87storms Posted January 3 Share Posted January 3 51 minutes ago, ers-wxman1 said: Wrote about this yesterday. It is a mistake just to look at the model output, QPF etc. Analyze the scenario from the top down. 500/700/850. Are you seeing any features that align with known weather patterns that generate heavy snow across our area? Ridging out west, 850/700/500 energy is closed, deepening as it swings to our south? Strong high to the north? Blocking? Also with the CAD…what kind of air mass is being dammed? Nowhere in the northern tier do we see wind chill or extreme temperature headlines. These are flags. It’s been mild. The big difference last night on the 00z I saw was the 850 low became closed and stronger with the vort passage, while the high became stronger, and more dynamics, ridging hinted over the western U.S. that amplifies things enough to deepen the surface low in the right spot, however this isn’t slam dunk. It’s all marginal and not dealing with a textbook winter storm here, so any minor shift in these subtle features will significantly alter snowfall amounts. That is what is happening. It’s simply not the ideal pattern. It would be a heavy front end thump then hope for wrap around as it winds up offshore before subsidence kicks in. Many moving parts. Strong SW upper flow makes this fast moving system, rely on front end WAA. Thermals also marginal, no good source to fuel this. These types of systems are a nightmare to forecast, especially with regard to headlines and where to put them. LWX mentioned in their disco this morning what one of my concerns was and that's an onshore/return flow prior to the system arriving. That primary setup has been shown the last couple days with the hp moving off the mid-Atlantic. I think that's going to make it difficult for areas further east. Further west, we're gonna need to rely on CAD, but I could picture that being an issue, too, until you get to the higher elevations. And I'm not saying this because I think I'm right, but I agree with you that (at least through my hobbyist tracking) that this wasn't a clean setup. Hopefully, most of us can at least get some snow on the front end while the antecedent conditions allow for it...from there, roll the dice. 1 Link to comment Share on other sites More sharing options...
psuhoffman Posted January 3 Share Posted January 3 47 minutes ago, WxUSAF said: Oooohhh…that’s encouraging. Tossing 6z euro with extreme prejudice! If you look at both the gefs and eps members there is a mix of all 3 possible outcomes. A 0z gfs ggem type sweet spot solution. some phasing and a primary with a NW solution A weak washed out solution It’s not shocking to see the 6z ops pull out from any of these camps. But it does seem the EPS as a whole took a step towards the option we want. All 3 camps still have support within the spread though. 6 Link to comment Share on other sites More sharing options...
87storms Posted January 3 Share Posted January 3 8 minutes ago, psuhoffman said: If you look at both the gefs and eps members there is a mix of all 3 possible outcomes. A 0z gfs ggem type sweet spot solution. some phasing and a primary with a NW solution A weak washed out solution It’s not shocking to see the 6z ops pull out from any of these camps. But it does seem the EPS as a whole took a step towards the option we want. All 3 camps still have support within the spread though. I gotta think areas closer to the M/D line are in good shape...I'm actually not really even that concerned up here (though I probably should be lol). I think it's the 95 corridor that is going to be the most challenging forecast. I grew up in Silver Spring, so I know exactly what that's all about. 1 Link to comment Share on other sites More sharing options...
clskinsfan Posted January 3 Share Posted January 3 NAM is a hot mess. Disaster run. 1 Link to comment Share on other sites More sharing options...
Paleocene Posted January 3 Share Posted January 3 NAM'D 10 Link to comment Share on other sites More sharing options...
konksw Posted January 3 Share Posted January 3 It’d be hard to describe what 12z NAM is showing as a storm at all… Link to comment Share on other sites More sharing options...
mattie g Posted January 3 Share Posted January 3 3 minutes ago, clskinsfan said: NAM is a hot mess. Disaster run. Looking forward to my drizzly Saturday evening. NAM at 84...lol. 2 Link to comment Share on other sites More sharing options...
87storms Posted January 3 Share Posted January 3 44 minutes ago, clskinsfan said: NAM is a hot mess. Disaster run. That follow-up wave is becoming the main show. It's actually a hecs-level looking vort lol. If we can get that to trend south, then it's game on. 1 1 Link to comment Share on other sites More sharing options...
Alfoman Posted January 3 Share Posted January 3 2 minutes ago, clskinsfan said: NAM is a hot mess. Disaster run. Won't ever take Hours 60+ on the NAM with any sort of seriousness - but on that note, there was better confluence and slightly lower surface temps this run. Link to comment Share on other sites More sharing options...
osfan24 Posted January 3 Share Posted January 3 52 minutes ago, WxUSAF said: Let’s not do this “it won’t accumulate” game for the 1081st time please. Could 10:1 be too high? Sure. But I will bet my retirement fund that if 10:1 shows 3-4” that falls in 6 hours, the snow depth won’t be 0.0”. I didn't mean it will literally be zero but my point was that it won't be anywhere near that, especially if the timing of afternoon into evening is accurate as opposed to more evening and overnight. I am well aware we can overcome warm temps if it snows hard enough, but I am not sure a half inch per hour is thumpy enough given all of the other mitigating factors for the metro area. 1 Link to comment Share on other sites More sharing options...
RDM Posted January 3 Share Posted January 3 NWS posted a large swath of notices from Fredericksburg South for Hazardous Weather Outlook for Fri night/Sat. Somewhat odd - nothing N of that. Link to comment Share on other sites More sharing options...
Kmlwx Posted January 3 Share Posted January 3 Just now, RDM said: NWS posted a large swath of notices from Fredericksburg South for Hazardous Weather Outlook for Fri night/Sat. Somewhat odd - nothing N of that. That's a different WFO Link to comment Share on other sites More sharing options...
clskinsfan Posted January 3 Share Posted January 3 RGEM still really nice west of the fall line. Heavy snow for Loudoun. Good run. 8 Link to comment Share on other sites More sharing options...
Warm Nose Posted January 3 Share Posted January 3 New Sterling discussion, SIAP. .LONG TERM /SATURDAY THROUGH TUESDAY/... A strong southern stream mid/upper-level trough over the Mid-South Friday night quickly moves northeast as it phases into a flat trough over the OH Valley/Mid-Atlantic on Saturday. At the surface, an associated area of low pressure develops along the northern Gulf Coast and very quickly moves across the Southeast states through Saturday morning. The surface low becomes better organized as it crosses eastern NC into far southeast VA, where it moves offshore along the NC/VA border. Precipitation overspreads the area from southwest to northeast starting late Friday night into Saturday. Temperatures Friday night are forecast to be below freezing for most of the area. However, there is considerable uncertainty to the east of US-15 as easterly winds advect in a warmer marine airmass and strong WAA ahead of the surface low help to increase temps along/east of I-95. All that being said, precipitation is likely to start out as snow west of US- 15 and a rain/snow mix along/east of US-15. As the morning progresses, areas east of I-95 are most likely to transition to a cold rain, with steady snow west of US-15, and a mix in between. Having the surface high well to the north and weak onshore flow preceding the surface low are not generally favorable for accumulating snow along I-95. Any chance to see higher snow totals there will be dependent on higher precip rates and wet bulb effects overcoming the marginal temperature profile. Still, p-type is going to be highly sensitive to the track of the low, with a tight rain-snow gradient likely. Significant snow accumulations are most likely along/west of the Blue Ridge and Catoctins. Where precip is more likely to be in the form of rain, near and east of I-95, there is the potential for instances of flooding. Continue to monitor the progress of this storm as the weekend approaches. The coastal low tracks northeast and away from the area Saturday night, then a reinforcing upper trough traverses the area on Sunday. Some lingering rain and snow showers possible during the first part of Monday north of I-66 and west of the Blue Ridge, though conditions dry out quickly in the afternoon. Upslope mountain snow showers continue into Sunday night. 1 Link to comment Share on other sites More sharing options...
aldie 22 Posted January 3 Share Posted January 3 2 minutes ago, Warm Nose said: New Sterling discussion, SIAP. .LONG TERM /SATURDAY THROUGH TUESDAY/... A strong southern stream mid/upper-level trough over the Mid-South Friday night quickly moves northeast as it phases into a flat trough over the OH Valley/Mid-Atlantic on Saturday. At the surface, an associated area of low pressure develops along the northern Gulf Coast and very quickly moves across the Southeast states through Saturday morning. The surface low becomes better organized as it crosses eastern NC into far southeast VA, where it moves offshore along the NC/VA border. Precipitation overspreads the area from southwest to northeast starting late Friday night into Saturday. Temperatures Friday night are forecast to be below freezing for most of the area. However, there is considerable uncertainty to the east of US-15 as easterly winds advect in a warmer marine airmass and strong WAA ahead of the surface low help to increase temps along/east of I-95. All that being said, precipitation is likely to start out as snow west of US- 15 and a rain/snow mix along/east of US-15. As the morning progresses, areas east of I-95 are most likely to transition to a cold rain, with steady snow west of US-15, and a mix in between. Having the surface high well to the north and weak onshore flow preceding the surface low are not generally favorable for accumulating snow along I-95. Any chance to see higher snow totals there will be dependent on higher precip rates and wet bulb effects overcoming the marginal temperature profile. Still, p-type is going to be highly sensitive to the track of the low, with a tight rain-snow gradient likely. Significant snow accumulations are most likely along/west of the Blue Ridge and Catoctins. Where precip is more likely to be in the form of rain, near and east of I-95, there is the potential for instances of flooding. Continue to monitor the progress of this storm as the weekend approaches. The coastal low tracks northeast and away from the area Saturday night, then a reinforcing upper trough traverses the area on Sunday. Some lingering rain and snow showers possible during the first part of Monday north of I-66 and west of the Blue Ridge, though conditions dry out quickly in the afternoon. Upslope mountain snow showers continue into Sunday night. Curious what part of Western Loudoun are you in....is it for real Western Loudoun or Ji's version of Western Loudoun? If it's for real Western then i think your area is in a pretty good spot for this one especially Round Hill on West 1 Link to comment Share on other sites More sharing options...
winter_warlock Posted January 3 Share Posted January 3 3 minutes ago, clskinsfan said: RGEM still really nice west of the fall line. Heavy snow for Loudoun. Good run. Where are u getting longer range rgem? Link to comment Share on other sites More sharing options...
NorthArlington101 Posted January 3 Share Posted January 3 2 minutes ago, winter_warlock said: Where are u getting longer range rgem? Nasty gradient... 10" in NW Arlington, 3" in SE. It's also still ripping at this point in DC. 3 4 Link to comment Share on other sites More sharing options...
Warm Nose Posted January 3 Share Posted January 3 2 minutes ago, aldie 22 said: Curious what part of Western Loudoun are you in....is it for real Western Loudoun or Ji's version of Western Loudoun? If it's for real Western then i think your area is in a pretty good spot for this one especially Round Hill on West Just west of RH, @ 800ft on the nose... 2 Link to comment Share on other sites More sharing options...
Paleocene Posted January 3 Share Posted January 3 Can always count on RGEM or NAM to have a juicy snow output at this range. Link to comment Share on other sites More sharing options...
North Balti Zen Posted January 3 Share Posted January 3 1 minute ago, Paleocene said: Can always count on RGEM or NAM to have a juicy snow output at this range. Generally. Also genuinely hilarious that RGEM looked like that and the NAM had light mist for everyone. 2 Link to comment Share on other sites More sharing options...
clskinsfan Posted January 3 Share Posted January 3 I think the CMC uses the RGEM up to 84? So I would expect it to be absolutely ridiculous. Link to comment Share on other sites More sharing options...
WxUSAF Posted January 3 Author Share Posted January 3 Just now, clskinsfan said: I think the CMC uses the RGEM up to 84? So I would expect it to be absolutely ridiculous. Yeah they usually are pretty simpatico, so I’d expect GGEM to be similar if maybe a little tamer overall. 1 Link to comment Share on other sites More sharing options...
aldie 22 Posted January 3 Share Posted January 3 5 minutes ago, Warm Nose said: Just west of RH, @ 800ft on the nose... Great spot...probably my next area to move to if I stay in Nova Link to comment Share on other sites More sharing options...
NorthArlington101 Posted January 3 Share Posted January 3 ICON is a step back at 12z. 2 Link to comment Share on other sites More sharing options...
Ravens94 Posted January 3 Share Posted January 3 Slightly warmer at the surface pretty much everywhere but really noticeable south. It's essentially just waffling run to run tho after the last few runs. Link to comment Share on other sites More sharing options...
NorthArlington101 Posted January 3 Share Posted January 3 Just now, winter_warlock said: Its the icon... lol Thanks! Not concerned - just saying. We'll talk about it for pages when it's good, though. 2 2 Link to comment Share on other sites More sharing options...
clskinsfan Posted January 3 Share Posted January 3 Whoever is skirting that rain/snow line is gonna end up happy in the end. 2 Link to comment Share on other sites More sharing options...
mattie g Posted January 3 Share Posted January 3 1 minute ago, clskinsfan said: Whoever is skirting that rain/snow line is gonna end up happy in the end. I've been on that line for virtually every model run - whether on one side or the other - for the last 36 hours. I've been on the wrong side slightly more often, so I'm more than a little twitchy. 3 Link to comment Share on other sites More sharing options...
psuhoffman Posted January 3 Share Posted January 3 1 hour ago, WinterWxLuvr said: I like your use of the median I love that WXbell finally added this to their package. I was calculating it manually for a while but that was annoying. The median and snow probabilities show a much better representation of what guidance is predicting that the skewed means. Link to comment Share on other sites More sharing options...
adelphi_sky Posted January 3 Share Posted January 3 9 minutes ago, clskinsfan said: Whoever is skirting that rain/snow line is gonna end up happy in the end. I must say College Park has ended up on the winning side as far as I can remember. We've done pretty good with these setups. Link to comment Share on other sites More sharing options...
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