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Winter 2021/2022 January Thread

AMZ8990

By AMZ8990,
in Tennessee Valley

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Kasper
Kasper

I haven’t seen things this Active since my X-Wife slept with her co-workers! Keep ‘em coming! 

Holston_River_Rambler
Holston_River_Rambler

To follow up on what John said, the 0z GFS was what I call the space invaders pattern. The northern stream and the STJ keep shooting energy at each other like the old video game:  

Wurbus
Wurbus

Best I could do while working. Euro rolling

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Carvers Gap

Carvers Gap

Posted
Posted
3 minutes ago, Icy Hot said:

Wonder why MRX is down playing this?

Have not seen their discussion.  If it was the morning disco, they were working off just a few oddball runs showing this.  With back-to-back Euro runs, they will likely give it some consideration.  With 5-6 days to go, they have room to go that way if need be.  Never know, the Euro could be erroneously holding energy back which would allow for the 12z run to occur.  That said, seems to me the cold air is not getting as far south as LR modeling had it, hence the NW jog.  

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Carvers Gap

Carvers Gap

Posted
Posted

During the last three storms, it seems like the western envelope of modeling at this range has generally been correct IMHO.  Anyone see that differently?  Seems like all 3 storms had sharp northwest trends for 2 days worth of model runs, then jogged back the opposite direction by maybe ~10-20% of that mileage.  But for now, we need to get that storm on all three globals.  It is on 2/3.

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tnweathernut

tnweathernut

Posted
Posted
3 minutes ago, Carvers Gap said:

During the last three storms, it seems like the western envelope of modeling at this range has generally been correct IMHO.  Anyone see that differently?  Seems like all 3 storms had sharp northwest trends for 2 days worth of model runs, then jogged back the opposite direction by maybe ~10-20% of that mileage.  But for now, we need to get that storm on all three globals.  It is on 2/3.

At least for east TN, this one has quite a bit more potential than the last.  Cold air already in place.  Overrunning to Miller A vs Miller B into a marginal airmass, etc…..

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PowellVolz

PowellVolz

Posted
Posted
They have to measure this on pavement or something.

Apparently TYS only recorded 0.1” yesterday.  I call shenanigans.


Last year Christmas Eve they recorded 1.5” of snow but admitted they had at least 3” on the ground at one time earlier in the day. They said there’s a particular time during the day they are required to check for the “official” snow fall total for that day. That’s ridiculous imo. Would be like checking the high temp for the day at a particular time when it could be warmer before or after that time.


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PowellVolz

PowellVolz

Posted
Posted
The afternoon discussion from MRX really downplays this weekend’s system.  Not sure how you can just totally ignore the Euro, EPS, etc.  I would think that they would at least say they need to keep their eye on it.

The CMC has the storm also, just a little SE of the area.


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Holston_River_Rambler

Holston_River_Rambler

Posted
Posted

If we want snow, here's how we want the long range AFDs to go through Friday AM:

~3 AM 1/18: Generally followed the WPC guidance which pushes the arctic front far enough south to have little impact from overrunning precip, broad-brushed a few hundreths of an inch of precip. over the mountain counties since ensemble means hint at this possibility

~330 PM 1/18: Afternoon guidance continues to flip/flop considering a late week/ weekend system. The 0z deterministic ECMWF had been showing more amplitude with this shortwave, but 12z guidance has come more in line with the deterministic GFS which keeps all the precip over the mountains and in the Carolinas 

~335 AM 1/19: Overnight ensemble means have trended a bit westward with moisture, but any impacts are several days away, so generally populated the grids with 20% chance of wintry mix in the valleys and snow in the higher elevations

~315 PM 1/19: models continue to struggle with a fast flow progressive pattern. Several runs of both the deterministic GFS and ECMWF had been showing a rather strung out strand of vorticity riding a boundary along approximately I-20, but the GFS now shows a 999mb surface lp over Macon while the ECMWF has trended towards the GFS's solution. Based on poor run-to-run consistency, stuck with a broad 20 -30% chance of snow in the eastern zones, transitioning to rain during the day in the lower elevations

~4 AM 1/20: Ensemble means continue to suggest a more robust shortwave is possible into the weekend, but won't make many drastic changes to the forecast based on a single suite of NWP data. 

~358 PM 1/20: Big changes to the forecast as deterministic guidance argues that a strong shortwave dropping in from the N high Plains races in to partially phase with some southern stream energy over TX. CMC, GFS, and ECMWF all have similar solutions, but minor differences in track of the slp result in major forecast headaches. CMC is the coldest and thus the snowiest, but since this is a known bias of that model, its solution was only weighted slightly in forecast means. Regardless of the track, all global deterministic guidance suggests ample isentropic ascent and positive vorticity advection would produce precip., much of it of a wintry nature. To avoid confusion with other forecast offices, followed the NMB for any snowfall accumulation. Will leave any WWX products for future shifts. 

 

I in no way mean this as a dig at the NWS AFDs. I love reading them and hopefully I kind of got the tone right. Imitation is the sincerest form of flattery. It was interesting coming up with stuff to write though, lol. I can see why some of the offices are having a little more fun with them now (I'm looking at you BNA). But let's be real East Tennesseeans, I don't know if it is a curse or what, but I have never seen a storm happen, when any pros were honking on it at this distance. I literally won't tell my wife if I think there is something coming, because of jinx fear. 

 

Back in the realm of actual pattern discussion, the GFS continues the trend NW with the Thursday system and the two shortwaves in question for the weekend are inching closer together at 18z. 

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PowellVolz

PowellVolz

Posted
Posted
If we want snow, here's how we want the long range AFDs to go through Friday AM:
~3 AM 1/18: Generally followed the WPC guidance which pushes the arctic front far enough south to have little impact from overrunning precip, broad-brushed a few hundreths of an inch of precip. over the mountain counties since ensemble means hint at this possibility
~330 PM 1/18: Afternoon guidance continues to flip/flop considering a late week/ weekend system. The 0z deterministic ECMWF had been showing more amplitude with this shortwave, but 12z guidance has come more in line with the deterministic GFS which keeps all the precip over the mountains and in the Carolinas 
~335 AM 1/19: Overnight ensemble means have trended a bit westward with moisture, but any impacts are several days away, so generally populated the grids with 20% chance of wintry mix in the valleys and snow in the higher elevations
~315 PM 1/19: models continue to struggle with a fast flow progressive pattern. Several runs of both the deterministic GFS and ECMWF had been showing a rather strung out strand of vorticity riding a boundary along approximately I-20, but the GFS now shows a 999mb surface lp over Macon while the ECMWF has trended towards the GFS's solution. Based on poor run-to-run consistency, stuck with a broad 20 -30% chance of snow in the eastern zones, transitioning to rain during the day in the lower elevations
~4 AM 1/20: Ensemble means continue to suggest a more robust shortwave is possible into the weekend, but won't make many drastic changes to the forecast based on a single suite of NWP data. 
~358 PM 1/20: Big changes to the forecast as deterministic guidance argues that a strong shortwave dropping in from the N high Plains races in to partially phase with some southern stream energy over TX. CMC, GFS, and ECMWF all have similar solutions, but minor differences in track of the slp result in major forecast headaches. CMC is the coldest and thus the snowiest, but since this is a known bias of that model, its solution was only weighted slightly in forecast means. Regardless of the track, all global deterministic guidance suggests ample isentropic ascent and positive vorticity advection would produce precip., much of it of a wintry nature. To avoid confusion with other forecast offices, followed the NMB for any snowfall accumulation. Will leave any WWX products for future shifts. 
 
I in no way mean this as a dig at the NWS AFDs. I love reading them and hopefully I kind of got the tone right. Imitation is the sincerest form of flattery. It was interesting coming up with stuff to write though, lol. I can see why some of the offices are having a little more fun with them now (I'm looking at you BNA). But let's be real East Tennesseeans, I don't know if it is a curse or what, but I have never seen a storm happen, when any pros were honking on it at this distance. I literally won't tell my wife if I think there is something coming, because of jinx fear. 
 
Back in the realm of actual pattern discussion, the GFS continues the trend NW with the Thursday system and the two shortwaves in question for the weekend are inching closer together at 18z. 




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Daniel Boone

Daniel Boone

Posted
Posted
16 minutes ago, Holston_River_Rambler said:

If we want snow, here's how we want the long range AFDs to go through Friday AM:

~3 AM 1/18: Generally followed the WPC guidance which pushes the arctic front far enough south to have little impact from overrunning precip, broad-brushed a few hundreths of an inch of precip. over the mountain counties since ensemble means hint at this possibility

~330 PM 1/18: Afternoon guidance continues to flip/flop considering a late week/ weekend system. The 0z deterministic ECMWF had been showing more amplitude with this shortwave, but 12z guidance has come more in line with the deterministic GFS which keeps all the precip over the mountains and in the Carolinas 

~335 AM 1/19: Overnight ensemble means have trended a bit westward with moisture, but any impacts are several days away, so generally populated the grids with 20% chance of wintry mix in the valleys and snow in the higher elevations

~315 PM 1/19: models continue to struggle with a fast flow progressive pattern. Several runs of both the deterministic GFS and ECMWF had been showing a rather strung out strand of vorticity riding a boundary along approximately I-20, but the GFS now shows a 999mb surface lp over Macon while the ECMWF has trended towards the GFS's solution. Based on poor run-to-run consistency, stuck with a broad 20 -30% chance of snow in the eastern zones, transitioning to rain during the day in the lower elevations

~4 AM 1/20: Ensemble means continue to suggest a more robust shortwave is possible into the weekend, but won't make many drastic changes to the forecast based on a single suite of NWP data. 

~358 PM 1/20: Big changes to the forecast as deterministic guidance argues that a strong shortwave dropping in from the N high Plains races in to partially phase with some southern stream energy over TX. CMC, GFS, and ECMWF all have similar solutions, but minor differences in track of the slp result in major forecast headaches. CMC is the coldest and thus the snowiest, but since this is a known bias of that model, its solution was only weighted slightly in forecast means. Regardless of the track, all global deterministic guidance suggests ample isentropic ascent and positive vorticity advection would produce precip., much of it of a wintry nature. To avoid confusion with other forecast offices, followed the NMB for any snowfall accumulation. Will leave any WWX products for future shifts. 

 

I in no way mean this as a dig at the NWS AFDs. I love reading them and hopefully I kind of got the tone right. Imitation is the sincerest form of flattery. It was interesting coming up with stuff to write though, lol. I can see why some of the offices are having a little more fun with them now (I'm looking at you BNA). But let's be real East Tennesseeans, I don't know if it is a curse or what, but I have never seen a storm happen, when any pros were honking on it at this distance. I literally won't tell my wife if I think there is something coming, because of jinx fear. 

 

Back in the realm of actual pattern discussion, the GFS continues the trend NW with the Thursday system and the two shortwaves in question for the weekend are inching closer together at 18z. 

Good one !

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PowellVolz

PowellVolz

Posted
Posted
With this pattern in place, it'd be a real shame if the eastern Valley misses out on a good thumping. Looks good for now. We just need good low placement and colder temps to remain in place.

Absolutely.. with these temps we don’t even need a perfect track/placement. For the most part with cold air in place, the last three systems would have been fine.


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TellicoWx

TellicoWx

Posted
Posted

WPC, wouldn't take much of a NW trend in their thoughts to be in the game.

 


The area with slightly higher confidence (albeit not "that" high given lingering model spread) is
the Southeast and Mid-Atlantic. The aforementioned jet streak on Thursday sticks around into Friday
with a favorable low level baroclinic environment hovering atop the Southeast. How long the region
is under the influence of this potentially wintry setup depends on how a pair of upper level
disturbances interact. The Euro ensembles suggest a slower and more amplified look on Friday while
the GEFS are more progressive, but still wintry nonetheless with just under half of is 12Z members
showing freezing rain potential in the Carolinas to close out the week. Have introduced heavy snow
and sleet/freezing rain areas for parts of the Mid-Atlantic and Southeast where these regions may
witness potentially up to a few days worth of wintry weather. 

Screenshot_20220117-194747_Chrome~2.jpg

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