wdrag

Am on the cusp of a Topic for a potentially large event Feb 12-13, snow ice and maybe even rain. Would like to see a little GEPS or EPS consensus. I'll add a few graphics from ensembles and hold off til either late today or tomorrow if the model vision continues. In essence a little WAA snow or ice on the 9th (no thread unless the snow-ice sags south to I80-LI), then turning a bit colder in advance of what appears to me to be a developing trough in the eastern USA around the 13th. There could be a lead short wave on the 12th that splits the energy. It might be better that way because if all the energy goes into one primary, that primary might go west of us. For now am going to count on overall blocking being an assist to the colder side. Really would like to see a bigger southward dive to the trough but what you see attached should be a good start. Have added the 00z/5 RMOP which is arguing for a trof - positive tilt for now Great Lakes southward and the comparison look from 00z/4 which had a flat w-e flow with a modest vortex over se Canada. Thats the change in 24 hours. Then the 06z/5 GEFS mean trough with the blocking in eastern Canada, followed by the 06z/5 GEFS Plumes for qpf at LGA. I didn't post snow plumes because their are precip type issues so resultant snow etc is up in the air, and finally the chance of 1"+"of qpf in 48 hours...already about 60% just on the southern edge of the forum. No guarantees that much qpf but I do think an event is coming, at least with a period of wintry precip types for part of the event.

Wantage NJ 0.3" in 40 minutes. treated roads wet. continues to snow. back down to 31.5 after briefly up to 33.

Wantage NJ, first batch prior to sunrise passed overhead with nary a flake, but SB 720A and about 0.2" in 20 minutes with temp having risen from the 20s early today to 33.1F now with main roads wet.

Friday the 5th - 649AM: Little change. Snow is coming and will continue increasing area seasonal snow totals higher (pushing normal or above by the start of the Super Bowl). I haven't checked seasonal normals except what I know for NYC (already above) and our area of nw NJ (at or above). Thinking the 06z/5 NAM may be a bit robust and since the GGEM/RGEM are keeping the bigger snowfall se NJ southward, therefore am reluctant thinking of warning amounts in our subforum, more generally a 1-5", 6-12 hour snowfall North to South. A pleasant refresher on an almost national holiday. Graphics are 1) NWS statistical ensemble chance of 2+" by the time the Super Bowl is complete (does not include this morning). 2) NWS snow forecast issued at 4am/5.

Good morning, the lead band already into western New England has been mostly aloft although it should be reaching the ground there very soon. Meanwhile, the main band in eastern PA at 630AM is producing snow. I see mPing even has flurries happening in the Hudson Valley. This probably won't be a big deal for most of us except for 2 hours in nw NJ/se NYS/ne PA where a quick 1/2-2" should occur with the heavest in the high terrain. The region NJ immediately west and southwest of NYC (I-I195 northward) sees a period of snow/sleet or even possibly freezing rain this morning where it all ends by 10 or 11am.

Hi! No topic quite yet for 9/10??, or more likely 12-14, but need another day or two to see if modeling is erratic. I like the potential. We're certainly on the northern side of an active blocked southern stream. It's how far north that they can poke northward?

I'll update in the morning if any change from this morning and the initial thread. I think the range in our forum is generally 1-9" with 9" unlikely (NAM already has 8" as did the EC wayyy back) but we want to resolve the model differences. For the heavier 4+ amounts I want to the see GGEM/RGEM continue to edge north in their future cycles and remaining models hold firm. Overall, I see a potential advisory event for a portion of the forum but cant rule out 6+ LI/NJ. Will take a longer look at this tomorrow. The only other note I have, if this does come to pass, as it appears, this will be the second successive event that the EC had a good idea about 5-7days out or beyond, and then all models lost it at about 96-114 hours and recovered northward (not as far north as D6-7) beginning at about 84 hours. Others might see it different? It remains to be seen if this forecast on forecast is going to verify. This history of models losing an event well modeled in the courser modeling 6-7 days in advance and then losing it closer in, hen reacquiring in the shorter term dates back decades. This is written (96-120 hr loss, then reacquisition ~84 hours) needs to be debunked, or, it's something that I will be looking forward to, the rest of this winter, for possible subsequent events. Later, Walt

A challenging period of travel is possible Friday morning across northwest NJ, northeast PA and se NYS; possibly into the CT portion of our forum as multiple bands of precip sweep eastward across the region. Amounts will be light but where possibly freezing rain or sleet, untreated surfaces could be quite slippery. Additionally there will be a tendency for any rain/freezing rain to briefly change to steady snow even to just west and north of NYC with little or no accumulation there, while high terrain in nw NJ/ne PA/se NYS and w CT are modeled to pick up 1/2-2" before melting begins ~ 11 AM or Noon. mPing. This thread will help concentrate interest Friday mornings system while the other threads occupy the Sunday event and beyond.

Ok... I have a SREF source and its waist a hit, but I do see the hit by the NAM. Haven't seen anything else for the 12z cycle and am off line til 530P. I think this is a very good sign and am counting on an event for Sunday. Hopefully RGEM supports as well as future 12z/4 GFSv16/GGEM.

I saw SREF, but was a little surprised at it giving freezing rain interior. Your source?

GEFS 06z plumes for LGA for your review... Try not to buy into the high end, as NEG NAO and others have stated, getting a big one after a top 10r, within a week, is highly unusual. This may all be in response to Stratwarm of Jan? I don't know but I do think high end qpf anomalies, per research, are a little more common-possible in the warmer thermal columns. Our coastal SST's are still above normal with a steadily weakening Nina. For now, let's see the future modeling straighten this out the next day or so and think much lower than the extreme seen here. That prevents disappointment, but eyes wide open and expect anything from nil, to melting on LI and possibly heaviest inland. The plumes are unquestionably more numerous than the 00z/4 version. Whether this was correct? I'm continuing to lean an event, particularly because of other ensemble trends and the V16. Always prepared for downside (nil) in the next few cycles but could be interesting.

Focus below is the I-84 corridor inclusive of just w and n of NYC by just a few miles. May post an OBS thread for this at 530PM if it looks close enough to NYC to measure. For now probably not. Friday 4AM-2PM: Two bands of snow cross the area with 1/2-2" accumulations Poconos - nw NJ (high terrain there) and Trace to around 1 inch CT/MA. Slight chance of freezing rain mix but mostly snow. It will be slippery on untreated surfaces in ne PA/nw NJ Friday morning, and may be slippery in norther CT and MA, especially high terrain.

One additional note: I think the NAM which has hints on its 06z run will be helpful in trends, whether this was an aberrant 06z GFS northward cycle. The 06z GGEM says no way and we need that on board for an event.

Thursday Feb 4: 614AM topic update. Have dropped the wind event (45MPH+) and wind chill (-15 Poconos) and narrowed the date range. As many are witnessing, the modeling has been uncertain but always the ensembles have suggested a little bit of snow Sunday. Individual model operational cycles have tended to be nil (exception EC and V16 robust early on) until the 06z/4 GFS V15 and 16. The 06z GEFS has developed an 850MB LO just south of LI and increased qpf dramatically. (graphic added). Noting also other 00z/4 ensemble MINOR increases in QPF and NAEFS indications of rapidly developing low pressure as it passes southeast of our subforum Sunday night. Until the ensembles nix the event, am continuing the snow threat. The 00z/4 MEX MOS was only 14% chance of qpf Sunday, so it's difficult to be sure about an event Sunday. Ensembles suggestion and recent GFS northward trend (uncertain) in my mind require consideration of a general 1-4" snow event Sunday (may be melting on pavement on LI with marginal near freezing temps during any snow). I've kept the 9" max in there, just in case the coastal comes closer but 9" is highly unlikely. We do know it's going to be a vigorous event but its northwest proximity to our area is in doubt. Gusty north-northwest winds may follow Sunday night and it could be quite a bit colder Monday morning (near 14 NYC?) than statistical guidance suggests. No thread on the 9th-10th, if ever) until Super Bowl Sunday is better resolved. Added 06z GEFS 24 hr qpf, as well as a number of plumes for LGA , qpf, snow, 2m temps and 850 temp)

Forgetting about records--- and barring seeing a specific message on the discounting of 35... which I have no stake in, but I do have a stake in useful snow measuring. For sure, imperfect. There are different standards. once/day SD as per CoCoRAHS does not work for me as most useful, where some NWS offices use the clear the board every 6 hours technique which I think has useful application commercially. Attached p 63 of the CoCoRAHS snow guide. I had 27" of snow FALL, (right in the middle of the pack), but the SD I measured amid morning Tuesday in this part of Wantage NJ was 18". This 9" less than fell report is I think easily possible, due to crystal packing in gusty winds, as well as increasingly wet snow during the the 45+ hour storm evolution would result in packing. There may be some science regarding snow packing down with time? Just wanted to make sure the differences were noted between snowfall measuring processes and the large difference in SD vs what fell in 6 holy increments. Which is best? I argue differently for possible commercial snow clearing application and rate alerts etc. Nothing will get solved with this today.

On WPC snow amount probs for Long Island, which i like to use as a self check for expectations. This should provide greater understanding of some of the problems and is offered as helpful information for those who may use this guidance. --- I agree with you that this guidance looks pretty bad. I looked back at some individual members of the ensemble, and it wasn't a QPF problem, but a precip type issue. I think that a large part of this has to do with the resolution of the ensembles. The GEFS is only 1/4 degree and the ECMWF ensemble is 1/2 degree. These two sources are pretty predominant through the entire forecast period, and I'd assume they can't handle what are probably relatively sharp temperature gradients and/or are including nearby warmer SSTs in the grid boxes due to the geography of the area. The higher resolution Day 1 guidance did not suffer from this error, but don't make up a large percentage of the ensemble, so they tend to get lost in the calculations. Unfortunately, a short fuse fix is not really possible. To solve this problem, we'd need to use mainly high resolution guidance (at least for Day 1) and cut out the lower-resolution ensembles. This is a big change, and to get approval would be difficult. In addition, we'd have to do a fair amount of testing to see if the results would be acceptable. We have this problem with lake effect, too. We are starting to explore running smaller domains with different ensemble membership to improve the lake effect. We could try something similar for nor'easters.

Good evening will rewrite the thread headlines tomorrow morning, probably dropping the wind, wind chill and sub14 potential and maybe even snow. If we get down to 60hours and the ensembles are zero, near zero then this thread won't work. For now, while op models are not interested in any qpf here, 1/3 of the 12z GEFS ensembles have qpf snow. Much lower chance than a couple of days ago. The big change seems to be associated with the 5th short wave being stronger and further east, while the second has receded into the Great Lakes only on the 7th, with rising heights immediately following on the 8th.

AND...if no one believes now...please the 00z/3 GGEM move up 1 day. It's meager for now, compared to prior EC ops but a confused atmosphere, which means I dunno but think the opportunity is there...especially when you look at GEFS 06Z 2m temp anoms that show a window of opportunity here around late 7. Off line til probably 230. It is so beautiful here too... wow!

Wantage NJ (this part) 8a report 0.2" since midnight. snowing lightly at 8a. I don't consider as direct to the storm of 2/1-2 (indirect yes, direct not me).

There is plenty to digest and try to sort out for all of us. I am going to post something later today on a communique I've received regarding an inquiry with WPC about their probs for snow and ice on LI. (my over reliance for 2/1 and subsequent under prediction on my part-it's illuminating and now allows me to take the guidance for Li with more grains off salt). Sometimes I think throwing everything into a pot and blending is best, though some modeling is clearly better than others, especially when it comes to snow-ice vs rain.

They might allude too these in their heavy snow discussions... I just don't read those - no time. Yes, it would be cool to see those stats. If they have them, they might be fluid (sorry, didn't mean it that way, maybe should have said, snoid). In other words as sample sizes grow the stats change.

Sorry... you're way ahead of me on programming and I cannot help. You might want to write NWS EMC-NCEP. Someone there might be able to assist.

Good morning everyone, As noted above the EC has temporarily (hmmmm-do we remember about 4-5 days before this top 10r just past?) dropped the ball. GFS now closer. V16 not posting due to data flow problems with an unknown (to us, or at least me) return. As noted above the UK unreliable but on. What I think, and I'll attach as a placeholder for WPC, is that we're still on... with atmospherics needing to sort out the myriad of disturbances and bring us a little more consensus (or is the consensus too many short waves and a relatively flat but cold westerly flow?). One thing that's changed since the thread inception. Great Lakes 500MB troughing has put much more stock in the first disturbance carving into the northeast Friday, and holding back on the 7th-8th. That would probably negate sub 14F cold into NYC by the 9th, but not necessarily beyond as modeling persists with anomalous cold from the Great Lakes to the Northern Plains beyond Valentines Day. One of these disturbances coming through between now and the 19th 'should' become a substantial northeast wintry weather event and draw in a pretty decent cold shot. So, since the ensmbles and modeling are flipping and uncertain, I keep the thread alive as is, with doubts about wind and temps meeting thread options by the 9th but not a shut down yet, in my mind. Snow is definitely on the table (aside from current on going at this 6AM writing, and the 5th 1" potential for the I84 corridor for which I may eventually start an OBS thread I84?). I do think we'll see some sort of snow here in NYC 7th or 8th- but will be corrected by reality. Not every thread works out... this one may be that. Too much uncertainty as of now.

Am not adjusting anything in this thread headline til at least 630A Wednesday. EC seems a little robust, but we're getting down to D5-6 so it's got life. GFSv16 is right there with the EC. Keep at it... will review again Wednesday morning.

I didn't google but am sure it's related to water content and light passing through.