wdrag

Will get new topics up for both Monday and Wednesday-Thursday (14, 15-16) around 230PM. This per taken the cue from one of participants- a good idea. That may be a good time to shift discussions. I'll add some base graphics that will serve as a spring board for the future.

Have seen 12z GEFS... same as 06z..half a foot+ southern CT to nw NJ... also develops the 850 low a little sooner and a tad further south restricting the nrn extent of qpf to just n of I90. Long ways to go... wont have it studied up til 330P and then will definitely separate this thread to the weak low risk northern fringe snow on Monday and good sized snow event for a portion of our forum. Later... Walt

And so, for those who want an event Monday... I'm betting the 12z GGEM will be on aboard... 12z RGEM has qpf. Unfortunately that model shows generally rain.

Understood... I see your point. Plan to get this done around 5P. Thanks.

Also for those who like to hunt these comparisons down... the last time we've seen a modeled surface pattern similar to Wednesday's projected (early this mornings WPC guidance)???... I think its' been at least back to March 2018, if not before?

One model I've not heard much about... the IBM model that is supposed to be much better than the available models that we all look at. This model made some news a year or two ago about picking up on some storms sooner. Has it been implemented? Any public guidance available?

Tentatively, based on 12z/11 and 00z/12 model cycles,, I'll update-rewrite the topic for the 14th and 16th-17th events (saving the original at the end) and drop the 18th. This could be a nice pair of events around parts of our area. No changes for me though, prior to 5P or possibly not til 6A Saturday.

RMOP added for the GEFS. Lots of confidence on trough ne USA... and confluence to me appears across NNE. fwiw..the 06z GEFS and 00z EPS are about the same on snowfall..nice ~6" SNE nw NJ and ne PA. Plenty of time to move south, or north.

If it does, we're going to have to see the 850 LOW's on both GEFS/EPS trend south. Could happen. If the ensembles on this feature don't trend south in the future, then the winter action will be more n of I80 than s. I just don't know.

The 14th is a likely event I think, because there is not going to be much rain this weekend (less than a tenth or two) and we'll need a flushing of the mild air For Wednesday event). Therefore an event Monday takes advantage of some WAA leftover low lvl moisture (dew point 30+) from this weekend and wrings it out as short wave passes by, which should result in decent BL CAA Tuesday. (corrected PWAT reference at 822A to dewpoint).

Sferics: I remember interviewing with a Cincinnati private met around summer 1980 talking about the lightning triangulation., Yes..I remember both NYC names. Yes.... on 30 Rock--the gold walls... and back around 1962-63, US Weather Bureau Chief Gerald Shak (recently passed) allowed an in-person interview for my ~ 7th grade Elementary School science class in his office. Was pretty cool- it might have been there that I received copies of Weatherwise that highlighted the great Dec 1960, and Jan 1961 snowstorms (Kennedy Inaugural etc).

00z/11 cycle impressions: Will post the main show first: Wednesday-early Thursday 16-17. Caution: some models have had a southward trend. Something to think about. Continues to look good for a potential snow event. Water equiv as per WPC... am thinking 0.5 to 1" is a good start. Water temps in the 40s nearby LI will probably require an 850MB temp of -3 to -5C for snow not to change to rain in the +0C Boundary Layer for L:I (NYC too). That's a caution for LI, especially south shore and eastern tip as well as NJ coast. 00Z/11 ECMWF operational model pressure down to 984 MB is not likely. Look for a more reasonable 995-1000MB low s of LI with a 1030-35MB high over Quebec. Very nice set up...potentially a 40 MB difference (possible 40kt easterly flow near Montauk?). The 00z/11 ECMWF operational snowfall/depth has to be biased high because of the extreme with respect to multiple models and it's own EPS (which is closer to half foot or a bit more, along and n of I80). 00z/11 52 member NAEFS looks very good but with variability on qpf. The 00z/11 GEFS 850 low is weaker and develops later but develops. So it's game on (GGEM is back on board, more or less). The question is where will the max axis be? The track of the 850MB Low is close to LI... which to me favors I84 or northward for max snow axis. I think we need to be careful along the southern edge and there are still options for a further south track but for now...the WPC D6 probability of 3" or more of snow (1/4" or greater frozen water equivalent) looks good (30-49%). You would think this is too low, but what that tells me, is that there is a lot of variability on placement of colocated cold enough temps for snow and the 1/4" qpf. It also was generated without the benefit of the 00z model cycle. Tides: could be minor flood event either Wednesday or Thursday morning as the tides are astronomically very high. Duration of northeast flow, and pressure will determine. Fortunately...it looks like the worst of the inflow is at the lower high tide Wednesday evening with a wind turn to northerly probable Thursday morning. Meanwhile Monday the 14th: Don't toss this away. EC is coming north and so while the GEFS is locked south of us, the EC and 06z NAM suggests to me that there could be some snow in our forum Monday- minor and melting on roads except small chance of an SPS hazard income of the hills (Poconos -nw NJ?) Friday the 18th: this possible event will not arrive the 18th - instead warm air advection---probably delayed til the weekend sometime. Two graphics added: WPC D6--please see legend for your area of interest and the 00z/11 GEFS prob for 1" of snow Wednesday-early Thu. 551A

Let's enjoy the slippery slope greased with a little snow one of these days.

I used to listen to Don Kent-BZ, WCAU had a good met team in Phlegms, There was Denardo-McFarland in PIT, and WTIC Barbara Allen Buzz Bernard etc... they all helped get me psyched on events. WNYC used to have a 145PM radar report, right off the Weather Bureau Radar at Rockefeller Center. Anyway, better not digress any more. Gotta rest.

That's correct... Let's presume it will be back by Saturday... if it's not, then I'll be concerned. All these op runs are single members... even the EC op could lose it tomorrow but it might show the single member OP that represents only 10% of the ensemble. So--- my fingers are crossed. I like the setup... for a moderate event of 1/2-1" qpf... modeling can change my thinking but for now a conservative progressive approach. Any snow we can get now is nice to have. Most everyone on here is probably under age 60... I presume. Modelers-researchers-computerization and platforms for data have provided us with modeling that can be pretty accurate to D5 and alert us to a potential event D6-10 with some reliability. Back in 1960-65 I was reading the Farmers Almanac, and local long rangers (Gordon Barnes) for my hope... not a Weather "Bureau" D5-7 forecast (as the NWS referenced back then). Let's see what happens and keep the options open that there could be some sort of failure here.

Also, I've been away from guidance most of the afternoon and won't spend much time on it this evening, so I'm less appreciative-aware of the evolution. Stay on top of it. I'll probably be able to immerse myself in this early Friday.

I'm waiting this out ... no topic change til I'm sure Monday is a NO and Wednesday its big and south. I try to frame these topics so they're reasonable ballpark and will be helpful. If it looks like south will prevail, and/or many other guidance portend a big one, I'll reword the topic and try to be more accurate. This was written Tuesday evening. There is still time for many model adjustments and not necessarily favorable for us snow weenies. I just can't talk about this coming event as a done deal. Still somewhat a thread the needle-lucky timing- and will it develop. Tomorrow morning I'll use the 00z/11 guidance to reconsider everything. For now, best to be patient- wrap the holiday gifts, so you have more time closer to the event(s) to have fun with models and maybe shovel and appreciate those dendrites.

Sure... I've not seen significant QPF events of more than ~1 tenth inch not have the GGEM op on board. It doesn't necessarily have to be snow but we need it to give us decent qpf. I am aware as one of our posters indicated, that GGEM and RGEM were furnace and wayyyy too low on the snow idea (dynamic cooling) of this past Saturday the 5th. I also think the RGEM and GGEM, if I recollect correctly were more conservative regarding the western (extent) boundary of that event. Lots of folks deride the GGEM and statistically (500MB stuff) it doesn't compare with the EC/UK/GFS in that order... BUT it's a good basic starting point for me... and fwiw... I've lost confidence during 2020 in the UK operational being of much consistently reliable value. To test this GGEM hypothesis... please send me examples as we move forward in these synoptic storms where the GGEM was never on board and we got our selves a decent qpf event. That's the best way too refute my contention and reduce my use of the GGEM as a guide. I've never taken the time to document with stat analysis, just like my experience with the BL wind on the FOUS needing to exceed 26 KT to consider and verify a wind advisory. So... we're well in advance of the likely Wednesday-early Thursday storm event... If the GGEM doesn't climb on board by Sunday, I'm going to be losing hope and will be reluctant to commit to a big event. Regarding the topic: I have no plans to change the topic... I still think Monday the 14th is decent chance for 0.10 qpf or greater at LGA, along with some snow on the northern fringe in our area and I kind of think it will be needed to help draw colder BL air southward in it's wake and set up for Wednesday. That was a good question: Hope this helps a little and it's worthy to check GGEM for our area.

A little late and after the fact, but here is the CoCoRAHS snowfall report for Thursday December 9, 2020, NYC forum.

Hi! A few different things... just to try to keep perspective. I need op GGEM on board... i see some of it's ensembles are there but I need GGEM op on board. I don't think it will be much of a snow storm for us, if it isn't. 12z NAEFS has slightly warmer thickness than it's 00z/10 version...5540 cutting thru LI now 00z/17. That increases risk of mix or rain LI, for at least a time. Caution on buying in on the ratios til till we know for sure the sounding is all snow, and that the 1000-500 thickness is preferably ~5400m Thereafter it's the DGZ and Banding. WAYYYY too far off for me to count on anything except decent snow I84 north (heart of the ensemble axis). For now we in the NYS forum seem to be close to the gradient of snow and no snow. Gradient error's can be very large. I've added the WPC D7 GEFS forecast for 3" or greater of snow Or 1/4" water equivalent glaze or combo thereof. The prob is 30-49% in dark green. Will revisit tomorrow morning...

I wasn't there, but did CP not have any cover on grassy surfaces yesterday? They had .05" of melted snowfall... and moderate snow at times. I would ave thought a slimy wet snow covering of 0.1?

Good Thursday morning all, My morning update on this thread. I probably won't comment again til Friday. My primary dates of interest for wintry precip elements in the NYC forum are Monday the 14th, Wednesday the 16th and Friday the 18th. All dates have possibilities and I suspect will have qpf. The jet stream will be just to our south throughout. In addition there will be 3 southern stream short waves to monitor which should have qpf impact here and a NEAR 50/50 500 MB low will be developing mid and late week (actually closer to 55N, 50W). Thinking the primary date of concern for snow here is Wednesday the 16th, but let me begin with this coming Monday the 14th. When you look at the models, It doesn't look much qpf with the front on the 13th, at the expense of a trailing short wave in the lower Mississippi Valley, that currently is modeled mostly to our south. However, if it trends a little north, wintry precip could easily occur on it's northern fringe-just north of NYC. This would be a minor event, at worst, if my impression of what will happen is correct. This Monday event is my lowest confidence, but the GEFS is flagging decent qpf just to our south. NAEFS image attached. The 16th event to me is clearly cold enough for snow and ice, even down to NYC. BUT, given that it's at D7 and that modeling could be too cold (sfc pressure too low on the presented ensemble for 00z/17), I have to leave open the door for all rain NYC-LI and s of I80 in NJ. I've added a number of NAEFS graphics including small qpf, cold enough 1000-500 thickness, Surface pressure. Later the 18th is flagged as well. I think that one in part depends on what happens the 16th- If the 16th ends up as strong as the 00z/10 ECMWF op run, then the 18th probably is delayed or suppressed- however if we end up with a 1000MB surface low just to the south of LI next Wednesday evening, then the next southern steamer has a chance. Regarding the 00z/10 ECMWF op... I'm recommending tempering the amounts seen (especially the whopping Kuchera). Just too early and how often do those huge values verify at D7? I have added the 10 to 1 ratio EPS which looks like a reasonable start to me, realizing the southern edge amounts could fall as rain and make snowfall nil. I do not expect the EPS amounts to disappear I84 northward but what I expect and reality could be wrong.. Still, I have above average confidence that a wintry event of some sort is coming to the northeast USA the middle of next week, whether NYC/LI are involved is the most uncertain and could end up just wet and windy. Let's monitor. 542A/10

Timing timing timing... I'm no long ranger - no skill. I do look at basic (non MJO) patterns and it seems like we're running a bit different than Dec 2019.

I don't think you need as much cold air with respect to normal anymore. I am definitely interested in the 14th (weak wave of precip) and something more substantive 16-17 (wintry mix)... and with blocking in Greenland modeled by both the GEFS-EPS for the foreseeable 16 days... rainstorms are not a constant lock.Even seasonable temps give us a bit of a chance.

I see OKX afternoon prelim CLI for CP as T snowfall today.