stormtracker Posted February 18, 2019 Share Posted February 18, 2019 Here we are again. You all know the drill. I've asked the mods here to be hyper vigilant and enforce a tight discussion with this one. Lately, I've been hearing from a few posters that the discussion has gone downhill and that it's become tedious to participate and follow these threads. we've all got to do better, including yes, myself. So the familiar spiel: If you see your posts disappearing, change your posting habits. There's not going to be much of a warning phase...no banter...there's a thread for that. Stay strictly on topic. It's ok to have some friendly banter WITHIN a post that contains some solid, on topic information. Just be mindful of how and what you post! 18 4 Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 @WxUSAF 6z 3k NAM pretty much covered the meaningful part since it went to 18z when it’s changed to ice in DC. I didn’t like where it was aiming the snow. Seemed in the euro north camp. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 18, 2019 Share Posted February 18, 2019 Snow that typically falls in a setup like this is a solid thump on the front end in strong warm air advection then over to sleet and freezing rain. The setup still looks good. No change in thinking here. Cities see 2-4, west of 95 see 4+, locally 8-10 in the heaviest rates. Icing will be an issue. Uncertainties remain with where exactly the heaviest stuff occurs and that may not be honed in for some time. 5 1 Link to comment Share on other sites More sharing options...
LeesburgWx Posted February 18, 2019 Share Posted February 18, 2019 Didn't the 6z Euro come south some with the main band of snow? So we have the euro and most recent NAM in the north camp, GFS in the south camp, and the others in between? Link to comment Share on other sites More sharing options...
Eskimo Joe Posted February 18, 2019 Share Posted February 18, 2019 1 minute ago, ers-wxman1 said: Snow that typically falls in a setup like this is a solid thump on the front end in strong warm air advection then over to sleet and freezing rain. The setup still looks good. No change in thinking here. Cities see 2-4, west of 95 see 4+, locally 8-10 in the heaviest rates. Icing will be an issue. Uncertainties remain with where exactly the heaviest stuff occurs and that may not be honed in for some time. What are you thinking from an ice perspective for the NW suburbs through the US 15 corridor? Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted February 18, 2019 Share Posted February 18, 2019 4 minutes ago, WxWatcher007 said: I'm heartened to know that I'll actually be in town for this one. Haven't followed terribly deeply yet, but with a nice CAD signal and a cold front end thump, I think the DC can do pretty well. I think the LWX map might be a tad bullish, I am concerned that we end up with more icing than mixing if warm air aloft is too fast in arriving, but we're probably right where we want to be. I shouldn't have left. Some of y'all are lapping me in snowfall. Yeah a bit surprised how bullish LWX is on that initial map, this early. Then again was likewise surprised how much snow they went with at first for the January event so who knows. Icing is obviously a major concern even in the metro area, moreso than last week. Link to comment Share on other sites More sharing options...
WxUSAF Posted February 18, 2019 Share Posted February 18, 2019 2 minutes ago, ers-wxman1 said: Snow that typically falls in a setup like this is a solid thump on the front end in strong warm air advection then over to sleet and freezing rain. The setup still looks good. No change in thinking here. Cities see 2-4, west of 95 see 4+, locally 8-10 in the heaviest rates. Icing will be an issue. Uncertainties remain with where exactly the heaviest stuff occurs and that may not be honed in for some time. I think that’s a good forecast for now. HM has been talking about watching the main frontogenesis band and where it peters out. We want it to stay coherent up to us and dissipate to our north to max our potential. 1 Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 18, 2019 Share Posted February 18, 2019 Just now, Eskimo Joe said: What are you thinking from an ice perspective for the NW suburbs through the US 15 corridor? Looks good for 1/4” accumulations especially closer to the M/D line. 1 Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 Again...there will be some snow outside the main band. But probably only 1-3 or 2-4”. The warning 5”+ snow will be in that band. Where it sets up hasn’t been determined yet. Euro and NAM are in the north camp. NAM was south at 0z but 3/4 runs have directed it into PA. Same euro euro. Gfs and rgem/ggem are south and direct it south of DC. Fv3 and icon are in between with a MD jack. Fv3 is trending north consistently the last 5 runs though... You all can make your own guess and decide which guidance you trust. Typically when there are divergent camps a compromise works out. Where exactly you live determines how much you need that compromise to be skewed towards the GFS vs EURO 1 Link to comment Share on other sites More sharing options...
WxMan1 Posted February 18, 2019 Share Posted February 18, 2019 Some of the latest probability maps from my fellow colleagues at WPC. 50/50 (most likely) snow 2-4" east of 95, 4-6+" west. Over 70% probs that we all see at least 2" (so we at least have that going for us, which is nice). Some ice, but certainly a better shot at .10" or more west of the cities. We'll see -- that March freezing rain event in 2017 was certainly an overachiever as the CAD wedge held strong. 6 Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 Sref fwiw...not much. It did trend south some Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 17 minutes ago, LeesburgWx said: Didn't the 6z Euro come south some with the main band of snow? So we have the euro and most recent NAM in the north camp, GFS in the south camp, and the others in between? Yea some but mostly noise. Euro has targeted either along the md pa line or southern pa for several consecutive runs. Minor shifts within that general zone. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 18, 2019 Share Posted February 18, 2019 There are always surprises in a CAD wedge. Some are not ever progged in the guidance. We are moving into the timeframe where the high resolution models better handle these setups. Global become less useful. 1 Link to comment Share on other sites More sharing options...
Buddy1987 Posted February 18, 2019 Share Posted February 18, 2019 Kicking off the 12z model runs, 12Z NAM has once again shifted the precip axis much further south comparing it to 6z. Should be a good run incoming with front end thump aspirations in mind. 1 Link to comment Share on other sites More sharing options...
DDweatherman Posted February 18, 2019 Share Posted February 18, 2019 I will be watching what the NAM has to say, especially with the precip maxima and onset. Parsing small details may be a bit early still, and the NAM hasn't performed spectacularly well this season. However, it seems to have a decent handle on this event and likely is doing pretty well with the CAD evolution and strength. Link to comment Share on other sites More sharing options...
Solution Man Posted February 18, 2019 Share Posted February 18, 2019 2 minutes ago, Buddy1987 said: Kicking off the 12z model runs, 12Z NAM has once again shifted the precip axis much further south comparing it to 6z. Should be a good run incoming with front end thump aspirations in mind. Agree, looks similar to yesterday's 12z at this point Link to comment Share on other sites More sharing options...
Buddy1987 Posted February 18, 2019 Share Posted February 18, 2019 Just now, Solution Man said: Agree, looks similar to yesterday's 12z at this point HP is in a much more favorable position at 36 compared to 6z as well and isnt wanting to slide east as fast. Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 I think the CAD is a lock. It’s trending better across guidance. That’s no shock. The DC Balt region should hold snow until midday sometime and stay ice into the evening. The question becomes qpf during those periods. How thumpy is the thump in the morning and how much qpf as ice in the afternoon. Getting in that heavier band doesn’t just mean more qpf it means higher ratios as typically that heavy banding both cools the column better and is associated with better lift to get better DSG 2 Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 NAM looks like a better consolidated moisture plume with a better trajectory so far. 1 Link to comment Share on other sites More sharing options...
stormtracker Posted February 18, 2019 Author Share Posted February 18, 2019 5 minutes ago, psuhoffman said: NAM looks like a better consolidated moisture plume with a better trajectory so far. Was just about to post that. Looks like it should hit the wall and shunt the heavier precip on more of a West to East trajectory. I hope. ETA..was looking at the 32km NAM (not sure why!) looks better on the 12km. Dark blues over us Link to comment Share on other sites More sharing options...
psuhoffman Posted February 18, 2019 Share Posted February 18, 2019 Just now, stormtracker said: Was just about to post that. Looks like it should hit the wall and shunt the heavier precip on more of a West to East trajectory. I hope. Looks better but sometimes extrapolation is a dangerous game. I’m rooting for this to target right at MD. That would get DC up to me both into the best band on the south and north side. Most of us would win. Not to hate on the south of DC folks but the only way they win is if I lose so...I’m just not that nice a guy. 1 4 1 Link to comment Share on other sites More sharing options...
Solution Man Posted February 18, 2019 Share Posted February 18, 2019 2 minutes ago, psuhoffman said: NAM looks like a better consolidated moisture plume with a better trajectory so far. That High stands strong Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 18, 2019 Share Posted February 18, 2019 Heavy front end thump on the 12z NAM. Strong frontogenesis. Snow overspreads the entire area between 4-6 am Wed. 4 Link to comment Share on other sites More sharing options...
stormtracker Posted February 18, 2019 Author Share Posted February 18, 2019 3 minutes ago, psuhoffman said: NAM looks like a better consolidated moisture plume with a better trajectory so far. Well, not so sure now. Looks like it's going to be centered north of the M/D line (the heavier stuff I mean). Still looks like a 10/12z start. Link to comment Share on other sites More sharing options...
snowfan Posted February 18, 2019 Share Posted February 18, 2019 9z Wed shows a decent slug of snow inbound with precip expanding further S/W of the metro area. A bit of a better look than 6Z. By 12Z most of the area is engulfed in snow. Link to comment Share on other sites More sharing options...
EastCoast NPZ Posted February 18, 2019 Share Posted February 18, 2019 7 minutes ago, psuhoffman said: I think the CAD is a lock. It’s trending better across guidance. That’s no shock. The DC Balt region should hold snow until midday sometime and stay ice into the evening. The question becomes qpf during those periods. How thumpy is the thump in the morning and how much qpf as ice in the afternoon. Getting in that heavier band doesn’t just mean more qpf it means higher ratios as typically that heavy banding both cools the column better and is associated with better lift to get better DSG It could also mean accumulating vs. Mood flakes and wet streets. Link to comment Share on other sites More sharing options...
WxMan1 Posted February 18, 2019 Share Posted February 18, 2019 9 minutes ago, ers-wxman1 said: There are always surprises in a CAD wedge. Some are not ever progged in the guidance. We are moving into the timeframe where the high resolution models better handle these setups. Global become less useful. NAM3 is especially useful, as it did comparatively well during the last freezing rain event, and especially well during the March 2017 icing event. The thing is, while the CAD will likely keep surface temps aob freezing for a longer while than most progs, it obviously has no bearing on temps aloft. Which is why there's no doubt an 'upper bound' with respect to snowfall potential before those temps aloft rise above 1C. And that's likely 2-4" for us east of 95. 1 Link to comment Share on other sites More sharing options...
clskinsfan Posted February 18, 2019 Share Posted February 18, 2019 The NAM bulleyes The NOVA/DC corridor this time with inch per hour rates for 4 or 5 hours. Really nice run. 2 Link to comment Share on other sites More sharing options...
mappy Posted February 18, 2019 Share Posted February 18, 2019 Just now, BaltimoreWxGuy said: 51 looks pretty darn good for Baltimore to me... Gonna need to add more information than it looks good. Link to comment Share on other sites More sharing options...
DDweatherman Posted February 18, 2019 Share Posted February 18, 2019 Just now, BaltimoreWxGuy said: 51 looks pretty darn good for Baltimore to me... Very, very strong frontogenesis at h7 on that frame. Would imply some dynamic banding and great rates/DSG. Link to comment Share on other sites More sharing options...
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