jbenedet

The kink south to the surface warm front is likely severely under-modeled. Cold Air damming and ageo flow along the Apps—this looks like a classic example down to the mid Atlantic. At the margin this will likely have important implications and cause the surface low to travel southeast of I90. And how this feeds into the potential development of a mesolow near 40N, mitigating easterly fetch, we could still be looking at cold surprises down to I95. But this latter points seems far less likely at the moment, outside of persistence factors—climo, snowpack etc... A surface low track halfway between I90 and I95 —or thereabouts—is my best guess at the moment...Hedging colder than guidance...

I’m with you. Away from the coast I just don’t see surface temps moving up at all from Monday night lows. Are sig icing events ever forecasted accurately? Serious question—even the recent event in the Pacific Northwest caught everyone off guard. I feel like the less it’s anticipated the more likely it’s to happen with these things. The nature of it I suppose: an intersection of multiple marginal conditions...and an atmosphere that achieves a prolonged period of “steady state”. The opposite of dynamic.

The ARW’s are cold

Not saying this is LI’s ice storm by any stretch but I am saying someone there or close going to get sig ice from this. I see a lot of similarities ... http://www.northshorewx.com/19780113.html

I think everything is trending weaker except the boundary itself. Thinking we’ll see slightly lower heights into the Northeast as a result as well. The orientation of the surface high into southern Ontario is still quite favorable for surface CAD down to the coast. All comes down to where the surface boundary sets up... The old runs looks more like a significant snowstorm with sleet at the margins, this looks more like an ice storm as major impact.

Yea this increasingly has the look of a significant ice storm. All high level factors are favorable, timing, snow cover, cold surfaces, climo. The final wave (of 3?) will be weak, and insufficient to modify the mid to low level temps, simply ejecting northeast along the pre-existing boundary. At the same time a surface high will remain in southern Ontario upon its approach. The weakness of the two key players favors more freezing rain and less sleet...A higher impact event.

Closer to 25 miles. Small state. 68 miles wide at its widest point. We know how much a few miles means in these things. Not different now. I think the coast has a good shot of seeing a glancing blow from the parting deform band as this thing really winds up tonight. Deerfield etc has no shot at that—too far northwest. If that doesn’t happen then you will be correct.

Heh Deerfield. Yea I mean, technically I guess that’s SE NH, but I never considered it that way. That’s central NH in my book. Semantics aside, yes, I agree they aren’t seeing 6-8”; not even close. But I think portions of the sea coast area will. That’s all I’m saying.

>20mb drop in surface pressure modeled over next 12 hrs. Should be a fun one to watch for eastern zones right down to the end...

6-8” in parts of SE NH will verify. Widespread? Probably not. But def on a localized basis. Hampton up to Portsmouth seems a strong bet for at least 6” Seeing first mod obs in the area now. Definitely picked up in past hr.

I see snowing in Boston until 0z/1z on guidance. A foot seems like a low bar to clear given the latest obs, banding and ratios...

That band from Boston down to New Haven is awesome. Just training, and intensifying over time. Boston and south west suburbs are going to come out of this with highest totals I think...and easily over a foot.

Some general obs/rule of thumbs that argue against a weak system and for a bigger event. Today is a beaut by mid winter standards...(seriously get outside). Great weather days often immediately precede strong storms... Sound of snow melt, at 9:00 am doesn’t exactly fit with the progressive/suppressed SE solutions...

It’s getting closer to significant winter storm despite the recent surface trends. Boston to SE MA should def hedge snowfall forecasts significantly higher. We’re seeing a -NAO develop with UL heights building into New Brunswick, and QC from the central Atlantic. This is having the effect of slowing the disturbance and increasing chances of an earlier northern stream phase.

“Progressive progressive progressive “ I mean, even if you want to leverage the hell out of that point, the PNA ridge axis is off the west coast...This disturbance has A LOT of longitude to pump UL heights...

That was 987 mb at the BM on the 12z ukie. Nice.

Feb 7 2003. Good low end benchmark. I’d reference this for a “conservative forecast” right now.

My mistake.

The upside potential remains very high.

And that’s with very limited northern stream involvement.

I mean it’s both. No? Instead of the track ENE/NE trajectory more like an open wave we see it bend/tug back a bit, more akin to a maturing system. That’s my thought process.

Increased phasing, and more rapid synoptic wave development... that’s my guess anyway.

The northern stream is trending towards increased phasing... What happens if 6z GFS hr 42 looks more like this?

All op guidance is on the progressive/fast side of the envelope. The teleconnections and a short wave traversing the Northern GOM argues for the amped/slow side .... Risk remains strongly in favor of major guidance trending further in this direction...