Carvers Gap

Honestly, I doubt we have another cold shot that is as cold relative to norms, but I don't have a crystal ball. My guess is opening shot to winter. The CFSv2 at 0z would end winter. I doubt it is right, and it doesn't have support from its own 24hour model suite(4 runs) and doesn't have support from the Euro Weeklies. If we are sitting in mid-January w/ the cold pattern still 14-16 days away....then we know. LOL. There is a possibility the MJO rotates back into 6 and stalls. My guess is that we get at least one more rotation through the cold phases. The Nina "should" weaken as winter progress, and that might help.

Great points. I am going to run the fireplace wood stove insert today, though! Yeah, the RGEM/ Canadian combo have been good so far this winter.

Digging a little deeper this AM, the MJO is handled quite differently by several models, and I think that situation is fluid - meaning the final result is not fixed understandably. I do expect model fluctuations. For example, the 0z CFSv2 is a complete reversal of its 18z self and keeps the ridge in the east. For now, I stick w/ the Euro weeklies (which are fallible at times) which do have a reasonable MJO projection. This morning, the GEFS MJO loops back into phase 6. Most other modeling either continues into low amplitude cold phases or COD. Again, the colder water where phase 8 would be is highly likely hampering the MJO progression. I have seen many comments about this being a Nino look. I definitely disagree. Cold in December, especially west of the Apps and not east near the coast, is a massive Nina signal. The real question going forward is whether this does an '89 and winter disappears. Or, and what is more likely IMO, does winter have several more punches to throw? The Canadian ensemble/operational, GFS operational, and Euro control support a quicker return to winter. I like the 10-11 analogs in addition to some stronger cold analogs(but toned down). I do think January and Feb might well run neutral to warm as a base phase, but w/ strong colder interludes similar to November. Edit: The cold analogs along w/ a base neutral/warm sound juxtaposed to each other. The cold analogs would be used to help identify cold shots. Many of our coldest winters had very warm interludes.

Both the GFS/CMC and some combination of their operationals/ensembles sped up the return of cold/seasonal temps. They returned to the original timeline of the 5th.

The clipper on the 27th looks like it is legit, especially for middle TN. It falls apart as it heads across the forum area which is not uncommon for a feature like that. In NE TN we need clippers on a NW flow vs East/west, especially if modeled as weak as this one is currently. Trend for many clippers is to lift north at the last minute. Many will drop more snow than middles as a little precip goes a long way.

Cmc and did well w MBY - no accumulation. The GFS didn't handle my location well. Most modeling did well w showing the lee side snow shadow. Just a strong cold front here. Addendum: Light snow streamers are in the area. Understandably, most modeling doesn't see those.

Whichever model has low accumulations for E TN is gonna nail it. On to the clipper which might deserve its own thread if real.

Just digging through 500 vort maps....that is close to partial phase just to our east as the clipper catches energy rising in latitude along the coast. Going to have to watch that carefully.

The 0z GFS and 0z CMC both have the clipper early next week. Good look and makes since given the cold shot. Most cold shots of this degree have a clipper right on their heals.

Even looking at the 18z GFS...it rolled the ridge right through and put the trough back in the East right after New Year. No idea what the analog would be as the details are still a bit blurry. Honestly, it has a lot of 09-10 and 10-11 in that look. I just don't know if it verifies, because we are talking like 15-17 days before the transition...unless the 18z is correct, and we just continue as is....

Agee

18z GFS looks better over the eastern valley north of 40.

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.