hazwoper

December 16/17 Snow Wall Obs Thread

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IP has really picked up over last 30 minutes temp now starting back up now at 25.8....just measured another 0.3" of IP bringing our snowfall for the day up to 6.0" - also noting a few mangled snow flakes starting to mix back in over the last few minutes...should see a transition back to snow later tonight from NW to SE....someone will pick up several more inches in wrap around later tonight....not sure where but - nice storm for December!!

The front end thump is so important as the wraparound is generally over-predicted in these storms and often disappoints. It is tough to say what will happen with this one as the nowcasting presentation is questionable to our southwest but let’s see what happens as the low cranks up further to see if it fills.


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25 minutes ago, RedSky said:

The warm punch has been modeled for at least the last 24hrs it was a clear and present danger. Also all the snow maps that have been flying around with 10:1 ratios are garbage and now you know why.

 

 

Warm punch was modeled on the NAM since Sunday actually. Most of us shrugged it off as the NAM at range but it led the way....again.

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3 minutes ago, Animal said:

see phl airport reporting 5.7 of snow!!

Based on Mt. Holly's climatology report if they get no wrap-around, it would be a couple inches short of the record for the date (other locales probably broke theirs like Allentown definitely and possibly Wilmington, depending on any other reports) -

Quote
&&

.CLIMATE...
Here are the daily snowfall records for Wednesday, Dec 16 and
Thursday, Dec 17:

Dec 16
Allentown...4.5" in 1973
Atlantic City Airport...0.8" in 2010
Philadelphia...7.1" in 1896
Wilmington...3.5" in 1896

Dec 17
Allentown...2.1" in 2013
Atlantic City Airport...0.2" in 2013
Philadelphia...7.3" in 1932
Wilmington...2.2" in 1973

&&

 

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14 minutes ago, Hurricane Agnes said:

I popped open RadarScope and it is really show the incoming dry slot.

radarscope-750pm-12162020.png

Yep, I'm thinking that's about it here. I'll be shocked if we see anything on the backside. Fun little event even if a little disappointing. Think we have around 5 inches out there. 

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It's been quite an evening here.  We now have sleet pellets mixed in and according to Dual Pol Doppler we will be transitioning soon.  We have had 8" so far.  19F / DP 18F.  Blizzard conditions reported at ABE. 

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1 hour ago, CoolHandMike said:

Anyone want to hazard a guess as to why all the models and predictions turned out to be so wrong with this storm? Two days ago we were supposed to get almost 2' of snow, then yesterday they backed it off to 13", and now I have barely 4" with sleet coming down much further north than predicted, with not much else seemingly incoming. I mean, I want to be happy for the first major snowfall in a long, long while, but why the huge bust this time?

Perhaps someone else can better describe this, but I think a main problem was some of the models were keeping the low fragmented at 700 mb and 500 mb and not quite closed off at all levels of the atmosphere, so that it was more just an 850 mb low level circulation with a progressive ripple trough higher up that would gently slide east off the coast. But the low closed off --I don't think it's fully stacked ? (someone better can say for sure)...but the trough tilted more negative, and this sort of yanked back on the surface low to hug into the coast close, taking the track over the Chesapeake and Delaware Bays we see tonight. 

Again, someone probably knows a better website (?) but you can see the different upper air maps here from Norman, OK --  all of them have a low plotted generally over the Delmarva (though I don't think the low is quite that far NW attm fwiw). 

 

 

 

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Snow and sleet battling here in Macungie, i thought snow was back at 100% but sleet now back big time. I think the line is literally wavering north and south along I78 / US22. About 7” here.


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1 hour ago, The Iceman said:

Yep, I'm thinking that's about it here. I'll be shocked if we see anything on the backside. Fun little event even if a little disappointing. Think we have around 5 inches out there. 

6" fluff before the flip.

The sleet is factored as liquid equivalent I assume? But at what ratio? 

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4 minutes ago, 40/70 Benchmark said:

Philly get 6"?

The 8:34 pm PNS lists 5.7 at PHL - https://www.wrh.noaa.gov/total_forecast/getprod.php?new&prod=XXXPNSPHI&wfo=phi

Quote
...Philadelphia County...
 Philadelphia International A 5.7 in    0700 PM 12/16   ASOS                 
 Rittenhouse Square           5.0 in    0515 PM 12/16   Public               
 2 SE Point Breeze            3.8 in    0530 PM 12/16   Trained Spotter      
 1 SW Mantua                  3.5 in    0424 PM 12/16   Public               
 1 S Philadelphia             3.0 in    0435 PM 12/16   Public               
 Northeast Philadelphia       2.0 in    0342 PM 12/16   Public               
 1 ENE Mantua                 0.7 in    0300 PM 12/16   Public               
 &&
 

ETA - am guessing that is including IP.

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4 minutes ago, RedSky said:

NAM has it almost done with another .5 - 1" 

I want a refund.

 

 

 

No other way to code it except as a good old fashion bustorama with the forecast for the north and west burbs. Can’t complain to much on my street. I was always on that shaft zone.

sleeting hard again.

 

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