John1122 Posted January 30, 2018 Author Share Posted January 30, 2018 The Euro and GFS are coming into a line with this being a .5-2 inch type event in the lower elevations along 40 and north in the Eastern forum. The GFS is more NE of Knoxville and Plateau and mountains with it's snow accumulations. Euro includes Knoxville. Euro map is actual snow depth too, so it probably shows a solid 1-3 inches of snow falling. Link to comment Share on other sites More sharing options...
ShawnEastTN Posted January 30, 2018 Share Posted January 30, 2018 SREF Plums for the storm still look pretty good actually, below are the mean and big dog member for area locations. Some have seen large jumps in mean and big dogs over 24 hours. TYS: Mean 1.47" - Big Dog - 5.44" TRI: Mean 1.89" - Big Dog - 5.12 BNA: Mean .47" - Big Dog - 2.23" CHA: Mean .22" - Big Dog - 1.60" CSV: Mean .92" - Big Dog - 3.47" LOZ: Mean 1.42" - Big Dog - 4.22" Link to comment Share on other sites More sharing options...
ShawnEastTN Posted January 30, 2018 Share Posted January 30, 2018 MRX on the Thursday into Friday storm: Quote For Thusday night, frontal boundary will move across the region during the evening with vertical temperature profile becoming cold enough for rain change over to snow. There is some disagreement on the amount of forcing and moisture left after change over to snow. The GFS and ECMWF are more aggressive and the NAM the least. Will follow the GFS solution for now which suggest 1 to 3 inches possible Thursday night through Friday morning. Winds will become strong and gusty behind frontal passage producing upslope flow into the Mountains. Will have the 3 to 5 inches for the higher terrain. These amounts may warrant advisory issuance over the next couple of days. Link to comment Share on other sites More sharing options...
ShawnEastTN Posted January 30, 2018 Share Posted January 30, 2018 18Z GFS is virtually nothing, for anyone this event. Link to comment Share on other sites More sharing options...
Stovepipe Posted January 30, 2018 Share Posted January 30, 2018 1 hour ago, ShawnEastTN said: 18Z GFS is virtually nothing, for anyone this event. On the other hand, it has 5 inches for TYS on the sat/sun storm. Link to comment Share on other sites More sharing options...
John1122 Posted January 31, 2018 Author Share Posted January 31, 2018 Euro is expanding and upping this one a bit still in the eastern areas. Snow reaches down to Athens now, .4-.8 there. 1-2 north and northeast of there, 2+ in NETN. 3-5 in the mountains. Link to comment Share on other sites More sharing options...
Carvers Gap Posted January 31, 2018 Share Posted January 31, 2018 18z 12k NAM...comments? Link to comment Share on other sites More sharing options...
Wurbus Posted January 31, 2018 Share Posted January 31, 2018 41 minutes ago, Carvers Gap said: 18z 12k NAM...comments? Just when I gave up on this system, the 18z NAM reels me back in..... Link to comment Share on other sites More sharing options...
ShawnEastTN Posted January 31, 2018 Share Posted January 31, 2018 1 hour ago, Carvers Gap said: 18z 12k NAM...comments? Funny thing is watch this one over perform, and the next one be a dud for us... lol Take it where we can get it. Also plumes had all but died off, now they are at least for TYS the highest they have been for the event, Mean at 1.56" big dog over 6". Link to comment Share on other sites More sharing options...
Stovepipe Posted January 31, 2018 Share Posted January 31, 2018 7 minutes ago, ShawnEastTN said: Funny thing is watch this one over perform, and the next one be a dud for us... lol Take it where we can get it. Also plumes had all but died off, now they are at least for TYS the highest they have been for the event, Mean at 1.56" big dog over 6". 18z NAM at TYS has that snow falling at 35-36 degrees. I doubt anything ends up sticking. Might be able to get up in the middle of the night and see flakes though. Link to comment Share on other sites More sharing options...
ShawnEastTN Posted January 31, 2018 Share Posted January 31, 2018 1 minute ago, Stovepipe said: 18z NAM at TYS has that snow falling at 35-36 degrees. I doubt anything ends up sticking. Might be able to get up in the middle of the night and see flakes though. I'll take slush with big giant wet snowflakes if that is all I can get. Link to comment Share on other sites More sharing options...
ShawnEastTN Posted January 31, 2018 Share Posted January 31, 2018 MRX on Thursday into Friday system: Quote .SHORT TERM...(Tonight through Thursday night)...Moisture will begin to increase tonight ahead of an approaching cold front. The front will move through tomorrow afternoon and exit in the early evening. Some rain will move in during the day, but the better forcing will lag behind the front with the strengthening upper jet and better frontogenetic forcing. The best lift will be northern areas late Thursday into Thursday night. With the colder air moving in, this will allow for some snow across the higher elevations first, and likely ending as snow even in valley areas. Best chances for accumulations will be higher elevations of SW VA and the central/northern mountains of E TN, where 2 to 4 inches looks likely and localized higher amounts cannot be ruled out. The northern plateau higher peaks may also see an inch or two, while northern into central TN valley areas look to be around an inch or less. It is still early, so these amounts are likely to be adjusted further. Since it will be primarily a period 3 event will not issue the winter weather advisory yet, but likely to end up needing one at least higher elevations. Will keep mention in HWO for now. Link to comment Share on other sites More sharing options...
ShawnEastTN Posted January 31, 2018 Share Posted January 31, 2018 GFS looks a bit more robut with the first system and a degree or 2 cooler, and better accumulating snow than 12Z. Link to comment Share on other sites More sharing options...
John1122 Posted January 31, 2018 Author Share Posted January 31, 2018 The RGEM is all in too. Gives my area 3-4 inches. The NAM 12k does as well and the 3k gives the area 1-3 inches too. So all the higher res short term models are moving on board at this point. Link to comment Share on other sites More sharing options...
Greyhound Posted January 31, 2018 Share Posted January 31, 2018 MRX graphic on the Thursday/Friday systemSent from my XT1585 using Tapatalk Link to comment Share on other sites More sharing options...
Greyhound Posted February 1, 2018 Share Posted February 1, 2018 Robert Gamble (WxSouth) thoughts:Tomorrow brings a rapid change in the weather for TN, KY and then into West Virginia and the NC mountains overnight, with rain turning to snow very quickly. A few inches pile up in southeast Kentucky, northeast Tennessee and West Virginia down to the mountains of NC north of Asheville mainly. The more important thing may be the fact that all of that fast falling moisture along and just west of the mountains will become a frozen brick by Friday morning, affecting your drive, as temps are in the teens or low 20s there. So snow , plus frozen rain (ICE) will create havoc on the ground.Rain showers may end as brief snow in eastern VA and NC as well, but not amount to much there.Then, the next system which is much bigger but is proving to be a major headache to forecast. I have both storms covered in my updates tonight for subscribers.Sent from my XT1585 using Tapatalk Link to comment Share on other sites More sharing options...
Greyhound Posted February 1, 2018 Share Posted February 1, 2018 Latest SREF plumes have 2.67 average for Knoxville and a 2.81 average for Tri-Cities. And .78 average for our Chattanooga friends.Sent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
Wurbus Posted February 1, 2018 Share Posted February 1, 2018 11 minutes ago, Greyhound said: Latest SREF plumes have 2.67 average for Knoxville and a 2.81 average for Tri-Cities. And .78 average for our Chattanooga friends. Sent from my iPad using Tapatalk I just noticed this. The last 4 runs for Knoxville has been kinda crazy. 03 - Average .43 Big dog 2.66 09 - Average .17 Big dog 1.19 15 - Average 1.53 Big dog 6.21 21 - Average 2.67 Big dog 2 @ 6.5 The 00z Nam looks to be about the same as the 18z. Good trends on this system and maybe folks Knoxville north can squeeze out something. Link to comment Share on other sites More sharing options...
Stovepipe Posted February 1, 2018 Share Posted February 1, 2018 14 minutes ago, Greyhound said: Latest SREF plumes have 2.67 average for Knoxville and a 2.81 average for Tri-Cities. And .78 average for our Chattanooga friends. Sent from my iPad using Tapatalk It's interesting if you pull up two windows and look at the Total-SNO and 3hrly-TMP together. It's all about how fast those temps crash and there is a decent amount of spread. It's good to see the mean is up significantly. Link to comment Share on other sites More sharing options...
John1122 Posted February 1, 2018 Author Share Posted February 1, 2018 The RGEM and NAM12k and 3k once again bring the 1-3 inch range across the area from 40 north in Eastern Tennessee. It's going to be very close between heavy rain and heavy wet snow. I wish we all had an extra 1000 feet in elevation. Link to comment Share on other sites More sharing options...
John1122 Posted February 1, 2018 Author Share Posted February 1, 2018 The Canadian joins the NAM suite and RGEM and even gives Nashville a little love. Link to comment Share on other sites More sharing options...
kvskelton Posted February 1, 2018 Share Posted February 1, 2018 MRX reminding us that travelling might be a bit dicey this time tomorrow in parts of eastern TN: Special Weather Statement National Weather Service Morristown TN 313 AM EST Thu Feb 1 2018 313 AM EST Thu Feb 1 2018 /213 AM CST Thu Feb 1 2018/ ...AREAS OF SNOW TONIGHT... Rain will spread across the Southern Appalachian Region today as a cold front moves into the area. With cooler air moving in behind the front...the rain will transition to snow this evening. The Chattanooga area could see a dusting to a few tenths of an inch of snow overnight. The Cumberland Plateau, Knoxville and Tri-Cities and surrounding areas as well as extreme Southwest North Carolina can expect a half inch to around an inch and a half of snow accumulation. With the daytime rainfall, temperatures falling below freezing tonight and accumulating snow...area roads may become slick, especially during the morning commute. If you will be traveling on area roads tonight or Friday morning, be prepared for icy or snow covered roads. Link to comment Share on other sites More sharing options...
ShawnEastTN Posted February 1, 2018 Share Posted February 1, 2018 SREF Plumes have jumped even higher this morning. TYS up to 3.09" mean, TRI 3.11", BNA 1.89", LOZ, 3.12" CHA .87", all with Big Dogs around and above 7", with the exception of Chatt with a big dog around 4". Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 1, 2018 Share Posted February 1, 2018 Still having a difficult time buying this setup...cold chasing rain is usually heartbreak city. But, here is the TRI SREF plume. Link to comment Share on other sites More sharing options...
1234snow Posted February 1, 2018 Share Posted February 1, 2018 Still having a difficult time buying this setup...cold chasing rain is usually heartbreak city. But, here is the TRI SREF plume. Look like a tight cluster around 2” with a big outlier at 7 inches that is skewing the mean a little bit. I have always thought the SREF means were always a little beefy. MRX has a WWA out for me for 2-4” but I would reserve the 4” for places like High Knob. Link to comment Share on other sites More sharing options...
kvskelton Posted February 1, 2018 Share Posted February 1, 2018 1 hour ago, 1234snow said: Look like a tight cluster around 2” with a big outlier at 7 inches that is skewing the mean a little bit. I have always thought the SREF means were always a little beefy. MRX has a WWA out for me for 2-4” but I would reserve the 4” for places like High Knob. MRX has expanded the WWA into TRI now. Calling for 1-2" for us. Link to comment Share on other sites More sharing options...
ShawnEastTN Posted February 1, 2018 Share Posted February 1, 2018 MRX mid morning update referencing what KVSkelton mentions, and also pointing to how tricky this is they are still uncertain on change over pace. Interesting mid morning update, don't get these that often from MRX. I have a feeling by afternoon updates we may see some WWA further down the valley, at least central valley locations by this evening. Quote .DISCUSSION...Strong southwesterly winds this morning is pulling warmer air into the region. Temperatures are already climbing through the 40s. Have upped high temperature for most of the location. Very strong 300mb jet of nearly a 170kts will move across the Ohio Valley later today and tonight. This is an abnormally strong upper jet with the upper forcing associated with the right entrance region quite strong. This jet forcing will quickly strengthen the frontal-genetic along a boundary moving southeast into Kentucky. Models continue to show strengthening fronto-genetic forcing rapidly developing precipitation over kentucky this afternoon, then moving into the area by late afternoon and evening. The precipitation type is the tricky part as initially the boundary layer temperatures will be relatively warm, but strong diabatic cooling due to the strong forcing will quickly cool the vertical column. A fairly quick change over from rain to snow will occur this evening. The questions are the following: 1) How fast will the change over occur? 2) How fast will snow accumulate after transition? 3) How long will accumulating snowfall last? 4) Snow will initially accumulate on the grassy areas, but how soon on the roadways? After looking at new NAM/RAP runs and SPC SREF snowfall plumes have decided to extend the advisory to the Plateau and northeast Tennessee for now. Link to comment Share on other sites More sharing options...
Vol Man Posted February 1, 2018 Share Posted February 1, 2018 So, it we do end up with a couple of inches from the first event, and we stay in low 30s tomorrow and get a good frozen base over night, how will that actually affect the snow to rain to snow sequence on Sunday? I'm guessing the models would not have the capability to pick up on any effect from that? Also....agree with Carvers, Nut, KV and others...great to see more posters here...seems like this maybe the most I've seen active. A little snow brings out the kid in all of us! :-) Link to comment Share on other sites More sharing options...
jaxjagman Posted February 1, 2018 Share Posted February 1, 2018 11 hours ago, John1122 said: The Canadian joins the NAM suite and RGEM and even gives Nashville a little love. Thanks for the map,unfortunate tho the surface temps will steal a big chunk of that,plus looking at the short range it might last 1-2 hours depending on how fast the cold gets in.If we get a dusting i'd consider it a win,right now. Link to comment Share on other sites More sharing options...
Wurbus Posted February 1, 2018 Share Posted February 1, 2018 29 minutes ago, Vol Man said: So, it we do end up with a couple of inches from the first event, and we stay in low 30s tomorrow and get a good frozen base over night, how will that actually affect the snow to rain to snow sequence on Sunday? I'm guessing the models would not have the capability to pick up on any effect from that? Also....agree with Carvers, Nut, KV and others...great to see more posters here...seems like this maybe the most I've seen active. A little snow brings out the kid in all of us! :-) If the low pressure ends up in northern Ohio, I don't think it matters. Looks like it's going to be too warm on Sunday for most of us at this point. Link to comment Share on other sites More sharing options...
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