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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.

Agreed... nice lapse rate post to demo the potential. I do not think we can say no problem. IF this occurs as anticipated. roads will not be treated during the heavier of whatever Inauguration morning commute, but I'm pretty sure slippery spots will develop, un beknownst to some of our faster drivers from PA to NYC. Definitely a potential SPS event.

Dustings occurred into Sussex County NJ of nw NJ last night with a nice cover in ne PA. Wantage, T but nothing visible. But Newton-Andover Township a slightest cover on grass/roofs. Past 24 hours attached. Accept what we can get.

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. 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. --- 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.

Thanks... March 2001 was not a highlight of my career. We lucked out in EMA/RI but definitely missed the front end. I think it was that storm botch from PHI newd, that helped accelerate the change to a collaborative effort with WPC and soon the implementation of ENSEMBLES, to ballpark our forecasts and limit the extreme solutions. I definitely think that has helped me, and possibly many others, be more realistic about the forecast-a benefit for the users of weather info. Thanks again!

Good Tuesday morning everyone, I've an errand to run shortly so I'll start the thread for 25-26 only at about 9A. Still fraught with uncertainty but looks cold enough for any qpf to be a snow or ice mix except the usual mess for LI, with an ice/snow line in my mind either I78 or I195. SOOOOO early so will probably play it a loose and tighten up the topic as the days move along. Later, Walt

This may be getting a little more interesting for ne PA/se NYS/n NJ/ LI/s CT Wednesday morning, Probably worth monitoring for a small accumulation within 4 hours of sunrise Wednesday. Some of the modeling is trying to combine the cold frontal trough instability snow showers with an area of weak low pressure moving off s NJ. No consensus on that occurrence. Otherwise the cold frontal surge of instability changes, spikes in RH etc as discussed yesterday prevails. If it doesn't snow by Noon Wednesday, then the afternoon snow showers will be gradually drying out to virga in the gusty northwest flow of drier colder air. Right now I expect fairly widespread coverage of dustings to 3/4" ne PA/n NJ/se NYS/s CT - LI including NYC. Whether it's more than a trace NYC or observed officially before melting (NYC mostly 8A-11A), that i don't know. If the 12z and beyond cycles of the RGEM/HRDPS drop it, then I've hit this too hard.

I had to run some errands... , so rather than have anyone wonder, I just delayed til tomorrow. After review of the 12z/18 NAEFS (available ~230P/A) we continue on target as outlined this morning around 6A... advisory snow/ice with most of this on the 26th but as you say, not only a piece possible on the 25th, it could wait til late 26/27. Think this can wait til 6A ish/19 and get off the fence and topic at that time. That will still be 6-8 days in advance, so the uncertainties are likely to persist-will run it broad but give us the probable blended outcome. NAEFS continues colder thicknesses and BL temps along I95 so not too bad, despite the differing model solutions. From my view, IF we do get 0.4" frozen qpf up here...where sleet doesn't occur, there might be some larger snow water ratios of 12-13 to 1 instead of our typical 10-7 to 1 along the coast? Will havre to check some guidance on that. I like the LF quad of 2H jet.

No thread from me this afternoon on anything here 1/25-26 etc. Solutions too variable and there seemed to be a large southward displacement since the 00z cycle. Have no idea if that will hold firm. Will rereview in the morning.

Likewise here in Wantage around 145P... brief. just wet. Thanks!

Snow showers on their way for parts of nw NJ, se NYS and CT... see radar sewd moving. Probably a dusting-coating for terrain above 1000 feet. sleeting near NYC recently. I'm 38.8/29.8. Just too warm to show snow on grass but thats at 700 feet. Cooler at 1000 feet. This is a potentially a tease for stronger activity sometime Wednesday morning-midday.

Thank you Don, I don't have BUFKIT because of my MAC and so get by with Tsecs, R#, and various gust algorithms. On dustings coming soon to nearby yards in our forum. Not sure if anyone noticed the dew point isn't dropping. That's a very good sign that we'll have enough low lvl RH to support snow showers making it to the surface. A few graphics follow that focus here near NYC 6A-2PM Wednesday. My dewpoint has been sitting around 30 since late yesterday. Where they measure 1/4-1/2"... within10 Mi of CP?? Here's the 12z/18 FOUS. Note T1-T5 lapse rates over 15C and ... strong stability change (drying out late Wednesday afternoon +15C change from 18z/20-00z/21). That and the wind shift-cold pool aloft should result in a chance of measurable SPS snow showers down to LI. Used the NAM12K. 3K not quite as impressive but still notable. ICON, RGEM and recent EC have it in or within 15M of NYC. I don't expect the GFS to be as clear cut. The HRRR per NWS friend telcon is supposed to shine in convection. Not summer, but this is convective signal. Here's the12z/18 HRRR model for 12z Wednesday...bearing down from the nw. Let's see if this risk diminishes or materlializes. I'm thinking this will happen but whether CP gets more than flurry?? But it could drop briefly to 3/4mi? We'll see what gives. IF the dew point can hold near 25F through 12z Wednesday... I like the odds. I also added for those unfamiliar: credit to the online met and his support group... the FOUS interp guide. Most people probably don't use the FOUS to their advantage. It's a good tool to have for a quick idea. Back at 4PM for a new thread to take into account NEG NAO impressions and others, plus my own reevaluation for a new thread (25-26 and or possibly 27).

NYC CP: While I expect scattered dustings to ~1/2 snow shower accumulations this week in parts of the I84 corridor down to just north and and west of NYC, the chance of CP seeing 0.1" snowfall in time for an observation is rather low. It's a matter of timing any snow shower with temps cool enough to allow accumulation and the observer to record it. The only reason for any attention to such a minor occurrence, is that it hasn't measured snowfall here in CP since the storm of the 16th-17th December. Instability and changes in instability with a trough passage both surface and aloft will be notable Wednesday (th instability already is). A NAM TSection check is showing the cold pool aloft and the RH spike but only a smattering of measurable around the NYC forum so odds favor no occurrence of 0.1" snowfall in CP. Already, late today, the snow showers sliding out NYS and PA from the west northwest may turn to sprinkles as they approach the near NYC environs but it will be colder Wednesday for a much more likely sustaining of flurries or even a snow shower into NYC or LI. Haven't studied Thursday-Friday, as it's a minor chance as it stands now-still possible but not a probable measure for NYC CP.

Good morning all, My take based on the 00z/06z ops and 00z/18 ensembles. 00z/18 NAEFS helped guide the wintry and qpf call (~0.4" w-e I80 axis) The I84 corridor has basically scattered dustings this afternoon and evening, Tuesday afternoon-Wednesday afternoon, and again Thursday-Friday. Amounts in the Poconos might add up to 1 or 2 inches by Friday, trace to 1/2 inch elsewhere by Friday eve. Basically just be alert for quick changes but overall no big deal. Travelers into the northeast USA Monday-Tuesday the 25th-26th should be aware that an extensive light to moderate hazardous wintry episode is expected for all untreated surfaces, especially the I84 corridor. It may even briefly begin as snow-ice down to Philly Monday. 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 late Monday night into Tuesday night the 26th. Odds favor a change to rain south of I80 by Tuesday morning the 26th, but ice or snow north of I80, especially the I84 corridor. NYC-LI--- have no confidence on sleet-snow start or just rain...close but for now both are options, from a multiple model blend. Right now, I think most of the wintry is to the nw-ne of NYC, though a start as wintry is possible. I'll probably start a thread on this, this afternoon pending receipt of the entire slate of guidance. I do see the para is south and that the EPS ensembles are south. I just think there is enough ensemble data for an event of sorts. Will check back mid afternoon.

GFSV16 has started for the 12z/17 cycle. at 24 hours as of this post.

Added from the American Meteorological Society (AMS) Dec 2020 Digital edition. I think they would like to see this info shared and I think it valuable...especially Lead Time on SVR and Synoptic Scale events. It definitely supports my basis for acting on threads. This is from page 1125. AMS STATEMENTS Priorities for a New Decade: Weather, Water, and Climate A Policy Statement of the American Meteorological Society (Adopted by the AMS Council on 28 September 2020) One to three hours. Our national investment in research and observations has paved the way for severe weather guidance to extend beyond traditional 30- to 60-minute warnings into the 1- to 3-hour time frame. Such guidance could lead to major benefits in preparation and safety. It also raises new questions. How will people respond if they expect to have more than an hour to take action ahead of a possible tornado or a flash flood? How can the probabilities and uncertainties inherent in such guidance best be conveyed? How can schools, workplaces, and other institutions act to support public safety measures in these extended time frames? Weeks to months. Specific local weather forecasts cannot be issued with accuracy beyond about 10 to 14 days. However, many other types of outlooks have demonstrated accuracy over periods of weeks to months (subseasonal to seasonal periods) when they are presented in terms of probabilities or likelihoods. For example, some periods of increased regional tornado risk Predicting and respond- ing to such multipronged threats will require new forms of collaboration and data sharing across sectors and disciplines.

Thanks... still learning. It's tough to be realistic ...but in forecasting, credibility goes to crud pretty quick if you miss more than the coin flip. Good to discuss everything as is done on these forums.. helps me see data use that I'm not up to speed on. Speaking of which: watch those lapse rates this week and R1(boundary layer RH aka Temp-dew point spreads less than 20F)... We'll have to see if downslope dries out the potential for snow showers all the way down to the city. I like what I see but models and MOS are pretty dry so that tempers my enthusiasm. Plus the observation process might miss the tiny sub one quarter inch amounts. Making the most out of this winter pattern.

On frigid weather - enjoyment of-- cause some of us lived through it (we're older but still alive). I think there was the 30 days or so of subfreezing weather in NYC that contained the damage of a January garbage strike back in the 60s. How about pond hockey regularly every winter in the 1960s. how about the wonderful chill of the freezer NFL bowl in Jan 82 ... that was some pretty decent cold. I remember MKE Jan 1982... two separate super cold episodes out there where electronic means were needed to keep the oil in your engine from congealing (ie so you could drive to work). and I know one of those shifted episodes into the northeast USA. BRRRR... and that's why I own too much long under and outer wear. Now that was ARCTIC... The were the days in the northern USA...

As of 7AM Sunday 1/17 I have no changes to anything written since inception of this thread. No increases, no decreases. It's minor if it occurs. I sort of like Wednesday morning when I think we could see pretty decent lapse rates and a decent short wave passage. The possible snow or flurry event for late Thursday-early Friday is more WAA related, after what should turn out to be a pretty cold Wednesday. Hdre's the 06z/GEFS membership and mean as well as the anomaly modeled for 18z Wednesday.

Good Sunday morning everyone, Jan 17. No insight except my own interp of what the models are trying to say up here. No big deal til the 25th and even then, quite a bit of uncertainty, including ptype along I80-LI. I84 corridor Today-Tuesday... a few flurries and maybe one or two short periods of minor accumulative snow showers, especially Poconos Monday-Tuesday where dustings are probable. I84-I80 corridors including LI Wednesday morning-early afternoon including LI: COLD. A period of flurries seem likely or even minor accumulative snow showers. I84-I80 corridors including LI Thursday afternoon-early Friday: A period of flurries or minor accumulative snow showers, except possibly sprinkles-light rain for LI. 25th-26th: No 06z V16 as of this writing and the 06z op was scary dry. NAEFS has a widespread light event of snow or ice I80 northward (Rain LI?). Not convinced yet of the NAEFS amounts of 0.4" melted. Could be less. Have a good day and let's cross fingers for something.

Have no additional contributions on the 22nd. the 25th-26th yes. Notoriously, Modeling doesn't handle ejection of the sw USA 500MB closed lows very well. Impact differences are huge in the eastern USA. Think I want to wait 3 more days (19th before getting my hopes too high).

Not too worried about the 25th-26th...something should happen. I am paying attention to this Thu night-Fi. Doersbt mean it will happen but surprised the GEFS is up a little on qpf.

I like the conversation and my only thought with the 26th, watch the 22nd. For those who wish NIL for the 22nd.. root for the 12z/16 GEFS to back off a bit on qpf and for UKMET to not have developed some sort of short wave in the Ohio Valley to join with the northern tier ese driver. We'll have to count on this being one of the UKMET'S spurious wrong off by 300 miles on qpf axis operational cycles. It does this kind of thing...am saving the UK for qpf for 12/22 night/23 AM for a future compare. I'll be away from the computer for awhile after 1P.

Snowfall reports so far, extreme northwest portion of the forum area as of CoCoRahs reports this morning prior to 830AM.

Wantage NJ (this part) 0.76 and still clicking a bit.