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Central PA - Winter 2020/2021 Part 2


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Lol, you guys have been reading the Mid-Atlantic thread haven't you?

I know this isn't looking as great as it was but it still should be a general advisory type event for the LSV. The NAM and company had been the guidance in particular leading the way with that widespread 6"+ and we should all know the NAM can giveth.. but it most certainly can taketh away. Most other guidance has generally been less of a widespread 6"+ threat and more of a debate of how expansive the precip extent is going to be. I thought the coastal low had a chance to run up right on the coastline but it's looking like it will track offshore some, pulling the axis of best snowfall associated with that back southeast some. Basically back to my original SE of I-81 thinking with the best accums. 

Jury still somewhat out on that NW extent of the precip shield between blossoming coastal and also the area of precip back out over MO/IL/etc. I like a general T-2" NW of I-81 covering back to the I-99 (AOO,UNV,IPT) corridor and perhaps even western PA as we certainly can't rule out a period of mostly light snow anywhere in those areas. Obviously the best chance of 2" or perhaps a bit more is closer to I-81 or perhaps some southern Laurels locations. 2-3" (advisory event) for places like MDT and more of a 3-5" York/Lancaster with an outside chance at some scattered higher amounts near the MD border.. but mostly this is looking to top out at 4-5" by the looks of it.    

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22 minutes ago, MAG5035 said:

Lol, you guys have been reading the Mid-Atlantic thread haven't you?

I know this isn't looking as great as it was but it still should be a general advisory type event for the LSV. The NAM and company had been the guidance in particular leading the way with that widespread 6"+ and we should all know the NAM can giveth.. but it most certainly can taketh away. Most other guidance has generally been less of a widespread 6"+ threat and more of a debate of how expansive the precip extent is going to be. I thought the coastal low had a chance to run up right on the coastline but it's looking like it will track offshore some, pulling the axis of best snowfall associated with that back southeast some. Basically back to my original SE of I-81 thinking with the best accums. 

Jury still somewhat out on that NW extent of the precip shield between blossoming coastal and also the area of precip back out over MO/IL/etc. I like a general T-2" NW of I-81 covering back to the I-99 (AOO,UNV,IPT) corridor and perhaps even western PA as we certainly can't rule out a period of mostly light snow anywhere in those areas. Obviously the best chance of 2" or perhaps a bit more is closer to I-81 or perhaps some southern Laurels locations. 2-3" (advisory event) for places like MDT and more of a 3-5" York/Lancaster with an outside chance at some scattered higher amounts near the MD border.. but mostly this is looking to top out at 4-5" by the looks of it.    

Thanks Mag.

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1 minute ago, Wmsptwx said:

What’s this week ahead looking like? Hearing a bunch of threats but not sure what days specifically.

Possibly some kind of a light event Tuesday, with some light snow streaking across PA (perhaps light mix southern tier depending on the model). It seems the bigger trouble brewing will be late week in the Thur/Fri timeframe. This is looking like a drawn out warm advection type event at first with an eventual wave(s) of low pressure coming up towards PA. My concern with this setup is given the gradient pattern and the arctic air nearby is it looks like quite a favorable setup for having a significant icing swath. Not necessarily here, but somewhere. 18z GFS for instance mainly snow with this while the afternoon Euro run had alot of ice into PA. Those details are impossible to nail down at this point, but that Thur-Fri timeframe looks to be where the next more significant precip event materializes. 

Also the question of cold air, as the big time arctic air is on the playing field but trying to figure out how much eventually releases into the eastern US. Models have literally been all over the temperature spectrum, from the mixing events and temps near somewhat above freezing at times to throwing the whole polar vortex over the Great Lakes/NE and what would likely be record cold. Still going to be pretty cold immediately behind tomorrow's system but the significant arctic cold that was looking to happen earlier this coming week now looks to hold off to perhaps D6-7 or so. Guidance is having alot of trouble handling location of the gradient/storm track and the longwave pattern in general.

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27 minutes ago, Wmsptwx said:

What’s this week ahead looking like? Hearing a bunch of threats but not sure what days specifically.

I was busy the last few minutes pulling maps from the 18z GFS.

The snow opportunities over the next 2 weeks are lining up! It’s quite a long line of chances...

The first major chance begins Wednesday night with overrunning snow breaking out over CTP which continues at varying intensities until Friday. The Euro and Canadian today had most of CTP changing over to a long period of mixed precip after several inches of snow. The 18z GFS came in with more of a cold press, so it kept CTP in mostly all snow for the duration of the event.

It will all depend on where the boundary sets up to determine if we stay all snow or change to a mix on Thursday into Friday.

Here is the 18z GFS for the beginning of the event Wednesday night and then towards the end of the storm on Friday. The snow map is just for this late week event.

 

 

 

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22 minutes ago, Blizzard of 93 said:

The 18z GFS entire 16 day total snow map is just too good to not post!

The 10 -1 ratio map is epic, but the Kuchera is out of this world!

I think most of us would be thrilled with just half of this !

This just screams “Potential” !!!

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That would be insane. Let’s hope for an active week ahead and no sleep lol. For tracking. 

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2 minutes ago, Blizzard of 93 said:

If you want good snow, you typically don’t want the Arctic descending right on top of you. It’s much better to have it nearby in order to keep the storm track active. Otherwise, too much Arctic air & the storm track heads way too far south.

Blizz you and I can’t think alike. It’s nice to have but to have it close is the most important thing. Otherwise suppression. 

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The 12z EPS & GEFS snow maps are just beyond fantastic looking with the potential that these next 2 weeks hold for our region.

I have NEVER seen a 2 week EPS map show 15 inches of snow over the LSV unless we had a major event arriving within the next day. 
There are multiple chances embedded in different windows of opportunity over the 360 hour run.

Rest up now, we are going to be very busy tracking!

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9441B014-E0D0-4A53-A2B4-B7529E16836B.png

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32 minutes ago, Blizzard of 93 said:

The 12z EPS & GEFS snow maps are just beyond fantastic looking with the potential that these next 2 weeks hold for our region.

I have NEVER seen a 2 week EPS map show 15 inches of snow over the LSV unless we had a major event arriving within the next day. 
There are multiple chances embedded in different windows of opportunity over the 360 hour run.

Rest up now, we are going to be very busy tracking!

Man, you've been the busy beaver this afternoon and evening, haven't you?  As always I want to thank you both for the time you take to post those WB maps and also for your overflowing optimism.  Keep it up!:snowing::shiver:

PS>>The 18Z GFS also showed amazing cold coming starting next weekend with a massive arctic front passing through here Saturday night.  Temperatures start out in the mid 20's at midnight (sat) and fall off the cliff during the entire day Sunday with the LSV down into the positive single digits by Sunday evening, and even further down into the mid minus single digits by Monday morning.  Nearly all of Ohio 12Z Monday are all -20 to -25 degrees, western PA is in the minus teens, and central/LSV are -3 to -8 degrees F.  Baby, that's cold!

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Here was the CTP update a couple hours ago. Def more leery of the NAM's optimism by the sounds of it. 

Quote
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
10 PM Update...
Latest guidance shows the NAM and cousins to be consistent
high-end outliers for QPF/snow amounts. Have brought the fcst
back closer to a GFS/GEFS feel, but left the numbers fairly
similar in the advy area. We are skeptical of the NAM due to
errors which may be introduced from gravity wave interactions.
Have decided to just shave 0.5-1" off the accums most places for
those reasons. Will keep the timing and coverage of the advy the
same for the time being, but have big doubts that the NW half of
the advy area will meet even the 2" criteria, and Fulton county
has a very low chc of making it to 3" average accums across the
small county. Tough to pull back too far point since the snow
hasn`t even started yet.

HRRR has looked like garbage in terms of any decent snows, with the latest full run (03z) not even having advisory snows in CTP or pretty much the northern half of LWX's CWA... where there's warnings up. I think HRRR is underestimating precip shield.. it definitely did during the latter stages of last weeks winter storm with the roving bands of snow. How much so is debatable. DC's problem with the lack of accums being presented is the HRRR has half the event as rain. LSV shouldn't have to worry about that. Speaking of temps.. sure wish I had direct incoming with the nice crisp 21ºF and overcast conditions here currently.   

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6 hours ago, CarlislePaWx said:

Man, you've been the busy beaver this afternoon and evening, haven't you?  As always I want to thank you both for the time you take to post those WB maps and also for your overflowing optimism.  Keep it up!:snowing::shiver:

PS>>The 18Z GFS also showed amazing cold coming starting next weekend with a massive arctic front passing through here Saturday night.  Temperatures start out in the mid 20's at midnight (sat) and fall off the cliff during the entire day Sunday with the LSV down into the positive single digits by Sunday evening, and even further down into the mid minus single digits by Monday morning.  Nearly all of Ohio 12Z Monday are all -20 to -25 degrees, western PA is in the minus teens, and central/LSV are -3 to -8 degrees F.  Baby, that's cold!

I get the idea of snow, but why would anyone want cold air like that? 

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