Carvers Gap Posted February 12, 2014 Share Posted February 12, 2014 The 12z GFS has jogged east a smidgeon, but it does NOT even remotely resemble the radar returns over TN during the early part of its run. In other words, does not appear it is modeling the northwest quadrant correctly. Link to comment Share on other sites More sharing options...
BrianP Posted February 12, 2014 Share Posted February 12, 2014 What's falling up 75 above sweetwater? Link to comment Share on other sites More sharing options...
Vol4Life Posted February 12, 2014 Share Posted February 12, 2014 NWS is going all in...just updated WSW for 5-9 inches in Knox and surrounding areas Link to comment Share on other sites More sharing options...
Seabeejason Posted February 12, 2014 Share Posted February 12, 2014 000 FXUS64 KMRX 121623 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 1123 AM EST WED FEB 12 2014 From MRX at 11:23AM: ".DISCUSSION...EXTENDED EXPIRATION TIMES IN WINTER STORM WARNING INTO THURSDAY AFTERNOON. LOW TRACK HUGGING COASTLINE THURSDAY WITH NEGATIVELY TILTING UPPER TROUGH OVER SOUTHERN APPALACHIANS KEEPS SNOWFALL GOING A FEW HOURS LONGER ACROSS EASTERN AND MAINLY NE AREAS ON THURSDAY. RAISED SNOWFALL AMOUNTS SLIGHTLY FOR ADDITIONAL THURSDAY SNOW. ADJUSTED SNOW AMOUNTS UPWARD TODAY ACROSS SOUTHERN AREAS THIS AFTERNOON." Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 12, 2014 Share Posted February 12, 2014 Latest full run of the RAP....15 UTC. Looks like it is modeling a prolonged period of snow in the eastern valley. Low pressure deepens just inside Hatteras and goes boom.....Rare air. Enjoy the ride everyone. Radars filling in... QPF(and not over yet) Picture Perfect... Link to comment Share on other sites More sharing options...
zippity Posted February 12, 2014 Share Posted February 12, 2014 Here's a local met's explanation of why temps are 36F and a changeover has not happened yet in north AL: https://m.facebook.com/pages/Jeff-Castle-WAFF-48-Meteorologist/157575714314392?id=157575714314392&_rdr Basically, UAH sent up a weather balloon this morning, and found we have 1500 ft of 36-37F air, so while a chageover will occur, north AL is not expected to get as much as predicted. The map he posted still said 4 inches, but I don't know if this was a new or old map. Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 12, 2014 Share Posted February 12, 2014 The 16 UTC RAP is absolutely an epic run. Sets up the outside bands of the comma head over E TN and just turns on the fire hose. Pretty incredible. Hope it verifies. If you haven't had a chance to look at this model, here you go... Click it! Link to comment Share on other sites More sharing options...
nrgjeff Posted February 12, 2014 Share Posted February 12, 2014 Keep calm HSV and CHA; this was supposed to happen at lunch time. It will go back to snow early this afternoon in CHA and around mid-afternoon in HSV. I'm going to defer to John about BNA. Mr. Bob probably explained it better than me; and, lots of other posts have addressed the downslope issue. It is not as bad Maryville north due to the orientation of the Valley. Northeast winds put CHA in the lee of the Smokies; Knox is on the side of that downslop plume, rather than in it. Today the Plateau is playing havoc farther west too. What giveth in NW flow, taketh away with the opposite wind direction. Should go to snow later this afternoon that way, but like I said John probably has better local knowledge than me. I'll focus on the literal Tennessee River Valley. HSV temps are victim more to the Lower Plateau than the Smokies but comma head looks to push North Alabama back to snow. CHA will switch over before HSV since cold air is deeper here. MRX says it is 6,000 FT thick, which should mitigate too much downslope. Should. Even if it is trying to mix right now, after 18Z more northerly winds should turn the tide in favor of the cold. If I'm wrong, at least we have an inch on the ground. Knoxville is absolutely golden, deeper cold airmass. You are above freezing right now but your web bulb should settle below 32; remember, it is a moving target. That 6,000 FT deep cold layer should hold just fine up there. TRI be patient; it is coming! Never really believed those modest totals by models 24-36 hours ago. Pattern recognition; TRI will get heavy snow - at least heavier than TYS. RGEM (Environment Canada NWP) did in fact hit the precip shield well. It also got that 18Z warming at 850 HSV-CHA. No problem. All NWP have 850 Ts and thicknesses dropping off by mid-afternoon. CHA-HSV will lose a couple tenths QPF on liquid and sleet, but the majority of QPF is scheduled after 21Z. It was always forecast that way; light in the morning and more late afternoon. As I'm typing a new post regarding HSV came in. Thank you UAH for releasing that balloon. Pls consider that too from their local knowledge. Otherwise this winter storm is behaving and going as planned. I like NWS totals from the WFOs, even things verify on the low side of the ranges. Comma head will create local verification on the high side. Looking good. Enjoy! Link to comment Share on other sites More sharing options...
Tabbycat Posted February 12, 2014 Share Posted February 12, 2014 MRX has light snow from TYS, I guess? edit - It's hit West Knox! Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 12, 2014 Share Posted February 12, 2014 Keep calm HSV and CHA; this was supposed to happen at lunch time. It will go back to snow early this afternoon in CHA and around mid-afternoon in HSV. I'm going to defer to John about BNA. Mr. Bob probably explained it better than me; and, lots of other posts have addressed the downslope issue. It is not as bad Maryville north due to the orientation of the Valley. Northeast winds put CHA in the lee of the Smokies; Knox is on the side of that downslop plume, rather than in it. Today the Plateau is playing havoc farther west too. What giveth in NW flow, taketh away with the opposite wind direction. Should go to snow later this afternoon that way, but like I said John probably has better local knowledge than me. I'll focus on the literal Tennessee River Valley. HSV temps are victim more to the Lower Plateau than the Smokies but comma head looks to push North Alabama back to snow. CHA will switch over before HSV since cold air is deeper here. MRX says it is 6,000 FT thick, which should mitigate too much downslope. Should. Even if it is trying to mix right now, after 18Z more northerly winds should turn the tide in favor of the cold. If I'm wrong, at least we have an inch on the ground. Knoxville is absolutely golden, deeper cold airmass. You are above freezing right now but your web bulb should settle below 32; remember, it is a moving target. That 6,000 FT deep cold layer should hold just fine up there. TRI be patient; it is coming! Never really believed those modest totals by models 24-36 hours ago. Pattern recognition; TRI will get heavy snow - at least heavier than TYS. RGEM (Environment Canada NWP) did in fact hit the precip shield well. It also got that 18Z warming at 850 HSV-CHA. No problem. All NWP have 850 Ts and thicknesses dropping off by mid-afternoon. CHA-HSV will lose a couple tenths QPF on liquid and sleet, but the majority of QPF is scheduled after 21Z. It was always forecast that way; light in the morning and more late afternoon. As I'm typing a new post regarding HSV came in. Thank you UAH for releasing that balloon. Pls consider that too from their local knowledge. Otherwise this winter storm is behaving and going as planned. I like NWS totals from the WFOs, even things verify on the low side of the ranges. Comma head will create local verification on the high side. Looking good. Enjoy! So, Jeff, you feel the models were on the light side 24-36 hrs ago for TRI when you say modest OR do you mean the modest totals forecast for this afternoon were inaccurate? I am assuming you mean the NAM and GFS...Anyway, great write-up as usual. All systems go. Link to comment Share on other sites More sharing options...
liltwilite2011 Posted February 12, 2014 Share Posted February 12, 2014 Light snow in northwest Knoxville, Karns area. Link to comment Share on other sites More sharing options...
zippity Posted February 12, 2014 Share Posted February 12, 2014 Thank you, Jeff; extremely helpful explanation! (Sorry to banter, but thought a thank you was in order). Link to comment Share on other sites More sharing options...
Tabbycat Posted February 12, 2014 Share Posted February 12, 2014 I don't trust the Weather Channel, but they just showed the Tri-Cities easily in their 12 inch circle. Easy by a good bit. Link to comment Share on other sites More sharing options...
Silas Lang Posted February 12, 2014 Share Posted February 12, 2014 Tabbycat, If its supposed to snow for a long period of time, I believe it. Everything is already white here in Johnson City and its only been going for a little over an hour. Link to comment Share on other sites More sharing options...
1234snow Posted February 12, 2014 Share Posted February 12, 2014 The 17z RAP closes this off by 2 CONTOURS at the end of the run at 500mb! This is a perfect position for east TN. I really like how this storm is coming together. Someone will see 1-2" per hour rates in the deform band tonight when it closes off. I willing to say that we could wake up in the morning with snow still falling (if you go to sleep!). Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 12, 2014 Share Posted February 12, 2014 A video from MRX. Outstanding. Link to comment Share on other sites More sharing options...
Reb Posted February 12, 2014 Share Posted February 12, 2014 also from MRX We've been getting reports of a mix of rain, snow, and sleet around Chattanooga and Cleveland. The image below shows what that transition area looks like on our radar, taken from early this afternoon. The product is called "correlation coefficient", and tells us whether precipitation is mixed sizes or a uniform size. The white line is the transition area from rain (yellow and orange colors) to snow (purple colors). Your reports help us to better know that what we're seeing on radar is really happening at the ground. Link to comment Share on other sites More sharing options...
ChattChaser Posted February 12, 2014 Share Posted February 12, 2014 also from MRX 2 of those reports were mine lol Link to comment Share on other sites More sharing options...
WinterWonderland Posted February 12, 2014 Share Posted February 12, 2014 Finally seeing snow in Oak Ridge. Snowing nicely right now! Link to comment Share on other sites More sharing options...
tnweathernut Posted February 12, 2014 Share Posted February 12, 2014 9z sref mean for KTRI is 9.5 inches For TYS it was over 7 Link to comment Share on other sites More sharing options...
dwagner88 Posted February 12, 2014 Share Posted February 12, 2014 Wasted 0.10 of our qpf as rain, and it still can't change over. How depressing. Apparently the cutoff is the Hamilton county line. A coworker confirmed that it is snowing and starting to stick in Cleveland. Link to comment Share on other sites More sharing options...
ChattChaser Posted February 12, 2014 Share Posted February 12, 2014 Yeah I'm really starting too wonder if it's going to happen. It's basically been sleet for the last hour here in north Chattanooga Link to comment Share on other sites More sharing options...
1234snow Posted February 12, 2014 Share Posted February 12, 2014 18z HRRR shows a lull after this 1st band comes through but then everything fills back in. This model seems to be handling the radar very well. Link to comment Share on other sites More sharing options...
Tabbycat Posted February 12, 2014 Share Posted February 12, 2014 Euro discussion from the SE Forum. Some said the low would go off the coast, but Hurricane Tracker, a Met says not so - it'll go up the coastal plain of SC and then through Pamlico, NC. I haven't checked a map yet, but we need him to be right, right? Pamlico is on the main part of NC, not the Outer Banks, so I assume that helps. Link to comment Share on other sites More sharing options...
Mr Bob Posted February 12, 2014 Share Posted February 12, 2014 Just have to say that this was not unexpected. Temps were marginal on the models all afternoon leading into the event. Despite the clouds, insolation still does its work. If it precipitated hard enough it could over come but we also knew that was not the case. As the storm really explodes and the low wraps up and our 500 low forms expect the temperatures to drop and everything to go back to snow. There will still be good amounts...perhaps not epic but there should be a good period of heavier snow even in Chatt this evening. Link to comment Share on other sites More sharing options...
saltslugs Posted February 12, 2014 Share Posted February 12, 2014 From rain to moderate sleet/snow mix in Dalton. First wintry precip since around 9 this morning. Sending it your way, Chatty! Link to comment Share on other sites More sharing options...
Carvers Gap Posted February 12, 2014 Share Posted February 12, 2014 18z HRRR shows a lull after this 1st band comes through but then everything fills back in. This model seems to be handling the radar very well. I am rolling w/ the RAP. It is just about the only short-range model that correctly handled the precip in TN today. There may be a lull between bands, but I would guess the evening unfolds in a RGEM/Euro/RAP way. Those models have done the heavy lifting this week. The Euro ruled the roost on this one. The NAM and GFS have struggled IMO up to this point. Link to comment Share on other sites More sharing options...
Tabbycat Posted February 12, 2014 Share Posted February 12, 2014 Mr. Bob "this was not unexpected" meaning Chatt, or all of East TN? Link to comment Share on other sites More sharing options...
valkhorn Posted February 12, 2014 Share Posted February 12, 2014 Mr. Bob "this was not unexpected" meaning Chatt, or all of East TN? I'm wondering because it's been all snow at my house in Knoxville, and the ground is coated white. Link to comment Share on other sites More sharing options...
Mr Bob Posted February 12, 2014 Share Posted February 12, 2014 any place really in the "Great Valley" except apparently up near KTRI....even MRX had highs in the mid 30s for TYS and CHA. Link to comment Share on other sites More sharing options...
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