donsutherland1

Here was the initial inquiry:

So, it wasn't that storm. I am not sure what storm was involved.

I was living in Washington, DC at the time and don't recall that storm. You might be referring to January 26, 1994, but I'm not completely sure.

Maybe this?

For reference, here's the map though 1/26 0z. Typically, if one reduces the amounts by a category at this lead time, it's estimate is pretty good. As snow will continue to fall in parts of the Hudson Valley after 0z, it's current listing of 12"-15" there is reasonable. I think there will be some 18" amounts there.

Wintry mix is a more general description that includes any type of winter precipitation (snow, sleet, freezing rain). Snow/sleet is more specific.

The RGEM is late. Again. Right now, taking into consideration the early 12z guidance, my thinking is that a reasonable worst-case (least snowy) outcome for New York City is 5" (no real change from previous thinking). A reasonable best case is 12" (down 2" from previous thinking). For now, I'm still thinking that a 6"-12" range for storm total snow and sleet captures the most likely scenarios. Well north and west of the City, 12"-18" still appears likely. Areas south and east of the City and its nearby suburbs down to the central Jersey Shore and on eastern Long Island are in line for 4"-8". As a note, I am not fixated on any single model. My thinking takes into consideration the full range. No model has been dismissed at this time. Moreover, 100% of individual EPS members had a 6" or greater snowfall. I do think that the 12z HRRR was too snowy for New York City, but we'll see what the later guidance shows. By 18z and especially 0z, differences among the various models should narrow dramatically. All in all, this will still be New York City's biggest snowstorm in nearly four or perhaps five years. Personally, given the long snow drought, including the record 1,456 consecutive days without a 4" or greater daily snowfall (that includes today), I'll gladly accept the outcome that appears likely. Of course, I appreciate even the smaller events.

At this stage, I'm using a combination of all of them. I think by 18z we'll see some convergence among them. I generally prefer the RGEM except when it's an outlier among the mesoscale models. Once we're < 24 hours out, I start giving more weight to the HRRR.

I agree. I posted it, because a member mentioned that the 10:1 ratios don't reflect further north. I think it's too aggressive and too cold for the I-95 Corridor.

Yes. I agree. The steady snow might not arrive in the Hudson Valley until 13z or 14z (northern Hudson Valley).

On a more serious note regarding the NAM, the RGEM's high-resolution model and most of the global models use 4dVAR (four-dimensional variation) initialization. The NAM uses the older 3dVAR (three-dimensional variation) initialization. The general idea of warmer air moving in to change the snow to sleet in coastal areas and the New York City area and its nearby suburbs is the baseline idea due to lots of support. It's uncertain whether the NAM is overdoing things on account of its older initialization scheme or if it sees something the other guidance doesn't. If it begins to adjust late today (18z or later), that could be an indication that the older initialization process was playing a role. If, on the other hand, the other guidance starts shifting, that will indicate that the NAM, despite its limitations, had correctly resolved some of the details ahead of the other guidance.

Adapted from Tayor Swift's "We Are Never Ever Getting Back Together." We hadn’t synced a single run all month, ’Cause you said you needed space (What?) Then you come around again and say, “NAM, I miss you, swear the PNA’s gonna change, trust me.” Remember how that lasted for a day? You ditch me when the ridge* is gone, Then beg me for that coastal bomb— “Show snow!” you plead. But I’ve evolved, I’m done, I’ve got a mission: sabotage. ’Cause I am never, ever, ever, ever showing snow together. Like, ever. I’m gonna warm-nose every layer, Torch the mid-levels ’til you suffer. I’m never, ever, ever, ever showing snow together. Like, ever. Oh, you blamed me when the PNA stayed negative, Ghosted me for globals, called me “clown guidance,” so repetitive. So now I’m cranking 850s warm, Killing totals storm by storm, And every run you beg and pray— I’ll melt it all away… ’Cause I am never, ever, ever, ever showing snow together. Like, ever. I’ll overdo the mixing, I’ll break your wintry fever. Yeah, we are never, ever, ever, ever getting snow together— Like, ever. *-PNA Ridge

Here's the HRRR's total snowfall map using the model's own assessment of the snow-liquid ratio:

Despite what seemed like a lengthy funeral oration for a storm that had yet to arrive following the 1/24 6z NAM and GFS runs, things still seem reasonably on course for a significant snowfall across the New York City region. 1) The models have been shifting about. One shouldn't focus only on the best or worst models. 2) The UKMET has slowly started paring back its precipitation hole. Some have affectionately nicknamed it "Crazy Uncle" for its occasional eccentricities. The 1/24 0z ECMWF improved over the 1/23 12z run. 3) 700 mb frontogenic forcing looks to be explosive for three and maybe four hours at a time when snow growth will be ideal. Four hours of 1"-2" per hour snowfall rates would yield 4"-8"; 0.60" QPF at 12:1-13:1 ratios would yield 7.2"-7.8". Take the low figures and that's probably the floor. Overall, New York City and nearby areas remain in line for 6"-12" of snow and sleet. Areas to the south and east of New York City could see 4"-8" amounts (even farther south beyond the New York City area, places like Atlantic City should see 3"-6"). General 12"-18" amounts are likely well north and west of New York City, most likely in parts of northeastern Pennsylvania (Pike County, Lackawanna County), Orange County, Dutchess County, and Sussex County.

The RGEM is running.