Historic Christmas Cold & maybe snow?! Dec 23rd-30th

[TellicoWx]

Can you tell the front passed the station NW Jonesboro, AR lol...graph can't keep up (temp actually at 32)

[Kentucky]

 

[Holston_River_Rambler]

Looks like Cumberland and Fentress counties in a WSW  now too 

[Carvers Gap]

Winter Storm Warning hoisted for northern middle TN.

[Holston_River_Rambler]

I think that was a textbook ninja Carvers 

[Carvers Gap]

Just now, Holston_River_Rambler said:

I think that was a textbook ninja Carvers 

LOL.  Nashville as well.

[Carvers Gap]

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.

 

[Carvers Gap]

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.

[Carvers Gap]

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.

 

[Daniel Boone]

23 minutes ago, Kentucky said:

 

If I were working at any of the NWSFO'S in much of Kentucky, Indiana and Ohio I'd put out Blizzard Warmings. 

[John1122]

NWS Nashville Disco

 

"However, we are starting to pick up on the potential
for some additional forcing behind the front when the cold air gets
here and we start to transition from rain to snow. This added
feature could signal underperforming of the models in regards to
snowfall totals, especially for areas north of I-40 and on the
Cumberland Plateau. Several spots along the KY/TN state line are
pushing 3 inches. On top of this, ground temperatures are pretty
warm, so the question is how are we going to get snow to stick?
Well, if it comes down hard and fast, we can get those accumulations,
no doubt. My first concern lies with the melting snow and rain
just before the cold air gets here. Temperatures look to drop
below freezing FAST and while the wind will help to dry up some of
that liquid, any additional water on area roadways is going to
freeze, causing an icing situation. For these reasons, we`ve
decided to push out a Winter Storm Warning for areas along and
north of I-40 from 6 pm this evening until 6 am tomorrow morning."

[Carvers Gap]

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.

[Carvers Gap]

6 minutes ago, Daniel Boone said:

If I were working at any of the NWSFO'S in much of Kentucky, Indiana and Ohio I'd put out Blizzard Warmings. 

Criteria will likely be met.  Yep.

[John1122]

I think the Hi-Res models are trying to downslope a bit too much off the Plateau in the northern areas. It doesn't fall off a cliff here like it does in the Central and Southern areas. Those areas go from 2000ish feet to 800ish feet or even more extreme drops down towards Chattanooga. Up this way like in Claiborne, Union and even Northern Knox it's more 1200-1400 even in valley floor areas and those valley floors are really narrow with a lot of 1500-1800 foot ridges. The area of SE Campbell it shows drying out is almost all 1400-1800 foot ridges with very steep, narrow valleys down into the lake. Same on the other side in NW Union. That hilly country extends down to House Mountain. That's not really favorable downslope country.

[PowellVolz]

I think the Hi-Res models are trying to downslope a bit too much off the Plateau in the northern areas. It doesn't fall off a cliff here like it does in the Central and Southern areas. Those areas go from 2000ish feet to 800ish feet or even more extreme drops down towards Chattanooga. Up this way like in Claiborne, Union and even Northern Knox it's more 1200-1400 even in valley floor areas and those valley floors are really narrow with a lot of 1500-1800 foot ridges. The area of SE Campbell it shows drying out is almost all 1400-1800 foot ridges with very steep, narrow valleys down into the lake. Same on the other side in NW Union. That hilly country extends down to House Mountain. That's not really favorable downslope country.

I’m at 1200 feet and I’m in what I’d consider a low area for my region of N Knox Co


.

[John1122]

The RAP is more smooth with accumulations. The HRRR has placed it's downslope/dry slots oddly today. At one point a run had it in Western Campbell where elevation go from roughly 1600 feet in Scott to 3400 feet in Campbell. Not the best location to place your snowhole, with a near 2000 feet elevation rise.

[Holston_River_Rambler]

7 minutes ago, John1122 said:

I think the Hi-Res models are trying to downslope a bit too much off the Plateau in the northern areas. It doesn't fall off a cliff here like it does in the Central and Southern areas. Those areas go from 2000ish feet to 800ish feet or even more extreme drops down towards Chattanooga. Up this way like in Claiborne, Union and even Northern Knox it's more 1200-1400 even in valley floor areas and those valley floors are really narrow with a lot of 1500-1800 foot ridges. The area of SE Campbell it shows drying out is almost all 1400-1800 foot ridges with very steep, narrow valleys down into the lake. Same on the other side in NW Union. That hilly country extends down to House Mountain. That's not really favorable downslope country.

Might could be time to whip out ye olden topo map for analysis and disucssion

:

I'll be interested to see how my area does, since I'm in a limbo situation. 1300 feet or so, just on the edge of the plateau:

[John1122]

You can see in my expertly drawn white circle, why downsloping makes way less sense in this are but makes at least a little more sense further down towards the Central and Southern Plateau.

[ShawnEastTN]

Might could be time to whip out ye olden topo map for analysis and disucssion
:

I'll be interested to see how my area does, since I'm in a limbo situation. 1300 feet or so, just on the edge of the plateau:

Your topo is why I do better with Northerly flow. I'm due south in the valley of the sort of gap between the mountains around Frozen Head and the higher terrain down around black and hinch mountains. Generally I do better when the flow funnels through your neck of the woods vs a west wind. Not only do I do better there seems some weird enhancement when the wind funnels through there.

Sent from my SM-F721U using Tapatalk

[Carvers Gap]

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

[Scottie16]

Be curious to see how fast the temperature drops for our friends our west. It looks like the  front is about over Memphis.

[PowellVolz]

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

And the snow hole makes more sense IMO.


.

[Scottie16]

Memphis.

[John1122]

13 minutes ago, Carvers Gap said:

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

It's downslope area seems to more align with actual terrain than the hi-res models.

[AMZ8990]

10 minutes ago, Scottie16 said:

Be curious to see how fast the temperature drops for our friends our west. It looks like the  front is about over Memphis.

Sitting at 46 in Hardeman County at the moment with a light breeze and overcast skies.  snow/rain is supposed to get here around 6.  

[mempho]

6 minutes ago, Scottie16 said:

Memphis.

What station is that?  

[Carvers Gap]

12 minutes ago, John1122 said:

It's downslope area seems to more align with actual terrain than the hi-res models.

Agee

[Scottie16]

 

[Scottie16]

 

[Scottie16]

 

 

Seems like the radar is filling in?