Wurbus Posted December 23, 2020 Share Posted December 23, 2020 Knoxville down to .5 inch Plume average. Not a great sign for the NAM. Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 The NAM is almost the same on it's features for the past 8 runs, but the difference is it doesn't bring the cold air in nearly as fast the last couple of runs. Yesterday's 06z run the changeover line was about 100 miles East of where it is on todays at 1pm Thursday. So where I was getting heavy snow by then with a LP just across the mountain from Greene County, I'm now getting heavy rain with a low in the same spot. That greatly affects snow totals, basically cutting them in half. 1pm Friday on the 06z from 24 hours ago vs 1pm Friday on the 06z that just ran. 1 Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 3k NAM is faster with the front than the 12k, very aggressive with backside banding that drops strips of heavy snow and also features some freezing rain accumulations along the Plateau but moves the main shield of precip out much faster than the 12k. Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 The 06z 48hr HRRR is similar to the 3k with the banding. It has areas that get 3-4+ inches under what looks almost like convective snow showers while areas on either side of the convective showers get half that or less. Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 MRX issues a winter storm watch for the Smokies, NE Tn and SWVA. About what I expected. 1 Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 Reading JKL's discussion from yesterday evening, they reason that models are showing way too much accumulation due to warm ground/day time snow falling. That really seems a stretch at this point in the lowest sun angle of winter on what should be a very thickly cloudy day. Also a stretch to say the ground is warm, December has been BN in the area temp wise and lows have been in the 20s multiple days this week and are in the 20s right now, I don't see one warmish day causing the ground temps to shoot up. Snow falling at rates being shown by some models will almost immediately stick and begin to pile up. 2 Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 RGEM is the same as it was at 00z through 06z. Pounding snow across northern Middle. The rain/snow line has just reached mby. It's basically a mirror of the NAM with features, frontal placement, LP placement etc but has a much bigger precip shield on the backside than the NAM. 2 Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 Pummeling all of East Tennessee by 42. May be it's biggest run yet if the backside stuff is as robust as the last few runs. 2 Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 Through 48 the first wave of snow is in NE Tn and SWVA and the bands of snow showers behind it are starting to get rolling. 1 Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 Frigid by early Christmas morning, RGEM has snow pockets and temps in the low to mid 10s. 2 Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 Morristown gets under a particularly aggressive band and goes from 4.9 inches through the first map I posted to 7.2 inches over the course of Christmas day. 2 Link to comment Share on other sites More sharing options...
BlunderStorm Posted December 23, 2020 Share Posted December 23, 2020 Christmas morning. 06z RGEM vs 06z NAM 1 Link to comment Share on other sites More sharing options...
John1122 Posted December 23, 2020 Share Posted December 23, 2020 GFS looks about as bad as the RGEM does good for all except far NE areas. The GFS was slower with the cold and way more progressive with the moisture getting out of dodge than even the NAM. 1 1 Link to comment Share on other sites More sharing options...
Jed33 Posted December 23, 2020 Share Posted December 23, 2020 2 hours ago, John1122 said: Morristown gets under a particularly aggressive band and goes from 4.9 inches through the first map I posted to 7.2 inches over the course of Christmas day. I see you RGEM! I like that model a lot bc I have seen it get a lot of things right over the years. That said it seems a little overdone. I like that the 3k NAM has the same general idea though. Seems like an Arctic front with a 1050+/- hp pushing it along would line up more like this scenario. The NAM/GFS seems more like what you would expect with a 1035ish or so HP pushing it, and that looks to be true. The rgem has a high as strong as 1052 at one point that weakens to a 1047, while the gfs never gets stronger than 1047 and weakens it to around 1040. Could that difference could be the reason in the slower frontal passage on the gfs? Link to comment Share on other sites More sharing options...
Nash_LSU Posted December 23, 2020 Share Posted December 23, 2020 2 hours ago, John1122 said: a much bigger precip shield on the backside than the NAM. I think that's our only hope here in Middle TN. Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted December 23, 2020 Share Posted December 23, 2020 The rum's worn off now @kvskelton, no more Latin until this evening, lol. 6z Euro: 3 hr snowfall: totals 10:1 (no Kuchera ratios available to me for the 6/18z runs): 2 1 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 4 hours ago, BlunderStorm said: Christmas morning. 06z RGEM vs 06z NAM MRX mentioned that wind chill values could range from -5 to 5 above at their worst. That is COLD! 1 Link to comment Share on other sites More sharing options...
Icy Hot Posted December 23, 2020 Share Posted December 23, 2020 Really surprised we don't have more chatter here. It has been a long time since we've been under a Winter Storm Watch. Combine that with the extreme cold that is on the way and the fact it is coming on Christmas Eve; I thought this forum would be hopping. 1 Link to comment Share on other sites More sharing options...
TellicoWx Posted December 23, 2020 Share Posted December 23, 2020 9z SREF looks better than the 3z...mean looks more like what the 6z Euro map did Plumes still haven't loaded Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 3K NAM is much more robust over NE TN and maybe even back to MRX. Pops a lee side low - finally seeing that dynamic. Doubt it is done correcting. 3 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 That is a pretty massive move by the 3k NAM. Accumulations back into northern Knox Co with that...Significant bump up for SE KY, NE TN, SW VA, and W NC. 1 Link to comment Share on other sites More sharing options...
Jed33 Posted December 23, 2020 Share Posted December 23, 2020 6 minutes ago, Carvers Gap said: That is a pretty massive move by the 3k NAM. Accumulations back into northern Knox Co with that...Significant bump up for SE KY, NE TN, SW VA, and W NC. Trending toward the RGEM? Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 Just now, Jed33 said: Trending toward the RGEM? Let's see what the 12z RGEM does...but yes, closer to the 6z RGEM. I am super gun shy with modeling being all over the place. Let's hope the trend is "up" in terms of snowfall. The 3K NAM pops a lee side low and backs flow into areas north of I-40 - progressively more as one gets to the NC state line and progressively more NE. Honestly, that change has caught me off guard a bit as it had been adamant that the amounts were going to be light, even here in TRI. Without the lee side low, would have been similar to 6z. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 7 minutes ago, Jed33 said: Trending toward the RGEM? I think the change is most easily seen on the Tropical Tidbits website. The storm itself is much more robust. However, the hover feature on PivotalWeather will give you a good idea for Morristown - looks like those totals went up. 1 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 12z RGEM is rolling. I can see hour 42 of all things...but it doesn't tell me much. Flow "might" be backed a hair more...though initially it is a bit faster. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 RGEM is a bit flatter at 22. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 The 12z RGEM still looks steady through 27 when compared to 6z. Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 Though 36, the RGEM has snow in pretty much the same spots as 6z. Much quicker with the cold air and further extension west of the snow due to that. 1 Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 23, 2020 Share Posted December 23, 2020 The 12z RGEM is a nice run. 3 Link to comment Share on other sites More sharing options...
Jed33 Posted December 23, 2020 Share Posted December 23, 2020 Man that rgem run looks like those GEFS runs from the past few days. Hmmm Link to comment Share on other sites More sharing options...
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