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Central PA - Winter 2018-19


pasnownut

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State college in afd hinting at perhaps heavier amounts due to deformation zone for se areas. Perhaps some bonus snow.

 Model Cycle and latest SREF indicates the potential for
2-3X the snowfall forecast for the far SE zones thanks to a
mesoscale deformation zone just to the north of a compact
700-500 mb closed low Sunday afternoon into early Sunday
evening. The SREF shows the nose of a -2 to -3 sigma, u-wind
anomaly (easterly LLJ) pointed right into that area. There will
be a very tight SSE to NNW gradient in snowfall within 20-30
miles north and south of the I-76 corridor. Will take the
measurable approach to gradually increase amounts across our far
SE zones (near and to the south of a KTHV to KLNS line Sunday
into Sunday evening), but still keep the bulk of Lancaster and
York counties below Winter Storm Warning criteria of 5 inches
for now.

BUFKIT time/height cross sections show a distinct second period
of moderate to briefly heavy snow from about 22Z Sunday to 04Z
Monday INVOF KLNS and points south from this potential
deformation snow band.
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6 minutes ago, Gosnow said:

State college in afd hinting at perhaps heavier amounts due to deformation zone for se areas. Perhaps some bonus snow.


 Model Cycle and latest SREF indicates the potential for
2-3X the snowfall forecast for the far SE zones thanks to a
mesoscale deformation zone just to the north of a compact
700-500 mb closed low Sunday afternoon into early Sunday
evening. The SREF shows the nose of a -2 to -3 sigma, u-wind
anomaly (easterly LLJ) pointed right into that area. There will
be a very tight SSE to NNW gradient in snowfall within 20-30
miles north and south of the I-76 corridor. Will take the
measurable approach to gradually increase amounts across our far
SE zones (near and to the south of a KTHV to KLNS line Sunday
into Sunday evening), but still keep the bulk of Lancaster and
York counties below Winter Storm Warning criteria of 5 inches
for now.

BUFKIT time/height cross sections show a distinct second period
of moderate to briefly heavy snow from about 22Z Sunday to 04Z
Monday INVOF KLNS and points south from this potential
deformation snow band.

Welcome to the forum! 

Seems like some boom and bust potential right up to and through game time. Will be interesting to see how this unfolds...

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12 minutes ago, Itstrainingtime said:

Welcome to the forum! 

Seems like some boom and bust potential right up to and through game time. Will be interesting to see how this unfolds...

Thank you! Live in Lititz and a weather hound. Love snow most of all. Yeah this will be interesting to see how it unfolds.

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17 minutes ago, Itstrainingtime said:

Where is Nutter? He's made like 3000 posts in the past 30 days and now's disappeared at showtime. 

Overcast, 32 and the sky has that classic look here.

That’s funny, I was just thinking the same thing. He hasn’t been posting in the other thread either. I’m sure we will hear from him soon with some snow on the way tonight, plus the possibility of more next weekend.

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8 minutes ago, Blizzard of 93 said:

What are your thoughts on potential snow amounts at this time for both your area & also the LSV ?

At the very least I think CTP's advisory lineup and numbers look pretty good across the board over the region for now.

Things to watch for will be with the initial shield of warm advection precip (which is generally the primary source of the snowfall for our region) and how well it presses northeastward into PA. HRRR has looked pretty good with pressing it pretty far NE, nearly getting the 1" line at 10:1 to IPT on the latest run. Ratios will be a key to get to advisory amounts. A straight 10:1 wouldn't get there with the QPF in all but the southern tier border counties. I know in earlier CTP discos they've mentioned 13-15:1 ratios, which is good but could be better. A limiting factor mentioned was that despite good dendritic growth high up, falling through the lower levels could cause riming and accretion. So if we were to end up getting better ratios (15-18:1 type stuff), then we'd squeeze a bit more snow out on the fluff factor. So i'll be curious if we end up with some better enhancement in the JST-AOO-MDT corridor with the WAA snows. It also wouldn't take much to squeeze out an extra tenth or so of precip either, especially turnpike south. 

Last night from CTP:

Quote

Best UVVEL is inside or just above the DGZ as this band moves in. The DGZ is
well aloft, about 15kft up. So, despite a good set up for
dendrites to grow nicely, they may rime/accrete as they fall
through the lower clouds and keep the SLRs in check. SLRs look
exactly the same as last few runs, about 13:1 in Somerset with a
slight gradient up to 15:1 at UNV and MDT.

The other and more potentially impacting thing to watch is what happens when the coastal low starts to take over. For one, the models have been pretty quick to snuff out the warm advection shield over PA once that starts happening. Does it really do that? Or will it linger more, and then be part of the deform shield of the coastal low that will have the heavier precip and better forcing. The 18z NAM kind of tried to do that, and illustrated how it's possible that the border counties join in with the Mid-Atl forum in getting warning snows. It'll be interesting to watch this unfold tonight. It's a moisture laden Gulf Storm, and these types of events always seem to find a way to squeeze out more snowfall. 

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First flakes flying here....a bit warmer than I was expecting.   34.  DP will drop that shortly.   North trend seems to have stopped as Canderson was alluding to so as Mag mentioned the larger amounts are going to be all about where a possible coastal deform sets up.  Will be the difference between 3" and 8".   Here is our "Icon"

icon_apcpn_neus_17.png

 

 

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Thanks MAG.

The precip in the Tennessee area looks juiced up & is heading north east. The precip from IL to OH is also up to their respective northern borders. I agree that if we stay in the precip shield as the low shifts toward the coast, then we could be looking at more snow than modeled.

I think we have the chance to get a little more QPF than currently modeled & we could do better than 15-1 ratios with this cold air in place. 

 

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1 hour ago, bubbler86 said:

First flakes flying here....a bit warmer than I was expecting.   34.  DP will drop that shortly.   North trend seems to have stopped as Canderson was alluding to so as Mag mentioned the larger amounts are going to be all about where a possible coastal deform sets up.  Will be the difference between 3" and 8".   Here is our "Icon"

icon_apcpn_neus_17.png

 

 

Hopefully this is indeed our “ICON” !

If we get .4 or .5 QPF in the LSV, we would get to warning criteria snow with ratios!

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