wdrag

Mostly all rain should be confined to the region s of I-78, LI-NYC. Sleet or snow begins near I78 ~9 or 10A and spreads northeast, possibly possibly drying out to flurries reaching CT/se NYS midday. Thereafter the bigger part of this event occurs 2PM-2AM as mostly wet snow just nw of I95. Heaviest snowfall seems slated for the elevations including the Poconos-Catskills with 3-5", 2 to possibly 5" rest of se NYS, nw NJ along and north of I80 to the Merritt Parkway-in other words west of the CT River, but possibly a dryer zone of under 2" to at most 4" ne CT-central MA. These amounts are uncertain-based on guidance through the 06z/3 cycle. There will be melting on pavement today below 700 feet elevation during the day but a plowable snow seems certain for the hilly areas, especially w of the CT River with accumulation on all untreated surfaces after sundown. The precipitation driver will probably at least in part be an inverted trough developing northwest from a rapidly deepening low pressure system heading east northeast of the mid Atlantic coast. The inverted portion of the trough should be back to the Poconos and that I think is why the heavier qpf tends to be modeled there.

Not on the sea level streets, but it's pretty clear to me from the snow depth forecasts that accumulations will occur inland and possibly spotty 6" between I84 and I95. These are the more typical snows for the interior. Will revisit in the morning. Also, sorry for the brevity explaining. Snow depth forecasts from EC/NAM are my base starting points... the rest to me is gravy. Tomorrow morning will examine banding potential... and also noting one reason the extra confidence on snow accumulation , the bulk of this event will probably occur after sundown Sunday. a solid 6-9 hour event of variable intensity snowfall light - moderate. Since temps are generally the concern, let's revisit what the 00z/3 models say and how our temps are looking at daybreak Sunday. Just seems like a nice wet snow fall for the Merrit Parkway on across northwestnj/ne PA and se NYS. Til tomorrow.

fwiw... 12z/2 NAEFS and GGEM are drifting north. Might not have enough wavelength if it stays separated from the northern stream, but possible the northern stream joins forces and it comes all the way up the coast. Too early for me... I'm staying put on expectations until I clearly see a southward block and not enough ridging ahead of it.

My error... I read too fast. Thanks.

January 2, 2021 605AM Update: Am probably not commenting for our NYC forum on anything beyond 9AM January 4, which is about the still possible extension for eastern New England. That part of our oncoming light to moderate Nor'Easter snow event for the entire I84 corridor, will not happen for us. The remainder of the NY Day comments below seem reasonable. My anticipation is a widespread plowable 2-6" elevation dependent snow event from I95 northward through the I84 corridor and probably I90 eastern NYS and northern NJ/ne PA eastward through southern New England. I-84 valleys will manage this better because of marginal melting temps (32-34F) and the southeast edge near I95 will also be manageable, in part because a little rain/freezing rain/sleet is possible there. as well as the daytime temps near 33F. So, it's a mixed bag but the I84 corridor should enjoy this, with the primary event mainly Noon Sunday-6AM Monday. This storm will probably affect some of the return home holiday travel and also may force some Monday morning 2 hr cleanup delays, especially CT-MA portion where it still may be snowing a bit. NYC-LI should see a touch of snow/sleet but whether it measures or not and where, i don't know. My guess is eastern LI may do a little better and thats where there will probably be some wind gusts to 35 MPH but NYC might also see less than an inch?? There will be 1 or 2 brief periods of moderate snow with this event, but I'm not thinking of more than 10 to 1 snow ratios, possibly only 7 or 8 to 1 near I95. Will begin the OBS/NOWcast thread later tonight. Earliest part of snow/sleet/very brief ice arrival is around 8A-10AM Sunday for our NJ eastern PA membership. I don't anticipate adding any further potentially helpful information until maybe this evening. Noting the WPC ensembles for more than 2" are not very enthusiastic for this event, so we need to keep in mind failure. They also weren't as enthusiastic as they should have been for glaze this past night and the SPc SREF did much better. It already has 2-4" in ne PA by 7PM tomorrow night. Keep an eye on the SPC HREF MEAN snowfall after the 12z/2 cycle completes around 1030AM. The HRRRX was all over the place for this freezing rain/sleet/snow event that is wrapping up now and am not referencing it today. I as others here , like consistency in the modeling. One event at a time. reposted here at 755A

Ice pictures from a nighttime 0.2"+ freezing rain event with estimated radial thickness of 0.12". Pix at 715AM This icing followed a max daytime temp of 34-35F and occurred at 31.5 throughout the night til the 430AM ZL- 32.0. This in my mind, counters an argument that we need 20s temps for a good freezing rain event. Nighttime I deny that. Treated surfaces wet but I think we need to be careful about dismissing dangerous icing for pedestrians at night at temps of 31.5F. Was a good advisory throughout inside I95 and maybe I95 itself. I will stand corrected with any science that says otherwise. These pix I think help my concerns about icing at 31F. off my pulpit for now and will listen to counter arguments. Can redistribute as you wish.

No topics posting from myself for the 11th, or mid month event potential til we move at least beyond the Sunday-Monday Jan 3-4 event and have read the 8th-9th potential seemingly correct. Nice pattern but marginal thermal profiles continue til at least mid-month as others have noted.

Good Wednesday morning all, Jan 6. Unless something highly unusual occurs, I've made my last update for this topic. This was a busted January 2 outlook that faded with model cycles only 24 hours after issuance, beginning around the 00z/3 cycle., blocked to our south and southeast. Good Tuesday morning Jan 5: Update dropped the 8th from the topic, and dropped the tag of ice. The preponderance of 00z/06z January 5 2021 guidance favors a miss for this developing mid Atlantic coast nor'easter and so my Jan 2 confidence is probably wrongly over confident for an 7-8 day outlook. However, we're still at 96 hours (4 days) with somewhat delicate northern-southern stream trough interactions in the northeast USA Friday and Saturday. Some of the guidance has minor amounts of precipitation skimming the NJ coast/e LI with ensembles interestingly showing a little more extensive minor qpf coverage for southern New England. That New England coverage may be due to the eventual development of an upper level low over central or southern New England on Saturday (light wind), and a possibility for a period of easterly flow aloft , caused by the flow interactions of the modeled offshore storm and the northern stream short wave in New England. So it would not surprise to see some light or very light snow on the coasts into CT/MA but for now--- please go with your take on the event. I can't push this occurrence in the face of all the recent 3 days of modeling. We're still 96 hours in advance of the storms passage and once in a while models make significant adjustments in somewhat uncertain northern -southern stream interactions. -- Happy New Year and welcome to what will probably be the 3rd wintry event of January 2021! Just too early to detail but ensembles have something. The current Aleutians east central PAC short wave is modeled to dive southeastward into the nations mid section and by Next Friday the 8th turn northeastward into the northeast USA. This could be snow to ice to rain, but something wintry is coming (my guestimate is a 70 to 80% likelihood). Is there enough cold air and confluence in the right area of northern New England to allow-keep it wintry? -NAO Block impact? Will update these tags and potential impacts when confidence increases. Just wanted to get this thread started for any comments/model considerations etc as we move forward.

Good Saturday morning everyone, QUICK review: My guess, from a quick 430A check of temps from multiple resources... the ICON/NAM did best holding onto freezing temps this late into the event I84 northwestward. If others see it different, please speak up. Models are getting better but just 1 degree can be a BIG problem at critical temps. imo, the Global Models cannot as precisely detect the subtleties. They're all getting closer but still advantage can be to those who know the nuances of the guidance in light boundary layer winds that do not have much CAD support from the typically desired east of south 850MB winds.

Wantage NJ 4sw: Freezing drizzle...32F at 430AM. Everything well iced except some of the driveway. We'll wake up to glazed trees. STP At least 0.21" freezing rain...glaze thickness unknown but estimated 0.1"? Not easy to see branches at night. Walt

Wantage NJ This post at 740'MSL. Plenty of freezing rain. Sleet and snow mix began 435P went to zr- at 5P. At least 0.14" liquid since it began. glaze on all surfaces except driveway spotty. Unsuspecting would fall.. it's not the solid ice at 25F zr- but it's slippery with thin film on all trees. Temp 31.6F.

Hi All, I only thread it, when I think it has a legit chance of being worthy of a NWS hazard or something out of the ordinary that the forum will want to follow. Great group of participants on AMWX and other forums... all having interest in winter storms or summer heavy convection, hurricanes, big wind etc. Thats us..weenies but appreciators also of the modeling. One of my goals: demonstrate success at extending heads up for potential weather events that will affect travel etc. Not all work out (12/29). Folks can look back anytime, see some of the guidance and expressions of confidence and judge for themselves. Scientists generally think I push the envelope of interest too far... I tend to think we don't prepare far enough in advance with contingency plans, should something turn out close. Models are raising the quality of all forecasters... not always, but more often than not. AND it will continue to improve, incrementally... That's why the GFSV16 (parallel) Anyway for 1/8-9, 11 and 17...am holding off... grazers and uncertainty, in some cases not enough separation between short waves, thermal profiles shakey, all argue caution. Soon as I see EPS or NAEFS jump on one of these... I'll cue it up (or yourselves can initiate). Just keep discussing and dreaming, always with climo and ENSO stats in mind, tempering enthusiasm of a big occurrence, beyond a few days. What I'm seeing in the NAEFS...and others have pointed out previously using other ensemble systems = the warmth in the USA will gradually diminish from south to north as the core of the warm anomaly shifts north of the border into perpetual nighttime snow covered Canada. That should allow a little more confidence mid-month as others have discussed. I hear and use the term outlier... also good to know that many times, early outliers sometimes become the result (ie the predominant predictable group as we draw closer to the event). Also, sample sizes broaden and adjust with time. This winter may or may not be an example. I'll check back in the morning: Just holding off for now. Good that this is all discussed. Will do whatever the forum consensus directs, if different from recent lead time topic issuances. Later, Walt

Wantage NJ: snow and sleet began around 435P. now all light sleet. 32.4/27.1 at 457P Road crews just salted but no covering yet.

34.2/26.7 Wantage NJ with a wall of mixed precipitation coming at us in the bright band I78 -I80 region. I see ice pellets and grauple in 1 or 2 reports ABE-TTN at 155PM. Recent approximate 14z HRRRX cycle has surprisingly large amounts of ice pellets and freezing rain coming to the NWS advisory area in the NYC subforum. 12z/1 SPC HREF continues with the ice amounts as previously posted from the 00z cycle-this seems a little robust but the ridges above 1000 feet may do quite well. Noticed the 12z /1 NAM has cooling its 12 hr fast for 00z/2 at LGA T1,3 and I dont believe its +5/+6C T1 temps at 1am and 7a Saturday...BL wind not strong enough to drive those temps up, i dont think. Looking for a ne flow there. Therefore, I think the warming is going to have to come more from conduction or precip quitting after the initial 4 hour burst, rather than advection, in our NYC subforum. Should have reports coming into this page by 4 or 430P.

I agree regarding a specific 1/8-9 thread. Just not convinced yet on the quick check of 12z ops. Also thinking of a thread: "Is this boring?: I84 and possible I95 ice/snow threats 1/8-9 and/or 1/11 with marginal thermal profiles prevailing." Just waiting on this til i get a chance to be more ensemble cognizant of potential, which is not likely to be til Saturday morning.

I84 corridor is in my mind ~25 either side of entire stretch I84. Scranton to Worcester (excluding CT coast where the 25 mi mark overlaps). Yes se NYS/ne PA. Hope that helps. Have a day.

Likewise, wishing everyone a Happy New Year and to add another topic later today for Jan 8-9. Just need time to think it through. Ensembles are timid despite 00z/1 GFS parallel, EC and GGEM on board. Will probably add the topic this afternoon but leave room for blocking forcing system too far south of us- ie a miss. I don't think it's a miss but I'm sure we can all envision how this might fail. Later, Walt

NY Day 2021 558AM quick update: Extended the event date to Jan 4. Ensembles suggesting a pretty good chance of 3+ inches for some the I84 corridor high terrain in possibly two long duration episodes. A short wave diving into the back side of the initial short wave trough may prolong the event considerably for the New England portion of the forum by forming a a very slow moving upper low along the New England coast. So it's complex but potent, especially if the 850-500 MB lows form in a favorable position for banding on the northwest side of this storm near I84. Just too early to overcommit but this could be a nice snow event for the I84 corridor and as previously proposed (modeled), can't rule out a touch of wet snow on the back side for NYC and especially eastern LI on the 4th. Just too early, especially with marginal thermal profiles and absolutely do not want to buy into any 8" amounts seen on some of the single member operational models for New England, at least not this early with so many differing solutions. If it's progressive and mainly afternoon of the 3rd into early 4th, then the 8" amounts won't happen and this would be an interior I84 standard climo modest event. Graphics is the 00z/1 GEFS prob of 2+ inches for this coming storm-- 10 to 1 ratio. Just an idea of primary risk area. Doubt if I'll comment again on this snowier looking Jan 3-4 event until today's is complete, which means I'll try to add some useful thoughts-graphics tomorrow morning - Jan 2. Have a good start to the New Year!

A routine wintry ice event, that will create some travel problems in high terrain above 1000 feet late today and early tonight, primarily along the I84 corridor.

Happy New Year! No significant change to yesterdays post. This event will focus it's main impact on ne PA, se NYS, nw corner CT into w HFD county and the Worcester Hills, in that order of priority, Valleys in pretty good shape s of I84. A little sleet possible at the start many areas but less chance of a few minutes ice pellets LI. the leading of qpf will increasingly grow sleet to an hour or two duration as it gets into far northern CT and maybe briefly mix snow there with snow on the leading edge along the MA Pike. Main risk of 1/4 inch glaze is ne PA high terrain, Catskills, and extreme nw HFD County into the northern Litchfield east facing slopes. graphics: Orange where best chance of problem icing in WPC ensemble, the second graphic is the SPC HREF ensemble FRAM icing potential=worst case scenario in my mind, showing ridge icing best but amounts may be a touch high? and finally the 06z/1 HRRR snow and sleet accumulator, which I think is a reasonable baseline for this event.

I don't like it either... probably good to wait it out a few runs. On that RGEM, notice the banding developing VT... if it occurs as portrayed... pretty darn good snow rates there. That's a nice signal... maybe it will edge down to I84? Till tomorrow.

I look at every model every cycle through 7 days. I just notice the HRDPS is slightly colder than the RGEM and consistently so. Once the HRDPS loses freezing, then I think the door shuts on new ice...even if there is a 1 or 2 hour delay from th HRDPS time. it has longer duration on western fringe of forum than many models are offering, With a grain of salt... HRRRX has quite a bit of sleet late NY Day...even LI will probably see at least spotty sleet during the first 2 hours of precip. Upshot of all this: a messy advisory cause most don't like ice.. and at night---it's impact is a little larger. I see model qpfs are increasing again. I definitely see whatever sleet-snow ice occurs, having a good chance for sunrise visuals Saturday, before melting increases. Someone noted big ice doesn't occur til we get down into the 20s. I don't have stats on that, but freezing is freezing and the northeast facing slopes will do well... even at 30F. Might even have enugh ice to break some small limbs (1/4")...Cats, Litchfield and Berks high terrain. 33 here at 746PM... wish there was better cold pool to our northeast.

Agreed 100% ... marginal but need to see FGEN mid level convergence near I84. Too early yet, i think. Gotta go. Thanks for the inputs.

agreed on all. Lets watch that HRDPS for ice and see how it goes.