purduewx80

yup, temps above the sfc look to support a good amount of fzra or even rain. with such deep warm air aloft (even on the ukmet) i doubt any pellets would last long.

yes, it has been consistently a southern outlier, but each run has shown considerable variability on the details, including sfc temps, amount/location of N/S stream phasing, etc.

no it hasn't.

Exactly. I think most of the solutions imply cold air hanging tough despite whatever their 2m temp/wind progs show. The sagging isobars extending out of the high up north will allow for ageostrophic northerly flow rather than the E or SE winds the models spit out.

this ukmet run is very close to what deep thunder has been showing since its past few runs. implies a 2-part system with snow > ice > snow for the metro.

no one model is more likely to be correct at this juncture than another. best bet is to look at the range of solutions and realize reality will be somewhere in the middle.

Yes, it will become "operational" and will see an upgrade sometime this year. Ultimately, we will have a 3km "nest" and it will be renamed GRAF. DT can already be seen via IBM's The Weather Company (fka WSI) site, which many TV mets have access to.

not publicly available unless someone with access posts it online.

deep thunder much like the ukmet is even more supressed on the 12z run; jackpots the city w/ 12-18" and is an all snow event.

Temps no warmer than 29 at Central Park at onset (falling into the mid-20s as precip becomes heavy); perhaps some pellets on LI but all of NE, NYC, PHL and even parts of DC do well on that run.

like i said...

they are cracking down on it, sorry. i'm sure someone else w/ access might share it though...

00z UKMET has at least one other model on its side now w/ the 6Z run of Deep Thunder. Manages to get double digit totals into the city and absolutely buries PA to BOS.

Agreed. Also noticed the higher amp in 5.

any one of them with a surface low track near the area is likely too warm w/ 2m temps, yes. the synoptic evolution could change all of this, but it is a pattern we've repeated many times this cold season.

In many ways, this is just a repeat of the pattern we've seen repeatedly since Fall. A beefy Atlantic ridge with greatest + height anomalies over Newfoundland and - anomalies over the OH/TN Valleys and Appalachians. This helps promote deep southerly flow that has produced so many heavy precip events. While the end result this weekend does come down to how energy phases into the developing trough, I think assuming the surface low passes within 50 miles of NYC is a good bet at this point. No model in this pattern was able to capture the small-scale nuances of the low level wind field, with colder air generally holding in place longer than modeled region-wide. Now we're just adding climatology, cold water and the development of widespread frigid air into the mix. The ECMWF had a warm/NW bias with many of these coastal lows, while the GFS and its family were often too cold/SE. Whatever warm sector makes it in will likely be brief and after the heaviest precip has passed through, so this is still a wintry, albeit less snowy setup.

EPS made some changes towards the GEFS in the extended. Even if this weekend doesn't pan out, there is pretty good agreement that storm helps turn the NAO negative early next week. Many of the ensembles now bridge that NW Atlantic ridge with a NE Pac ridge in a couple of weeks, which locks the PV in place somewhere between Hudson Bay and the Great Lakes. A fun and intense pattern by the looks of it.

same goes for the 12z eps, but the majority drop more of the polar vortex into the southern vort complex/low than the gfs or gefs are.

the back end snow on the 18z run was simply a 500mb jet max passing by, putting us in a brief sweet spot for lift. the soundings aren't that impressive, but this does seem to be the kind of pattern where multiple vorts come into play. it's as likely as any other operational run out there for the time being.

thank you, seriously. that can not be said enough. even it has a nice signal for arctic air surging down the hudson valley if you look at its 10m winds sunday. that would meet little resistance on its way south.

Based on today's version of the ensembles, I think this is one of the more likely scenarios. It will come down to where the low-level jet sets up; those are always good for getting southerly surface winds into the coast/city/LI - when overhead. The low-level Arctic air would have no issue surging back south quickly, as some of the operational runs are showing. That's why I think an ice storm is a credible threat for at least parts of this forum. As many have pointed out, the synoptic evolution is critical Thursday-Sunday, but what happens Thursday night in terms of fresh snow cover is another important wild card. The more snow that accumulates in the Northeast with that first piece, the more likely the shallow cold air will be close by.

The east pac pattern is fun to watch on the new GOES-17. There are a ton of vorts coming together out there. I'd recommend looping it on the CSU slider. That's channel 9 (mid-level water vapor) above on the CONUS sector.

2m temps top out in the 50s for all of NYC/LI.

another snow to ice to rain back to snow scenario.

I agree 100%.