40/70 Benchmark

That 5-10" range was a last second edit after the 00z EURO...I had that part of the 4-8" area.

Final Call for Moderate to High Impact Sunday Snowfall Upwards of One Foot Possible Well North & West of Boston Synoptic Overview: The latest in a long line of El Niño fueled, moisture laden southern stream systems will eject northeast out of the southwestern US this weekend. However, unlike the previous systems, cold air is being introduced into the equation on the heels of Thursday's seaward system and in advance of this weekend's storm. At the same time, heights over the southeastern US will be rising in response to the deepening system over the southwestern US. This will work in conjunction with the pressing of Canadian high pressure behind the departing 50/50 low to compress the flow ahead of the first disturbance that approaches the region late Saturday night and early Sunday. While the confluence to the north will compress and attenuate the lead wave, it now appears as though a follow up wave will reinvogirate the system during the day on Sunday to some degree, as it is departing the region. Just how quickly this system closes in the mid level is crucial to whether there is simply snow showers during Sunday afternoon, or heavy banding of accumulating snowfall. While guidance has trended more aggressively with the rate of intensification upon exit, the ultimate evolution is often slower and the system more progressive than guidance suggests, which can lead forecasters astray by overestimating snowfall to a degree. This situation it has high risk for such a development given the fact that there is no upstream ridging over the western CONUS to slow the flow down. Anticipated Storm Evolution: Snowfall should break out across western Connecticut early Saturday evening. Meanwhile, back in eastern sections, coastal frontogenesis will be triggered by onshore east-northeast (east of the front) to northeasterly winds (west of the front). Then snow mixes with and changes to rainfall along the south coast of Connecticut, Rhode Island, and southeast Mass by midnight, as precipitations begins as rain over the cape and islands. This is the warmest point of the storm as the marine influence propels the coastal front to its furthest north and west point, just beyond the I-495 belt in Mass and down through eastern Connecticut and along the south coast. Snowfall is enhanced via added lift just to the northwest of the coastal front, over southeastern New Hampshire, NW Middlesex County and the eastern slopes of the Worcester hills. The latter of which will also see augmented snowfall via upslope from a deep easterly fetch in the mid levels of the atmosphere. The risk for power outages will be greatest where a significant amount of heavy, wet snow falls to the east of the coastal front in the initial stages of the storm, along the immediate north shore, Boston area and down I 95 over interior southeastern Mass. While precipitation will be heaviest along the east slopes of the higher terrain, this deep easterly fetch will coincide will enhance precipitation in general across the region during the predawn hours of Sunday morning. There may be somewhat of a lull later on Sunday morning, which represents a crucial point of inflection for this storm system and its degree of regional impact. The evolution of the storm system in the mid levels of the atmosphere is what will determine whether or not this system has a moderate or major impact on the area. And it should become clear how quickly the energy infusion into the lead system from the trailing wave will coalesce into an intensifying coastal system by midday Sunday. The trend during the day on Friday has been for the system to begin to close off in the mid levels of the atmosphere by early afternoon on Sunday. Which will begin to increase snowfall just to the northwest of the fledgling 700mb low over the same areas that experienced enhancement during the first half of the event from coastal frontogenesis and upslope. These heavier bands will begin to crash towards the coast as the surface system pulls the coastal front back towards the coast and the mid level system continues to mature. Briefly heavy snow and " 'flash freeze conditions are possible near the coast at this point during Sunday afternoon. The system should begin to pull away by Sunday evening. Taking the snowfall with it, but not before light accumulations on the cape and islands, as any rainfall transitions to snow prior to ending prior to midnight over the outer cape. FINAL CALL: First Call issued Wednesday 1/3 @ 11AM.

https://easternmassweather.blogspot.com/2024/01/final-call-for-moderate-to-high-impact.html

Looking at some of the soundings, and it's really not that impressive....NAM has most of the OMEGA above the SGZ @KLWM.

May as well wait on the EURO to fire away at this point.

Man, I am nervous about busting low....but my map is done. I am just too leery of totally biting off on this damn last minute capture.

It doesn't JP scooter....that is using 10:1. Kuchera has it near my area...at. least relative to eastern MA.

The color scheme is confusing....it does look like rain vs snow, as it's near the freezing line.

@weatherwizIt is ...that map does not delineate prcip type.

After that point.

That isn't precip type....it's the 30 isotherm.

Warmest point on 00z NAM...4am Sunday

A lot of the meso guidance is cold.

Giving myself in ice cream headache going over data....NAM looks like it gets the CF right to about MBY....has the 32 isotherm over me, but really holds it this far north. Odd that its gets so far inland further south into areas that normally have less marine influence than I do....like Westford and Shrewsbury.

That could be nuts up here where the angle of the coast gets sharper.

I think it sets up over like Windham.

Man, I would love to work some CJ in there with that reach around....just work me over from every angle.

Yea, that is what I mean...I'm not worried about warning criteria....I want to get it right.

Still around 6".....not bad.

Maybe another inch of 2 after 00z Sunday.

God....I hate, hate, hate relying on Kraft's decrepit, flaccid, Asian schlong to wrap around at the last moment, but that is an emphatic signal. May draw everything up and wait on the 00z EURO to fire.

You know yourself the NAM is good to look at for warm layers....like I said, every tool has utility if you know how to apply it.

Wow....impressive PDC on NAM

Do what?

That is impressive because as much as the NAM blows, it is like a pitbull finding warm layers at short range.