February 17-18th Winter Storm Thread.

[Carvers Gap]

Hit my forecast high on time.   Should start coming back down.

[Shocker0]

This guy seems more confident in heavy snow on the Plateau now:

https://meteorologistmark.com/2021/02/17/special-winter-wx-update-issued-at-320-pm-wed/

 

[PowellVolz]

1030ish high pressure over the top.
CAA invasion
Over night low of 18
Strong low pressure to the south
33 degrees and rain in the middle of February





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[PowellVolz]

This guy seems more confident in heavy snow on the Plateau now:

https://meteorologistmark.com/2021/02/17/special-winter-wx-update-issued-at-320-pm-wed/

 

I think you all will get hammered. I think my buddy who lives in Livingston might be the overall winner in the state. I feel bad for him though after all that ice damage they had and 6 inches or so of snow will be a disaster for them.

 

 

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[TellicoWx]

Sleet being reported just to the NW of Birmingham (Dora, AL) with a temp/dp of 41/25. Those returns weren't picked up by the HRRR

[Mrwolf1972]

2 minutes ago, PowellVolz said:

I think you all will get hammered. I think my buddy who lives in Livingston might be the overall winner in the state. I feel bad for him though after all that ice damage they had and 6 inches or so of snow will be a disaster for them.

 

 

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My daughter lives in livingston its bad there with all the ice and hasn't git above freezing snow will make alot of problems. 

[John1122]

Last run of the HRRR pushed snow back into the Knoxville area and had lots of heavy sleet involved too.

[jaxjagman]

 Mesoscale Discussion 0111
   NWS Storm Prediction Center Norman OK
   0322 PM CST Wed Feb 17 2021

   Areas affected...southern/central Arkansas...southwest through
   Middle Tennessee...and northwestern Mississippi

   Concerning...Heavy snow 

   Valid 172122Z - 180115Z

   SUMMARY...Areas of heavy snow will continue across the discussion
   area for several more hours.

   DISCUSSION...Recent observations suggest that the heaviest of
   snowfall in the discussion area (with rates likely exceeding 1" per
   hour) was occurring in the general vicinity of Little Rock, Pine
   Bluff, and Camden in central/southern Arkansas, with lighter, but
   still moderate snowfall observed farther northeast toward Memphis
   and Nashville in Tennessee.  The region continues to reside in a
   regime characterized by appreciable lift due to isentropic ascent,
   with strong low-level flow across central/southern Louisiana
   impinging on a shallow cold airmass.  Though the general focus of
   warm advection has begun to shift slightly to the east, additional
   ascent from a mid-level wave apparent via water vapor imagery over
   north-central Texas was also likely contributing to enhanced
   snowfall rates in the region.  This general regime should continue
   for at least several more hours (perhaps through 01-03Z or so)
   before beginning to taper off from west to east in Arkansas later
   tonight.  Beneath heavier precipitation bands, 2" per hour snowfall
   rates cannot be ruled out.

   ..Cook.. 02/17/2021

[TellicoWx]

1 minute ago, John1122 said:

Last run of the HRRR pushed snow back into the Knoxville area and had lots of heavy sleet involved too.

I've noticed it's not counting the sleet in the snow accum or freezing rain categories..may not amount to much but with temps right at the freezing line, it's something to watch

[ShawnEastTN]

Yeah the 20z HRRR looks like extended heavy sleet imby tonight.

 

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[TellicoWx]

Sleet now reported in Birmingham and Tuscaloosa..so the leading edge must be overcoming the dry air

[codgator]

Not liking the fact that the snow transition stopped and we’re back to straight up sleet. Pouring sleet - mid levels not helping.

[John1122]

RAP has moved back east and se with the snow shield too. Has a heavy area around northern Knox. Sometimes it takes getting within 5-6 hours before the HRRR and RAP really lock on.

[TellicoWx]

For those who don't know..this is how the HRRR ingests it's data. So right now it's running off 12z data, while trying to ingest the previous hours RAP, current hour sim radar/obs. If the HRRR is going to make a move, it should happen at the 01z run (if the new data is any different from the 12z.)

 

The HRRR is initialized from the RAP one hour prior to the forecast start time. Then the model is advanced for one hour, assimilating radar reflectivity observations every 15mins. This is referred to as a one hour pre-forecast. Following the pre-forecast step, final data assimilation and hydrometeor analysis occurs.

 

 Most of the 00/12 UTC radiosonde observations are assimilated into the 00/12 UTC HRRR. The 00/12 UTC HRRR uses an "early" data dump of the available observations, which includes approximately 2/3 of the of the radiosonde data (mostly lower-to-mid levels). The 01/13 UTC HRRR runs benefit from the complete radiosonde observations via the initial conditions from the 00/12 UTC RAP.

[ShawnEastTN]

Little comforting seeing my temp begin falling again. Reached 41 but in the last hour have dropped back to 39, DP 24 and still NE winds down the valley. Those winds have been stubborn NE direction. Can remember many many situations all the way back to my childhood where this winds out of the NE kept winter weather from switching to rain. Will it this time, who knows....

 

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[Shocker0]

Feeling better now about the temps. Was 38 about an hour or so ago here. Now it is right at 32

 

[PowellVolz]

I’m down from 41 to 38. Great point someone said about radiational cooling if the sky can stay broken. Low humidity will help temps fall faster also.


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[Sweetpea Farms]

WHAAA? I have been busy as a bumblebee today and I finally get to look at a forecast and it's for 3-5 INCHES of snow and ice in Lincoln County? Looks like models here support it, too. Ew. 

[Shocker0]

1 minute ago, PowellVolz said:

I’m down from 41 to 38. Great point someone said about radiational cooling if the sky can stay broken. Low humidity will help temps fall faster also.


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We are full blown cloudy here now. It got noticeably colder once that finally happened, but for the eastern areas, hanging on to a little clear weather around dark might be all the difference.

[John1122]

32/24. Temps falling quickly with the sunset.  

[Kentucky]

1 minute ago, John1122 said:

32/24. Temps falling quickly with the sunset.  

Down to 26 here, Dewpoint of 20

[John1122]

1 minute ago, Blue Moon said:

I've been getting nothing but light sleet. Everything if going wrong here if you like snow.

Per the HRRR the sleet area in the mid state south of Nashville should transition to heavy snow by 8ish central time. 

[codgator]

That would be great! Currently just light slight in Franklin holding at 27

[jaxjagman]

9 minutes ago, John1122 said:

Per the HRRR the sleet area in the mid state south of Nashville should transition to heavy snow by 8ish central time. 

We have IP now

[John1122]

The WVLT meteorologist is hilariously bad. He said "Heavy snow will fall for 2 or 3 hours on House Mountain in Knox but it won't stick because it will be falling into a puddle."

That's actually the area getting a heavy dollop  on the hi-res models.

[PowellVolz]

North of Nashville is puking it...


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[PowellVolz]

The WVLT meteorologist is hilariously bad. He said "Heavy snow will fall for 2 or 3 hours on House Mountain in Knox but it won't stick because it will be falling into a puddle."
That's actually the area getting a heavy dollop  on the hi-res models.

It’s around 2k feet


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[John1122]

1 minute ago, jaxjagman said:

We have IP now

It's on the HRRR for your area and southwest.  By 7cst it's here. Just a few sleet areas left. 

[PowellVolz]

Memphis interstate


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[John1122]

1 minute ago, PowellVolz said:

It’s around 2k feet


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I know it's around 1880feet. I cracked up that he doesn't think it will stick there because of the "puddle". He's pretty new and seeks clueless about terrain.