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Dec 17-18 Front End Snow/Ice/Rain Event

dmillz25

By dmillz25,
in New York City Metro

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snowman19

snowman19

Posted
Posted
12 minutes ago, jm1220 said:

I'm thinking 1-2" around the city and most coastal areas (maybe less than 1" right on the shore). 3-5" once you get to northern Westchester, Rockland and I-287 and west. Far northwest near I-84 locally 6" or more. I'm not liking this near the coast and city, we really needed the heavy onset of snow. Looks like dry air will eat up the start of precip and make it choppy, allowing the increasing south wind to rocket up the temps. 

Yea, JM, virga with the dry arctic is going to be a problem at the start, I mentioned it earlier this week, I saw as being an issue as is the other issues I pointed out. I think 3-5 inches is too high but we shall see. This event was not impressive from the get go IMO and today the models have flipped

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nzucker

nzucker

Posted
Posted
14 minutes ago, jm1220 said:

I'm thinking 1-2" around the city and most coastal areas (maybe less than 1" right on the shore). 3-5" once you get to northern Westchester, Rockland and I-287 and west. Far northwest near I-84 locally 6" or more. I'm not liking this near the coast and city, we really needed the heavy onset of snow. Looks like dry air will eat up the start of precip and make it choppy, allowing the increasing south wind to rocket up the temps. 

I think 2-4" may be a better forecast for NYC, with 1-2" amounts located near the South Shore/JFK. I wouldn't be surprised if someone in the hilly parts of the Bronx like Van Cortland Park/Riverdale/Botanical Gardens picks up a 4" total. I'd go with 3-5" for Westchester, with the lowest amounts near the LI Sound where south winds can do damage and the highest amounts at 1000' near Pound Ridge.

The EURO snowmap posted looked more impressive than I expected, with 5" in NNJ and 7" in northern Westchester. The RGEM, which was great the last few winters, shows about 4" for Central Park, tapering off towards the South Shore.

The climatology of SWFEs is for precip to start earlier than expected, for the surface to stay colder than the midlevels which allows for more sleet than plain rain, and for precip to shut off as the airmass warms because at that point the 700mb and 850mb lows are passing to the northwest of us. All these tendencies point to a slightly heavier snowfall than models depict. It is also a very cold airmass.

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MJO812

MJO812

Posted
Posted
Just now, snowman19 said:

Yea, JM, virga with the dry arctic is going to be a problem at the start, I mentioned it earlier this week, I saw as being an issue as is the other issues I pointed out. I think 3-5 inches is too high but we shall see. This event was not impressive from the get go IMO and today the models have flipped

And the models could flip back tomorrow. The short range models are colder than the globals and they also develop another low near the coast. Hopefully the globals also develop that low. Also, the  models might be underestimating the cold air that's in place. If so, that's a big factor. This storm would have some surprises. Hopefully that's the case. Right now, I would say 1-3 is a good call for NYC.

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MJO812

MJO812

Posted
Posted
Just now, nzucker said:

I think 2-4" may be a better forecast for NYC, with 1-2" amounts located near the South Shore/JFK. I wouldn't be surprised if someone in the hilly parts of the Bronx like Van Cortland Park/Riverdale/Botanical Gardens picks up a 4" total. I'd go with 3-5" for Westchester, with the lowest amounts near the LI Sound where south winds can do damage and the highest amounts at 1000' near Pound Ridge.

The EURO snowmap posted looked more impressive than I expected, with 5" in NNJ and 7" in northern Westchester. The RGEM, which was great the last few winters, shows about 4" for Central Park, tapering off towards the South Shore.

The climatology of SWFEs is for precip to start earlier than expected, for the surface to stay colder than the midlevels which allows for more sleet than plain rain, and for precip to shut off as the airmass warms because at that point the 700mb and 850mb lows are passing to the northwest of us. All these tendencies point to a slightly heavier snowfall than models depict. It is also a very cold airmass.

Agree. We have seen this happen many times in the past.

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jm1220

jm1220

Posted
Posted
1 minute ago, snowman19 said:

Yea, JM, virga with the dry arctic is going to be a problem at the start, I mentioned it earlier this week, I saw as being an issue as is the other issues I pointed out. I think 3-5 inches is too high but we shall see. This event was not impressive from the get go IMO and today the models have flipped

The north and west suburbs have more time to work with on a south wind but they will change over a few hours after NYC does. We'll see what happens. With the mild pattern setting in by the 20th, this month looks about done for real snow near the coast. La Niña winters tend to be warmer later in the season, and we've already seen the constant Nina cutter pattern start up, so hopefully there can be some kind of turnaround late in the season. 

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nzucker

nzucker

Posted
Posted
3 minutes ago, snowman19 said:

Yea, JM, virga with the dry arctic is going to be a problem at the start, I mentioned it earlier this week, I saw as being an issue as is the other issues I pointed out. I think 3-5 inches is too high but we shall see. This event was not impressive from the get go IMO and today the models have flipped

I'm going to get you 5 posted soon. 

The models have not changed much. The 12z GFS still has .25"+ as snow, the RGEM shows 4" for Central Park, the Euro snowmap looks like 4-5" with 6-7" in the suburbs.

The event has maybe trended a little weaker but it was never a warning snow for NYC metro. Central Park only got 4.5" in Dec 19 2008 SWFE; their limit in December SWFEs seems to be around 5" due to warming on south winds. This one has a much worse high position which is why I'd go with 2.5". Here are my airport/station predictions:

JFK: 1.7"

NYC: 2.5"

LGA: 2.4"

HPN: 4.3"

EWR: 2.9"

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nzucker

nzucker

Posted
Posted
3 minutes ago, jm1220 said:

The north and west suburbs have more time to work with on a south wind but they will change over a few hours after NYC does. We'll see what happens. With the mild pattern setting in by the 20th, this month looks about done for real snow near the coast. La Niña winters tend to be warmer later in the season, and we've already seen the constant Nina cutter pattern start up, so hopefully there can be some kind of turnaround late in the season. 

The Euro has a major coastal on December 23rd, but mostly for New England. It threads the needle between the 12/21 and 12/25 warmups.

The EPS shows a decent Day 10-15 with a more negative WPO/EPO. The period around New Year's looks to average around normal with some snow chances following the XMAS torch.

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MJO812

MJO812

Posted
Posted
Just now, nzucker said:

I'm going to get you 5 posted soon. 

The models have not changed much. The 12z GFS still has .25"+ as snow, the RGEM shows 4" for Central Park, the Euro snowmap looks like 4-5" with 6-7" in the suburbs.

The event has maybe trended a little weaker but it was never a warning snow for NYC metro. Central Park only got 4.5" in Dec 19 2008 SWFE; their limit in December SWFEs seems to be around 5" due to warming on south winds. This one has a much worse high position which is why I'd go with 2.5". Here are my airport/station predictions:

JFK: 1.7"

NYC: 2.5"

LGA: 2.4"

HPN: 4.3"

EWR: 2.9"

I don't know how he can say that this even is not even impressive when this event didn't even start yet. He calls for warmth and little snow with every storm.

Anyway, the models did get a little weaker but the short range models didn't. Rgem still shows 2-4 inches and also develops a low near the coast which holds the cold air longer. Nam also develops a new low.

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MJO812

MJO812

Posted
Posted
Just now, nzucker said:

The Euro has a major coastal on December 23rd, but mostly for New England. It threads the needle between the 12/21 and 12/25 warmups.

The EPS shows a decent Day 10-15 with a more negative WPO/EPO. The period around New Year's looks to average around normal with some snow chances following the XMAS torch.

It shows some snow for our area

ecmwf_z500_mslp_us_9.png

 

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nzucker

nzucker

Posted
Posted
40 minutes ago, Snow88 said:

It shows some snow for our area

ecmwf_z500_mslp_us_9.png

 

Thanks for the image man...all the models are showing a rollover ridge in the Plains, which gives us the XMAS cutter (you can see the beginnings with the low cutting off in the Baja).

Before the ridge rolls over, though, it gives us a pretty nice trough in the East. There should be a wintry opportunity around the 22-23. 12z ECM barely misses OTS with a major storm; we get light snow as does New England.

The XMAS warm-up looks to last around 4-5 days; models show a WPO block and potential snow threat for New Year's.

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SnowGoose69

SnowGoose69

Posted
Posted
3 hours ago, snowman19 said:

Allsnow, Looks like the RGEM is on its own now, forecasting the most snow accumulations for the metro area. GFS, NAM, CMC, UKMET and the Euro have all dropped snow totals and qpf since 0Z and have also sped up the warming and changeover to all rain

I would not trust the RGEM at this range yet.  It it still shows this tonight and especially on its 12Z run tomorrow and the other models are not coming around I would begin to buy into it more

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LongBeachSurfFreak

LongBeachSurfFreak

Posted
Posted
2 hours ago, jm1220 said:

I'm thinking 1-2" around the city and most coastal areas (maybe less than 1" right on the shore). 3-5" once you get to northern Westchester, Rockland and I-287 and west. Far northwest near I-84 locally 6" or more. I'm not liking this near the coast and city, we really needed the heavy onset of snow. Looks like dry air will eat up the start of precip and make it choppy, allowing the increasing south wind to rocket up the temps. 

Pretty much spot on. This is the type of setup where there is a gradient on the island from south to north. Granted not as pronounced as years past, but there none the less. I could see Long Beach with a coating and great neck with 3". Any type of onshore flow this early in the winter is a killer regardless of how cold the proceeding airmass

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SnowGoose69

SnowGoose69

Posted
Posted
59 minutes ago, Snow88 said:

4k nam shows 2-4 for the coast

The RGEM is trying to go 12/5/05 on the NYC area.  It pretty much shows 4 inches to EWR/SI and almost NYC then drops it right off to 1 by JFK.  I'm still skeptical that the boundary layer warms as fast as some models show.  I do think by 15Z its raining within the 5 boroughs.  I'm not so sure its raining at 12-13Z though, and many models show that.  Could see as much as 2-3 inches more if the changeover does not occur til 14-15Z vs 12Z

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Rtd208

Rtd208

Posted
Posted
36 minutes ago, Snow88 said:

NYC Sanitation getting ready for tomorrow. Snow alert was just issued by Sanitation and will be in effect at 11pm tonight.

Talked with one of my friends who works for our DPW last night, he said they were going to be prepping the trucks for snow removal and salting operations today. It wouldn't surprise me if they do some pre-treatment as well since we do have a brine truck but the temps may be to cold for it to be effective.

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