wdrag

Just trying too work with everyone... for good conversation but also a little learning about ensemble value (or lack of), as a self check. Thanks for your reply. There may be others...I'll check back. Later, Walt 1138z/18

Hello to all and the Moderators especially, I need a little guidance. Have checked forum coverage areas. Don't see a map (or I missed a link). In any case, can someone define the western and northern fringe counties of our coverage area. Can I presume north of I78 out to the Delaware River... do we extend into Pike, Monroe and Northampton Counties in PA? Also the north fringe...is that bounded by I84 or is that too far north? I presume no CT coverage but all of LI is covered. A little more clarity will help guide me on any topics. I also noticed some participants might not want to know of any NYC snow amount topics under 1". Is there any guideline for topic starter? Have started topics, when confident that there will be a wintry type hazard, even if I80 south including LI is out of it. Maybe thats too liberal and I should limit to when I think even NYC might get 1+"? Thank you kindly for American Weather Forum consensus advice. Walt Drag 351PM/17

Good Friday morning everyone, Jan 17. I wish my confidence was greater for Saturday. Concerned about qpf modeling... and as often mentioned by group members, southwest flow event, (especially 850MB)...just hard to get my hopes up. I expect 2 inch minimum just north and west of NYC. The city I think should still be snowing at 7PM but surface temps govern accums. FGEN embedded in the ridge well ahead of the short wave should develop a band or 2 of moderate snow for an hour or 2 Saturday afternoon-early evening. Modeling later today and tomorrow may help... anyway, with less than 3" so far in Central Park... if an inch falls....that would be noteworthy. I've added some ensemble graphics. The first two are courtesy NWS ensembling system for snowfall. The last is the ECMWF EPS chance for 3+ inches courtesy of Weather.US posted 718AM, data gathered around 5AM.

Good Thursday morning everyone (Jan 16). Here's a few graphics I used for a briefing this morning. NYC doesn't look good for an inch but for Morris and western Passaic Counties westward and northward including Orange County...even though it's not big, its a travel problem for ~ 5 hours during Saturday afternoon-evening due to temps hovering in the upper teens to mid 20's during the snowfall out there. NWS ensemble graphics are appended for 1"+ and 4"+. The EPS is courtesy of Weather.US and the ECMWF, and also is appended for the chance of 3+ inches. This differs from the NWS and I suspect is less detailed on terrain and its impact on qpf. I noticed the UK and EPS/GEFS all favor heaviest qpf in two stripes...one is I78 area southward and then well to our north. Surface temps and timing of snowfall will determine Central Park accumulation (if any). I wont be reposting til Friday morning...allowing models to fluctuate. 638A/16

Good Wednesday morning everyone, Yes... its a relatively snowless winter so far for NYC and maybe this is the way it goes the rest of the way but I think we need to work the science of ensembles for predictability and self checks against our own personal snow forecast processes. I've added again here, and I hope to add to the original post... the NWS ensemble chance of 3+" of snow and the EPS chance of 3+ inches of snow. The EPS is still pretty close to what its been for several days, but the NWS ensemble has decreased considerably s of I84. It doesn't look too good for NYC though I think a decent short burst of snow-sleet should occur during the early afternoon start---surface temperatures being a little on the warm side for much of a street problem. Looks a little dicier nw corner NJ into parts of se NYS with the bulk of this event there snow to ice before dribbling out to drizzle - showers later at night. I'm just not seeing much of a south wind in the interior, presuming it does snow-sleet 1+ inches. Snow growth at this distant forecast time for Saturday actually models okay for an hour to two Saturday afternoon. 733A/15

Good Tuesday morning the 14th. I added here and in the originating post the NWS ensemble forecast for 3+" of snow sleet (higher than yesterday and similar to the EPS). The EPS has also been added courtesy Weather.US and the ECMWF TOS. You can see a break down of confidence n of I84 in the EPS, til you get to the Adirondacks. In any case, the modeled chill via the 00z/14 GFS MOS and the ECMWF 2m temps appears to me to make it lock for hazardous travel on on all untreated surfaces Saturday afternoon when you get northwest of NYC tho it could be snow quickly to sleet-freezing rain with snow accumulation limited by duration of snow prior to the phase change. This system to me just doesn't have much chance for NYC being a big snow event, due to the track of the shortwave. Should it dig more, then there'd be a little more hope but I'd like to see southeast flow at 850 MB instead of strong southwest. Just not a good winter for us... but I'll take what little I can get. I only post ensemble guidance once/day since there are so many nuanced changes and I'd rather try to capture the essence of trends over several model cycles while still 3+ days from the event. 652A/14

Good Monday morning everyone, Have offered to focus the general discussion thread on next weekends storm into one single thread. It's been a terrible winter so far s of I80 and not much to boast about north of I80. I'm adding graphics daily at about this time, until the threat fails to materialize. No guarantees on anything. It does not look good for NYC south, so far. Contributions are from the NWS public domain and the Weather.US and the ECMWF. We'll see how this verifies for long range value. The first two graphics are the NWS ensemble chance of greater than .25" water equivalent of frozen precipitation. These are run off of late day ensembles and post, "prior" to the 00z cycle ensembles. The two graphics courtesy of the ECMWF are the chances of 3+" of snow for this event which are increasing a bit in the I84 area and are from the 00z ensembles. No LOCK on any of this coming to pass though I'm pretty confident the interior west and north of NYC will have some sort of winter hazards this weekend. Depends I think, in part on how strong the northern stream short wave is that crosses the Great Lakes. The stronger it is, then I think the storm tracks further north. At 633AM the 14th, I added the 00z/14 NWS ensemble and EPS chance of 3+ inches of snow so that it's easy to go back and compare to reality. The risk has increased a bit for the NWS ensemble system to something similar to the EPS. Certainly no lock for 3+ inches s of I-84. At 457PM/19 added the NOHRSC snowfall analysis. Gives a feel for value in the ensembles. Later, Walt