Scraff Posted February 17, 2018 Share Posted February 17, 2018 I’ll continue to hug the NAM. Praying it’s right... Link to comment Share on other sites More sharing options...
cae Posted February 17, 2018 Share Posted February 17, 2018 Looks like I was posting in the wrong thread this morning. Here's the 06z Swiss model. It has been good with temps the couple of times I've looked at it, and it really shows the benefits of elevation. I also put up last night's RGEM ensemble, which basically looks like a low-res version of the above map. https://www.americanwx.com/bb/topic/50960-weekend-snowfestrainfestmixed-mess/?do=findComment&comment=4826411 Link to comment Share on other sites More sharing options...
EastCoast NPZ Posted February 17, 2018 Share Posted February 17, 2018 17 minutes ago, clskinsfan said: We need that though. We need it to be heavy with the marginal temps. We do, but the timing now is pretty bad. Precip commences at the warmest part of the day and ends about the time we enter diurnal cooling. See altocumulus overspread to my west, but still under clear skies and blazing sun. 35F according to nearest PWS, but feels much, much warmer. Link to comment Share on other sites More sharing options...
Allisong Posted February 17, 2018 Share Posted February 17, 2018 35/23 ☀️ here in Gaithersburg. Link to comment Share on other sites More sharing options...
clskinsfan Posted February 17, 2018 Share Posted February 17, 2018 Cloudy and 31. The clouds made it right on time. Link to comment Share on other sites More sharing options...
clskinsfan Posted February 17, 2018 Share Posted February 17, 2018 4 minutes ago, EastCoast NPZ said: We do, but the timing now is pretty bad. Precip commences at the warmest part of the day and ends about the time we enter diurnal cooling. Clouds are in now. We arent going to be warming too much more at this point. Link to comment Share on other sites More sharing options...
osfan24 Posted February 17, 2018 Share Posted February 17, 2018 11 minutes ago, Scraff said: I’ll continue to hug the NAM. Praying it’s right... That looks amazing. Would be a WSW type storm for almost the entire region. We NEED this. We DESERVE this! Link to comment Share on other sites More sharing options...
nj2va Posted February 17, 2018 Share Posted February 17, 2018 P&C shows 5-9”...currently under a Winter Storm Warning. 27 degrees and mostly cloudy. URGENT - WINTER WEATHER MESSAGE National Weather Service Pittsburgh PA 408 AM EST Sat Feb 17 2018 MDZ001-WVZ512-514-171715- /O.CON.KPBZ.WS.W.0003.180217T1900Z-180218T0900Z/ Garrett-Eastern Preston-Eastern Tucker- Including the cities of Mountain Lake Park, Oakland MD, Grantsville, Terra Alta, Rowlesburg, Hazelton, Davis, Thomas, and Canaan Valley 408 AM EST Sat Feb 17 2018 ...WINTER STORM WARNING REMAINS IN EFFECT FROM 2 PM THIS AFTERNOON TO 4 AM EST SUNDAY... * WHAT...Heavy snow expected. Total snow accumulations of 5 to 7 inches, with localized amounts up to 8 inches, are expected. * WHERE...In Maryland, Garrett County. In West Virginia, Eastern Preston and Eastern Tucker Counties. * WHEN...From 2 PM this afternoon to 4 AM EST Sunday. * ADDITIONAL DETAILS...Plan on difficult travel conditions. Be prepared for significant reductions in visibility at times. Link to comment Share on other sites More sharing options...
Interstate Posted February 17, 2018 Share Posted February 17, 2018 36/25 I said yesterday the temps might just make it rain for most. Link to comment Share on other sites More sharing options...
Mrs.J Posted February 17, 2018 Share Posted February 17, 2018 33/24 here in Frederick. Heading over to Round Hill, VA to get a ride in outdoors before the slop commences. Link to comment Share on other sites More sharing options...
SnowGolfBro Posted February 17, 2018 Share Posted February 17, 2018 17 minutes ago, Scraff said: I’ll continue to hug the NAM. Praying it’s right... Its pretty good at 12 hour lead times Link to comment Share on other sites More sharing options...
Interstate Posted February 17, 2018 Share Posted February 17, 2018 Just went outside. Definitely does not feel like a snowstorm coming. Link to comment Share on other sites More sharing options...
SnowGolfBro Posted February 17, 2018 Share Posted February 17, 2018 1 minute ago, Interstate said: Just went outside. Definitely does not feel like a snowstorm coming. The storms got you right where it wants you. Link to comment Share on other sites More sharing options...
NorthArlington101 Posted February 17, 2018 Share Posted February 17, 2018 Suns out and 37. Beautiful day at George Mason University! Link to comment Share on other sites More sharing options...
Interstate Posted February 17, 2018 Share Posted February 17, 2018 LWX include/exclude areas from a WWA reason Link to comment Share on other sites More sharing options...
high risk Posted February 17, 2018 Share Posted February 17, 2018 27 minutes ago, Fozz said: What's the difference between the Ferrier map and the normal 10:1 map? Why the huge disparity? The NAM keeps track of what percentage of falling hydrometeors are snow and sleet. It's called the % of frozen precip. As the model is running, it continually multiplies QPF x % of frozen precip to get its "snow" (really snow + sleet) accumulation. So in a situation with 0.6 liquid and 70% snow flakes or 70% snow and sleet, you get .6 x .7 = .42 liquid as snow+ sleet. Slap a 10:1 ratio on it, and you have 4" of snow, even though we all know that a situation with 70% of what's falling from the sky being snow (or sleet) is not likely to pile up on the ground. That's what the maps with snow depth are useful in marginal situations, as they realize that snow isn't really accumulating. The Ferrier maps take advantage of the NAM microphysics and apply a ratio based on the rime factor which accounts for pure snow (low value of rime factor) or heavily rimed snow (high rime factor). The more rimed the snow (supercooled water is accreting on the ice nuclei), the less it will stick, and the Ferrier method cuts down on accumulations. It's clear here based on the Ferrier and snow depth maps that the NAM doesn't think that this is a big accumulating event despite the generous 10:1 maps. Link to comment Share on other sites More sharing options...
Warm Nose Posted February 17, 2018 Share Posted February 17, 2018 Sun has returned Link to comment Share on other sites More sharing options...
high risk Posted February 17, 2018 Share Posted February 17, 2018 29 minutes ago, Scraff said: I’ll continue to hug the NAM. Praying it’s right... It's awesome to look at, but the way that map is generated is completely inapplicable to this setup. Link to comment Share on other sites More sharing options...
George BM Posted February 17, 2018 Share Posted February 17, 2018 Call me a pink elephant dancing in a toto but I actually like the northward trend of the heavy southern band over the past 24 hours. I'll gladly take the heavy rates and worry about precip type later. Anything to get me up to a 1-2% chance of seeing the T word rather than a 0% chance. ETA: I also like the radar trends over Tennessee right now for the heavy bands to be over/closer to the metro area. PS: (Hopefully not too bantery) Link to comment Share on other sites More sharing options...
Interstate Posted February 17, 2018 Share Posted February 17, 2018 2 minutes ago, high risk said: It's awesome to look at, but the way that map is generated is completely inapplicable to this setup. So what model should we look at or are you talking about all snow maps in general Link to comment Share on other sites More sharing options...
high risk Posted February 17, 2018 Share Posted February 17, 2018 4 minutes ago, Interstate said: So what model should we look at or are you talking about all snow maps in general I'm saying to use the 10:1 maps in conjunction with the snow depth maps (and the Ferrier map for the NAM3). With the setup is "right", they'll be in close agreement. When they differ a lot, use the 10:1 maps with extreme caution. I explained it a little bit a few posts back. It doesn't mean that the 10:1 maps won't end up being right if the model has some errors with the setup, but those maps are not consistent in these marginal, complicated setups with what the model really thinks is going to accumulate. Link to comment Share on other sites More sharing options...
nw baltimore wx Posted February 17, 2018 Share Posted February 17, 2018 2 minutes ago, high risk said: I'm saying to use the 10:1 maps in conjunction with the snow depth maps (and the Ferrier map for the NAM3). With the setup is "right", they'll be in close agreement. When they differ a lot, use the 10:1 maps with extreme caution. I explained it a little bit a few posts back. It doesn't mean that the 10:1 maps won't end up being right if the model has some errors with the setup, but those maps are not consistent in these marginal, complicated setups with what the model really thinks is going to accumulate. Isn't the "Positive Accumulated Snow Depth Change" a better indicator of accumulations? On TT, I mean. Link to comment Share on other sites More sharing options...
wolfpackwxDC Posted February 17, 2018 Share Posted February 17, 2018 Anecdotal observation: On the dog walk, saw cardinals, robins and a few other spring birds. Need to go dust off my MET books to see what those mean for our snow chances...I'm guessing not good. 42/26 Link to comment Share on other sites More sharing options...
Eskimo Joe Posted February 17, 2018 Share Posted February 17, 2018 Clouding up nicely. Still got a nice NW wind off the Catoctins. Link to comment Share on other sites More sharing options...
smokeybandit Posted February 17, 2018 Share Posted February 17, 2018 Cardinals and robins aren't necessarily spring birds. Many are in the area year round. Link to comment Share on other sites More sharing options...
KingJWx Posted February 17, 2018 Share Posted February 17, 2018 39F, hoping to see white missiles later Link to comment Share on other sites More sharing options...
high risk Posted February 17, 2018 Share Posted February 17, 2018 5 minutes ago, nw baltimore wx said: Isn't the "Positive Accumulated Snow Depth Change" a better indicator of accumulations? On TT, I mean. yes, and in the post of mine that you quoted, I mentioned the snow depth maps (I should have used the full "accumulated snow depth" term). They sometimes run a bit low, so I don't treat them as gospel, but I always view them in conjunction with the 10:1 maps. When they're radically different, the model is trying to tell us that it's not nearly as favorable for big accumulations as the 10:1 maps show. In the "no doubters", they'll be in the same ballpark. Link to comment Share on other sites More sharing options...
WxUSAF Posted February 17, 2018 Share Posted February 17, 2018 1 minute ago, high risk said: yes, and in the post of mine that you quoted, I mentioned the snow depth maps (I should have used the full "accumulated snow depth" term). They sometimes run a bit low, so I don't treat them as gospel, but I always view them in conjunction with the 10:1 maps. When they're radically different, the model is trying to tell us that it's not nearly as favorable for big accumulations as the 10:1 maps show. In the "no doubters", they'll be in the same ballpark. I'm hoping that if you and I actually stay all/mostly snow, this will be a good test comparison of the 3. This is the first winter where they've been widely available, but we haven't really had a storm where they can be evaluated. 39/22 here Link to comment Share on other sites More sharing options...
high risk Posted February 17, 2018 Share Posted February 17, 2018 12z GFS is noticeably lighter than the 12z NAMs with QPF and is therefore warmer. Link to comment Share on other sites More sharing options...
Interstate Posted February 17, 2018 Share Posted February 17, 2018 36/25. Clouds moving in. Link to comment Share on other sites More sharing options...
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