wdrag

554A: Topic headlines were adjusted from the original of ate last week to the snowier wintry solution. A burst of moderate to briefly heavy snow Thursday, begins lightly between midnight and 6AM Thursday much of the area, though it may delay a bit to the daylight hours north of I84. QPF etc has decreased since originally threaded. Modeling allows sleet/freezing rain to get involved near the Thursday evening rush hour and eventually back to manageable, possibly intermittent snow on Friday. Some modeling has a decent burst of snow Friday. ~Half a foot or more seems likely for much of the area with sleet/freezing rain (even maybe eventually even a bit of rain e LI) limiting the risk of 6" south of I78 and possibly LI as well. Graphics added are WPC 09z ensemble chance of 8"+, chance of .01 freezing rain for the periods indicated (note it's got higher probs southwest Harrisburg, but that would include earlier than the 48 hours shown) and the NWS regional snow forecast through 7PM Friday. OBS NOWCAST thread will post this evening.

Let's review the Feb 7 initial post. The title changed enroute (i think I had 14-18 for the event window 7+days in advance). Perspective on what our modeling was indicating follows. Initial post from 2/7 midday. Have included rain in the tags, because we're close to having rain ,at times, within the overall cold enough pattern for snow and Ice, mainly along and northwest of I95. QPF this 5 day period should be in the range of a general 0.5" minimum, to possibly a maximum ~1.5". How much falls as snow, ice, rain is unknown and debatable. Multiple ensembles offer plenty of snow in and to the west and north of our subforum. Favorable blocking for northeast snowfall appears to remain through this period, and well beyond. Am witnessing via modeling and reality, a balancing of the cold core from southwest Canada to the northern Plains and Great Lakes shooting off pieces into the northeast USA, then on into the north Atlantic. These reestablish-reinforce the blocking -NAO from northern Canada to Greenland, and, following each pulse of CAA that moves through our subforum, there is WAA ahead of the next short wave. So far, the cold core has not broken off in total, to change the pattern and so, the snow opportunities continue on and on. February is already off to a special start and we may be heading for a top 10 snowiest February (see attached February Central Park ranking and year). Will narrow the goal posts on these possibilities for this 5 day period as we draw closer. My most confident period of something significant-substantial is the 16th-17th, but I have to consider some of the modeling that likes Valentines Day for an event and also the 16th-17th, delayed a day til the 18th. What happened? A little bit of junk ice/flurries here and there the 14th (better ice the day before on the 13th along and se of I95, (that was our RIC ice storm). The primary event was the night of the 15th, morning of the 16th. It was generally ~0.4-1.25" of rain as far as I can tell, with rain and non hazardous spotty icing I95 corridor southeastward and ice northwest of that, with a busted heavy ice forecast for the northwest part of the forum. That bust I think in part was related to twice the reality qpf forecast (please see attached), not the temperatures. So in the middle of where the ICE was supposed to be thickest, the rainfall was significantly less. This happens. QPF modeling imperfect and I doubt if I can improve on banded qpf deviating from the models. Power outages and downed trees/wires occurred in parts of the Poconos northward, just outside the members in the northwest part of our area (see Monroe County reports). Experimental guidance such as the HPC HREF and HRRX can be too heavy on icing and were again or are displaced. The GFSV16 did a nice job on the FRAM ice expectation as did NAM temps and eventually RGEM temps. QPF's, not so good. And an event is coming the 18th. IF anyone has a better archive of RADAR qpf from DIX or OKX, please attach. Thanks much.

Hi. I'm not a long ranger. I don't study seasonal base states, MJO phases, and not sure how accurate the Ensemble Oscillations are beyond 11 days. With the Nina base state the southeastern ridge may want to get dominant, but somehow, I don't think we're done. (too early for mud season). If this was March 21, then probably done for LI, but things happen... including 'thread the needles'. Multiple modeling is trying... trying to go -NAO beyond 10 days but will it be effective cooling for us and can the EPO go back negative? Taking one event at a time. 18-19, and 21-24 to me continue on the books. Do you like the GEFS... then it's north, but even that has lowering heights and spread in solutions. Do you like the EPS,? Then you add a period of snow to the forum, albeit wet and probably changing to rain I80 south.

Yes I agree... shows just how close we came to having a bigger - more extensive problem. I see some decent power outages ne PA, se NYS, just on outside the edge of subforum. I think also, in the tend, the RGEM was best at indicating icing holding to 12z Pocs/se NYS High Point NJ. Took awhile for the RGEM to come to that conclusion.

Regarding the national unprecedented in recent history event. From the NWS, a quick check of the top 10 national coverage's since 2005 per Greg Carbin WPC. --- As many have noted on Twitter and elsewhere over the past 24 hours, the CONUS area covered by Winter Storm Warnings is quite remarkable! That was about 1.6 million square kilometers with active warnings or, put another way, the area currently covered by Winter Storm Warnings over the CONUS is larger than the land area of Alaska. That is crazy and puts the events of these days into some amazing perspective. I wrote a script this afternoon to download all the warning shapefiles from the Iowa Mesonet and take a look at the area covered by Winter Storm Warnings (technically Winter Storm Watches that are upgraded to Warnings) from November 2005 through February 14, 2021. For the 2,158 days with Winter Storm Warnings in effect back to November 2005, the average area covered on any day with active Winter Storm Warnings is about 77,000 km^2, or about the size of South Carolina. The median warning area size is about double that, 142,000 km^2, or about the size of Illinois (using land area sizes from here). The standard deviation of the daily warning size distribution is 170,000 km^2. Thus, the current area covered by Winter Storm Warnings is about 8 sigma above the long-term mean area of Winter Storm Warnings covered on any day with active winter warnings over the past 17 years. Here are the top 10 WS Warning Days since Nov. 2005, based on warning areal coverage: Date WSW Area (km^2) 1) Feb. 14, 2021: 1,558,699 2) Feb. 01, 2011: 1,182,685 3) Dec. 29, 2012: 1,099,780 4) Nov. 26, 2019: 1,091,375 5) Dec. 01, 2007: 1,057,336 6) Mar. 02, 2014: 991,728 7) Feb. 20, 2011: 974,886 8) Dec. 30, 2010: 954,343 9) Dec. 24, 2009: 901,811 10)Dec, 01, 2018: 889,846 -- Greg Carbin | Chief, Forecast Operations Branch NOAA / National Weather Service National Centers for Environmental Prediction Weather Prediction Center

The value of giving yourself wiggle room on perfect prognosis. Added the actual 1157Z obs that got into the verification for 12z/16. Note a touch colder in some of sheltered interior very difficult to handle the gradient. Then the EC op from 00z/16 and GFS/NAM ops from 06z/16 (their 00z versions were similar). A degree or two can make a large difference and EC was just too warm at 12z in the strong temp gradient except southern Manhattan heliport (elevated) and JFK eastward.

An image of the Paper Birch in front of our Wantage NJ home at 715A, and the white pine in our backyard at 645AM.Eestimated .15" Radial Ice. Last 32F wa about 440AM. Melting now but plenty to go. Have no idea why these don't post without a download? F7883524-CAEA-47E0-B429-70EA6280F338.heicF7883524-CAEA-47E0-B429-70EA6280F338.heic

This could be a dud thread, but modeling still has a little snow for the I78 north portion of the forum, but low passage NORTH of our area which doesn't bode well. Still something to monitor but not pin a lot of hope upon.

Wantage NJ 524aAM. Rain-melting at 33.6F.

517A: A nice solution coming (overall colder and snowier than what modeling was generally offering Friday the 12th) with a range of accumulations of 1" to possibly as much as a foot in the upper high end scenario. Thursday's evenings commute should be snowy for much of the area and see delays, as it readies for a possible change to ice Near I78-LI (rain far south part of the subforum) and then ends Friday, most of it done by sunrise Friday (but with early morning delays/cancels). Too early for me to be sure for the NYC/LI/NNJ membership but plenty of modeling close to half a foot. A watch/warnable snow-ice event seems to be coming for a portion of NYC subforum,. IFFFFF NYC were to report half a foot, that would place NYC in the top 5 snowiest February's. This coming snow-sleet, whatever, should rejuvenate snow depth , and maybe allow half a foot or more for much of the area into Monday Feb 22. One WPC graphic added: the 24 hour prob of 2" of snow by 7P Thursday.

I remember: WX works now? 431A: Still zr- 31.5. Just 54 meters out in our rural coop at 430A, power outages larger Warren County. everything solid ice here. Has to be delays in the County, especially north. Post event summary: SPC HREF exhibits the continuing cold bias and too robust FRAM output until within 12 hours of the event.There fore too far southeast. and too heavy not rewarding good verification but ice did occur e PA much of nw NJ and all I84 corridor. Still a few reports to come, I'm sure. I think the GFSv16 did a good job flagging 0.1-0.4" FRAM accretion where it occurred-forecast. 444A: 32.0F melting should begin shortly. Ice via ASOS radial at 4A looks like an estimated BDL .04, IJD 0.2, POU .07, FWN 0.11 which matches my estimate at 740'MSL, MPO near 1/4". High terrain accrete seems best.

Wantage NJ 4 św 336AM. ZR- brief ZR. 30.6F all glazed, est thickness at least 0.1" Isolated power outages Sussex County NJ

Thanks... power back at 901P. out 3 hrs 25 min. Down to 27.5F

17900 meters out in Sussex county NJ. Cause unknown.

Power out Wantage cause unknown. Doubt if ice

NWS products around 3P. Power outages increasing WVA. 18z RGEm looks a touch colder tonight while the NAM slightly milder. Split the difference. Will all depend on qpf prior to above freezing. lost all our pavement ice while i was away at 29F. We'll see what happens after sunset. ZL- and 29F.

There is probably a ~30 mile shift to west of the problematic power outage 1/4" iso1/2" glaze axis from the early morn ing cycle. 12z HPC HREF here. and the 12z HRRX. Both seem high on amounts due to runoff at marginal temps late tonight but its pretty certain there will be branch/powerline power line problems with treated surfaces possibly mainly wet ne PA/far nw NJ, interior se NYS nw CT, especially east-northeast slopes of the higher terrain. Your judgement. For those east of I287 in NJ, probably little or no problem but I cant rule out problems in ne NJ to the Merritt Parkway.

Remote check: I think moving the axis of greasiest ice impact west 30 miles will work very well. Haven’t checked any details but I95 east agoils be easily manageable but I think differently vicinity ABE-POU-BDL. Along or couple miles northwest of that axis is where ice accum branches and wires will be a problem tonight. Treated roads wet.

Wantage NJ light freezing rain showers and a few ice pellets. 26/21. treated roads wet. all other surfaces icy. some softening due to solar radiation.

For check back Thursday: The Winter Storm Impact graphic which looks a little on the light side for northern PA/ I84 corridor. Not sure why... but either this experimental product doesn't apply power outages, or some of the modeling is too warm? I don't know. Also added for the record the powertoutages, nationally, so that we may check back tomorrow. The only way to learn- in advance. I went back and grabbed the D2 ice WSSI graphic for VA - seemed to underestimate impacts, despite model guidance.

Just one thought' I'm seeing a more eastward trend to the end of the week, possibly because of a little shortwave in advance of the primary trough on Thursday. 00z/19 Friday projection from the 06z/15 MREF shows this. This gives us the first snow WAA shot, but also cools the column a bit as it shoves eastward Thu night while the primary lags slightly. Definitely of interest for those who prefer slightly cooler-southward scenarios. I'm not so confident of as big an ice situation here THU night as tonight. I could be wrong on this.

610A updated thread....my last topic update and all my other posts will be in the observed below. Adding several graphics to the topic part of the thread from the 4AM NWS forecast process inclusive of the ICE STORM WARNING coverage area (purple), the HPC HREF ensemble 1/2" of glaze expectation by 7A Tuesday (blue), WPC ensemble probs of .10 glaze (orange) by 7A Tuesday and the much lower prob of 1/2" glaze. I would expect power outages in the NWS warning area and SPC HREF Blue coverage area. IF these amounts work out- I think it will be big. Modeling doesn't necessarily guarantee freezing longer than 4AM Tuesday, so if it's not, then the rain is non freezing its heaviest 3 hour period. Still the ground is cold so I'd plan on a bad night, and in fact a bad day today in the I84 corridor on all untreated surfaces. Regarding info near NYC... just be careful. Untreated's slippery near NYC-LI today-this evening, should ease sometime tonight. Looking at 06z/15 NAM FOUS...if that surface wind stays ne in NYC through tonight as the sfc low transits coastal NJ, the guidance will be too warm at the surface. This needs careful monitoring. My guess, via the 06z/15 guidance, there may be an underplaying of extensive ice damage, especially just west of the 4AM warning. Just a degree or two makes a huge difference. I'm not expert enough to know for sure. So for me here in Wantage NJ, if its still 31-32F at 4A Tuesday, we've got pretty big problems in far nw NJ/se NYS/nePA. We will see how the probs work. Prep worst and hope for the best.

550A. Wantage NJ. Intermittent freezing rain showers since ~430A. Deck icy. 26/20.

Good morning American Weather membership interested in ice. I am no longer posting on this thread, only the OBS thread which is now active with icing. Will not be posting much if at all 930A-4P as in travel.

Freezing rain shower here in Wantage NJ at 440A. 26F.