm going to start looking to see what this storm is doing on its way here.

I am really interested to see if this wind anomaly stuff comes into play to make this event over perform from what the models have been showing for our area... 0z GFS has this u-wind (easterly component of wind) anomaly between 5 and 8 standard deviations... SREFs greater than 5 as well... going off of the research NWS did (that article I have posted the link to on here before) they say everytime SREFs forecasted to meet or exceed the threshold, which it is in this case, there has resulted an east coast winter storm.  This is what is keeping me interested despite GFS and Euro not showing higher precip totals.

[Paweatherguy1]

Nam looks to be bumping north!

[canderson]

CTP going with an inch tonight and 3-5" tomorrow for MDT, for downtown (17101) an inch tonight and 2-4" tomorrow. FWIW.

[Wmsptwx]

Heights are dampened at 21 to 24

[JamieOber]

Here are my thoughts then I will see what you guys think. It basically breaks down into three categories. No snow zone: IPT, FIG. Models will continue to tighten up and dry air will likely eat up anything that falls. On the edge: UNV, SEG abd AVP. In this area you are right on the edge of meaningful precip. A bump south, high and dry. A bump north solid low end advisory snows. And the It Will but How Much crew: MDT,.LNS, AOO, JST, THV. At least a solid advisory snow if a bump north very nice warning event.

Sounds reasonable but you've just eliminated dry air as a factor, given every time this year you've posted about dry air it hasn't been a factor at all

[sauss06]

To me, it looks to be snowing before midnight around here. But what do i know.

[Festus]

This is looking like a grass special to me.  Even if we manage 4-6", I'd guess maybe an inch of slush on roadways, especially mid to late Wednesday afternoon.  If we manage more after that, then possibly a little more on the pavement.

 

A lot of factors favoring reduced pavement accumulation,

1. Above surface temps during the event.

2. Early October sun angle equivalent.

3. Decent but not excessive rates.

4. High of 40 today and low of 30 tonight.

 

At least that's how I see it in my neck of the woods.

[Wmsptwx]

Looking at the NAM at 33 hr I get excited bc lets face it its in a perfect spot for us, then I remember its scooting ENE.

[JamieOber]

This is looking like a grass special to me.  Even if we manage 4-6", I'd guess maybe an inch of slush on roadways, especially mid to late Wednesday afternoon.  If we manage more after that, then possibly a little more on the pavement.

 

A lot of factors favoring reduced pavement accumulation,

1. Above surface temps during the event.

2. Early October sun angle equivalent.

3. Decent but not excessive rates.

4. High of 40 today and low of 30 tonight.

 

At least that's how I see it in my neck of the woods.

That's one of the worst possible driving conditions. I'd rather drive through 5 inches of powder than an inch of slush. 

[djr5001]

This is looking like a grass special to me.  Even if we manage 4-6", I'd guess maybe an inch of slush on roadways, especially mid to late Wednesday afternoon.  If we manage more after that, then possibly a little more on the pavement.

 

A lot of factors favoring reduced pavement accumulation,

1. Above surface temps during the event.

2. Early October sun angle equivalent.

3. Decent but not excessive rates.

4. High of 40 today and low of 30 tonight.

 

At least that's how I see it in my neck of the woods.

The difference between sun angle issues in October and that of March is in October we do not have a frozen surface yet and coming out of summer temperatures are still warm aloft.  Here in March, coming out of the dead of winter, only warming we have is near the surface which is still frozen or close to frozen.  Days where winds have been light and there has been ample sunshine we have seen temperatures jump well into the 40s, which is possible today.  After sunset on these days, however, temperatures have quickly dropped back into the 30s.  Cloudy and windy days have held temperatures more in the 30s to prove that despite the sun angle increasing, we need these rays to reach the surface to do any considerable warming.  That is why it will be less of an issue tomorrow than many think unless we have light flurries and breaks in the clouds.

 

Most snow events we have had this winter around here with the temperature issues have come after a period of daytime heating prior to the start of the event.  This event will be starting overnight to near sunrise. 

[sauss06]

The difference between sun angle issues in October and that of March is in October we do not have a frozen surface yet and coming out of summer temperatures are still warm aloft.  Here in March, coming out of the dead of winter, only warming we have is near the surface which is still frozen or close to frozen.  Days where winds have been light and there has been ample sunshine we have seen temperatures jump well into the 40s, which is possible today.  After sunset on these days, however, temperatures have quickly dropped back into the 30s.  Cloudy and windy days have held temperatures more in the 30s to prove that despite the sun angle increasing, we need these rays to reach the surface to do any considerable warming.  That is why it will be less of an issue tomorrow than many think unless we have light flurries and breaks in the clouds.

 

Most snow events we have had this winter around here with the temperature issues have come after a period of daytime heating prior to the start of the event.  This event will be starting overnight to near sunrise. 

and the rate in which its starts would also have an affect correct? Say if it starts heavier, it would accumlate quicker!