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Two Mdt to high impact events NYC subforum; wknd Jan 6-7 Incl OBS, and mid week Jan 9-10 (incl OBS). Total water equiv by 00z/11 general 2", possibly 6" includes snow-ice mainly interior. RVR flood potential increases Jan 10 and beyond. Damaging wind.


wdrag
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8 minutes ago, WestBabylonWeather said:

I remember watching the weather channel religiously too. Watching the storm maps for the five day starting with slamming into the Pacific Northwest and making their way across. I feel like that’s changed dramatically 

It’s been years since I last watched that channel.  My service does not even offer it.

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1 hour ago, Albedoman said:

Walter Drag, I find this really unusual that Henry would post such a map in a topsy turvy weather pattern we are in right now. There is no set weather pattern at this time This amount of snow he is depicting is not even on the NAM 84 hours yet?  This type of  snow hype is nonsensical. Whatever happened to realistic forecasting?

Just need to hold all of us accountable. I can't add anything more than what is within the thread.  

Models are good, but not that good on ptype.  When we use 10-1, that's outdated methodology that doesn't really properly baseline accumulation.

I always start with positive snow depth change. If you have sleet....  that inflates snow totals considerably.  

10 to 1 or Kuchera might be good to communicate when we get within 3 days or so, and you know no mix and temps aob 32 at the surface throughout.  

Positive snow depth change doesn't do so well, imo, in these 33-34F nighttime heavy wet snows when the snow overcomes melting processes. 

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18 minutes ago, wdrag said:

Just need to hold all of us accountable. I can't add anything more than what is within the thread.  

Models are good, but not that good on ptype.  When we use 10-1, that's outdated methodology that doesn't really properly baseline accumulation.

I always start with positive snow depth change. If you have sleet....  that inflates snow totals considerably.  

10 to 1 or Kuchera might be good to communicate when we get within 3 days or so, and you know no mix and temps aob 32 at the surface throughout.  

Positive snow depth change doesn't do so well, imo, in these 33-34F nighttime heavy wet snows when the snow overcomes melting processes. 

I agree with your analysis. The biggest issue IMHO for this event --- if the snow falls Saturday afternoon into the evening as currently shown, the ground melting will cave quickly. I can easily see us reaching a foot if that happens by Sunday mid morning especially if dendritic growth becomes expansive. and if any frontogenesis occurs too. I will assume that the moisture content of the snowflake  itself will be very high too. That will lead to serious medical issues throughout the region as many are not used to shoveling wet heavy snow in the last 3-4 years because of the light in moisture content with snowfalls in the past La Nina years. 

I too rely on the positive snow depth change totals in the 5 day LR models  then work up from there based on the aforementioned factors.  The NAM models as well as the HRRR models will fine tune and sniff out  the final snow accumulations, usually with 36-48  hours of the event . In my past years forecasting , I alway relied on the LR Euro at 5 days  and if the SR NAM backed  the totals too, it was pretty a dam accurate forecast for snowfall events.

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51 minutes ago, WestBabylonWeather said:

I remember watching the weather channel religiously too. Watching the storm maps for the five day starting with slamming into the Pacific Northwest and making their way across. I feel like that’s changed dramatically 

i watched the twc everyday when i get a chance... sometimes i look at the accuweather for like 2 minutes..

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3 hours ago, gravitylover said:

@Albedoman and I are on the same train. Good post dude.

yes, I agree... the only thing I can't count on yet is 8-12 Lehigh Valley... yes on the equiv qpf but am unsure on all snow there. I just checked... 19z BOM is hanging tough on 4-7"axis e PA though NNJ n of I80 to CT and qpf by 00z/1 1of 3-4".  We'll see if the magnitudes hold.

I wasn't too keen on that AFD.  You need  to offer guidance for preparations. NHC is ahead of our forecast offices by and large on doing that (my opinion only but not necessarily shared by many) and if we go back to the CPC outlook from last Friday that was posted here... they too offered some info for people who need to think about options (8--12 days in advance, including my own personal work life snow/wind/flooding rains- I work for the county inspecting Guiderails, drain pipes, bridges etc)).   A forecaster arbitrarily capping a pop is overriding national center guidance which is 88% for NYC.  That sitting on the fence forecast for D6 is eventually going to get AI'd out... models are getting better. I'd say capping a pop is more reasonable when you're on the gradient of much to nil.  One of those POPS Sagt night or Sunday has to be higher than 50%.  For now, we in the NYC subforum continue in the max storminess axis.  Yes this could change... but the longer we stay in this axis, the less chance for a miss. 

Now its a matter of communicating concerns.  There's always a chance of failure but my own choice is try to ballpark potential well in advance, especially if BOM/multi ensemble support.

18z/1 EPS is almost identical to the 12z... if anything slightly flatter with a decent short wave and strong 5H LF quad with jet out across there Carolinas and signs of RRQ support south of Nova Scotia with an 850 low edging ever further north but forming from NJ- eastward. 

The GEFS is now much sharper and unless the models flatten out in future cycles, I find it hard to believe we will avoid a significant precip event. It's FAST... most of it out of here by 12 or 15z Sunday which means most of this event is 12-18 hours (I think).   Failure can occur.  I sort of think, if its going to fail, the models will have to make an abrupt shift January 2nd cycles (just like the pre Christmas storm last year when the EC suddenly went inside runner  around D6 and stayed there and wiped out a snow event). 

 

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18 minutes ago, Albedoman said:

I agree with your analysis. The biggest issue IMHO for this event --- if the snow falls Saturday afternoon into the evening as currently shown, the ground melting will cave quickly. I can easily see us reaching a foot if that happens by Sunday mid morning especially if dendritic growth becomes expansive. and if any frontogenesis occurs too. I will assume that the moisture content of the snowflake  itself will be very high too. That will lead to serious medical issues throughout the region as many are not used to shoveling wet heavy snow in the last 3-4 years because of the light in moisture content with snowfalls in the past La Nina years. 

I too rely on the positive snow depth change totals in the 5 day LR models  then work up from there based on the aforementioned factors.  The NAM models as well as the HRRR models will fine tune and sniff out  the final snow accumulations, usually with 36-48  hours of the event . In my past years forecasting , I alway relied on the LR Euro at 5 days  and if the SR NAM backed  the totals too, it was pretty a dam accurate forecast for snowfall events.

well done imo.

We'll see what happens. Tomorrow (2nd) will be D5 for the EC. I still am leery of much snow NYC/LI--- I could easily be wrong. I'm just not confident of PTYPE with general 1000-500 thickness over 540.  I may not be able to post again til Tuesday night. 

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i watched the twc everyday when i get a chance... sometimes i look at the accuweather for like 2 minutes..

You all want a blast from the past ? RE-LIVE the weather channel in its glory days. It’s best viewing this on computer because it has all the music too:

https://battaglia.ddns.net/twc/#


Using it on IPhone sucks
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11 minutes ago, Jersey Andrew said:

His two volume book on Northeast snowstorms is bible for winter weather weenies. Wonder if he participates in any weather discussion boards?

He doesn't want to be on the forums. I asked him in the past.

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4 hours ago, MJO812 said:

Henry Marguisity

 

FB_IMG_1704149954113.jpg

Even as there remains considerable uncertainty, it is unlikely that Allentown will see 12"-18" of snow. The potential exists for 6"-12" if things come together.

Select Data:

1/2 0z NBE: 6.2" (the 2z increased the snowfall to 9.0")

1/1 12z EPS Members: 12" or more: 20%; 18" or more: 2%

WPC Probabilistic Winter Storm Severity Index for Major Impact: < 5% (around 20% for a moderate impact)

image.thumb.png.84c30010a39fce70e82178b007ba8456.png

image.png.5d0acaed132fc3b17b87f5427d78e1ee.png

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1 hour ago, Albedoman said:

I agree with your analysis. The biggest issue IMHO for this event --- if the snow falls Saturday afternoon into the evening as currently shown, the ground melting will cave quickly. I can easily see us reaching a foot if that happens by Sunday mid morning especially if dendritic growth becomes expansive. and if any frontogenesis occurs too. I will assume that the moisture content of the snowflake  itself will be very high too. That will lead to serious medical issues throughout the region as many are not used to shoveling wet heavy snow in the last 3-4 years because of the light in moisture content with snowfalls in the past La Nina years. 

I too rely on the positive snow depth change totals in the 5 day LR models  then work up from there based on the aforementioned factors.  The NAM models as well as the HRRR models will fine tune and sniff out  the final snow accumulations, usually with 36-48  hours of the event . In my past years forecasting , I alway relied on the LR Euro at 5 days  and if the SR NAM backed  the totals too, it was pretty a dam accurate forecast for snowfall events.

Good points.  To amplify further, one thing most don't appreciate is that with moderate to heavy snowfall rates, ground melting will be overcome quickly and once there is a layer of snow on the ground, that snow, by definition is at 32F (or colder), meaning subsequent snowfall has a negligible melting rate, even if the air temp is a degree or two above 32F.  Also, sun angle is quite low and antecedent temps will likely be not far above 32F, so initial ground melting will likely be quite low anyway.  I also remember the old E/E rule (Euro/ETA - old name for NAM).  Let's just hope we get snow (the vast majority around here want that, lol).  

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