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Added 10z/14 ensemble chance of 1" and 4+" of snow: both by 7AM Monday. More careful details and graphics post this evening. The NWS GIS snowfall was only thru 7PM Sunday as of this writing so useless to post.

Basic thread headline looks acceptable to me still well in advance of the Sunday night-Monday morning storm. I'll rereview everything this event and possibly improve the headline but I just don't want to lock out possibilities yet. I know it says Noon Sunday start. I'm protecting at a slightly faster forward motion. And it looks like very little snow LI/coasts (less than 2", if that but it still could be messy for an hour or two, especially if cold air damming even holds sway along the coast for a little while. Have a good day: will revisit this evening.

on SREF reliability, I don't think it would to exist in NCEP USA model suite, if it wasn't a helpful tool. It can be stellar, and sometimes miss completely but wherever the core axis... it's pretty darn good.

SREF too early. 09z run is conservative on snowfall w NC and I like that. As multi above - wait to refine and cant rule out an ene turn once the storm gets near BWI. Out to sea, think the chance of that is less than 5%. Better chance of a miss all wet than out to sea no qpf.

My own view having reviewed most of the modeling through 06z/13. The Sunday-Monday morning storm, still has track uncertainty. The USA model is more snowy-icy than the European. Solutions below lean a little to the warmer less snowy scenario but not with high confidence of being correct. If you need to travel Sunday-Monday morning, please follow later forecasts from your reliable sources. Baltimore-Philly-NYC: seems like a short period of snow near or just after sundown Sunday changing to sleet-freezing rain for a little while, then to heavy rain overnight Sunday with gusty east winds, possibly to 45 MPH near or after midnight. Untreated surfaces possibly slippery for a few hours. I84 corridor from the Poconos-northwest NJ through interior northeast MA. Snow Sunday night, should be heavy for a time changing to sleet and freezing rain by dawn Monday and either ends as rain or snow midday Monday. I see significant travel problems, especially Poconos extreme northwest NJ (Sussex County) into the hills west of Hartford. Snow amounts uncertain due to how fast the snow changes to ice. Also, wind gusts in the ridges may reach 45 mph near sunrise Monday and if trees iced, that's a power problem=uncertainty on ice amounts. Graphics: The ensemble chance of 3" of snow or a significant combo of snow-sleet Sunday 7am through only 7am Monday. An incomplete first glance at potential impact from this storm, only through 7AM Monday. The orange area is a start. The new 06z EC OP (rather gross 10 to 1 snow-sleet conversion) for snowfall ending 7PM Sunday - slightly faster and a bit further east than the previous 00z/13 op for comparison. Sleet is high bias problem with these 10 to 1 ratio's, and I think too for the positive snow depth change products.

My only comment on all that is posted. Think ensembles mxd precip & sleet is counted as snow 10 to 1 ratio. Therefore be cautious where mixed precip can occur and think se EDGE might be way too high??? Gradients are always a problem. All modeling has se 850 inflow till late Monday morning= Cold Air Damming for the interior. In the meantime, I will probably wait til 6 hours before the period of snow (and possibly rain) that I think is going to occur LI/CT/MA, especially east sections of all, with small accumulation possible Friday. Not enough members covered for a thread except possibly OBS-NOWCAST. Will reevaluate all by 720AM Thursday.

Sort of agree but, I don't think we have another way, unless we look at clustering. ?? I thought this appended site would cease, but alas we still have it. GEFS... plume clustering if you will. I've taken a look back and the GEFS has been having LGA at 3-4" the last 4 cycles. Does not imply it's correct. Like all here, I could see it much less, but I think we need to think about a turn-redevelopment to the ENE off NJ. Just my thinking based on 06z ensembles. I could be wrong but I just dont see this storm up to ALB... the upper air I do not think supports that track. Again I could be wrong so I dont want to provide useless hope, but this is why I'm waiting another 24 hours before any further commitment one way or the other. Probably my last post til this evening or tomorrow morning. By the way, I see the NAM is coming west with qpf on FRI morning. Watching that carefully for E LI to BOS.

06z GEFS of interest on 2" snowfall: it cuts w of BWI-PHL, then turns ene across LI. What I'm seeing via the 06 GEFS is a tendency to close off the 500 short shortwave as it crosses LI Monday. I think interest in snowfall NYC north and west should be continued til future modeling closes the door. 5 days to go.

Good morning again, No thread e LI/e CT/E MA this morning for Fri morning of 1/14. Models basically dry. Still not convinced there won't be a band of snow in the FGEN zone, as added below. Also, I keep looking at the GEFS and impressive attempt at cold shot after the 22nd and continues cold looking through at least the 28th.

Looking periodically very cold here 21st-28th, my guess is colder than what occurred yesterday the 11th or this Saturday the 15th. Could be two more significant storms here, around the 21st and 25th and our coldest of the winter may arrive after one of those. Yesterdays CPC threats in the LR are added.

5AM Wednesday Jan 12: title and tags adjusted to drop Saturday, focus late Sunday-Monday morning for what appears to be an 18 hour storm of snow-rain-snow. Heaviest snow tends to be modeled west of the I-95 corridor but ensembles still warrant continued concern for the axis of heavy snow including I95. At this point far too uncertain but where it snows for 12 hours, widespread 6+" seems likely. Also a 6 hour period of potential 50 kt inflow gusts is possible for the coasts Sunday morning and if it occurs with the dawn Monday high tide, would result in coastal flooding, magnitude unknown. This does not appear to be a long duration storm (24 hours+) but it should be intense for a few hours Sunday night or Monday morning. Again track uncertain, and sensitive to the intensity of the surface low. There still is opportunity that this will track too close to our area for much snow but there are several days to adjust the track and resultant precipitation type. It does appear there will be a general inch to 1.5 inches of qpf with this system, maybe thunder too. A big storm with large scale impacts entire east coast-Appalachians. The only reason I didn't highly stronger wording for impact, is that this will occur later Sunday and the following Martin Luther King Jr Holiday. Added the overnight WPC ensemble thinking of 3+" of snow, which does not include the new 00z/12 GEFS/EPS/GEPS. So this favors Appalachian Rim, NYS to just west of of I95. Unknown but potential for a good sized fast moving storm is at hand, maybe KU?

Unsure if anyone posted but CPC has some interesting possibilities for 19th-22nd including a chance of heavy snow basically Chicago to New Haven northward and a high prob of very cold air invading the upper Midwest.

HI! Glad there is still a ballgame for the weekend. Will post an updated thread title at 8am Wednesday when I know I have the time. Will do a a semi thorough review at 1030pm but not attempt a successful adjustment til 8am Wed. Suspect will also start the Friday morning thread at 8am Wed. Everything needs to be on the table in advance in the forum we learn from each other. Fwiw, the 17z WPC D4-6 do not have the 12z ensembles incorporated. Tonight’s 5z issuance should be, Ithink a little further west and confident of a substantial event near ATL to interior N.C. VA. more as time allows overnight or Wed AM. On call. Walt

Having passed 24 hours of modeling, the diverse modeling/ensemble opinions remain undecided. On the table, too many shortwaves, or not enough separation. Am leaving the thread as is... my thinking is to grow this into something substantial but I may be wish casting. So keeping conservative. 14th morning: I think e LI, e CT and e MA will see a period of snow (1/2-3") Friday morning followed by scattered midday north wind gusts near 45 MPH. What I think we'll see is the 12z NAM be much deeper at 78-84 hours which a much tighter gradient and shoots a period of snow up the FGEN zone on the northwest side of the bombing ocean storm. I will wait til sometime this evening to start that thread if the modeling looks more acceptable for this NAEFS scenario. The weekend-Monday affair looks like a moderate or greater snow event from near ATL to interior NC and VA. This is only my opinion. LOW PROB follows: What I'm thinking is that the two shortwaves crossing the central-eastern USA this weekend early next week merge-phase. The lead short wave sets the stage ATL-NC to NJ Sunday with the following short capturing the stewing low off NC. NAEFS is marginal risk here in NYC. To have TWO bombing lows off our coast within 3 days is unusual and not the likely scenario, except that modeling a couple days ago was going for it and we seem to be in extremes cold season starting with the TORS in KY, w USA snows in Dec, I95 snows so far in JAN. Attached 06z EPS for Sunday morning...a westward shift. Offline til sometime this evening.

That is important, chicken or the egg. LONGGGG ways to go to forecast accurately the potential for extremes just 4 weeks ahead. Just my 2c.

Agree...

I'm looking at NAEFS 8-14 day and both 00z/11 ensemble patterns. I think east of the Rockies it's going to get very cold for a few days. Am thinking between the 18th-25th, somewhere in there it will be even colder than this week. I think the extreme of Dec has flipped coasts and I can't see this flipping back prior to February. Will need to lose the AK ridge and then I think it takes at least 5 days to lose the cold. I need to see the NAEFS D8-14 (week two) start warming before I give up on the cold.

Will comment at 745AM... need time for other home stuff. I may be starting a thread for LI/CT at that time for the 14th including wind gusts past 40 knots, then we move onto the 16th-17th. One at a time. Nothing locked.

Also, not sure who on here in December or copied from elsewhere, predicted all of NAM turning cold in January but it seems we're on our way to a rather cold January, my guess colder than this morning. Too much modeling keeping the 500MB trough in the east and the ridge in the west. This is a good opportunity for us.

Here is the 18z NAM FOUS for LGA-NYC: Note the large change in stability between 12-18 hours (+9C), the noticeable BL wind shift between 12 and 18 hours, the R1 over 50% at 12 hours, and the excessively steep 12z hr T1-T5 17C lapse rate. The overnight snow showers and squalls occurrence was predictable yesterday. Basically a strong cold front with a very cold core aloft, and Great Lakes boundary layer moisture being lifted by the cold front then swept south of us. 0.1": Wantage NJ but I've heard of more elsewhere. This was a lot more than a flurry situation.

In the meantime, do not be surprised to see a a band of snow showers, a few with SW+ thru the 184-I80 corridors into NYC-LI between 10P-3A. Think it's forming on BGM radar at 01z, with excessively steep low lvl moist lapse rates, a slight wind shift to NNW behind the band with much more stable air arriving at sunrise (and with the more notably falling temps-unsure if anyone noticed the 6C drop in BL temp between 06z and 12z on the NAM FOUS). Hopefully I was up to a dusting. Some places might get 1/2-1" fluff? Will rereview Thu night-Fri, Sunday centered snow opportunities tomorrow morning.

Late 13 -14 still a concern: GEFS in particular likes this bombing storm for a LI/SNE grazer. Did not start a thread for this due to most modeling and WPC missing east but this probable big ocean storm is a concern by not allowing enough separation between systems for the necessary ridging in the northeast ahead of the next Great Lakes diving short wave - ie depressed weaker further south on the 16th. The good news for an event are ensembles (GEFS, and especially the EPS) are in favor of a weekend centered snow event and the new overnight WPC D6-7 graphics are added - use time period and the low probs legend to continue D6-7 perspective on 3" chance. The EPS in particular is developing a nice 850 Low just to our south, Will check back on the modeling this Monday evening.

454AM Wednesday Jan 12: title and tags adjusted to drop Saturday, focus late Sunday-Monday morning for what appears to be an 18 hour storm of snow-rain-snow. Heaviest snow tends to be modeled west of the I-95 corridor but ensembles still warrant continued concern for the axis of heavy snow including I95. At this point far too uncertain but where it snows for 12 hours, widespread 6+" seems likely. Also a 6 hour period of potential 50 kt inflow gusts is possible for the coasts Sunday morning and if it occurs with the dawn Monday high tide, would result in coastal flooding, magnitude unknown. This does not appear to be a long duration storm (24 hours+) but it should be intense for a few hours Sunday night or Monday morning. Again track uncertain, and sensitive to the intensity of the surface low. There still is opportunity that this will track too close to our area for much snow but there are several days to adjust the track and resultant precipitation type. It does appear there will be a general inch to 1.5 inches of qpf with this system, maybe thunder too. A big storm with large scale impacts entire east coast-Appalachians. The only reason I didn't highly stronger wording for impact, is that this will occur later Sunday and the following Martin Luther King Jr. Holiday. --- At this 6-7 day lead time 8PM Sunday Jan 9 issuance, options are fairly wide open. For now, a light or moderate event 'seems' likely but absolutely not a lock, nor is a heavy event excluded. This event still could be demolished to zero by what happens off New England on the 14th, or what follows between the 19th-22nd. However there already has been discussion the past several days for the coming weekend. Ending 12z/9 the past 6 cycles of the ECMWF op, the last 4 cycles of the CMC GGEM [LI 3 cycles, I84-4 cycles] have some sort of snow event, especially I84. Maybe the GFS via it's 18z/9 cycle is shifting snow emphasis on the 16th for our area instead of bombing off the coast on the 14th? Having reviewed ensembles: 12z/9 EPS/GEFS/NAEFS all have some sort of frozen event is coming to the northeast USA, along and north of I80 including LI. Have added the broad coverage low chance WPC D7 issued at 17z/9, the EPS 24 hour qpf ending 12z/17 and the 12z/EC 850 MB low (GEFS so far has nothing, still favoring the 14th but not as far south and west as previous). NAEFS products for 00z/17 are added including previous 24 hr qpf, 00z sfc temp in C, and the sfc pattern. There will be quite a few model changes-conflicts and this could end up having been a wasted effort... but it seems worthy of further scrutiny as our next possible significant snow or ice event for at least a portion of the NYC subforum.

Wantage-Branchville NJ (the Distillery). Icing has started again since 6PM.... minor icing at worst. 31.8F. Road were being salted up here near the Appalachian Trail.

31.1F in this part of Wantage NJ and struggling up now but most solar exposed surfaces melting at Noon.