wdrag

Agree with everyone on north of GFS/EC cold snowy solutions. Added some 12z HRRR guidance. Near blizzard possible around 03z LGA, but short duration, could be some around 12z in the CAA but again short. The HRRR is very strong on wind and I can see it. NAM 10M has 50kt 10 miles east of Toms River late tonight. I'll add the graphics... from th 12z HRRR they look good to me. Also someone asked about Thunder. As you're probably aware SPC added T to a part of forum. And...the HRRR has a pretty strong signal for such this evening in those high snowfall rates. Snow depth: I like as my answer to what is coming. Use w your own best judgement. Added HRRR MAX gusts. and the 1am projected HRRR simulated radar...note sleet up here.

Wantage 19.8/6.3 (dry). Interesting mPing ob near Reading, PA recently..ice pellets. Tells us it's marginal but it will go to snow on our front end. 924A/16

No time to rereview... I see 0z/6 EC likes a colder scenario near I95. Could happen. The se edge still has to have sleet convert to snow which is incorrect but NYC and I95... I'm uncertain and I dont have all the tools NWS does. Please follow NWS. Appended 06z/16 EC 10 to 1. It says I'm a bit too far nw on my NYS expectations. Use your judgement. Thanks... offline til at least 930A. You'll know by then whether 12z 3K NAM has trended colder nr NYC. To me one bad sign... too much sun 6-8 hrs before an event starts. The classics have a long slow process of thickening and lowering cigs. This tells me an 8 hour front end thump down here then maybe sleet starts I80 LI midnight-2a. Have fun with this. Walt 744A

My thinking is north of I80 between MPO and IPT or I88 region to the northern Catskills for the NYS 20+. You have to be safe wherever, drifts and services including roads may shut down for a time there? Also, check with others herein, NWS updates and TWC, of course updated modeling including the HRRR. I'm doubtful of 20" here in Wantage... can happen but sleet is my concern between midnight and 4AM. You need to be in all powder, better snow rations but modeled 1.5" qpf. Again, this my opinion only and not gospel. Definitely seek other opinions. Let's hope this works.

Good Wednesday morning everyone, I've followed a recent example on the New England forum and offer this topic as a start over at 1PM with obs-nowcasts. The tags included hopefully cover the gamut of potential amounts. If we are certain about daily records being exceeded please add and ditto if we get top 20 at any xmacis climate site. Thank you all for contributing to the excitement-anticipation of a pretty good nor'easter.

543AM 12/16: No change in thinking including uncertainties along I95 which to me means we have a chance to exceed this winter, what will occur NYC-LI-coastal NJ tonight. I just cannot shake the basics: S+ axis is usually 90 miles left of the 850 low and the northern half of the 700MB low and the deformation zone near 500 MB with contribution from the nose of the 850MB 50-65 kt easterly jet (moisture transport). This favors I84 and banding casts northwest to a central PA - east central NY area (roughly IPT-ALB) where 20-25" seem probable within 60 miles of that axis - at least in the high terrain, but must consider mountain shadow lesser amounts in the leeward valleys. There a multiple models showing that axis. In our forum, I think most everyone will see a period of sleet near or after midnight and that the bulk of the snow occurs in a 6-10 hour period prior ~ midnight, but that there will be a tail of moderate to heavy snow toward dawn with still 1-4" after sunrise Thursday on top of whatever occurs before sunrise---the heavier 4" potential ne PA, extreme nw NJ, se NYS and CT {where 5" may occur in 2-3 hours after sunrise Thursday}. Drifts to 4 feet possible ne PA, se NYS and northern CT where 18" accumulates since winds will gust 30-40 Mph at times overnight. NYC CP still 6-10" in my mind but shakey and may be too high because of only 10-1 snow ratios at best, sleet and possibly rain compacting as well as temps near 33F at times during the night. The power outage concerns continue near I95 with 45-50 MPH gusts (9P-6A). Coastal flooding - please see NWS offices for minor or moderate near the time of high tide Thursday morning. Finally, even if it rains or is above freezing w LI and Monmouth/northern Ocean County NJ tonight--- there could be sudden icing near sunrise Thursday when the wind switches from northeast to north and drops temps 5-10F in an hour, and iceing the residue and make travel very hazardous again in leftover new snowfall. Otherwise temps in the I84 corridor ~20-25F throughout the event. Will add some graphics by 6AM on wherever the last page of the thread. NOT a top 20 for NYC...best chance is MPO-POU axis in our forum. This is my last topic update for this event. Will begin a storm accumulation obs (snow/rain/sleet/damaging wind/coastal flooding) and nowcast topic by 6A to begin to be used once the snow begins-which I think will be between 1-4PM in our NJ/PA/w LI part of there forum. Graphics: my last on adding prestorm graphics. NWS experimental severity index, the NWS snowfall forecast for our area as per 5A/16. 00z/16 EPS 10 to 1 snow ratio snowfall--i still think too high se edge and then snow ratios will magnify I84 corridor northwestward NWS probabilistic 6+ and 18+. (Note NYC prob of 6+ is not that high). The 00z/16 SPCHREF gives us a better chance of exceeding 6" but the edges are always shaky. SPC SREF plumes for NYC. Please use all as options and may your expectations verify-just be realistic.

Am comfortable with the topic as updated this morning at 5am and subsequent posts today seeing new guidance through 6PM. Will return in the morning. Basically this is a NWS amounts, phase change timing issues.

HRRR thru 12z Thu: have a look... might be pretty good. Am confident of big snow back to near ALB and n of BGM Borrowed from a modeler elsewhere.

Multiple models near 2" qpf near ALB... take a look. That tells me big banding. Usually does shift unexpectedly far nw... There could be two or 3 bands of 1"+ /hr snow at 4AM Thursday from NYS and ne PA across into SNE... I think our lurker friend from LOT might confirm how unexpectedly far nw these bands can go. Then SHARP SHARP drop off to nearly nil in possibly 60-80 miles north of that 25" IF it occurs as I can see this somewhere near ALY. Idea...most of the Adirondacks may have nothing for less than 2".

Hope you're right. Wind may be 050 degrees but it's still off LI sound. I'll go for 31-33F by midnight Wed night. I see wind damage here and there for LI and coastal NJ. When the wind changes to 020 toward sunrise, should drop into the 20s NYC BUT, i stand to be corrected. Let me know tomorrow night (If I can stay awake). No one should be surprised by the mesoscale modulation of snowfall... I can see one spot 8" say NYC, 2" MTK, 16" HPN or POU or BDR...but with large variations as the bands set up. I'm definitely good for tow 25" bullseyes...one in PA and the other somewhere near ALB or even back to n of BGM.

No changes for me in expectations based on the 12z model cycle. The sleet profile is marginal and strong VV at the time of it's impingement could keep it S+ til a mesoscale dry slot temporarily shifts ne along and e E of I95 later Wed night. I still think sleet up to I80. Power outages look like a big problem to me NYC-PHL NJT corridor wherever wind gusts 40-50 MPH and 6+ wet snow at 32-33F. That's a challenge to forecast. I'll be curious. Drifting to 4 feet I think is a possible problem wherever more than 18" of snow falls. (no rule of thumb for me on drifts). e LI might not exceed 4" snow??

I agree 100% - for NYC this could be an 8 hr snow blitz, sleet/rain/freezing rain after midnight for a while then back to snow by sunrise with 25-0F air lurking in CT to swoop south during the morning as the low track and ppp falls shift e of ISP longitude. Think its a heckuva a mess NYC.

SPC HREF: may a bit cold se edge but this is the snow amount from this model by 7AM Thursday, with I think 1-3" after that...maybe 4" in n CT. Legend has the numbers. NYC 6-8? MPO 21. Looking good for a top 20 storm there and the model qpf and NAM banding suggest seoncafry band big snow east central NYS (two separate 20-25" bullseyes one in PA and one IN NYS).

Results via CoCoRAHS yesterday - my non CoCoRAHS in Wantage was 0.9" I hear Randolph NJ had at least an inch... my senior softball practice group cancelled todays practice due to snow cover. We still have a 0.5 to 0.8" left. Updated maps provided 250PM.

comes the territory--- they are paid and I know they like the challenge and reward. I did.

That seems reasonable... Maybe some of the office AFD's will talk about snow ratios. If you have BUFLIT, I think you can look at ratio's there. Also, there may be some blended 6 hourly atio product out there, but for now... ??? You've got it

Wow... TOUGH forecast. I do think they will see sleet and rain after maybe 2" of snow to start. This based on 00z and 06z guidance. Could be wrong but thats a quick guess.

Good Tuesday morning, Dec 15. I have no change in my previously expressed opinions regarding what I think is coming. Not the worst ever, by far, but this will alter pandemic normal lives. If you have plans Wednesday and Thursday across parts of WV, western VA, PA, NJ along and northwest of I95 as well as NYS and all of southern New England, I would think twice (and probably change plans) about traveling there (especially 4PM Wednesday to 10AM Thursday). Follow local NWS Warnings/Statements/ forecasts and that of local government officials. Other than e LI and portions of coastal NJ near and s of Toms River, where an uncertain less than 6" of snow-sleet should occur, this will be a widespread 6"+ snow storm with a period of sleet possible in the overnight hours up to I80. The 45-50 MPH wind gusts are still expected on the coasts 9P Wednesday to 6A Thursday, This with the periods of heavy wet snow changing to sleet and/or rain should result in extensive power outages, somewhere near or just east of the NJT, or on LI. Moderate coastal flooding is probable along the coasts-inlets for the Thursday morning high tide (follow local NWS guidance). With a likely 10-20" of powdery snow from I80 (or I78?) northward through the I84 corridor, it will be time to sit back and sip hot cocoa and get into the Holiday Spirit. Those with heart conditions, be careful...the snow will be wetter and heavier as you get close to NYC. Otherwise removing a batch of snow around 9PM Wednesday will make it easier not to break overwhelmed with snow removal Thursday morning. My guess for CP is 6-10"--it will be wetter snow there and I think sleet mixes in and I could see 2-4" of snow on the ground there by 7PM. Top 20 snowfall potential exists for MPO, POU, BDR. Banding will be big and may overcome some slightly above freezing layers aloft to keep snow going over w LI and I80. The banding could yield isolated 2 foot snowfall somewhere near I84. These storms have suppressed areas and enhanced areas of snowfall and I've no way to predict where. So while you see the base snow amounts in the EC ensemble graphic... snow ratios will possibly add 10" to this in a few spots of ne PA or NYS, CT? Then there are snow measuring guidelines, and the 30 MPH gusty wind fracture of dendrites overnight Wednesday as well as drifting that will make it a bit more difficult to figure out the amounts. You may want to regionalize your post-storm assessment (the mean of multiple snowfall abs within a 15 mile radius?) Graphics are: NWS office collaborated impact product-please use as an experimental guidance. WPC 304AM QPF assessment. The EC EPS ensemble baseline 10 to 1 snow ratio snowfall (be careful southeast edge where sleet is treated as snow), the WPC probability of 6"+ and 18+". This gives a feel for confidence by the NWS and axis of concern. Added SPC Short Range Ensemble Forecast (SREF) plumes for snowfall amounts at LGA, AVP, POU, IJD. We see the spread in the members and mean (Bold line). Then close with the two day top 20 snow accumulations - Note the shorter Period Of Record (POR) at some stations. Sussex is in there to show that we have quite a hurdle to exceed here, but MPO, POU (valley shadow lower amounts??) and BDR are vulnerable for top 20. Follow local NWS products and the advice of officials. My posts do not represent the NWS, only utilizing all the available models-tools to the public including NWS generated products. I may be off-line many hours today and probably won't have a comment on whether I overdid this, until about 6PM tonight or 6AM Wednesday. Have at it and do the downside checks to help keep perception of future reality, realistic, with hopefully few disappointments Thursday. 533A/15 I'

Forgive me if this is a repeat... I haven't been following for 5 hours. WPC heavy snow discussion from ~430P. ...Appalachians/Mid-Atlantic to New York and Southern New England... The latest forecast continues to advertise a significant winter storm for portions of the central Appalachians, the Piedmont area of the Mid-Atlantic, and much of south-central/southeast NY and southern New England, as a nor'easter develops and lifts up along the East Coast Wednesday into Thursday. The wave that crosses the southern Plains Tuesday will eject through the Mid-South Tuesday night and is forecast to take on a negative tilt as it arrives across the Appalachians on Wednesday. This will promote cyclogenesis off the Southeast coast with low pressure then lifting north and strengthening along the Mid-Atlantic coast and then arriving offshore of southeast New England by early Thursday. Meanwhile, a cold, 1036+mb high will be focused over Quebec and will be nosing south down across the interior of the Northeast and the Mid-Atlantic with a rather classic cold air-damming event expected to be in place as the low center moves up the coast. As strong warm-air advection/isentropic ascent occurs ahead of the upstream trough along with increasingly moist Atlantic inflow over the cold air, a large swath of moderate to heavy snow is expected to develop for portions of the central Appalachians and the adjacent Piedmont areas of WV/VA/MD and PA on Wednesday with the focus west of the I-95 urban corridor, and the bigger cities of Washington D.C., Baltimore and Philadelphia. By Wednesday night and early Thursday the focus of heavy snow will overspread areas of southeast NY and southern New England including the New York City and Boston metropolitan areas. The latest model guidance favors a rather strong comma-head/deformation zone impacting especially areas of eastern PA, southeast NY, northern NJ and southeast New England on Thursday as the low center further deepens and then begins to edge east-northeast and farther offshore. Meanwhile, down across areas of northwest SC, western NC, southwest VA, and southern WV, the cold air will be much more shallow by comparison, and it appears likely that there will be a period of freezing rain and locally some sleet as the event ensues on Wednesday. Some of this may sneak up near or just west of I-95 as well from Washington D.C. to Philadelphia. But the threat of ice farther north closer to New York City and certainly Boston will be notably lower. WPC favored a a multi-model blend approach for the precipitation forecast with a tad more weighting to the ECMWF, and lesser weighting to the NAM and GFS. The NAM is farther west and warmer with the evolution of this system, with the GFS a bit colder and farther east. While not totally dismissing the NAM and GFS, a model consensus somewhat closer to the ECMWF and ECENS mean was favored for QPF and was applied to the thermal profiles. Based on the latest forecast, the expectation is for storm total snowfall to be as much as 12 to 18 inches for the interior of especially the northern Mid-Atlantic, far southeast NY and southern New England. Where freezing rain occurs, the greatest ice accretions are expected over northwest NC, southwest to central VA and over parts of southern WV where locally as much as a tenth to quarter inch of ice will be possible. Added the collaborated snow range from the mid afternoon NWS forecast cycle. And , an example of the primary band of lift for ~4AM Thursday (18z/14 NAM)...in an arc fro nw NJ to SNE. IF this is reliable, a band of S+ should be occurring near or just north of the arc.

Wow... not sure when that changed? I do think this will suppress amounts do to settling, drifting. Up through March 2018, it was clear the board every 6. Anyway, you're saying 24 hrs... that's what it is. Thanks! Walt

Hi! I don't have any big changes for our forum... My thinking is we have a 6-12 hour blitz of with lingering lighter snows extending this to 20-24 hours. The EPS continues solid 1" to just s of the MA Pike and I agree with posters about sharp cutoff near or just n of I90. I also have concerns about the I95-LI stretch (PHl-NYC ) sleet/cold rain/junk mix after the first few hours off thump that will need traveler behavior modifications (S+ for 1-4 hours?) . Still the EC EPS continues steadfast on a nose of max snowfall from near HAR to somewhere along or just s of I84 to near BOS? I don't have enough time to study the 12z cycle (Xmas cards). This is the NWS collaboration. I do think this will be high impact nor'easter. Not the severity that it could be because it's shorter duration and not quite the gradient but folks are going to be shoveling and my thinking, they don't want to be out traveling in our forum roughly 6P-3A. I have to think a slew of watches will post by 4PM...then we just have to do what the NWS does... be patient, head for a reasonable blended solution and emphasize their points via social media. I think our topic is good... probably a touch overdone on top 20 snow event. Will NYC set a daily record snow tomorrow. I don't know. Can we get to 20" (several 20" reports) in our interior hilly forum... maybe but it's not my emphasis. If we see a widespread 6"+ snowstorm with a band of 12-15" ne PA/extreme nW NJ far se NYS into CT... I am satisfied, particularly since this has been modeled very consistently for days. LI/coastal NJ i our forum... no confidence yet on inches. 311P/14 One additional note: You may be noticing strange pockets of heavier and lighter qpf, ditto RH dry and wet fields at 700 and 500 MB. That's model signs of banding..modulation of the qpf fields. I'd look at the srn edge of the 700-400 moisture for potential banding,. 313P/14

Typically CO-OP stations and CoCoRAHS sites measure 1x/day...max depth on the board since the prior morning ob. However, more accurate snowfall that limits settling-drifting etc is taken every 6 hours with a snowboard wipe. Snowfall: Measure and record the greatest amount of snowfall that has accumulated on your snowboard (wooden deck or ground if board is not available) since the previous snowfall observation. This measurement should be taken minimally once-a-day but can be taken up to four times a day, (every 6 hours) and should reflect the greatest accumulation of new snow observed (in inches and tenths, for example, 3.9 inches) since the last snowfall observation. Here's the link. https://www.weather.gov/gsp/snow Hope this helps. Walt

Wantage NJ ... final 0.9" at our Wantage location - 740' MSL. Snow after 1P melted on contact. 34.0F at 237P.

Ditto this part of Wantage Nj ~740'MSL 1PM 6 hourly...deck cleared for new snow after the first 6 hr total was 0.9" Pavement 1/3rd" wet slushy. 33.4F gentle 1 to 1.5Mi s-.