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Central PA Winter 23/24


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7 minutes ago, CarlislePaWx said:

@Bubbler86You're speaking about a changeover (although not precisely where), but I'll assume SE LSV / Lanco.  However, none of my precip-type maps show any changeover anywhere in this region for any period of this storm.  Please specify where/what you meant regarding said changeover.

Different model sites use different algorithm's for the precip type.  Here is TT showing the changeover.    Pivotal's maps do not show the same, but they decreased snow in this same area from the 0z run that was pretty much all snow. 

image.thumb.png.9fcbe31533dded25a718cde82e20595d.png

 

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5 minutes ago, Bubbler86 said:

Different model sites use different algorithm's for the precip type.  Here is TT showing the changeover.    Pivotal's maps do not show the same but they decreased snow in this same area just the same.

image.thumb.png.9fcbe31533dded25a718cde82e20595d.png

 

Weatherbell really didn’t send a changeover across the Mason-Dixon Line. I know the algorithm gets a rap for being snowy or whatever but that particular map is a 6hr frame and if you use a 3hr frame bulk of QPF is thru York/Lancaster by 111hr. Thermals at 850/925mb/surface are still fine at that point. At the 114 hr frame the 850mb 0 line is shaped pretty much like the changeover line on that TT map but the 850 temps are still within tenths of a degree of zero in that little rain area that intrudes into PA as are 925 and surface. So if there’s any heavier precip left between that 111-114hr frame there it’s probably going to be snow… albeit likely at reduced ratios. 

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4 minutes ago, MAG5035 said:

Weatherbell really didn’t send a changeover across the Mason-Dixon Line. I know the algorithm gets a rap for being snowy or whatever but that particular map is a 6hr frame and if you use a 3hr frame bulk of QPF is thru York/Lancaster by 111hr. Thermals at 850/925mb/surface are still fine at that point. At the 114 hr frame the 850mb 0 line is shaped pretty much like the changeover line on that TT map but the 850 temps are still within tenths of a degree of zero in that little rain area that intrudes into PA as are 925 and surface. So if there’s any heavier precip left between that 111-114hr frame there it’s probably going to be snow… albeit likely at reduced ratios. 

Here is a skew-t from TT when it is showing rain in much of the LSV.  Definitely model site differences in interpreting the data but the Kuch snow map on Pivotal does look like one that shows the southern parts of PA had mixing issues regardless of the preip maps so it is close.  I do not have WB.

image.thumb.png.4c64571c08b1b09b81b20069910a47a8.png

 

 

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16 minutes ago, MAG5035 said:

Weatherbell really didn’t send a changeover across the Mason-Dixon Line. I know the algorithm gets a rap for being snowy or whatever but that particular map is a 6hr frame and if you use a 3hr frame bulk of QPF is thru York/Lancaster by 111hr. Thermals at 850/925mb/surface are still fine at that point. At the 114 hr frame the 850mb 0 line is shaped pretty much like the changeover line on that TT map but the 850 temps are still within tenths of a degree of zero in that little rain area that intrudes into PA as are 925 and surface. So if there’s any heavier precip left between that 111-114hr frame there it’s probably going to be snow… albeit likely at reduced ratios. 

Great post.  Like you , I looked at timestamps for periods in question and noticed much the same.  Skew T's had me at 33 max and much qpf was already laid down, and column was close enough to not yet worry (but 700's to surface were scarily close).  Even if I did end as drizzle/snizzle, I'd be happy to see an appreciable event.  

Mind you not much dissecting will matter at 4+ days out, and we should just be looking for consistency/trends to get hammered out right now, but it sure is fun to be seeing winter on the maps though.  

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28 minutes ago, Bubbler86 said:

Here is a skew-t from TT when it is showing rain in much of the LSV.  Definitely model site differences in interpreting the data but the Kuch snow map on Pivotal does look like one that shows the southern parts of PA had mixing issues regardless of the preip maps so it is close.  I do not have WB.

image.thumb.png.2157c69a0313f84e0252a3781ebd26f7.png

 

 

Yea, that’s an isothermal layer from surface to about 850 thats essentially between the 32-33ºF range (highlighted for you). Light rates might be drizzle/freezing drizzle depending on surface temp, but moderate to heavy rates would likely be snow with that kind of skew T presentation. 

Here’s the 3-hr precip from 111-114. A couple tenths fall in parts of Lancaster in that timeframe, but the rest of LSV west of there is mostly done at that point. That’s the furthest north I’ve seen the GFS take the primary with its Miller B solutions. The low’s weak and the transfer is already occurring so it still kept most to all of the state snow but the other part of that equation is the best overall QPF in the frozen precip zone went deeper into central PA. Though I suppose there’s not a huge difference since everyone in here generally gets in that .75-1.00” range.

image.thumb.png.eaf832eec2130aa9fa5ab1357ffc6a2b.png

Obviously one model run and a global model at that, but we are getting into the range we can start scrutinizing the details on these runs more. The high res stuff when we get to that range (NAM, HRRR, et al) is where we’re going to really hone on the thermals. 

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16 minutes ago, MAG5035 said:

Yea, that’s an isothermal layer from surface to about 850 thats essentially between the 32-33ºF range (highlighted for you). Light rates might be drizzle/freezing drizzle depending on surface temp, but moderate to heavy rates would likely be snow with that kind of skew T presentation. 

Here’s the 3-hr precip from 111-114. A couple tenths fall in parts of Lancaster in that timeframe, but the rest of LSV west of there is mostly done at that point. That’s the furthest north I’ve seen the GFS take the primary with its Miller B solutions. The low’s weak and the transfer is already occurring so it still kept most to all of the state snow but the other part of that equation is the best overall QPF in the frozen precip zone went deep into central PA. 

image.thumb.png.eaf832eec2130aa9fa5ab1357ffc6a2b.png

Obviously one model run and a global model at that, but we are getting into the range we can start scrutinizing the details on these runs more. The high res stuff when we get to that range (NAM, HRRR, et al) is where we’re going to really hone on the thermals. 

Yea, it is not worth too much stress over worrying.  Carlisle asked me where I saw it change to rain so I passed it on.  This pivotal snow map is also indicative of precip issues near the M/D line.  Those could definitely include super low ratio snow like you mentioned since this is a Kuch map.  Those circled areas are common first fall area when losing one or more level.   I am in the far left one so very familiar with the look.   If you switch to a 10-1 map you do not see the same layered intrusion signatures vs. more elevation related differences.  The meso's will tell the story like you said :-).

Kuch

image.png.423f68fbc3da4abede2ada06878f2384.png

10-1

image.png.f791ab4c4a92f227aafe3404b7c87b97.png

 

 

 

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Yea, it is not worth too much stress over worrying.  Carlisle asked me where I saw it change to rain so I passed it on.  This pivotal snow map is also indicative of precip issues near the M/D line.  Those could definitely include super low ratio snow like you mentioned since this is a Kuch map.  Those circled areas are common first fall area when losing one or more level.   I am in the far left one so very familiar with the look.   If you switch to a 10-1 map you do not see the same layered intrusion signatures vs. more elevation related differences.  The meso's will tell the story like you said :-).
Kuch
image.png.423f68fbc3da4abede2ada06878f2384.png
10-1
image.png.f791ab4c4a92f227aafe3404b7c87b97.png
 
 
 
Look at that Kuch. MAG is the big winner if that verifies.

Sent from my motorola edge 5G UW (2021) using Tapatalk

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