December 14-15 Winter Storm Part Two

[jm1220]

I didn't even post the actual clown map, just relayed what it shows and I get attacked. Plenty of other posters have posted maps numerous times.

 

>4" snow probs show a tight gradiant as you get down to Essex County and eastward

 

I'd say there's a 50-50 shot at Central Park making it to 4". One hour in either direction will make a big difference. If something like the NAM verifies, it could be more like 5-6". GFS might struggle to make 3" there.

[IntenseBlizzard2014]

I will say this folks...I think it's time to get off this freezing rain train. Just like the algorithms are crappy for the clown maps, I normally have about 10% confidence in the ZR algorithms. This is NOT a classic ZR setup; not even close. More likely than not, the ZR QPF will likely fall as pure rain. Folks have to realize that NWS has a specific checklist/criteria (normally geographically) that raises concerns...I don't get the sense at all that we will meet the various criteria to set up a ZR event anywhere.

I know it's long range, but folks worrying about laying down snowfall for Christmas with this event...it's not going to happen anywhere for the East Coast on this event. Even places that receive 1 foot from this event are going to torch around 12/21. The indices are very indicative of a significant warmup for 1-2 days as the -EPO reloads and the PNA plummets.

I'm very aware of the warm up. It's just a bump in the road.

[Rib]

Enough bickering. Keep this thread about the storm, thanks.

[LnbWx]

You live like 7 miles from me, we do fine. I think anyone north of I-80 and west of say Rt. 46 stay all frozen or freezing. Now moderate rain with temps of 31-32 isn't going accumulate like it would with temps in the 20's.

 

North of I-80 and west of Rt.46? As far as I know, Rt.46 runs east-west parallel to I-80. Surely you meant Rt.17 instead which runs north-south?

[IsentropicLift]

I'd say there's a 50-50 shot at Central Park making it to 4". One hour in either direction will make a big difference. If something like the NAM verifies, it could be more like 5-6". GFS might struggle to make 3" there.

My best guess is that the initial shot of WAA precip is mostly weak and stays to the west or NW of NYC. The 4k NAM shows this well with the first waves of snow breaking up, so it's probably just some flurries or virga. Then sometime after noon the snow comes in earnest and we're all happy with light to moderate snow until well after dark. The city then briefly flips to sleet around 1-2AM and then plain rain before ending sunrise. NW areas stay mostly snow with a thin stream of ZR somewhere near the I-287 corridor.

[donsutherland1]

Any soundings on GFS yet?

At 39 hours, 900 mb to the surface is > 0°C in NYC.

[IsentropicLift]

North of I-80 and west of Rt.46? As far as I know, Rt.46 runs east-west parallel to I-80. Sure you didn't mean Rt.17 which runs north-south?

My mistake, I should have clarified, North and west of the I-80, Rt.46 interchange in Wayne/Totowa.

[SnowGoose69]

I'd say there's a 50-50 shot at Central Park making it to 4". One hour in either direction will make a big difference. If something like the NAM verifies, it could be more like 5-6". GFS might struggle to make 3" there.

 

LOL, well a big part of that is when the transition occurs...remember those clowns measure at 7pm and 1am so if we get doused with 2 inch per hour rates from 7-930 then go over to rain they'll probably measure 3 inches too low, remember last year they had 1.5 inches easily at the start of a storm but since it went over to rain and all washed away they reported a trace.

[jm1220]

At 39 hours, 900 mb to the surface is > 0°C in NYC.

It really is all about the surface wind direction for us. That's another difference maker on the NAM-it keeps a NE/ENE wind direction in NYC, and keeps the snow in place longer, at least until the mid level warm air arrives-buying another hour or two. The GFS gets much warmer at the surface (probably too warm-it torches all the way through SNE as well) and ends the snow too early for any really significant accumulation.

[F5TornadoF5]

At 39 hours, 900 mb to the surface is > 0°C in NYC.

 

 

Really? You wouldn't think from the e wall map. 540 thickness is below.

[jm1220]

LOL, well a big part of that is when the transition occurs...remember those clowns measure at 7pm and 1am so if we get doused with 2 inch per hour rates from 7-930 then go over to rain they'll probably measure 3 inches too low, remember last year they had 1.5 inches easily at the start of a storm but since it went over to rain and all washed away they reported a trace.

Yup, there always the Zookeeper Factor, good catch.

[IsentropicLift]

LOL, well a big part of that is when the transition occurs...remember those clowns measure at 7pm and 1am so if we get doused with 2 inch per hour rates from 7-930 then go over to rain they'll probably measure 3 inches too low, remember last year they had 1.5 inches easily at the start of a storm but since it went over to rain and all washed away they reported a trace.

Most of what falls east of the city is probably going to get washed away with a GFS solution. Hopefully the NAM scores one.

[Radders]

Regardless, of the outcome, I enjoy these types of storms because of the challenges and surprises they bring to the table due to the extremes in sensible weather over such small distances and where the battlegrounds set up.   Hopefully everybody enjoys the meteorology of this event and the fun in tracking all the nuances.. It is going to be interesting to see how all of this plays out versus the model depictions during the lead up to the storm. These types of events are a great learning experience.

[jm1220]

Really? You wouldn't think from the e wall map. 540 thickness is below.

The warm air comes at the surface due to scorching east winds off the ocean. The instant the wind goes to E or ESE near the coast, it's over, or will be over very soon.

[LnbWx]

Just noticed (very late) that NWS issued a WSW for Eastern Bergen but not across the river to Manhattan. Interesting.

[IsentropicLift]

State College just flipped to warnings for 5-8" of snow and a coating of ice.

[IsentropicLift]

Just noticed (very late) that NWS issued a WSW for Eastern Bergen but not across the river to Manhattan. Interesting.

The probs for warning criteria are much less east of the Hudson River.

 

The watch for Ramsey (Western Bergen) Reads 6-10" of snow and a trace of ice.

 

They are going with a high of 22 on Saturday!

 

Point and click

 

Saturday Snow, mainly after 10am. High near 22. Northeast wind 5 to 9 mph. Chance of precipitation is 100%. New snow accumulation of 2 to 4 inches possible.

• Saturday Night Snow before 1am, then sleet. Low around 21. East wind 9 to 13 mph. Chance of precipitation is 100%. New snow and sleet accumulation of 4 to 8 inches possible.

[ace0927]

Total snow on the RGEM

That is a full-fledged KU for SNE/N NJ/PA....

[MJO812]

That is a full-fledged KU for SNE/N NJ/PA....

Those areas are going to get crushed.

[SnowGoose69]

The probs for warning criteria are much less east of the Hudson River.

 

The watch for Ramsey (Western Bergen) Reads 6-10" of snow and a trace of ice.

 

IMO the NWS should have more leeway on Winter Storm Watches, they should not be forced to be held to what the end result warning criteria must be, if there is going to be a major winter storm even if a location won't get 6 inches they should be able to issue a watch and then go to an advisory later.

[IsentropicLift]

IMO the NWS should have more leeway on Winter Storm Watches, they should not be forced to be held to what the end result warning criteria must be, if there is going to be a major winter storm even if a location won't get 6 inches they should be able to issue a watch and then go to an advisory later.

I agree, it seems like some winters they are very reluctant to issue the watches.

[donsutherland1]

Really? You wouldn't think from the e wall map. 540 thickness is below.

Sometimes the critical thicknesses can paint a picture that differs from the soundings. All in all, my guess based on the guidance that has come in is that most of the NYC metro area should see a 3"-6" snowfall (probably 2"-4" on Staten Island, parts of Queens, and Brooklyn). That's not bad for this time of year. Things could certainly be worse.

[UlsterCountySnowZ]

I feel pretty good here in Orange County... Plus I'll be at work tomorrow at West Point so it should be a beautiful day

[Blizzardo]

That is a full-fledged KU for SNE/N NJ/PA....

Really?? Most of that is 10-15 mm of liquid which is about .5 inch. Those pops of yellow and brown still dont get over 1.0 and they are small

[RU848789]

One comment: if one gets some snow and then an equivalent amount of cold rain on top of it, it's quite likely that most of the rain will simply be absorbed into the snowpack (which will, of course, compress significantly).  For example if one has 1" of snow on the ground now, which contains 0.2" liquid equivalent or LE, due to compaction, and gets another 3" of snow at a 10:1 ratio, that's another 0.3" of LE, adding up to 0.5" LE frozen as snow.  If one then gets another 0.5" of rain on top of that at 33-35F or so, minimal melting will occur and one would be left with a compressed snowpack (or slushpack, really) of a few inches, containing close to 1" of LE - which will freeze solid the next time the temp goes below 32F, i.e., Sunday night.  So even though many of us will likely get snow, then rain, odds are we'll still have a slushy and then frozen wintry landscape on Sunday. 

 

If you don't believe me, believe NOAA, as per the link, below, although I do think they're underestimating how much snow would melt at 40F with 1" of rain (many years ago, I could've solved this problem, but not now, lol - I've forgotten too much of what I learned).  My experience tells me 1" of rain would melt more than 1" (0.1" LE) of snow.  

 

"Air temperature is still the most important factor in melting snow. Rain will usually not add much heat to the process. At 40 degrees, one inch of rain will only produce a tenth of an inch of added water from snow melt. However, rainfall is often accompanied by windy and humid conditions which can greatly accelerate snow melt. At the same time, frozen ground will result in more of the available water running off directly to streams."

 

http://www.crh.noaa.gov/images/dvn/downloads/backgrounder_DVN_Snow_Melt.pdf

[IsentropicLift]

 

[markyk]

Those areas are going to get crushed.

i think 25 mm of water = roughly 1" of rain

 

KU is a bit of extreme terminology in this case

[LnbWx]

IMO the NWS should have more leeway on Winter Storm Watches, they should not be forced to be held to what the end result warning criteria must be, if there is going to be a major winter storm even if a location won't get 6 inches they should be able to issue a watch and then go to an advisory later.

 

I agree. But I wonder about the other way as well. For example, Jersey City gets a WSW of 4-8 inches whereas across the river in a mile or two, the city doesn't even get a WWA? May be they'll issue it down the line but just wondering how it works. Sorry if I'm clueless.

[SnowGoose69]

I agree, it seems like some winters they are very reluctant to issue the watches.

 

I think they get dinged on their verification if they issue a Watch and then only issue an advisory in the end, but for a metro area with 20 million people that rule should not apply, people see no watch for the 5 boroughs and they figure it won't be that bad.

[MJO812]

i think 25 mm of water + roughly 1" of rain

 

KU is a bit of extreme terminology in this case

This isn't going to be a KU but this is going to be a big snowfall for a lot of the areas to the north and west of the City.