PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 You're not missing anything, as far as I can tell. That's why I said it looks more like wet snow, than what the NAM was depicting as rain. Actually what I missed was not looking to see where we went -0c and it looks to be no higher/lower than 850mb. You’re right, definitely wet snow. . Link to comment Share on other sites More sharing options...
PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 With the last system, this area got lucky with accumulations because we spent several hours below freezing before precip started. This will not be the case for this system. I predict a RN/SN mix with no accumulation for the valley south of 40, light accumulations in the grassy areas above 1500'. Knoxville was 25ish that morning and it didn’t stick to the main roads. Bridges and off/on ramps became pretty bad but that was with only around an inch of snow. That being said, it’s never crossed my mind even at 2-3” that this snow would stick to the roads. Maybe the shaded areas. . Link to comment Share on other sites More sharing options...
nrgjeff Posted February 19, 2020 Share Posted February 19, 2020 Now that I'm briefing people at work, time to get serious. Unfortunately I'm afraid @dwagner88 is correct on the previous page regarding warmer surface temps compared to Saturday Surprise 8 Feb. My concern is actually just the opposite of MRX. They go cold enough to start as snow, changing to rain. I'm thinking, stays warmer overnight than forecast due to increasing clouds. Building HP might help; but, I don't know. We're talking about the southeast the Tennessee Valley in southeast Tenn, lol! Enough precipitation starting as virga and evaporative cooling could actually bring down temps after it starts. One would hope for that inverted trough to back winds closer to north. Again the trough is not shown in isobars, just a hint in surface wind fields. It's not the 2014 or 2015 storms. Finally while the track, thickness lines and even progged radar have similarities to Surprise Saturday, the system is quite different. Saturday was a tight feisty little thing. This is a lumbering wave. True it's just right (greater than post-frontal junk, less than WAA beast) it's still a lot different. I'm sorry my optimism is fading. Head is going with MRX. OHX also concerned about temps. Heart is of course going with bullish GFS runs! Oh, and the 12Z NAM, hello. Cage Match thread title is just epic! Probably the best in our sub-forum all-time. So I have to add this meme. When snow misses Jayhawks, we go all WWE! 1 2 Link to comment Share on other sites More sharing options...
John1122 Posted February 19, 2020 Share Posted February 19, 2020 The NAM is definitely determined. The weak gulf low is a classic moisture pump that normally avoids a raging warm nose. A big H in Iowa with a weak surface reflection near the gulf is snow event 101 here. The million dollar question as always, is the NAM correct? 5 Link to comment Share on other sites More sharing options...
PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 Now that I'm briefing people at work, time to get serious. Unfortunately I'm afraid [mention=1313]dwagner88[/mention] is correct on the previous page regarding warmer surface temps compared to Saturday Surprise 8 Feb. My concern is actually just the opposite of MRX. They go cold enough to start as snow, changing to rain. I'm thinking, stays warmer overnight than forecast due to increasing clouds. Building HP might help; but, I don't know. We're talking about the southeast the Tennessee Valley in southeast Tenn, lol! Enough precipitation starting as virga and evaporative cooling could actually bring down temps after it starts. One would hope for that inverted trough to back winds closer to north. Again the trough is not shown in isobars, just a hint in surface wind fields. It's not the 2014 or 2015 storms. Finally while the track, thickness lines and even progged radar have similarities to Surprise Saturday, the system is quite different. Saturday was a tight feisty little thing. This is a lumbering wave. True it's just right (greater than post-frontal junk, less than WAA beast) it's still a lot different. I'm sorry my optimism is fading. Head is going with MRX. OHX also concerned about temps. Heart is of course going with bullish GFS runs! Oh, and the 12Z NAM, hello. Cage Match thread title is just epic! Probably the best in our sub-forum all-time. So I have to add this meme. When snow misses Jayhawks, we go all WWE! The GFS is showing rain at this point but this looks like snow. Also it looks like the winds are N/NE down to the surface. Am I reading this right? 0c is down to 950. Isn’t that low enough? . 1 1 Link to comment Share on other sites More sharing options...
tnweathernut Posted February 19, 2020 Share Posted February 19, 2020 42 minutes ago, John1122 said: The NAM is definitely determined. The weak gulf low is a classic moisture pump that normally avoids a raging warm nose. A big H in Iowa with a weak surface reflection near the gulf is snow event 101 here. The million dollar question as always, is the NAM correct? Always a concern as to whether it's right or not, but we are in a time period where we are no longer talking about the NAM at LR. At the same time, other modeling has moved steadily toward what the NAM has had all along. It's probably overdone on amounts, but then again............when is it not? 1 Link to comment Share on other sites More sharing options...
PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 Always a concern as to whether it's right or not, but we are in a time period where we are no longer talking about the NAM at LR. At the same time, other modeling has moved steadily toward what the NAM has had all along. It's probably overdone on amounts, but then again............when is it not?3k NAM is really close to the GFS. One says snow, one says rain. . Link to comment Share on other sites More sharing options...
tnweathernut Posted February 19, 2020 Share Posted February 19, 2020 Just now, PowellVolz said: 3k NAM is really close to the GFS. One says snow, one says rain. It looks more marginal than the last system for areas south of 40. North of 40 it seems to be a better profile, but more concerns about amount of precip. As with almost all SE snow possibilities, there are factors for us all to overcome... lol 1 Link to comment Share on other sites More sharing options...
PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 It looks more marginal than the last system for areas south of 40. North of 40 it seems to be a better profile, but more concerns about amount of precip. As with almost all SE snow possibilities, there are factors for us all to overcome... lolNothing close to a slam dunk and I’m sure that’s why MRX is going safe. . Link to comment Share on other sites More sharing options...
John1122 Posted February 19, 2020 Share Posted February 19, 2020 The RGEM still wasn't much but it was quite a bit more North and West with precip. 2 Link to comment Share on other sites More sharing options...
John1122 Posted February 19, 2020 Share Posted February 19, 2020 The biggest plus for the NAM regarding precip type is two fold, moisture arrives earlier and its heavier. The GFS is much warmer because it only has light precip. Early arriving moisture is usually a hallmark of overrunning events. 2 Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 19, 2020 Author Share Posted February 19, 2020 Nice chilly ENE to NE down valley wind here in Oak Ridge 5 - 10mph It’s got a good feel to it. 2 Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 19, 2020 Share Posted February 19, 2020 1 hour ago, nrgjeff said: Now that I'm briefing people at work, time to get serious. Unfortunately I'm afraid @dwagner88 is correct on the previous page regarding warmer surface temps compared to Saturday Surprise 8 Feb. My concern is actually just the opposite of MRX. They go cold enough to start as snow, changing to rain. I'm thinking, stays warmer overnight than forecast due to increasing clouds. Building HP might help; but, I don't know. We're talking about the southeast the Tennessee Valley in southeast Tenn, lol! Enough precipitation starting as virga and evaporative cooling could actually bring down temps after it starts. One would hope for that inverted trough to back winds closer to north. Again the trough is not shown in isobars, just a hint in surface wind fields. It's not the 2014 or 2015 storms. Finally while the track, thickness lines and even progged radar have similarities to Surprise Saturday, the system is quite different. Saturday was a tight feisty little thing. This is a lumbering wave. True it's just right (greater than post-frontal junk, less than WAA beast) it's still a lot different. I'm sorry my optimism is fading. Head is going with MRX. OHX also concerned about temps. Heart is of course going with bullish GFS runs! Oh, and the 12Z NAM, hello. Cage Match thread title is just epic! Probably the best in our sub-forum all-time. So I have to add this meme. When snow misses Jayhawks, we go all WWE! @Holston_River_Rambler has shown himself to be a master thread namer. 3 1 Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 19, 2020 Share Posted February 19, 2020 39 minutes ago, John1122 said: The RGEM still wasn't much but it was quite a bit more North and West with precip. This is true. Great little short range model. Still not a big hit, but I though about a 100-125 mile jog to the Northwest. Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 19, 2020 Share Posted February 19, 2020 Time of day is a big deal at this time of year. Agree with those mentioning that. I also agree with John about true overrunning events arriving early. These types of systems are just pain in the butt to forecast though. Late winter/early spring storms usually have a card or two up their sleeves. For future reference, it has come north quite a bit to where it almost where it was originally forecast. So, need to file that away from any potential future windows. LR modeling after this event is not exactly benign. So, we probably need to learn as much as we can from this one as there may be more like it. I suspect this has the potential to continue to track northward right up to verification with some hiccups at times. I originally thought it would stop. Looks like it paused and is trending north again. That tells us that we need systems tracing south of Birmingham(at 5-6 days) to have a chance in this situation at this time of year. But the great thing about this thread and others, so many great contributors both new and old. I say it all the time, that is my favorite part of these events - just seeing the growth of this forum. This subform began with a handful of patrons. Still plenty of room to grow, but I think this is what we envisioned when we first started kicking this around years ago. The Tennessee Valley region IMHO is incredibly difficult to figure out because it has so many unique nuances, regions, and micro-climates. We aren't really the Plains and we really don't have a true EC climate. These systems leave the Rockies and roll 1,500 miles over flat land and then slam into the Plateau, the Smokies, and roll over the TN river twice. (not forgetting about the Ozarks, Arkansas folks...they count as well). I say this often, our weather is impacted by the Pacific, Great Lakes, GOM, and Atlantic. Not many places can say that. Things can and do get wild. Anyway, again just glad to see all of the interaction. 1 2 Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 19, 2020 Share Posted February 19, 2020 Is the GFS running slow? Link to comment Share on other sites More sharing options...
snowmaker Posted February 19, 2020 Share Posted February 19, 2020 1 minute ago, Carvers Gap said: Is the GFS running slow? Yep, just now out to 18. Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 19, 2020 Share Posted February 19, 2020 6 minutes ago, snowmaker said: Yep, just now out to 18. Wonder if they are having data problems? Link to comment Share on other sites More sharing options...
PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 Wonder if they are having data problems?In this case the only likely outcome would be 8 to 10” of snow CWA . Link to comment Share on other sites More sharing options...
PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 MRX going with a WWA for the mountains . Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 19, 2020 Author Share Posted February 19, 2020 @Carvers Gap SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD 1620Z WED FEB 19 2020 NCO is working to recover a WCOSS dissemination issue causing current model data to be delayed. Liddick/SDM/NCO/NCEP Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 19, 2020 Author Share Posted February 19, 2020 WCOSS means weather and climate operational supercomputing system Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 19, 2020 Author Share Posted February 19, 2020 UKMET was the furthest north its been, but the eastern valley seem to have gotten warm nosed: going to look at the soundings on pivotal Link to comment Share on other sites More sharing options...
PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 MRX starting to change their stance on this. Even saying they believe the temp profiles on the mods are to high. “Went ahead and issued a Winter Weather Advisory for the mountainswhere confidence in increasing for some impactful snowaccumulations on Thursday. Across mountain areas wheretemperatures will be below freezing, total accumulations areexpected to be between 2 to 4 inches with locally higher amountsabove 4000 feet.For lower elevations of the valley and plateau, confidence isstill significantly lower. Anticipate temperatures to be lower than much of current guidance suggests with strong dynamic lift within the right-entrance region of a strong upper jet. Saturationis present through the DGZ, and the thermal profile should support snow for much of the area, including valley locations. However, with much of the snow forecast to occur during the middleof the day, and the increased sun angle in late February, expect it will be difficult to accumulate much of the snow. For this reason, current forecast shows that most accumulations outside ofthe mountains will be light and limited to mainly grassy surfaces. Most snow will likely melt on contact. Do not expect many impacts to travel across lower elevations with the exception of reduced visibility and potential slick spots if snow rates are heavier than anticipated for a short period of time”. Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 19, 2020 Author Share Posted February 19, 2020 Hard to see on the gif, but it has 37 at the surface around Knoxville Looks similar to NAM 3k sounding Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 19, 2020 Share Posted February 19, 2020 45 minutes ago, PowellVolz said: In this case the only likely outcome would be 8 to 10” of snow CWA . CWA? Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 19, 2020 Share Posted February 19, 2020 54 minutes ago, Holston_River_Rambler said: @Carvers Gap SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD 1620Z WED FEB 19 2020 NCO is working to recover a WCOSS dissemination issue causing current model data to be delayed. Liddick/SDM/NCO/NCEP Sounds like their supercomputer lost its ability to speak to everyone else for a bit. LOL. Welp... Link to comment Share on other sites More sharing options...
PowellVolz Posted February 19, 2020 Share Posted February 19, 2020 CWA?MRX’s region is what I was getting at. Where most of us live. I was being silly. . 1 Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 19, 2020 Share Posted February 19, 2020 Just now, PowellVolz said: MRX’s region is what I was getting at. Where most of us live. I was being silly. . LOL. I understand it now...I was like, what airport code is CWA? Figured it was a joke, just didn't get the acronym. As an airport code, it is still funny. Our system is basically going to go to central Wisconsin... 2 Link to comment Share on other sites More sharing options...
TellicoWx Posted February 19, 2020 Share Posted February 19, 2020 Euro folds to NAM 3 Link to comment Share on other sites More sharing options...
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