Carvers Gap

Euro Weeklies look good. Control builds a glacier over NE TN, SW VA, And WNC. Pattern transitions between the 8th and 12th. Looks really good.

Criteria will likely be met. Yep.

All of it...why not. Sounds like Fairbanks, Alaska. FXUS64 KMRX 222054 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 354 PM EST Thu Dec 22 2022 ...New SHORT TERM, LONG TERM... .SHORT TERM... (This evening through Friday) Issued at 240 PM EST Thu Dec 22 2022 Key Messages: 1. A powerful arctic cold front arrives tonight, along with strong winds that will drop wind chills to unprecedented and dangerous lows. Power outages due to the high winds will be a concern late tonight and possibly Friday. 2. Rain will quickly change to snow after midnight, and with the rapid temperature drop, flash freezing of any moisture on roads will cause hazardous travel at least through Friday. Discussion: For tonight, anomaly strong 300mb jet of 170kt+ will move across the Tennessee valley overnight with the left exit region of the jet enhancing the fronto-genetic lift along a strong arctic boundary. A band of precipitation will move east across the region along this arctic boundary. NAEFS shows how much of an anomaly with the cold air with 850mb temperatures near historical values. The very cold air will quickly change the rain to snow. The limiting factor will be the strong downslope across the western valley off the Plateau. HREF shows this precipitation shadow quite well so having much lower snowfall over the western half of the valley makes sense. The band restrengthens over the eastern half of the valley (essentially along and east of interstate 40/81. Greatest snow accumulations of 1 to 2 inches there with the highest amounts of 3 to possibly 4 inches across the far east Tennessee Mountains. Main concern is the brutal arctic airmass and strong pressure gradients behind the front producing dangerous wind chills of 15 to 20 below zero in the valley and 30 to possibly 40 below zero in the high elevations late tonight through Friday night. Again, these are historical values that seldom occur across the area, and are life threatening to anyone not prepared. Also, a concern is the strong westerly winds along and behind the Arctic front. Westerly winds will increase to 20 to 30 mph with gusts up to 50 mph. Due to enhanced flow off the Plateau, HREF, HRRR, and WRF are showing the highest winds from Claiborne, Anderson, Roane, Rhea, and possibly western section of Hamilton county. These winds will likely produce Power Outages which is very concerning given the dangerous wind chills. For Friday, main snow band moves east but cold arctic air will likely continue chances of flurries over much of the area with temperatures struggling to rise into the teens. Dangerous wind chills area-wide. && .LONG TERM... (Friday night through next Thursday) Issued at 240 PM EST Thu Dec 22 2022 1. Historic, dangerous cold and wind chills will continue into Christmas Eve with record low high temperatures expected. Flurries or even light snow showers will also linger. 2. A slow but gradual warming trend will take place Christmas onward with temperatures near normal by mid-week. Friday Night through Sunday At the start of the period, the long-awaited historic cold event will be underway in the entire eastern U.S. The initial conditions will include deep upper troughing and the surface low near 970mb just north of the eastern Great Lakes. A strong MSLP gradient, record-breaking 850mb temperatures below -20 Celsius, and 850mb flow of 30+ kts will keep the continued concern for extreme cold, including wind chills overnight Friday. A Wind Chill Warning will remain in effect for the entire region with no changes anticipated. As such, travel concerns will linger into Saturday for remaining ice/snow on untreated roadways. For Friday night and Saturday, trended toward more cloud cover and chance of flurries. NBM typically underperforms in cold air advection stratus clouds and GFS is showing boundary layer moisture lasting a lot longer. Based on the forecasted values, Christmas Eve low maximum temperature records temperature records will likely be in jeopardy with record low temperatures to be nearly broken as well. The values are as follows with the most recent year of occurrence: Christmas Eve Low Maximum Temperature Records Chattanooga Knoxville Tri-Cities Oak Ridge 24(1983) 24(1989) 19(1989) 23(1983) Christmas Eve Low Temperature Records Chattanooga Knoxville Tri-Cities Oak Ridge 2(1983) -2(1983) -3(1989) -2(1983) A general weakening of the LLJ and MSLP gradient will certainly allow for wind chills to gradually rise above the double-digit negative values but will still remain of significant concern into much of the day. Heading towards Christmas Day, height rises and subtle, but still present WAA will support some recovery of temperatures from the previous two days. However, indications are for the region to still remain below freezing for the day.

And Memphis...KY video is listed above. Feel free to add your local NWS office afternoon discos for posterity. ...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 6 AM CST FRIDAY... ...WIND CHILL WARNING REMAINS IN EFFECT FROM 6 PM THIS EVENING TO NOON CST FRIDAY... * WHAT...For the Wind Chill Warning, dangerously cold wind chills expected. Wind chills as low as 15 below zero. For the Winter Weather Advisory, snow expected. Total snow accumulations around one inch. Winds gusting as high as 35 mph. A Wind Chill Advisory may be needed Friday afternoon into Friday night. * WHERE...Portions of East Arkansas and West Tennessee. * WHEN...For the Wind Chill Warning, from 6 PM Thursday to noon CST Friday. For the Winter Weather Advisory, from noon Thursday to 6 AM CST Friday. * IMPACTS...Plan on slippery road conditions. The hazardous conditions could impact the morning or evening commute. The cold wind chills could result in hypothermia if precautions are not taken. * ADDITIONAL DETAILS...Flash freezes may occur as cold air quickly builds in over wet ground. This may result in hazardous travel conditions. Reduced visibilities will also be possible. Travel is strongly discouraged.

Batten down the hatches. Wind advisory, WWA and Wind Chill Warnings for pretty much all of MRX's region. ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 7 PM EST /6 PM CST/ FRIDAY... ...WIND CHILL WARNING REMAINS IN EFFECT FROM 4 AM EST /3 AM CST/ FRIDAY TO 1 PM EST /NOON CST/ SATURDAY... * WHAT...For the Wind Chill Warning, dangerously cold wind chills expected. Wind chills 10 to 20 below zero in lower elevations, and as low as 25 to 40 below zero in the higher elevations. Winds gusting as high as 50 mph. For the Winter Weather Advisory, snow and blowing snow expected along with icy roads. Total snow accumulations from a dusting up to two inches in the lower elevations to 2 to 3 inches across the Mountains. * WHERE...Portions of southwest North Carolina, east Tennessee and southwest Virginia. * WHEN...For the Wind Chill Warning, from 4 AM EST /3 AM CST/ Friday to 1 PM EST /noon CST/ Saturday. For the Winter Weather Advisory, from midnight EST /11 PM CST/ tonight to 7 PM EST /6 PM CST/ Friday. * IMPACTS...Plan on slippery road conditions that could impact travel through Friday. The quick drop in temperatures may lead to rapid freezing of any moisture on roads producing icy roadways. The dangerously cold wind chills could cause frostbite on exposed skin in as little as 30 minutes. * ADDITIONAL DETAILS...Wind gusts Tonight through Friday are expected to be between 30 and 50 mph. Winds this strong may result in downed trees and power lines, which may cause power outages while temperatures are extremely cold.

From Nashville. Paging @Wurbus -> verified thread. ...WINTER STORM WARNING IN EFFECT FROM 6 PM THIS EVENING TO 6 AM CST FRIDAY... ...WIND CHILL WARNING REMAINS IN EFFECT FROM 10 PM THIS EVENING TO NOON CST FRIDAY... * WHAT...For the Winter Storm Warning, heavy snow expected. Total snow accumulations of up to two inches, with pockets of up to 4 inches. Winds gusting as high as 40 mph. For the Wind Chill Warning, dangerously cold wind chills expected. Wind chills as low as 25 below zero. * WHERE...Portions of Middle Tennessee along and north of I-40. * WHEN...For the Winter Storm Warning, from 6 PM this evening to 6 AM CST Friday. For the Wind Chill Warning, from 10 PM this evening to noon CST Friday. * IMPACTS...Plan on slippery road conditions. The hazardous conditions could impact the morning commute. The cold wind chills could cause frostbite on exposed skin in as little as 30 minutes. * ADDITIONAL IMPACTS...While falling precipitation will end before sunrise Friday, travel impacts are likely to last into the weekend. Please plan for slow travel as icy conditions on secondary roadways could be possible through the holiday weekend.

LOL. Nashville as well.

Winter Storm Warning hoisted for northern middle TN.

The clipper on the 27th is back on both the Canadian and Euro at 12z.

And since that snow will fall in a very short time as well.

Winter storm warnings for SW KY.

Someone post that recent HRRR w/ Kuchera, please! Euro is rolling.

Which means modeling isn't going to see that low level moisture, right? Some reports out west almost implied that a snow was rolling in like a fog when it hit.

Thanks, man! Modelling seems to be centering on Jan5-10 for a return to the eastern trough and significant PNA ridge. Let's if it doesn't show a pretty big drop soon as modeling is picking up on a fairly decent reshuffle.

I agree w/ ya'll. If there is ever a system which could over perform, it is this one.

I think at this point it is just coming down to the resolution of modeling as to where the shadow sets up. The overall message across modeling is dampening out precip once it crosses the Plateau, especially between the Plateau and I-75/81. Where that happens is probably microclimate climatology unique to this event. I would hate to be in MRX's shoes right now in terms of amounts. The system to our west is often over-performing in real time, but modeling is pretty meh in E TN. If MRX puts numbers out which are too high, loads of people will change travel plans. Then, if nothing happens, everyone is gonna be hot. OTH, if they go low and this thing over-performs like it has been....they catch people traveling on the roads. My gut says MBY is gonna see 0.5-1.0." East of I-81 could see 1-2" w/ bands(southwest to northeast) seeing slightly more. If this thing over performs and we get 2-3" of snow in the eastern valley, travel problems are going to be huge on Saturday w/ people traveling for Christmas Eve. I think the real story will be the rapid temperature drop and high winds IMBY. I hope the lights stay on....

FWIW, snow or no-snow(and I said this yesterday), I am going to stay up and watch this thing blow through. It is not very often that we get to see a front as powerful as this one is modeled.

And like clockwork, the 12z GFS has this....and no, I hadn't looked at it until after I posted above. I did look at the 3k Nam. The trend is less over E TN w/ the band re-intensifying as it gets east of I-81(sorry, I said I-26 earlier...prob more than once!). We have seen Cuba shred more than one intense hurricane. The Plateau is a formidable obstacle for systems. That said, E TN could bust high. This is one of the setups which could do it.

Models have pretty consistently allowed the system to lose moisture over eastern areas, though some re-intensification is also a consistent component in NE TN east of I-26. @TellicoWxsaid it best a few pages ago, I don't think modeling is handling this well at the surface. This front is FAST moving, intense, and it is thus very difficult for modeling to find the rain/snow line due to that. I do think E TN will have less precip to deal w/ as compared to middle and western areas(north of I-40). I think the cold makes it over the Plateau just fine. I think downsloping is legit for those closest to the eastern slopes of the Plateau. Conversely w/ big coastals, folks in the shadow of the western slopes of the Apps will be the first to tell you that downsloping w/ big storms is legit. How much downsloping is anyone's guess. Buckle up. Gonna be a wild ride. This is a strong, dynamic system which is going to likely hold some surprises.

LOL. I just ignore it on modeling. Being on the river and the EB, we are fighting dynamics most aren't. LOL. That said, modeling is often woefully wrong here. JC should get more w/ this set-up. There is DEFINITELY a rain shadow here w/ this angle of approach. But one thing I do watch is sometimes E TN does fill in w/ system like this. I think 0.5" to 1.5" is pretty reasonable. I am having a blast tracking this though. I am gonna set the alarm and watch this front blast through tomorrow night. Truly, I hope I have power. Losing power would be fun for about ten minutes....and then no wifi or electricity for days would be pretty awful. I am definitely worried about power loss with these winds.

0z CMC appears to have come somewhat to the table.

I kind of hold to the idea that Canada does a really good job of making its own cold. We just need "normal" temps in January to score. The -NAO will be responsible for this cold shot. If the STJ had been active, we would have seen a pretty massive storm in the East. Some modeling suggests it returns later in January. The ideal game plan is +PNA followed by the -NAO. That is on the table. I still hold out a little hope for Dec 27th-28th. That said, climatology really just does not favor December here(but it has been good during the last 10-15 years). I am good with periodic cold shots for the next ten weeks. We can score with that. Honestly, if this is the start of winter(and not and '89 end which I don't think it is), we will look back on December as a fun start.

Man, if we could get that to connect w/ some cold...........................

Sounds about right or just prior. Modeling is showing the second week in January switching to a decent PNA. If one accounts for modeling kicking the can, mid-month would be about right. If no can kicking, I might guess something in the 7th-10th range...and us actually beginning to track that system around the New Year. The end of the 18z GEFS is beginning the transition to an eastern trough. The operational flirted with that occurring much sooner. It really depends on which model is handling the MJO the best. The GEFS EXT this evening had a similar transition but maybe 2-3 days later.

If we had 5-6" of snow on the ground w/ this air mass, we would make a run at the all time record low.