Texas Winter 2020-2021

[Ralph's Weather]

What about us out here in east Texas? It seems when I started following a day or two ago, there was nothing, but it seems to be picking up some.

Can someone give me your prediction on the Longview area? I am in GIlmer, about 20 miles northwest of Longview.

Exciting next day or two!!!

I am in Lindale, I would say Gilmer is in the 3 to 5 inch range.

[TheProfessor]

https://images.weatherbell.com/model/nbm-conus/tx/total_snow_10to1/1610193600/1610323200-HTFta7NgTzQ.png

12z Blended model guidance snowfall totals. I also think it's important to recognize when looking at snowfall totals (I believe someone mentioned this yesterday) that the maps assume a 10:1 ratio and that isn't the case always so what you see "predicted" on the model doesn't always occur in real time. EWX also mentioned this in the early morning discussion stating "caution should be used when viewing total snowfall accumulation of individual models runs
online, as they can show a 10:1 snow to liquid ratio, not expected for this event, and also not capture the microphysics well"

Snow ratios are very important to talk about. Now the NWS probably isn't looking at Kuchera (I've seen a Wilmington, OH forecaster laugh at that for some reason even though it's just reading the models sampled sounding and converting that into snow ratios.) but Kuchera on both the GFS and 0z CMC shows very poor ratios for the Metroplex, especially the northern Metro. Even in the jackpot areas the CMC and GFS are showing 7/8-1 ratios. It's not until after the event around 12z Monday when the better snow ratios occur. I wouldn't call this a failure mode per say, but it does make the 10-1 maps misleading.

[txtwister78]

:uarrow: Looks like it doesn't quite make it to San Antonio.

Kerrville to Austin to College Station best shot further south. Still like Central Texas Waco area NW to Abilene and Lubbock as mentioned the past 2 days for higher snow amounts.

Yes, I believe that's a given. However, thinking that a round or two of heavy banding will make things interesting for the DFW area especially during the initial band.

Good luck to all.

Absolutely that can change totals in certain localized spots. The key obviously is where does that occur. Any model (even 24 hours out) would be guessing at this point on that. As others have mentioned those scenarios are often "day of" radar trends as the event unfolds. I just think in terms of more widespread higher totals the areas I mentioned have the best odds. Agreed good luck to all.

[Captmorg70]

I expect Dallas and Tarrant counties will have winter weather advisories before the storms tomorrow.

Does anyone know the criteria for winter weather advisory versus winter weather warning for N Tx?

Like TheProfessor mentioned, there are scenarios where the amounts will be varied based on the potential banding tomorrow.
I can understand why the NWS is cautious.

[Ntxw]

https://images.weatherbell.com/model/nbm-conus/tx/total_snow_10to1/1610193600/1610323200-HTFta7NgTzQ.png

12z Blended model guidance snowfall totals. I also think it's important to recognize when looking at snowfall totals (I believe someone mentioned this yesterday) that the maps assume a 10:1 ratio and that isn't the case always so what you see "predicted" on the model doesn't always occur in real time. EWX also mentioned this in the early morning discussion stating "caution should be used when viewing total snowfall accumulation of individual models runs
online, as they can show a 10:1 snow to liquid ratio, not expected for this event, and also not capture the microphysics well"

Snow ratios are very important to talk about. Now the NWS probably isn't looking at Kuchera (I've seen a Wilmington, OH forecaster laugh at that for some reason even though it's just reading the models sampled sounding and converting that into snow ratios.) but Kuchera on both the GFS and 0z CMC shows very poor ratios for the Metroplex, especially the northern Metro. Even in the jackpot areas the CMC and GFS are showing 7/8-1 ratios. It's not until after the event around 12z Monday when the better snow ratios occur. I wouldn't call this a failure mode per say, but it does make the 10-1 maps misleading.

10:1 maps in my opinion are only good for highlighting potential coverage and how much can come out of the sky, nothing about actual accumulation. There are so many other factors in play, but one thing I will say is this so unusual in that the air above is much colder than our typical events in North Texas with such a set up. It's usually borderline at 850mb so ratios may be higher liquid-dendritic growth. Even 2010 we were barely cold enough above. 500mb temps here is -25 to -27C.

[Ntxw]

I expect Dallas and Tarrant counties will have winter weather advisories before the storms tomorrow.

Does anyone know the criteria for winter weather advisory versus winter weather warning for N Tx?

Like TheProfessor mentioned, there are scenarios where the amounts will be varied based on the potential banding tomorrow.
I can understand why the NWS is cautious.

I believe warning criteria is 4 inches of snow for the FW office (not sure about freezing rain or sleet as those matter also) so any forecast of 3+ inches warrants a warning. That only speaks for North Texas, different regions have different criteria.

[bubba hotep]

Dragging in today lol

Noticed no upgrade for DFW but a quick look at the Hi-res models show an avg around 0.5" qpf for DFW and the last 4 SREF runs have an avg mean 0.9" qpf for DFW. However, the 00z HREF is more conservative at 0.25 - 0.5" qpf with a SW - NE gradient. So qpf isn't the issue.

[Ntxw]

Dragging in today lol

Noticed no upgrade for DFW but a quick look at the Hi-res models show an avg around 0.5" qpf for DFW and the last 4 SREF runs have an avg mean 0.9" qpf for DFW. However, the 00z HREF is more conservative at 0.25 - 0.5" qpf with a SW - NE gradient. So qpf isn't the issue.

We'll just go straight to warning by midnight .

[txtwister78]

https://images.weatherbell.com/model/nbm-conus/tx/total_snow_10to1/1610193600/1610323200-HTFta7NgTzQ.png

12z Blended model guidance snowfall totals. I also think it's important to recognize when looking at snowfall totals (I believe someone mentioned this yesterday) that the maps assume a 10:1 ratio and that isn't the case always so what you see "predicted" on the model doesn't always occur in real time. EWX also mentioned this in the early morning discussion stating "caution should be used when viewing total snowfall accumulation of individual models runs
online, as they can show a 10:1 snow to liquid ratio, not expected for this event, and also not capture the microphysics well"

Snow ratios are very important to talk about. Now the NWS probably isn't looking at Kuchera (I've seen a Wilmington, OH forecaster laugh at that for some reason even though it's just reading the models sampled sounding and converting that into snow ratios.) but Kuchera on both the GFS and 0z CMC shows very poor ratios for the Metroplex, especially the northern Metro. Even in the jackpot areas the CMC and GFS are showing 7/8-1 ratios. It's not until after the event around 12z Monday when the better snow ratios occur. I wouldn't call this a failure mode per say, but it does make the 10-1 maps misleading.

Agreed.

[Brent]

Dragging in today lol

Noticed no upgrade for DFW but a quick look at the Hi-res models show an avg around 0.5" qpf for DFW and the last 4 SREF runs have an avg mean 0.9" qpf for DFW. However, the 00z HREF is more conservative at 0.25 - 0.5" qpf with a SW - NE gradient. So qpf isn't the issue.

We'll just go straight to warning by midnight .

I was just watching WFAAs facebook live and they still have it mostly rain over Dallas while it's snowing like crazy everywhere else tomorrow afternoon this is ridiculous

[Ntxw]

I hope Porta has champ the charger ready to chase. Awfully quiet for once in a lifetime event potential down there.

[orangeblood]

https://images.weatherbell.com/model/nbm-conus/tx/total_snow_10to1/1610193600/1610323200-HTFta7NgTzQ.png

12z Blended model guidance snowfall totals. I also think it's important to recognize when looking at snowfall totals (I believe someone mentioned this yesterday) that the maps assume a 10:1 ratio and that isn't the case always so what you see "predicted" on the model doesn't always occur in real time. EWX also mentioned this in the early morning discussion stating "caution should be used when viewing total snowfall accumulation of individual models runs
online, as they can show a 10:1 snow to liquid ratio, not expected for this event, and also not capture the microphysics well"

Snow ratios are very important to talk about. Now the NWS probably isn't looking at Kuchera (I've seen a Wilmington, OH forecaster laugh at that for some reason even though it's just reading the models sampled sounding and converting that into snow ratios.) but Kuchera on both the GFS and 0z CMC shows very poor ratios for the Metroplex, especially the northern Metro. Even in the jackpot areas the CMC and GFS are showing 7/8-1 ratios. It's not until after the event around 12z Monday when the better snow ratios occur. I wouldn't call this a failure mode per say, but it does make the 10-1 maps misleading.

10:1 maps in my opinion are only good for highlighting potential coverage and how much can come out of the sky, nothing about actual accumulation. There are so many other factors in play, but one thing I will say is this so unusual in that the air above is much colder than our typical events in North Texas with such a set up. It's usually borderline at 850mb so ratios may be higher liquid-dendritic growth. Even 2010 we were barely cold enough above. 500mb temps here is -25 to -27C.

Yep, these upper levels are even colder than Feb 2010 event plus sun angle is lower. Feb 2010 managed to get to 10-11:1 ratios. See no reason why this would be too much different, believe the models have no clue on ratios. Have to go to old school analogs to do the best job, hopefully NWS is doing this

[Ntxw]

Dragging in today lol

Noticed no upgrade for DFW but a quick look at the Hi-res models show an avg around 0.5" qpf for DFW and the last 4 SREF runs have an avg mean 0.9" qpf for DFW. However, the 00z HREF is more conservative at 0.25 - 0.5" qpf with a SW - NE gradient. So qpf isn't the issue.

We'll just go straight to warning by midnight .

I was just watching WFAAs facebook live and they still have it mostly rain over Dallas while it's snowing like crazy everywhere else this is ridiculous

Give it next cycle of news. Maybe they are using the GFS based apps too . Given the GFS has come around little bit of lag.

[bubba hotep]

Latest update from FWD, it sounds like the are just going with "meh, any snow will be melting with no road impacts so no advisories"

[Brent]

Latest update from FWD, it sounds like the are just going with "meh, any snow will be melting with no road impacts so no advisories"

https://pbs.twimg.com/media/ErTZBelXEAMRaiL?format=jpg&name=large

lol if that verifies I may just head southeast towards Palestine

Funny their worst case there is lower than their forecast

[TheProfessor]

https://images.weatherbell.com/model/nbm-conus/tx/total_snow_10to1/1610193600/1610323200-HTFta7NgTzQ.png

12z Blended model guidance snowfall totals. I also think it's important to recognize when looking at snowfall totals (I believe someone mentioned this yesterday) that the maps assume a 10:1 ratio and that isn't the case always so what you see "predicted" on the model doesn't always occur in real time. EWX also mentioned this in the early morning discussion stating "caution should be used when viewing total snowfall accumulation of individual models runs
online, as they can show a 10:1 snow to liquid ratio, not expected for this event, and also not capture the microphysics well"

Snow ratios are very important to talk about. Now the NWS probably isn't looking at Kuchera (I've seen a Wilmington, OH forecaster laugh at that for some reason even though it's just reading the models sampled sounding and converting that into snow ratios.) but Kuchera on both the GFS and 0z CMC shows very poor ratios for the Metroplex, especially the northern Metro. Even in the jackpot areas the CMC and GFS are showing 7/8-1 ratios. It's not until after the event around 12z Monday when the better snow ratios occur. I wouldn't call this a failure mode per say, but it does make the 10-1 maps misleading.

10:1 maps in my opinion are only good for highlighting potential coverage and how much can come out of the sky, nothing about actual accumulation. There are so many other factors in play, but one thing I will say is this so unusual in that the air above is much colder than our typical events in North Texas with such a set up. It's usually borderline at 850mb so ratios may be higher liquid-dendritic growth. Even 2010 we were barely cold enough above. 500mb temps here is -25 to -27C.

850s are cold, but not cold enough to be in the DGZ. I've been going through some Skew-ts and the DGZs are pretty shallow on both global and mesoscale models. In some cases the DGZ is also a bit dry (CMC). Now assuming some of the models are too warm at the surface, then a good estimate for snow ratios would be nearby areas where the models have surface temps near freezing and similar DGZs. It would not surprise me if most of DFW saw snow ratios of 6-1 to 8-1. The higher snow ratios will be to that south closer to the low where there are better dynamics. DFW really needs that low further north to get in on the good dynamics. If I had to issue a widespread forecast for DFW I'd say 1-3" of snow with locally higher accumulations to the south. If the models happen to be too dry, then it's possible that gets bumped up to 3-6" so we'll see what upper air analysis shows us on Sunday.

[TheProfessor]

Latest update from FWD, it sounds like the are just going with "meh, any snow will be melting with no road impacts so no advisories"

https://pbs.twimg.com/media/ErTZBelXEAMRaiL?format=jpg&name=large

Personally I think they may be a bit too low with their totals from about Hillsboro to just north of Temple. I wouldn't be surprised to see 4-6" in that area if 8-1 ratios occur. If they get 10-1 then it would be even higher.

[Captmorg70]

Snow ratios are very important to talk about. Now the NWS probably isn't looking at Kuchera (I've seen a Wilmington, OH forecaster laugh at that for some reason even though it's just reading the models sampled sounding and converting that into snow ratios.) but Kuchera on both the GFS and 0z CMC shows very poor ratios for the Metroplex, especially the northern Metro. Even in the jackpot areas the CMC and GFS are showing 7/8-1 ratios. It's not until after the event around 12z Monday when the better snow ratios occur. I wouldn't call this a failure mode per say, but it does make the 10-1 maps misleading.

10:1 maps in my opinion are only good for highlighting potential coverage and how much can come out of the sky, nothing about actual accumulation. There are so many other factors in play, but one thing I will say is this so unusual in that the air above is much colder than our typical events in North Texas with such a set up. It's usually borderline at 850mb so ratios may be higher liquid-dendritic growth. Even 2010 we were barely cold enough above. 500mb temps here is -25 to -27C.

850s are cold, but not cold enough to be in the DGZ. I've been going through some Skew-ts and the DGZs are pretty shallow on both global and mesoscale models. In some cases the DGZ is also a bit dry (CMC). Now assuming some of the models are too warm at the surface, then a good estimate for snow ratios would be nearby areas where the models have surface temps near freezing and similar DGZs. It would not surprise me if most of DFW saw snow ratios of 6-1 to 8-1. The higher snow ratios will be to that south closer to the low where there are better dynamics. DFW really needs that low further north to get in on the good dynamics. If I had to issue a widespread forecast for DFW I'd say 1-3" of snow with locally higher accumulations to the south. If the models happen to be too dry, then it's possible that gets bumped up to 3-6" so we'll see what upper air analysis shows us on Sunday.

“The low further to the North”.

Is this reference to the surface low or the ULL?

[Ntxw]

10:1 maps in my opinion are only good for highlighting potential coverage and how much can come out of the sky, nothing about actual accumulation. There are so many other factors in play, but one thing I will say is this so unusual in that the air above is much colder than our typical events in North Texas with such a set up. It's usually borderline at 850mb so ratios may be higher liquid-dendritic growth. Even 2010 we were barely cold enough above. 500mb temps here is -25 to -27C.

850s are cold, but not cold enough to be in the DGZ. I've been going through some Skew-ts and the DGZs are pretty shallow on both global and mesoscale models. In some cases the DGZ is also a bit dry (CMC). Now assuming some of the models are too warm at the surface, then a good estimate for snow ratios would be nearby areas where the models have surface temps near freezing and similar DGZs. It would not surprise me if most of DFW saw snow ratios of 6-1 to 8-1. The higher snow ratios will be to that south closer to the low where there are better dynamics. DFW really needs that low further north to get in on the good dynamics. If I had to issue a widespread forecast for DFW I'd say 1-3" of snow with locally higher accumulations to the south. If the models happen to be too dry, then it's possible that gets bumped up to 3-6" so we'll see what upper air analysis shows us on Sunday.

“The low further to the North”.

Is this reference to the surface low or the ULL?

He's referencing the ULL. It would dramatically increase the QPF. But for me it's a win-lose situation. Hard thumping on the front and middle end but risk of quicker end assuming minimal dry air involved. I'd like to see a good hit early then drag it on with the wrap around. There are multiple ways to do this.

[Portastorm]

I hope Porta has champ the charger ready to chase. Awfully quiet for once in a lifetime event potential down there.

Watching and waiting, my friend. Watching and waiting.

I think it’s going to be close down here. We’re on the edge. Hoping we all add 30 pages to this thread by Monday with all of our snowfall pics and videos.