SnowGoose69

The oddest thing about the NAM to me is it does not even have crazy rates ahead of the changeover line. The frontogenesis is semi dislodged from the area where that would occur which may be why. But every other model shows insane rates 2-3 hours before that change occurs...so if the NAM is wrong on that idea the changeover may be delayed

The 3KM NAM does bear some similarities to the RAP as far as precip but the RAP seems to not even see the wedge. At least the 3km NAM has the wedge back well south and west of ATL 10-15Z tomorrow. The scary thing for the ATL metro is how far back the NAM has wanted to push the wedge as far as lateness into Sunday, if that verifies and IF significant ZR happens there will be way less time or chance to melt things off before winds pick up. But the fact now it has things so mild til 10Z is concerning on the bust end. I am not confident at all in any forecast I have out, even NYC it may be mainly sleet after 20Z tomorrow

I'm taking alot of abuse this morning lol, "you have been very accurate this winter but these last two storms you've been awful on your predictions". I'd be wary of the NAM given its been solid on these ideas this season thus far. Right now I'd be nervous about the 6 plus forecast for the coast for sure though it may be 6 plus with sleet included since official climo counts that.

I think they too may see more sleet than FZRA though they're on the border I think of where things setup on the FZRA/sleet line

We need to see what the 3km NAM does as we get closer in but the 12km at 12Z fits my idea that the sleet line makes it to the S shore of LI or just south and then collapses.

I'm wary of the NAM dryness in GA since it did this last year on 1/10 too...that said that was not the same setup, this is more of a case where I can somewhat buy the idea though the RGEM not showing it is a major concern and the 3km NAM seemingly bringing the wedge back to almost CTJ or the Bama border is a concern. I think in the end the risk of the metro seeing ice storm warning criteria is higher than some think while places like GVL E-NE may see more sleet.

Its wild how many Mets are going to miss this event because they'll be in Houston for AMS

Right now I lean towards a 2/11/94 type result. I think the sleet may make it to SI/S Bklyn and Queens at times and S shore of LI but I'd go with a forecast of all snow probably north of those areas.

ATL metro it all comes down to the surface feature and how strong it is/how far north it gets. If its as shown on the 18Z Euro I don't think they end up in too bad a place because they'd have a 6 hour window 06-12Z to really drop a ton of FZRA and thats just typically hard to do. If you rain at .15 an hour most runs off, if you rain at .07 an hour you may get a 1/2 inch of ice but if it goes to 48 degrees by 18z you melt it all off and limit the damage of future wind/time of it on trees and powerlines. They need to basically be frozen all event. Areas well NE of the metro that may occur but I am suspect on the metro itself doing that.

Yeah it was heavily downplayed near the coast but just inland a bit they were going big, I think for Philly and BWI the forecast was pretty big, the big issues with people being surprised were centered around NYC metro.

39 years ago today.... https://www.meteo.psu.edu/ewall/NARR/1987/us0122.php One of many terrible forecasts back in the 80s, especially the 87-89 period. 1-2 inches changing to rain I believe was the forecast the night before. As we began seeing during the 80s, models did sometimes begin catching on at the last second so I think they did upgrade to a heavy snow warning at like 4-5am for at least NYC on N and W but they did not for LI/Queens/Brooklyn so many people went to work and even some in NYC/NJ did because with no social media back then if you did not turn on the TV if you woke up at 5-6am you did not realize the forecast changed. My aunt made it home that day thanks to her 76 or 77 VW Rabbit which had FW drive, she said she was only car actually able to drive through the streets while everyone she navigated around was stuck. The Devils played a game that night with only like 300 fans showing and some players not even making it to the game.

If the trends hold I am less worried about ATL. I'd expect the GFS eventually goes way warmer there. Ultimately may only see a brief 8-10 hour period of FZRA there 03-12Z or so Sun AM but we have a ways to go

Yeah the wedge is insane on the RGEM.

You can almost automatically de-amplify the RGEM a bit at 60-84, thats a rule that seems to work 9 of 10, especially if its more amped than other models in the same period but I only use the RGEM past 48, never the NAM

Just based on historical climo alone. I know of no cases other than Jan 87 2/11/94 and 2/2014 where the area saw 8 plus near the coast then flipped over. I guess you can argue 2/2008 but that was not a setup like this. In general this type of setup is all snow most of the time NYC vicinity north

Color me shocked this went that far north but the fact the key southern disturbance was coming in from basically Mars and another piece from NW Canada I guess I should be less shocked. That said this is still a bit early so there may be corrections back the other way the next 2 days

The Euro/NAM/RGEM are really the only models that'll see wedging/CAD but even those tend to underestimate it at times beyond 48 hours. The UKMET/GFS/CMC can underestimate it.

20:1 is tough here outside of maybe a clipper in a very cold setup. Coastal lows usually its either too warm or too windy for ratios that good. PD2 is a case though where I think ratios may have been close to that and 2016

Having done forecasts there for years the wedge often times tends to be deeper in NE Ga so they end up more sleety in this storms. I think if this trends more to FZRA they'd probably see much less precip and just get like 0.25 FZRA and that is all. There is a narrow setup for them to see monster ice totals there. The wedge tends to save them or the system just usually cuts more north and they are drier.

Well the TWC behind the scenes folks sure like the NRN most solutions. Their depictions at least in the MA on S and W are on par with the CMC or UKMET.

Its pretty safe to say this event up this way will not be as insanely long duration in all likelihood as it may be down in the SE because they may see a crazy long overrunning period. I felt the 12Z Op Euro was gonna go full blown UKMET when I saw it through like 96 hours but it ultimately deviated after that.

I'd think no at this range. I think the mid-level warm advection will push a layer somewhere over 0C very early on

I still think they mostly end up sleet but long way to go. If some CMC version occurs or close to it the risk is there for mostly FZRA but they'd also be drier in that case though

CMC was just slower overall but also moved towards the more east later transfer idea. I said last night that either happens way west in the TN Valley or in coastal SC/GA in these setups. It won't typically happen over WRN GA/AL.

I would not worry a ton about the GFSAI. If the EUROAI begins going flatter its more a concern.