December 14-15 Winter Storm Part Two

[SnowGoose69]

JFK is above freezing (2.7C)by 0z Sunday per the Euro with .29" of precip prior to that. From 0z to 6z it warms to 6.9C with .68 of precip ( assuming rain mostly):

ECMWF Deterministic FORECAST FOR: JFK LAT= 40.65 LON= -73.78 ELE= 23

12Z DEC13

2 M 850 SFC SFC 700 6 HR 500 1000

TMP TMP PRS RHU RHU QPF HGT 500

© © (MB) (PCT) (PCT) (IN) (DM) THK

FRI 12Z 13-DEC -1.6 -11.1 1022 57 94 0.00 543 526

FRI 18Z 13-DEC 1.3 -7.3 1021 57 68 0.00 547 530

SAT 00Z 14-DEC 0.7 -8.1 1025 60 69 0.00 552 532

SAT 06Z 14-DEC -1.3 -8.8 1029 67 81 0.00 554 532

SAT 12Z 14-DEC -2.2 -8.4 1031 72 92 0.01 555 531

SAT 18Z 14-DEC -1.4 -8.3 1030 84 97 0.07 554 531

SUN 00Z 15-DEC 2.7 -5.1 1023 86 98 0.21 555 536

SUN 06Z 15-DEC 6.9 3.6 1008 95 100 0.68 554 548

SUN 12Z 15-DEC 2.3 3.9 1003 90 51 0.33 548 545

SUN 18Z 15-DEC 3.1 -1.6 1004 78 37 0.00 543 540

MON 00Z 16-DEC 3.7 -7.3 1010 73 33 0.00 543 535

MON 06Z 16-DEC 0.1 -7.5 1012 77 70 0.00 540 531

MON 12Z 16-DEC -3.2 -12.7 1015 75 3 0.00 538 526

MON 18Z 16-DEC -2.2 -14.3 1019 58 5 0.00 538 523

TUE 00Z 17-DEC -4.6 -12.1 1025 64 4 0.00 542 523

 

JFK will never be that warm at 00Z at the surface, thats typical Euro bias with surface temps, I'm not even sure they'd be 2.7C by 03Z to be honest, much less 00Z...the GFS and NAM MOS numbers at JFK are alot more legit for the surface temps.

[forkyfork]

look at the dry layer above 500 mb. precip is going to shut off when this arrives no matter how much precip the model spits out after this time

[mob1]

Bigger counties like Westchester get split routinely, the northern and southern halves are like completely different climates.

[NycStormChaser]

I've seen 5" in Bayside and 0-1" in the JFK area.

Happened in January of 2009 and many more times before.

Yep. I live in greenpoint, the northern most part of Brooklyn. Definitely have seen some sharp cut offs as well

[Guest Imperator]

JFK will never be that warm at 00Z at the surface, thats typical Euro bias with surface temps, I'm not even sure they'd be 2.7C by 03Z to be honest, much less 00Z...the GFS and NAM MOS numbers at JFK are alot more legit for the surface temps.

What's is the difference between the GFS MOS and the text ouputs? Is there a different formula used to decode?

 

 

JFK Decoded Output 12Z GFS:

 

SAT 12Z 14-DEC  -2.5    -7.2    1030      93      99    0.02     555     531   

SAT 18Z 14-DEC  -1.8    -7.8    1030      94     100    0.10     554     531   

SUN 00Z 15-DEC   2.4    -3.3    1022      95      98    0.16     555     538   

SUN 06Z 15-DEC   7.7     2.7    1006      95     100    0.64     552     547   

SUN 12Z 15-DEC   1.2     1.6    1003      94      57    0.72     545     543   

SUN 18Z 15-DEC   3.4    -2.4    1004      89      11    0.00     543     540   

 

 

JFK GFS MOS:

 

 

KJFK reported on 13-DEC-2013

KJFK   GFS MOS GUIDANCE   12/13/2013  1200 UTC

DT /DEC  13/DEC  14                /DEC  15                /DEC  16

HR   18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 06 12

N/X                    25          34          34          43    24

TMP  33 34 33 31 29 27 27 27 28 29 31 34 37 39 38 39 41 40 37 29 25

DPT  16 15 15 17 17 17 16 19 23 24 27 30 33 34 33 31 26 22 19 14 10

CLD  BK BK BK BK OV OV OV OV OV OV OV OV OV OV OV BK SC SC FW SC SC

WDR  27 27 28 32 35 01 02 05 06 08 10 10 07 02 33 31 31 30 30 29 30

WSP  17 14 11 07 07 07 10 11 12 16 13 11 16 16 14 15 17 17 16 13 18

P06         2     0    13    55    90    95    82     9     0  1  5

P12                    13          92          95           9     5

Q06         0     0     0     1     2     4     2     0     0  0  0

Q12                     0           3           5           0     0

T06      0/ 7  0/ 3  0/ 3  1/ 0  0/ 7  3/ 0  6/ 7  0/ 6  0/ 6  0/ 7

T12            0/ 9        1/ 4        4/ 7        6/ 9     1/11

POZ   1  0  0  2  2  0  0  0  0  2  3  5  2 10  5  6  0  0  0  0  0

POS  97 94 94 90 90 92 89 90 89 81 62 61 16  0 19 34 39 69 78 81 87

TYP   S  S  S  S  S  S  S  S  S  S  S  S  R  R  R  R  R  S  S  S  S

SNW                     0                       4                 0

CIG   8  8  8  8  8  7  6  5  4  4  4  3  3  3  5  7  8  8  8  8  8

VIS   7  7  7  7  7  7  7  4  3  2  2  3  4  5  7  7  7  7  7  7  7

OBV   N  N  N  N  N  N  N BR BR BR FG BR BR BR  N  N  N  N  N  N  N

 

[hohnywx]

Bigger counties like Westchester get split routinely, the northern and southern halves are like completely different climates.

 

Definitely...the sound shore of Westchester is a completely different animal from Northern Westchester. They will probably get split again this event, with warning in the north and advisory in the south.

[Sn0waddict]

SREF's

 

http://www.spc.noaa.gov/exper/sref/fplumes/index.php?YMD=20131213&RT=15&PRM=Total-SNO&SID=BDR&INC=ALL&NNC=&max=&min=&mZOOM=7&mLAT=41.20733386403477&mLON=-73.98235&mTYP=roadmap

[jm1220]

JFK will never be that warm at 00Z at the surface, thats typical Euro bias with surface temps, I'm not even sure they'd be 2.7C by 03Z to be honest, much less 00Z...the GFS and NAM MOS numbers at JFK are alot more legit for the surface temps.

This doesn't show the wind direction, if it's anything from 0-90 deg, anything above 35F won't happen IMO.

[jm1220]

look at the dry layer above 500 mb. precip is going to shut off when this arrives no matter how much precip the model spits out after this time

Good point-the dryslot looks to be coming in faster per the models today as well. Maybe the coastal areas can salvage it with only a couple or few hours of rain

[Weathergun]

look at the dry layer above 500 mb. precip is going to shut off when this arrives no matter how much precip the model spits out after this time

I'm thinking we cut qpf on the models by 1/3 at least. There NAM and GFS overdone with Tuesday's storm too.

[RCNYILWX]

look at the dry layer above 500 mb. precip is going to shut off when this arrives no matter how much precip the model spits out after this time

That's still almost saturated up through the DGZ.

[SBUWX23]

No it will not, first its still saturated up to -20C.  A lesson in microphysics will tell you snow grows from temperatures as warm as -5C (needles). While not dendrites, still can have crystalization. Second, it is completely saturated below this so there will still be precipitation, just the depth of the cloud will not be as high. 

look at the dry layer above 500 mb. precip is going to shut off when this arrives no matter how much precip the model spits out after this time

[ace0927]

look at the dry layer above 500 mb. precip is going to shut off when this arrives no matter how much precip the model spits out after this time

Im interested in learning - how can you tell its dry at h5? The black dotted line separates from the solid red? What does the black dotted line signify? Dew point?

[forkyfork]

That's still almost saturated up through the DGZ.

almost doesn't count. i probably should have posted the next hour... the dry layer extends past the -5C isotherm

[mgerb]

Im interested in learning - how can you tell its dry at h5? The black dotted line separates from the solid red? What does the black dotted line signify? Dew point?

 

You got it. That's exactly what's plotted. 

[forkyfork]

No it will not, first its still saturated up to -20C.  A lesson in microphysics will tell you snow grows from temperatures as warm as -5C (needles). While not dendrites, still can have crystalization. Second, it is completely saturated below this so there will still be precipitation, just the depth of the cloud will not be as high.

it will be light. and IMO it's not saturated until you get to -9C or so

[David-LI]

Why isn't anyone mentioning the 18z nam?

[ace0927]

You got it. That's exactly what's plotted. 

Great - thanks!

[ace0927]

Why isn't anyone mentioning the 18z nam?

quick glance at maps - not soundings, seems like its fairly similar thru 33hrs vs 39hrs

 

edit - at hr 36, the h85 low is further NW which allows even more warming - but we'll need to look at soundings to be sure.

[Storm At Sea]

Upstate NY with advisories...some aren't quite impressed. 3-6 for Monticello?

[Zelocita Weather]

quick glance at maps - not soundings, seems like its fairly similar thru 33hrs vs 39hrs

 

edit - at hr 36, the h85 low is further NW which allows even more warming - but we'll need to look at soundings to be sure.

 

18z NAM in line with all other guidance, dump and go, by hour 36 per sim radar precip is out after 4"-8" or so...barely any mix/rain as precip moves so quickly out of the area.

[earthlight]

almost doesn't count. i probably should have posted the next hour... the dry layer extends past the -5C isotherm

Yeah I wrote about it this morning..you could even see the dry slot on the mid level RH maps. This is a dump and go type storm..it'll end as freezing rain and drizzle. I think there's some heavy rain potential from the city south and east though.

[redbanknjandbigbasslakepa]

How reliable are the high-res ARW and NMM models in regards to upper level temps and precip? If they are to be believed it looks like areas from CNJ-NYC could see a quick 6" thump and the precip shuts off pretty quickly with the surge of WAA. Rather than snow on the front and appreciable heavy rain you get the heaviest period of precip as snow, 6" in 6 hours and then a bit of heavy rain tapering to just drizzle.

 

How do they stack up versus the NAM and Euro at this range?

[PB GFI]

How reliable are the high-res ARW and NMM models in regards to upper level temps and precip? If they are to be believed it looks like areas from CNJ-NYC could see a quick 6" thump and the precip shuts off pretty quickly with the surge of WAA. Rather than snow on the front and appreciable heavy rain you get the heaviest period of precip as snow, 6" in 6 hours and then a bit of heavy rain tapering to just drizzle.

 

How do they stack up versus the NAM and Euro at this range?

[/quo

U may eek out an inch two max. They r way overdone

[earthlight]

SREF plumes still have around 5" at Newark. Seems fair to me.

[wolfie09]

Mount holly updated map

[PB GFI]

SREF plumes still have around 5" at Newark. Seems fair to me.

Can we get to 3  20 miles S of the Driscoll and 18 Miles Inland ?  

No sounding down our way , So kinda using surface , qpf and 850`s , looks close

[Superstorm93]

Upton's map. 

 

Cut back totals a bit 

 

[killabud]

raised them on long island for some reason

[hudsonvalley21]

Upstate NY with advisories...some aren't quite impressed. 3-6 for Monticello?

Seems kind of light. My forecast for eastern Orange county is a little different. I don't think the QPF amounts will fall off that sharp.

 

My forecast from OKX,

 

• Late AfternoonPartly sunny, with a high near 30. West wind around 8 mph.
• TonightA slight chance of flurries before 7pm, then a slight chance of snow after 3am. Mostly cloudy, with a low around 15. Northwest wind around 6 mph becoming light and variable in the evening. Chance of precipitation is 20%.
• SaturdaySnow, mainly after 10am. High near 20. East wind 5 to 8 mph. Chance of precipitation is 100%. New snow accumulation of 3 to 5 inches possible.
• Saturday NightSnow before 4am, then snow and sleet. Low around 19. Northeast wind around 10 mph. Chance of precipitation is 100%. New snow and sleet accumulation of 4 to 8 inches possible.
• SundayA slight chance of snow before 9am. Mostly cloudy, with a high near 34. North wind 9 to 11 mph becoming northwest in the afternoon. Winds could gust as high as 21 mph. Chance of precipitation is 20%.