MD Snow Posted February 18, 2019 Share Posted February 18, 2019 12z nam is pretty similar to 6z. Slightly larger leaf of waa snow over us. Heavy stuff stays north and west before change over. Not a bad run. Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 NAM is better than 6z but not as good as 0z. It did shift south some. Does still target north but now as bad as 6z. ETA: ehh it started out better but ended up about the same as 6z. Maybe even a little worse in some places. Talking about 12k NAM. Link to comment Share on other sites More sharing options...
Ji Posted February 18, 2019 Share Posted February 18, 2019 Just now, psuhoffman said: NAM is better than 6z but not as good as 0z. It did shift south some. Does still target north but now as bad as 6z. that whole setup seems precarious lol. Id pay big for hour 57 to be all snow Link to comment Share on other sites More sharing options...
stormtracker Posted February 18, 2019 Author Share Posted February 18, 2019 Damn, NAM trying to keep even the city frozen until 7pm. Haven't looked at the boundary thermals, but it's probably like 32 and rain. So realistically, if we can hold until like 4pm, I'd consider it a win. Hell, it's already a win with some sig front end snow. Link to comment Share on other sites More sharing options...
clskinsfan Posted February 18, 2019 Share Posted February 18, 2019 Looking at some of the soundings for my area. The NAM has a warm nose at 700 pretty early this run. Verbatim it is snow through 51. But just barely. This may end up a bigger sleet bomb than we think. The rates for the first 4 hours are solid though. Would be a really nice hit to sleet. No ZR out this way this run. Which is what the Euro has been showing for two days. I like Martinsburg up through Hagerstown for the jack on this one. They should hold on to the snow an extra couple of hours and really only get a short period of sleet on top. Link to comment Share on other sites More sharing options...
MN Transplant Posted February 18, 2019 Share Posted February 18, 2019 3km looks just fine. 0.4”-ish QPF for DC through 16z, which seems to mark the changeover. Link to comment Share on other sites More sharing options...
snowfan Posted February 18, 2019 Share Posted February 18, 2019 Looking at the entire picture and not just snow, 12Z NAM is still a wintry mess for the area. Well over an inch of QPF for the area. Link to comment Share on other sites More sharing options...
Buddy1987 Posted February 18, 2019 Share Posted February 18, 2019 4 minutes ago, psuhoffman said: NAM is better than 6z but not as good as 0z. It did shift south some. Does still target north but now as bad as 6z. Strictly basing the outcome on the NAM, a little concerned down this way, as it only has me with like half an inch of liquid. Most other models do put out greater totals so that is one thing to watch for folks in the southern end of the forum. Link to comment Share on other sites More sharing options...
BristowWx Posted February 18, 2019 Share Posted February 18, 2019 Just now, Ji said: 00z NAM was the best run of the winter...weve gone downhill from there just fine tuning as we get closer you know this drill. Not aimed at you but early in the run analysis there were some "much better" comments. those tend to confuse. "much" to me is like 50 miles further south or 5 degrees colder. if its "much" then sure call it but if not then no reason to add descriptors in storm mode. my 2 cents. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 18, 2019 Share Posted February 18, 2019 There will be shifts, subtle changes in the next 24 hours. Rates are everything with the snow, heavy bands will be 1-2” per hour rates in DSG zone. Good amount of IP and FZRA too. There will be impacts. Things are locking in and it’s high confidence for a significant event. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted February 18, 2019 Share Posted February 18, 2019 To illustrate the dangers of using snow maps, and perhaps the NAM, the 6z NAM snow map has 20” of snow in Louisville (where my father lives). His forecast is for snow quickly changing to rain with a max of 1” of snow. I think it’s better to use total precip and temp profiles than those maps. Link to comment Share on other sites More sharing options...
WxMan1 Posted February 18, 2019 Share Posted February 18, 2019 3 minutes ago, stormtracker said: Damn, NAM trying to keep even the city frozen until 7pm. Haven't looked at the boundary thermals, but it's probably like 32 and rain. So realistically, if we can hold until like 4pm, I'd consider it a win. Hell, it's already a win with some sig front end snow. ...and wait 'till the NAM3 goes out into the 57h and beyond range. Much better vertical resolution than the 12km version...will simulate surface temps (degree/depth of CAD) much better. Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 4 minutes ago, Ji said: that whole setup seems precarious lol. Id pay big for hour 57 to be all snow Could be. It’s close. Look st 850s at 18z. Yea there is a warm later somewhere above that but you can clearly see the cooling from that heavy band. but I don’t like the NAM/euro aiming that best banding into PA. History in these setups says south of that band often gets disappointing results. Link to comment Share on other sites More sharing options...
osfan24 Posted February 18, 2019 Share Posted February 18, 2019 Just now, psuhoffman said: Could be. It’s close. Look st 850s at 18z. Yea there is a warm later somewhere above that but you can clearly see the cooling from that heavy band. but I don’t like the NAM/euro aiming that best banding into PA. History in these setups says south of that band often gets disappointing results. I remember the December 2013 storm was supposed to be mostly focused on our area but just a little bit of snow and instead we got a decent amount and Philly got dumped on when they really weren't expected to get much at all. I feel like you want to be north of the best banding on the modeling because it's usually going to end up farther north than the model shows. Link to comment Share on other sites More sharing options...
stormtracker Posted February 18, 2019 Author Share Posted February 18, 2019 2 minutes ago, WxMan1 said: ...and wait 'till the NAM3 goes out into the 57h and beyond range. Much better vertical resolution than the 12km version...will simulate surface temps (degree/depth of CAD) much better. Yeah, I keep forgetting about the 3k! Thanks for the reminder. One should hope that the better resolution would be a ton better. I'm watching the surface temps closely. At this point we know it's not going to be all snow and we're going to changeover. But we do have a chance to hold on to the surface longer than modeled now. Link to comment Share on other sites More sharing options...
Ji Posted February 18, 2019 Share Posted February 18, 2019 3 minutes ago, BristowWx said: just fine tuning as we get closer you know this drill. Not aimed at you but early in the run analysis there were some "much better" comments. those tend to confuse. "much" to me is like 50 miles further south or 5 degrees colder. if its "much" then sure call it but if not then no reason to add descriptors in storm mode. my 2 cents. most of the time when people say its much better than....its usually not. i hate model extrapolation. Let the run play out. The change was noise imo..if it had trended back to 00z NAM...than yes Link to comment Share on other sites More sharing options...
Maestrobjwa Posted February 18, 2019 Share Posted February 18, 2019 2 minutes ago, psuhoffman said: Could be. It’s close. Look st 850s at 18z. Yea there is a warm later somewhere above that but you can clearly see the cooling from that heavy band. but I don’t like the NAM/euro aiming that best banding into PA. History in these setups says south of that band often gets disappointing results. Yeah that's why I was a bit surprised to see some 4-6" totals predicted...unless things trend further south, this has a sloppy 2-4" for the cities written all over it, lol Link to comment Share on other sites More sharing options...
Ji Posted February 18, 2019 Share Posted February 18, 2019 2 minutes ago, stormtracker said: Yeah, I keep forgetting about the 3k! Thanks for the reminder. One should hope that the better resolution would be a ton better. I'm watching the surface temps closely. At this point we know it's not going to be all snow and we're going to changeover. But we do have a chance to hold on to the surface longer than modeled now. I would classify this as a major winter storm and not a major snowstorm unfortunately. Hopefully there is a error at upper levels like in November. Link to comment Share on other sites More sharing options...
WxUSAF Posted February 18, 2019 Share Posted February 18, 2019 3k NAM says the snow comes in hot and heavy. Doesn't last super long, but it works when it's here Link to comment Share on other sites More sharing options...
DDweatherman Posted February 18, 2019 Share Posted February 18, 2019 Just now, WxWatcher007 said: I highly recommend using the "zone" soundings on TT. I think they're more representative of what we may see than using the typical single point sounding. DC area for example. Looks like we rip for a bit if this is accurate. I like that sounding through the column. I'm keeping an eye specifically on the part of the column between 700-800mb for that warm nose that could push some to sleet. 850's in the absolute heaviest panel as PSU said are below zero, its not far from a snow sounding when h57 is bombing sleet. Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 Just now, WxUSAF said: 3k NAM says the snow comes in hot and heavy. Doesn't last super long, but it works when it's here Nice lift in the DGZ too Link to comment Share on other sites More sharing options...
Ji Posted February 18, 2019 Share Posted February 18, 2019 geez--the 3K Nam switches stuff at 10:00am to sleet. Not good. We need to go to 1pm Link to comment Share on other sites More sharing options...
nj2va Posted February 18, 2019 Share Posted February 18, 2019 7 minutes ago, stormtracker said: Damn, NAM trying to keep even the city frozen until 7pm. Haven't looked at the boundary thermals, but it's probably like 32 and rain. So realistically, if we can hold until like 4pm, I'd consider it a win. Hell, it's already a win with some sig front end snow. Yeah, a few days ago I thought we’d be lucky to hold frozen until early afternoon before the deluge. Now its looking more and more likely that frozen is the predominant precip type of the event for DC. 3k NAM keeps DC 32 or below for the whole event (obviously caveat applies that rain at 32 isn’t accreting much aside from elevated surfaces, decks, etc). Link to comment Share on other sites More sharing options...
Wonderdog Posted February 18, 2019 Share Posted February 18, 2019 NWS has snow or snow and pellets in its hourly forecasts on Wed until 4pm for Manassas area. Link to comment Share on other sites More sharing options...
WxMan1 Posted February 18, 2019 Share Posted February 18, 2019 3 minutes ago, stormtracker said: Yeah, I keep forgetting about the 3k! Thanks for the reminder. One should hope that the better resolution would be a ton better. I'm watching the surface temps closely. At this point we know it's not going to be all snow and we're going to changeover. But we do have a chance to hold on to the surface longer than modeled now. Totally agree! Here's what the NAM3 has at 21Z We'd for 2m temps. Link to comment Share on other sites More sharing options...
Buddy1987 Posted February 18, 2019 Share Posted February 18, 2019 Anyone have any verification scores for the HRW suite and how it performs? Link to comment Share on other sites More sharing options...
nj2va Posted February 18, 2019 Share Posted February 18, 2019 5 minutes ago, WxWatcher007 said: I highly recommend using the "zone" soundings on TT. I think they're more representative of what we may see than using the typical single point sounding. DC area for example. Looks like we rip for a bit if this is accurate. Thanks for this...where do you find the zone soundings? I’ve only done the P&C soundings for one location. (Mods, I kept this here vs banter as I thought others could benefit for tracking this threat with this feature. Feel free to move though). Link to comment Share on other sites More sharing options...
snowfan Posted February 18, 2019 Share Posted February 18, 2019 3K comes in hot/heavy like others posted. A general 3-5" snow for the area before the flip. DC loses 700mb by 18Z, but areas further north last longer. By 0Z, the surface is sitting at 31 for DC, but the column torches 900 to 700. Link to comment Share on other sites More sharing options...
midatlanticweather Posted February 18, 2019 Share Posted February 18, 2019 Well this would be a bit of an issue if true! Link to comment Share on other sites More sharing options...
clskinsfan Posted February 18, 2019 Share Posted February 18, 2019 Just now, snowfan said: 3K comes in hot/heavy like others posted. A general 3-5" snow for the area before the flip. DC loses 700mb by 18Z, but areas further north last longer. By 0Z, the surface is sitting at 31 for DC, but the column torches 900 to 700. Yes. I love that this isnt going to be a virga fest. It is going to come in like a wall of snow and hit really hard for a few hours. The 3K has a lot more sleet than any other model right now. Which is a bit concerning. But to be expected in this setup. Link to comment Share on other sites More sharing options...
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