wdrag

Am on the cusp of a minor snow topic for 1-3" of snow NYC combined events Sunday and Tuesday. Will review at 3P. If RGEM/GGEM NOT on board then probably, no topic.

Agree w you Don et al!! This is your $8/pp tax payer dollar whatever, WELL spent. You're getting bang for the buck from a broadly talented -dedicated - high effort group, throughout the agency.

Understanding NWS processes: While there are attempts to update all the local storm reports and public information statements with 'final' values, there are time constraints on what might in my words only not the NWS, meaningful work. If it's only an additional inch or so and will not make much difference to the analysis (accurate #s needed for NWS verification of their Watch, Warning, Advisory program), then I can see it is not done. Remember, there are hundreds of reports that need to be constantly filtered. (CoCoRAHS is considered official- my own report may not be included because I'm not CoCoRAHS). The climate program is always point specific accurate.- NWS controls. All the other reports are updated as time allows. We need to remember: Pandemic reduced in office staffing, that the forecast process is complex adjustments of digital elements that automatically make the words and interoffice and national guidance collaborated. That there are focal point duties -everyone has an area of responsibility- to maintain currency in the program and outreach to the partners-training the partners and vice versa- mine was the rip current and marine program for MT Holly 2010-18. This takes time to be fluent and then there is TRAINING of staff in your area of expertise. This akin to Research to Operations (RTO) training for frequent improvements in NWS processes and understandings (simulator requirement training). There is also training directed down from a national level, including do's and don'ts with regarding to security. So, it's not all about the numbers. NWS folks are paid well for their time and do the best they can to accomplish everything with multi customer satisfaction. Walt (my own interpretation of what we tried to accomplish during my days as a NWS meteorologist)

06z Euro continues dusting Sunday, almost to NYC.

The period of light snow that affects the nw-ne suburbs during the daylight hours Sunday might Trace in NYC.

Topic: not quite as robust this morning but no changes. The good news: If this less robust solution prevails, power will continue. There are diverse model solutions and so am riding this out as proposed yesterday. The 00z-06z/19 cycle might indicate a slightly slower onset-end? The EC moved its 70 MPH gusts to CC, but still has 75-85 KT 850 jet for e LI Friday morning, increasing to 90-100 kt for Cape Cod. So the 70 MPH could eventually come back west, if modeling eventually reverts to yesterdays 12z/18 solution. The 06z/19 GFS op is right there with the EC for LI at 850 MB. So I won't dismiss the topic as invalid, at least not till there is consistent modeling that says... only an ordinary storm. MMEFS suggests one or 2 rivers in NJ may flood but for now, nothing widespread major, based on snowmelt and ensembled qpf. Tail end snow on Christmas: still possible. Wish all a good day. Walt

Good Saturday morning NYC nw-ne suburbs... a chilly one over the suburbs snow cover. Generally near zero to above at 6am. Minor stuff next couple of days, mainly for the I84 high terrain... Tomorrow-Sunday the 20th: a dusting to 1 inch parts of the I84 high terrain, mainly during the daylight hours. Tuesday the 22nd: since the storm on Monday the 21st is still not quite close enough... a dusting to 1 inch possible I84 corridor Tuesday morning-midday.

CoCoRAHS 2 day totals. Most, if not all of these, are just one ob/day.

This will get buried and forgotten, but the HRRR seems to have a pretty good algorithm going for snow ratio incorporation. Here's a graphic to help describe.

My final, I think, on this event. CoCoRAHS two day totals.

20th and 21st continue with light snow threats.

Topic Edit 508AM: Added HIGH IMPACT and the time back in to the topic and extended 4 hours. Strongest winds in NJ/ne PA/se NYS roughly 10PM-4A, NYC/se NYS 1A-6A, LI/CT 2A-to possibly as late as 9A/25 e tip of LI. Minimum wind gust on LI 55 MPH with max 75MPH, NYC-se NYS minimum wind 50 MPH isolated max 70 MPH. Please follow NWS on all warnings/statements. I'll leave it yourselves to add graphics etc as need be. I'll begin an OBS-NOWCAST thread by 6A. Have not looked at soundings but everything else discussed in yesterdays 518AM topic edit below including HSLC SVR's continues. We may reach within 2F of the record 66F-2015 max temp for Christmas Day at CP. Flooding of some of the larger rivers, if it is to occur, may be delayed 24 hours or more after after the rain quits Christmas morning, Max rainfall axis in our forum looks to me to be CT, isolated 4", not including snowmelt runoff. If anything is missed, please let me know. Thank you. Topic Edit 518AM Wednesday 12/23: No significant changes. The prime threat period might by 2 hours too fast but not enough evidence to change the primary initialization period of weather related issues. My assessment tells me to prepare, without science, for many many thousands without power starting 9PM to midnight Christmas Eve evening, and then across se NYS, LI, CT, MA beginning midnight to 6AM Christmas morning. Gusts NYC airports should be 45-55kt, with potential for isolated 65KT LI/CT/MA. I expect SVR's for the HSLC lines of heavy showers to help focus the primary short-fuse threats. Lower chance of any damage northeast PA but ridges there will be most vulnerable there to ~ 55 MPH gusts. There is limited science on power outage wind damage with leaved trees, without, softer unfrozen ground versus frozen but I don't have this information nor any private services predictive algorithms. I still think that wind damage will prevail as the most important aspect of this storm, but please follow NWS flood watches, warnings as issued, due to the combined snowmelt and new widespread NYC subforum rainfall of 1-2", with isolated 4" potential inland-most of this in a 9 hour period during Thursday night, Any snow on the backside is exceedingly minor on the I84 high terrain. There actually might be a little better chance for a slight coating of snow Christmas night with the weakening trough aloft passage. --- Topic edit at 526AM Tuesday the 22nd: Changed the title to WILL be accompanied by damaging wind LI, and restricted the period of accumulative snow to the interior. I think the wind damage potential is the largest threat from this rapidly deepening 980s surface low moving northward up the front into NYS predawn Christmas. SVR's possible (in my mind likely, even if no lightning) for High Shear Low Cape (HSLC) heavy showers.The Richardson (R)#/wind profile combo on the NAM and even GFS tells me 45kt+ gusts all the major airports in NYC sometime between 10P/24 and 5A/25 . This is further supported by multiple models 80KT+ 850MB winds over LI, in some cases around 90-95kt. From my looking at R# and wind grab, this has the most favorable potential in my past 3 months of examining to realize downward transfer 50-65KT from the lowest 25 to 50 MB of the boundary layer. Whether an isothermal sounding in the lowest part of the boundary layer, or even a slightly inverted sounding can diminish-mute the potential, I don't know. What I do think, is that a lot of folks could wake up with lights out Christmas morning across LI, and possibly NJ/CT. Flooding potential to me looks the same as it did yesterday-previous days, all a matter of qpf, snowmelt combo to prompt a few rivers into minor or eventually moderate flood stage, even as temps plummet from 60ish near midnight Christmas morning, to near freezing by ~ Noon Friday. Please follow NWS closely on flood potential-they have more tools than I. Snowfall, accumulation less than 1 inch probably restricted in our forum counties only I84 high terrain northwestward. I'll copy this to the last page of this topic and add a couple of wind profiles there. The future posts will look at FOUS BL winds, which I think will exceed 34kt at LGA and BOS around 06z and 12z/25 respectively. IF not, then I'm a little too severe on my wind expectations. Also, I'll be adding shorter term wind gust potential graphics, especially Wednesday onward. (corrected many typos 826A) --- Below from the origination date of Friday evening the 18th. This topic is started primarily because of the recent operational model cycles at one time or another offering a more than ordinary 12-18 hour period of weather here near Christmas, on top of melting snow. Always uncertainty. Uncertainties abound, including how far inland can a couple of hours of 60 degree temperatures penetrate to melt the snowpack, and will there be any hazardous snow accumulation closer than the hilly western and northern suburbs? Add to that, is there an inversion thats prevent excessive low level winds from reaching the ground.? Snowpack will be melting a bit the next few days,, til a sudden brief surge of 60 degree warmth Thursday evening or very early Friday morning, associated with a strong cold front. That front is embedded within a high amplitude trough. It's slowed by a strong 1030-35MB high anchored near the Maritimes, and there is potential for northward moving low pressure along the front, as it traverses across the NYC forum. Max rainfall should be concentrated just inland (se or sse surface wind) and combined with remaining snow, may? be enough to promote some small stream flooding? Flooding will be dependent on how much snow melts on the 24th/early 25th combining with around 1" to possibly 2" of rain, prior to the sharp cool down to near freezing by midday the 25th. Current 12/18 river response models to multiple ensembles are not alarmed at this point so I don't want to make this look worse than it will be. Of greater concern is the ECMWF cyclic offering of 60+ MPH gusts to LI (50 inland) which may cause some damage. Recent experience with the storm of the 16th-17th suggests to me, that we will need at least 60 MPH gusts to see significant damage along the coasts and ridges. It's possible - IF the 850MB southerly jet can exceed 75 knots, preferably 85 knots. The 18z/18 GFS has 80 knots for e LI and the 12z/18 EC has near 100 knots for all of LI. IF the ECMWF were to verify, it would be lights out for many and not a pleasant Christmas morning. Timing of the event probably sometime at night (6P/24-6A/25 EST) Snow: Backside snow doesn't often accumulate significantly with temperatures falling rapidly from the 60s to near freezing. Thinking best chance I84 corridor high terrain sometime Friday morning the 25th. Graphics: 1) 12z/18 EC 850 wind. EC surface gusts, GEFS chance of 60 MPH wind gusts early Christmas and finally, the WPC qpf forecast from ~18z/18. 608P/18

Excellent posts this page - haven't had a chance to check anything else. I will begin a topic for 12/24-25 at about 715PM which will go without much ensemble support - always a concern, but the EC, GFS and WPC offers a good start 6-7 days in the future. It will include damaging wind, potential for ''minor or at worst moderate stream flooding" and maybe an inch or 3 of snow on the back side, Christmas morning.

Overall impact maximized nw of our forum where you're seeing top 20 event historically. Thanks for all the insight on NYC records. We will do better along the coast, maybe this winter??? I dunno. Might depend if the Nina continues weakening. That I don't know either. I just hope that everyone appreciates how locked in some of these events in Nov - Dec have been 7-11 days in advance. That is all the worlds modelers improving physics via research-more observation platforms contributing (satellite, radar, aircraft etc) and computers. The oldsters among us know. This graphic from the WPC web site.

Near closure on this event. Added NOHRSC snowfall analysis (multi platform). I think this analysis missed the 10" near Union or is it that spec of yellow?

Posts on p38 (This one) are helpful for me and it is an interesting time. Not to go against anyone, but I'm thinking we are tending to expand the database with more extreme weather the past couple of decades here in our forum. I might be wrong on this and will listen to counter science. This could be related to the warming (cycle) planet. Have appended several graphics to ensure everyone has seen this and has an idea in advance what is ahead (flooding? but if we're lucky, some spring snowmelt for the reservoirs in April). Also, there is anecdotal evidence (unsure of the science research on this) that the southern edge of the snowpack tends to set up the warm fronts and future low pressure development (easier in warmer air with northward advance of warm fronts often slowed by the colder denser surface air associated with snow cover). Didn't add snow density because I don't understand the numbers and how they relate to impacts but I think it may have to do with difficulty passing through (walk, transportation)and/or removal. If there is a link--- please add on. Thank you.

Good Friday morning everyone, I hope this is a snow satiated group this morning. I think more snow is coming for NYC this December. I posted event options for the I84 area in our nw - ne suburbs thread. I am thinking of a storm thread for Christmas eve-Christmas morning- but think it best to wait until all the 12z/18 guidance (ensembles too) is in. Even the 21st looks interesting to me for NYC/CT. The thread for the 24th-25th would be along the model lines you see now. Big snowmelt (virtually all melted se of I84) by rain and a brief southerly flow warmup. Damaging wind potential e Li (already ~40% prob of 50 MPH gusts from the 00z/18 GEFS), then cap it off with a 1-4" backside CAA snow the morning of the 25th. These backside snows are not easy to attain and uncommon (long shot in the coastal plain). Temperatures will dictate remaining snowmelt on the 24th, but if it's rapid and we get 1" of rainfall on top of the 1" snowmelt water equivalent in 12 hours, we might have minor flood problem?? Again, a long shot per current guidance with so many variables to consider. The main thing, we continue in a highly amplified pattern with 'overall' near normal temps the rest of the month. Have a good day.

Just a tease: May have a topic started late today or tomorrow morning (Christmas eve). Sunday: A pretty good chance for a period of Trace-3" snow I84 high terrain. Monday the 21st: Right now models have a storm just offshore. This could end up closer, bringing a hazardous snow event of several inches for the I84 corridor, especially CT/MA. Christmas eve into Christmas morning: Definitely a storm coming. It could be mostly heavy rain melting our I84 snow pack Christmas eve with a quick coating of 1-4" in its wake Christmas morning. Monday the 28th: another opportunity for wintry precipitation. One event at a time. Have a good Friday.

You may be right... I don't know. What I do know is that anything beyond two weeks with reliability is not easy and I myself, while I look to our long rangers for hope (or lack of), I don't think we yet have a good handle on the multiple influences that carve out a season. So, I'll continue to pay attention but I'm not confident of anything beyond 11 days.

You're right but ... an extreme event of 40, I know I'm not there predicting that with any confidence-reliability. The idea of 20-25 should cue up attention.

Hi! I've been offline for 4 hours. You may already have this imagery... CoCoRAHS snowfall for the event up through their ob time this morning. Tomorrow I may post a two day summary total for those locations that will report both days. No thunder: so despite no thunder...drama occurred NYC forum and NYS forums. Power outages: not much and in NYS concentrated where I didn't expect...well upstate near and w of BGM. Thanks much for all your reports, model posts-impressions, climate comments. I'll be curious as to the NESIS evaluation for this storm (not top 20 in our area but ne USA, maybe?)

Wantage NJ at this location about 11.9 for a final.

Wantage NJ Moderate snow at 759A. 1/2S

fwiw: I had remarked on banding qpf per multiple models n central PA to near ALB and mentioned 20-25" bullseyes in two states. The EC KUCHERA had 33" idea. I've added the northwest transition of the big band originally slated for I84 back to a IPT BGM ALB axis beginning the 00z/15 cycle. About 48 hours LT on a consideration that became much more emphatic with future model cycles. Here's 3 different model samples at various Lead times) (no UK added since the UK is referenced above), and finally the EC consideration on the 12th... too far south but it was this consistently modeled snow amount forecast that helped prompt my confidence for a top 20 event.

Small sample CoCoRAHS reports as of 730A. am probably offline til 945A.