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wdrag

Snow-ice-rain for the NYC forum 7PM Mon 1/25-6AM Wednesday 1/27

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Fifth topic edit Monday 635AM Jan 25, since the topic started Tuesday Jan 19:

35 AM Monday Jan 25: Added two graphics for the coming extensive minor snow-ice-snow event with main impacts LI-NYC-I95 corridor northwestward to the Adirondacks and New England

Could be sneaky icy along the coast. 

mPING will be helpful. 

NWS snowfall forecast map added from 5AM this morning (NYC-LI generally less than 1") and also the probabilistic chance of .01 freezing rain. 

Mostly a Tuesday-Tuesday night snow-sleet event changing to freezing/rain-rain during the afternoon I80 southward possibly going back to snow or flurries Tuesday night or Wednesday morning. Advisories already out near DC. 

Expect it will be briefly slippery everywhere in our forum for a time Tuesday, and probably Tuesday night-Wednesday morning LI-NYC-I80 northward, especially interior.

Expect plowing small amount amounts of snow entire I84 corridor with road treatments necessary most of the remaining portion of our forum except possibly just southeast of the I95 corridor. 

Weak boundary layer winds with a north-northeast drift will probably assist on keeping temps on the colder side of the available guidance.

Storm impact of all snow will be larger I84 northward and inclusive of I90 to Boston with decent amounts. 

This keeps this brief and we'll all be monitoring the models.  Hopefully there are no slips/falls/accidents Tuesday-Tuesday night on all untreated surfaces.

Screen_Shot_2021-01-25_at_5_18.11_AM.png

Screen Shot 2021-01-25 at 6.05.31 AM.png

 

Fourth topic edit Sunday morning 550AM: This is mostly a Tuesday-Tuesday night event. Periods of mostly light snow, at times changing to sleet, freezing rain (rain where above 32F along the coasts) or freezing drizzle up to I80, NYC, LI. Snow amounts trimmed a bit and I sure hope NYC can muster 1/2-3" depending on precip type and intensity for this event.  I pushed the start time back to 7P Monday but it could be delayed NYC-LI-CT til as late as 9AM Tuesday. Also took MODERATE event out of the headline.

Banding signature suggests snow should  break out across PA/NJ between 7P and midnight Monday. The primary event is the 26th, ending sometime Wednesday morning. 

While amounts are light, suspect there will could be a period or two of 3/4mi light snow - bordering 1/2S for an hour or two,  from northern NJ into ne PA/se NYS and western CT.

06z/24 NAM banding signature and also seen in the 06z/24 GFSv16 qpf, that the heaviest snow may occur early Wednesday near NYC.  This may be associated with a trowel/inverted trough departing shortwave and weak seaward moving low pressure. Something to monitor but not get hopes overly high. 

So, manageable delays sometime during this event due to plowable snow northwest of I95, except snow-ice I80 southward in NJ to Baltimore and snow/ice/rain NYC-LI southward along the NJ coast southeast of I95. Amount expectations lowered to range from an uncertain 1-4" CT with the least in eastern Connecticut and a less than certain forecast there, to between 3-5" se NYS, ne PA and 2-4" nw NJ north of I80. 
 
Temps will generally be subfreezing throughout the event except NYC/LI/NJ coast which are in the margins of ice-snow at the start, changing to periods of rain then ending as snow, so amounts of each element will depend on duration but it will probable get slippery there on untreated surfaces for a time as well-especially if and when precipitation occurs during the nighttime hours. Check others herein and other resources for other opinions. 

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Third topic edits 626A/23: Delayed the start in the forum 3 more hours and that may not be enough due to the dry air in place, but sometimes the snow-sleet breaks out faster than modeled. I've had to admit a slower departure, especially because of the GFSv16 and EC.  The following may be too high on amounts but it's just my opinion of the boiled down (in my mind) consensus of the 00z-06z/23 model suite. 

A colder week is now here with hazardous winter weather potential late Monday-late Thursday

Late Monday the 25th-early Wed the 27th: Manageable. Still uncertainty on evolution. There is general model consenses for slower arrival and later departure, and less precip amounts.
 
I am guarded about decreasing the wintry element amounts (low level pressure pattern, 500MB vort max track, GFSv16) but this update below may be an inch or 2 on the high side? 
 
Manageable delays sometime in this event due to plowable snow northwest of I95, except snow-ice I78 southward in NJ to Baltimore and snow/ice/rain NYC-LI southward along the NJ coast southeast of I95). The main event for I84 should Tuesday-Tuesday night. Expecting amounts to range from an uncertain 1-5" CT with the least in eastern Connecticut and a less than certain forecast there, to between 4- isolated 7" se NYS, ne PA and nw NJ. LI/NYC/NJ coast 1" to possibly as much as 4" by the time all is said and done with the best chance for a POSSIBLE 4" NYC (possible, not probable). I expect plowing will be needed sometime for most of our area northwest of I95,  except maybe east of the CT River.
 
Temps will generally be subfreezing throughout the event except NYC/LI/NJ coast which are in the margins of ice-snow at the start, changing to periods of rain then ending as snow, so amounts of each element will depend on duration but it will probable get slippery there on untreated surfaces for a time as well-especially if and when precipitation occurs during the nighttime hours. Check others herein and other resources for other opinions. 

 

Second topic edits 645A/22: Made it definite put in a time structure of Noon Mon-6P Tuesday and withdrew possibly from the description.

Good morning this Friday Jan 22: Think consensus is developing that most here will enjoy a significant plowable snow event late Monday-Tuesday.  My take below based on 00z/22 ops and EPS/GEFS/NAEFS, and 06z GFS op. 

 

Good Friday morning everyone, Jan 21. Focus shifts from the Adirondacks today to the region from I84 to NC next week, then back north to the I84 corridor northward the first week of February. This may be as good as it gets for our membership this winter who like snow. One event at a time follows.
Travelers into the northeast USA Noon Monday- 6PM Tuesday the 25th-26th: While still some uncertainty, if you have travel plans into the I84-I80 corridors or I95 Baltimore to NYC-New Haven Monday Night-Tuesday morning, prepare for delays due to snow, except snow-ice I78 southward in NJ to Baltimore. Expecting amounts to range from ~1" or less I90 in Mass (could be zero if the storm stays south), to an uncertain 1-5" CT with the least in northeast Connecticut (Ashford) and a less than certain forecast there, to between 4-7" se NYS, and 5-9" ne PA, nw NJ. The high side 9" amount is no guarantee but it's in some of the modeling. Best chance of 9" in ne PA is along I80.  LI/NYC my expectation this early is 1 to maybe as much as 6"??? with the best chance of 3"+ western LI/NYC. I expect plowing will be needed most of our area except maybe n CT/MA/and the region along or just southeast of I95 BWI-NYC. Temps will be subfreezing throughout the event except if it starts Monday afternoon when it will take an hour or two to drop below freezing. Baltimore-Philly is in the ice-snow zone so amounts of each element will depend on duration but it will get slippery there for a time, possibly as early as Noon Monday. Finally: the end of this event should be Tuesday afternoon, but it's possible that it could linger into the wee predawn hours of Wednesday?
 
Attached a NWS graphic ensemble 30+% chance of 3+" of snow Monday into early Tuesday. Blue is 50+%. This gives an idea of the focus only through 7AM Tuesday and it will snow beyond 7AM Tuesday- so this is conservative. Also the NAEFS qpf for the 24 hr period ending 00z/27 with .4" = to the 10MM line, and also the sfc temp for near 00z./27 which shows 0C along I95. 
 
--

 

First Topic edits 630A/21: Added widespread to the topic title. Uncertainty continues, especially northern extent of 2+" with I84 somewhat in doubt because of the last 24 hours of GFS depressed cycles. However, the GGEM/GEPS, and especially the EC/EPS have come back north since the 00z/20 cycles.  NAEFS is still south, and one can debate if the event lasts into Tuesday night but overall, the topic stands with considerable debate on what happens. I've added the latest WPC probability of 1/4" melted w.e. frozen which you can see has trended higher and more expansive and i think that is correct. It does not match some of the WPC prior to 08z/21 qpf which looks slightly lighter but going with the WPC prob, be cause of the GEPS and EPS. 

My take at 6A/21 Travelers into the northeast USA Monday-Tuesday the 25th-26th: Still considerable uncertainty on how this all transpires but we should be aware that an extensive hazardous wintry episode is expected for all untreated surfaces, especially the I84-I80-I95 corridors from Baltimore to I80, with less certainty I84. The front end Monday start time is uncertain. It could start for a couple of hours Monday morning then stop for 12 hours. The bulk of this event probably occurs Monday night into Tuesday the 26th. Odds favor a change to rain or ice along the I95 corridor Tuesday morning the 26th, but mostly snow northwest of I95, especially the I80 corridor northward. There is considerable uncertainty on where the primary snow or ice event will occur in the northeast so its good to be aware of the possibilities but no action recommended yet, unless you're headed to Baltimore-Philly where messy slippery wintry elements develop by Noon Monday. 

Below is the initial topic start from 940A/19.

Since there has been a lot of 25th-26th discussion prior to this topic start, let's continue it here. 

Potential exists for an advisory event in the NYC forum, but with uncertainty on how much coverage and where.  -NAO blocking and the strength track of the short wave breaking through the Appalachian ridge will ultimately determine the northern extent of wintry qpf, and amounts.  Solutions vary greatly but 00z-06z/19 ensemble consensus permits on the order of 0.1 to 0.5" qpf in the forum. 00z/19 NAEFS thicknesses and sfc-bl temps suggest snow or ice probable for at least a portion of this event with the eventual change to sleet or rain probably LI westward to just s of I80.  

Timing: Appears the first wintry elements should begin the 25th (possibly as early as 10AM) and should pretty much end by 3PM Tuesday the 26th. 

Outliers: Have not placed much confidence on one or two operational warning event qpf's through the 06z/19 cycle,  since ensembles appear to be predominantly less than warning. Maybe that will change but it's what I think is realistic at this point.

This topic will be amended as we draw closer to the 25th with more consensus.

A following short wave late 27th-28th appears to be steered south of the forum by the shortwave of the 26th redeveloping blocking northwest flow aloft over our NYC forum by the 27th.

The attached graphics are from WPC derived prior to the arrival of the 00z/19 cycle ensembles, but an idea of their upcoming ensemble solutions. Darker green shows their 30+% chance of more 1/4" melted water equivalent (w.e) snow-sleet.  As you can see, it's inland-higher terrain favored but that doesn't rule out a widespread 2+" snowfall elsewhere. This is a D7 forecast.  There will be changes as the models change. 

 

Screen Shot 2021-01-19 at 8.50.43 AM.png

Screen Shot 2021-01-19 at 8.52.09 AM.png

Screen Shot 2021-01-21 at 6.06.13 AM.png

Screen_Shot_2021-01-22_at_5_24.13_AM.png

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0Z Euro - yesterdays 12Z GFS was similar in amounts BUT we need a few runs in a row of this from more then 1 model  to gain any confidence in coming days IMO

sn10_acc.conus.png

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11 minutes ago, PoZitron20 said:

You could pretty much understand from this picture how phasing happens based on 00z ECMWF last night. This jet streak is the force (most likely) causing the "press" over the 500mb vort... / possible wintry event ; 1/25/2021-1/26/2021

Screenshot_2021-01-19 Models ECMWF Hi-Res — Pivotal Weather.png

yesterdays 12Z and the total snowfall - to gain any confidence we need consistency - a few runs in a row of the same solution200wh.conus.pngsn10_acc.conus.png

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8 minutes ago, MJO812 said:

The models are starting to show a brief spike in the pna around the storm for the 29th

I would be surprised if we have back to back SECS or MECS in the metro next week - BUT that would sure stop some of the belly aching about how winter is over here..........gfs_mslp_pcpn_frzn_us_35.png

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2 hours ago, wdrag said:

Since there has been a lot of 25th-26th discussion prior to this topic start, let's continue it here. 

Potential exists for an advisory event in the NYC forum, but with uncertainty on how much coverage and where.  -NAO blocking and the strength track of the short wave breaking through the Appalachian ridge will ultimately determine the northern extent of wintry qpf, and amounts.  Solutions vary greatly but 00z-06z/19 ensemble consensus permits on the order of 0.1 to 0.5" qpf in the forum. 00z/19 NAEFS thicknesses and sfc-bl temps suggest snow or ice probable for at least a portion of this event with the eventual change to sleet or rain probably LI westward to just s of I80.  

Timing: Appears the first wintry elements should begin the 25th (possibly as early as 10AM) and should pretty much end by 3PM Tuesday the 26th. 

Outliers: Have not placed much confidence on one or two operational warning event qpf's through the 06z/19 cycle,  since ensembles appear to be predominantly less than warning. Maybe that will change but it's what I think is realistic at this point.

This topic will be amended as we draw closer to the 25th with more consensus.

A following short wave late 27th-28th appears to be steered south of the forum by the shortwave of the 26th redeveloping blocking northwest flow aloft over our NYC forum by the 27th.

The attached graphics are from WPC derived prior to the arrival of the 00z/19 cycle ensembles, but an idea of their upcoming ensemble solutions. Darker green shows their 30+% chance of more 1/4" melted water equivalent (w.e) snow-sleet.  As you can see, it's inland-higher terrain favored but that doesn't rule out a widespread 2+" snowfall elsewhere. This is a D7 forecast.  There will be changes as the models change. 

 

Screen Shot 2021-01-19 at 8.50.43 AM.png

Screen Shot 2021-01-19 at 8.52.09 AM.png

It looks like the threat next week is suppressed, not cutter, given the -NAO block position and northern branch jet configuration

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18 minutes ago, snowman19 said:

It looks like the threat next week is suppressed, not cutter, given the -NAO block position and northern branch jet configuration

This feels like a 2/8-2/11/94 sort of event...it has potential to be a rare SWFE type setup where the metro is mostly snow or at least all frozen. 

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6 minutes ago, SnowGoose69 said:

This feels like a 2/8-2/11/94 sort of event...it has potential to be a rare SWFE type setup where the metro is mostly snow or at least all frozen. 

Snow and ice storm, February 8-9, 1994 - Storm Summary (raymondcmartinjr.com)

Snow and ice storm, February 11, 1994 - Storm Summary (raymondcmartinjr.com)

ALSO THIS PAGE I JUST POSTED  THESE LINKS FROM ONLY GOES THROUGH 2012 - 2013 SEASON - ANYONE INTERESTED IN STARTING A PROJECT TO CONTINUE IT WHERE IT LEFT OFF ???

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8 minutes ago, NEG NAO said:

Snow and ice storm, February 8-9, 1994 - Storm Summary (raymondcmartinjr.com)

Snow and ice storm, February 11, 1994 - Storm Summary (raymondcmartinjr.com)

ALSO THIS PAGE I JUST POSTED  THESE LINKS FROM ONLY GOES THROUGH 2012 - 2013 SEASON - ANYONE INTERESTED IN STARTING A PROJECT TO CONTINUE IT WHERE IT LEFT OFF ???

PM me, I offered to help Ray(the site owner) about continuing it over in the Philly forum but he said he currently doesn't have the time. I'm good at acquiring the archived forecasts/maps from past events but I don't have the webpage building skills to turn them into a page like that. So if you have the web building capabilities, it's definitely a project I would like to assist on. 

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16 minutes ago, The Iceman said:

PM me, I offered to help Ray(the site owner) about continuing it over in the Philly forum but he said he currently doesn't have the time. I'm good at acquiring the archived forecasts/maps from past events but I don't have the web skills to turn them into a page like that. So if you have the web building capabilities, it's definitely a project I would like to assist on. 

I don't have the web building capabilities either - plus some of the links on his page  where he obtained all the information from the NWS are no longer working ..... 

Also I did find this but it is not really detailed with maps other various graphics and other stats

A History of New York City Snowstorms Since 1900 - New York City Weather Archive (typepad.com)

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16 minutes ago, PoZitron20 said:

12z Euro tried transfer Miller B (Miller Theorem EE Electrical Engineering for reference).

More then likely we won't see anymore cutter solutions.............from any model - BUT this is a real thread the needle situation we could easily miss this to the south too now...IMO

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7 minutes ago, NEG NAO said:

More then likely we won't see anymore cutter solutions.............from any model - BUT this is a real thread the needle situation we could easily miss this to the south too now...IMO

I feel the same way, it’s a suppression threat, the jet on roids, the block, this could very well miss us to the south. I think a cutter would be extremely unlikely 

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The negative NAO is really killing our chances . Just give me a positive PNA and negative epo instead of a negative NAO.

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ALL: no question a bit southward trend past 12 hours... kind of early throwing in the towel.  NAEFS and WPC still has qpf and so am staying with the topic as posted and not saying anything different til I know for sure this is south with primary advisory threat south of I80. fwiw... and I won't post 16z ish/19 graphics here, because basically they repeat the posted topic graphics from earlier today... WPC is unwavering on 1/4" qpf just n of I80 and 1/4" frozen probs...actually has 30+% immediate w NYC suburbs now.  Today is 1/19  the event is still 6-7 days away. I am riding this out...there will still be differences.  Main difference I see that needs resolution...how much westerly flow at 500 MB across LI, vs the WNW flow of the EPS.  Hang in there.

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17 minutes ago, wdrag said:

ALL: no question a bit southward trend past 12 hours... kind of early throwing in the towel.  NAEFS and WPC still has qpf and so am staying with the topic as posted and not saying anything different til I know for sure this is south with primary advisory threat south of I80. fwiw... and I won't post 16z ish/19 graphics here, because basically they repeat the posted topic graphics from earlier today... WPC is unwavering on 1/4" qpf just n of I80 and 1/4" frozen probs...actually has 30+% immediate w NYC suburbs now.  Today is 1/19  the event is still 6-7 days away. I am riding this out...there will still be differences.  Main difference I see that needs resolution...how much westerly flow at 500 MB across LI, vs the WNW flow of the EPS.  Hang in there.

97ep48iwbg_fill.gif?1611086203

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44 minutes ago, snowman19 said:

I feel the same way, it’s a suppression threat, the jet on roids, the block, this could very well miss us to the south. I think a cutter would be extremely unlikely 

The models have moved away from phasing in the west so this storm isn't going to cut unless the modeling shifts dramatically back towards that.  

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45 minutes ago, MJO812 said:

The negative NAO is really killing our chances . Just give me a positive PNA and negative epo instead of a negative NAO.

-pna is killing us. 

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32 minutes ago, NEG NAO said:

which events we getting these snow totals from ???

Its a mean

There are 2 potential snowfalls coming up

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1 minute ago, PoZitron20 said:

CFS is onboard 1/25/-1/26 as well as a storm on the 29th attached both screenshots.

Screenshot_2021-01-19 Models CFS — Pivotal Weather.png

Screenshot_2021-01-19 Models CFS — Pivotal WeatherECMGFSCFS.png

both systems are stronger with larger precip field then some other models

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36 minutes ago, wdrag said:

Hi... Why does my EPS mean snowfall data differ?  Is it the res? Os my our error?  EPS I'm looking at is several inches less.

 I just need to know where to access the correct model guidance.

Thanks, Walt

Screen Shot 2021-01-19 at 3.48.19 PM.png

Sv counts sleet as snow

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2 hours ago, Rjay said:

The models have moved away from phasing in the west so this storm isn't going to cut unless the modeling shifts dramatically back towards that.  

Agreed. Next week’s synoptic setup has suppression written all over it, unless things change big time, I can’t envision a cutter

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