Discussion-OBS Noon Wed Feb 5-Noon Thu Feb 6 Snow-ice changing to rain Thu morning except ice may linger through Noon parts of I84 corridor.

[wdrag]

Discuss the possibilities of little more snow-sleet for NYC-LI.  Please check back on the 7th for the review of the attached guidance, maybe used as a learning tool.

Ensembles temporarily trended a little colder so that NYC CP-parts of LI may receive 1/2-1.5" of snow sleet to start before a change to rain. Most of the precipitation looks to occur 6PM Wed-Noon Thursday, starting as snow or sleet then changing to rain by sunrise Thursday NYC-LI, but freezing rain-sleet interior, northwest of I95.  That freezing rain sleet may linger into midday over parts of nw NJ/interior se NYS, interior CT and the Poconos where mixing warmer air to the surface should be minimal until sometime Thursday night (baggy flow Thursday morning).  Time of transition from snow-sleet to rain-ice will determine amounts of snow/sleet. 

This event may impact (slow travel-transportation delays) during the Wednesday evening commute depending on the start time, and "should" leave at least delays and/or widespread cancellations for the interior early Thursday. 

Total melted qpf should range between 0.3-0.8".. with the GEFS the least.   QPF factors into the resultant amount of the various wintry elements. 

Ensembles already included are recently colder prob of >1" snowfall (includes sleet) from the EPS, CMCE, GEFS.   the EPS 06z/6 2m temps,  the ensemble chance of >0.10 freezing rain qpf from both the 12z and 18z cycles. Those probs have been consistently very high for the past several days---BUT caution on interpreting .10 qpf as .10 glaze.  It could be significantly less depending on temp/rates of fall, drop size. I also added the EPS raw qpf interpreted as freezing rain. 

Ensembles show a primary low moving up into the eastern Great Lakes-upstate NY by dawn Thursday with a warm frontal wave moving northeast off the NJ coast, possibly maintaining itself through forenoon Thursday passing e of LI,  then merging with the primary low in eastern Canada Thursday night and returning subfreezing temps to the area by daybreak Friday. The amount of subfreezing cold that returns in the wake of the departing eastern Canada low on Friday, will help determine what happens here next weekend (Feb 8-9).

 If somehow the primary near the eastern Great Lakes is dominant and there is no warm frontal wave of low pressure coming up the NJ coast, then snow-sleet amounts would be less.  Final 757P/2. 

 

[Franklin0529]

Euro and GFS trended colder. Might be able to pull off a couple inches before it turns to sleet/rain

[wdrag]

Wed Feb 5-Noon Thu Feb 6 from Interstate 95 Baltimore-Philly-NYC through PA-NYS-southern New England: Snow-sleet begins sometime Wednesday or Wednesday evening then over to ice early Thursday, probably ending as plain rain midday Thursday, except still ice I84 high terrain. Timing of the worst is a little uncertain but problems could develop Maryland-PA-central-southern NJ between 9AM and 3PM Wednesday with widespread delays and cancellations anticipated for the Thursday morning commute entire interior region from I95 northwest. A map of ensemble chance of more than one tenth inch glaze is attached. Max glaze thickness is unknown at this time due to sleet mix. The chances for this ice event is now about 100 percent.  Suggest PLAN B-  consider altering plans in the interior for a short time Wednesday night-Thursday morning.

Also,  NWS ensembles seem much more conservative than this outlook. 

[wdrag]

I've left the timing as is.  Once it becomes clear that there wont be a streak of snow into NJ/ PA before 5PM Wednesday, I'll adjust the headline timing.  That probably wont happen til til late Tuesday at the earliest.  

[eduggs]

1 hour ago, wdrag said:

I've left the timing as is.  Once it becomes clear that there wont be a streak of snow into NJ/ PA before 5PM Wednesday, I'll adjust the headline timing.  That probably wont happen til til late Tuesday at the earliest. 

Too bad the Wednesday "snow streak" has shifted south of our region in recent days. It would/could have led to a sneakily snowy day without the immediate threat of a change to ice. Since it's kind of a subtle feature I guess there's a chance modeling will bring it back.

[Allsnow]

22 minutes ago, eduggs said:

Too bad the Wednesday "snow streak" has shifted south of our region in recent days. It would/could have led to a sneakily snowy day without the immediate threat of a change to ice. Since it's kind of a subtle feature I guess there's a chance modeling will bring it back.

Yeah, like a norlun it will move around the next few days. 
 

Short range models definitely hinting at a burst of accumulating snow in the metro before a change to ice/rain

[Stormlover74]

Yeah thursday morning will be a mess regardless. Takes a while to go over to plain rain and some places don't at all

[Allsnow]

1 minute ago, Stormlover74 said:

Yeah thursday morning will be a mess regardless. Takes a while to go over to plain rain and some places don't at all

Solid advisory event for the city and immediate burbs 

[wdrag]

31 minutes ago, eduggs said:

Too bad the Wednesday "snow streak" has shifted south of our region in recent days. It would/could have led to a sneakily snowy day without the immediate threat of a change to ice. Since it's kind of a subtle feature I guess there's a chance modeling will bring it back.

Yes,  I keep the door open for changes within the broad pix. And yes, I look at snow/ice probably more from a hazard view than actual perfect numbers - I ball park numbers. Too much stuff can wrong on numbers (just like the CP change this morning at 631).  

I'm guessing 1//2 to 3" heaviest case for NYC CP Wed night.  

Am offline til a short time on this eve, then back full bore tomorrow morning. 

[SnowGoose69]

2 minutes ago, wdrag said:

Yes,  I keep the door open for changes within the broad pix. And yes, I look at snow/ice probably more from a hazard view than actual perfect numbers - I ball park numbers. Too much stuff can wrong on numbers (just like the CP change this morning at 631).  

I'm guessing 1//2 to 3" heaviest case for NYC CP Wed night.  

Am offline til a short time on this eve, then back full bore tomorrow morning. 

Definitely need some sort of mesoscale help on this one to get more than a quick shot of snow, high positioning just not great though some higher res models show it could try to wedge itself in for a bit.  Its why I am nervous about LGA/EWR on north holding onto ZR or PL longer before going to all rain but the event that follows this one looks more promising though I still think its the 10th and beyond when any all snow event is likely.

[eduggs]

For reference, the ICON has for days shown the "snow streak" that Walt mentioned during the day on Wed. 6z NAM too. Most other guidance is/was less pronounced, so it would be easy to not know what he's talking about. This feature might turn out to be virga or disappear altogether.

[Allsnow]

Gfs 2-4 before ice 

[Stormlover74]

Ukie nice hit for Thursday 

[weatherpruf]

30 minutes ago, Stormlover74 said:

Ukie nice hit for Thursday 

Where? 2 inches? Mood flakes. 

[Stormlover74]

Just now, weatherpruf said:

Where? 2 inches? Mood flakes. 

Cool

[Allsnow]

Euro was at best an inch of slop before rain. 

[CPcantmeasuresnow]

1 hour ago, weatherpruf said:

Where? 2 inches? Mood flakes. 

Northern NJ and SENY are 4-5 inches. I have no complaints. 

[allgame830]

17 minutes ago, Allsnow said:

Euro was at best an inch of slop before rain. 

Where whole subforum or city? 

[Allsnow]

24 minutes ago, allgame830 said:

Where whole subforum or city? 

Sub forum 

[eduggs]

The 18z NAM says a snowy day (WWA-worthy) is incoming on Wednesday for Harrisburg to Phily to Atlantic City. No snow for most of NYC metro until Wed night and only relatively minor non-sleet accumulations.

This "snow streak" doesn't have a ton of support and is likely overdone but an interesting feature to track nonetheless.

[Allsnow]

 

[Allsnow]

The gfs actually got colder for the thump this run. 3-5 for the area. It’s hard to really buy it when the rest of the guidance dosent show that type of snowfall 

[SnowGoose69]

The AI which has probably performed best on start time in many of these precip events has 07-08z for NYC.  Probably means the UKMET/GFS/Euro might be too slow right now and NAM slightly too fast.  It also has a slight wedging signature showing up.  I think NE NJ/N parts of NYC have to be wary of this event staying frozen for most of it.  We'll see what the NAM shows as it gets closer.  As of today it shows most places turning SE on winds

[wdrag]

7 hours ago, eduggs said:

For reference, the ICON has for days shown the "snow streak" that Walt mentioned during the day on Wed. 6z NAM too. Most other guidance is/was less pronounced, so it would be easy to not know what he's talking about. This feature might turn out to be virga or disappear altogether.

Its isentropic lift (banding) with a decent shot of snow before it weakens when the steering flow changes from wnw aloft to wsw and then the band reforms during  Wed night advancing through NJ. MUCH of our NYC qpf will occur within a 6-9 hr window, I think. That could mean a decent 2-3 hour front end thump????    

A banding sample attached. 

[winterwarlock]

is there a reason why a threat 2 days out has very little discussion..am i missing something? this looks better than the half to one inchers that had long threads here

[Stormlover74]

6 minutes ago, winterwarlock said:

is there a reason why a threat 2 days out has very little discussion..am i missing something? this looks better than the half to one inchers that had long threads here

It's probably an inch or two at the most

[allgame830]

7 minutes ago, winterwarlock said:

is there a reason why a threat 2 days out has very little discussion..am i missing something? this looks better than the half to one inchers that had long threads here

Yeah idk I was trying to figure that out earlier. However it’s still only Monday 

[allgame830]

Just now, Stormlover74 said:

It's probably an inch or two at the most

That seems doubtful especially for areas NW 

[winterwarlock]

6 minutes ago, Stormlover74 said:

It's probably an inch or two at the most

that could still be one of the bigger events of the season especially with an ice threat...there was more discussion for a dusting non event yesterday

[Allsnow]

1 minute ago, winterwarlock said:

that could still be one of the bigger events of the season especially with an ice threat...there was more discussion for a dusting non event yesterday

Didn’t you get 4-5 in the January storm? 
 

This definitely looks impactful because of the timing (Thursday am rush) but It might just be a NW type deal