Texas Winter 2020-2021

[orangeblood]

CMC parks a massive Arctic HP over the central US early next week, leaving some interesting scenarios for winter weather. IMO, siding with the CMC at this point.... It's typically very difficult to erode this type of airmass so quickly like the GFS is suggesting!





Edit: several of the 12Z GEFS members showing a similar setup to the latest CMC..in fact, almost 50% of its members showing a significant winter storm early next week!!

[txtwister78]

That's part of the problem regarding the GFS (at least with the operational). Has the EPO going back into the positive phase early next week and begins to erode the cold.

[Iceresistance]

CMC parks a massive Arctic HP over the central US early next week, leaving some interesting scenarios for winter weather. IMO, siding with the CMC at this point.... It's typically very difficult to erode this type of airmass so quickly like the GFS is suggesting!

Maybe the GFS wants no snow for Texas but the CMC does.

12z GFS (Without Hotlinking)



In Comparsion to the 12z CMC . . .



Note that a weaker high pressure is more likely to move away faster.

[Iceresistance]

https://images.weatherbell.com/oscillation/gfs-0p25-all/epo/t_series/1612180800-NVz1YCZMeXM.png
https://images.weatherbell.com/oscillation/gfs-ensemble-all-avg/epo/box/1612159200-DjV8vEzjPg4.png

That's part of the problem regarding the GFS (at least with the operational). Has the EPO going back into the positive phase early next week and begins to erode the cold.

The EPO will tell us if it is going to snow or not, the CMC wants a BIG snowstorm in Oklahoma & Northern Texas, meaning that the EPO is going to be Negative.

[txtwister78]

https://images.weatherbell.com/oscillation/gfs-0p25-all/epo/t_series/1612180800-NVz1YCZMeXM.png
https://images.weatherbell.com/oscillation/gfs-ensemble-all-avg/epo/box/1612159200-DjV8vEzjPg4.png

That's part of the problem regarding the GFS (at least with the operational). Has the EPO going back into the positive phase early next week and begins to erode the cold.

The EPO will tell us if it is going to snow or not, the CMC wants a BIG snowstorm in Oklahoma & Northern Texas, meaning that the EPO is going to be Negative.

What I'm referring to is in terms of it's operational output (why it shows cold air modifying/eroding). Not suggesting it's right yet. I would still lean on ensembles more than individual operational runs 7-8 days out (especially for the CMC). Not a great track record hitting that far out. Nice to have the precip showing though on most model runs.

[txtwister78]

That's not a bad look 7-8 days out. With cold air hanging around (hopefully colder than what is shown). Some of the members not showing precip have frozen precip earlier or a bit later than this image stamp.

[Iceresistance]

That's not a bad look 7-8 days out. With cold air hanging around (hopefully colder than what is shown). Some of the members not showing precip have frozen precip earlier or a bit later than this image also across Texas.

https://images.weatherbell.com/model/gfs-ensemble-all-avg/tx/precip_6hr_ptype_multimember_panel/1612180800/1612893600-ifv2LkyirS0.png

Members 2, 12, 13, 18, 20, 26 & 30 are those cold blasts mixing with Moisture!!

[rwfromkansas]

Looks like more ice than snow for DFW though. Like usual. But, some snow at the end maybe. Really only one of the GFS ensembles there gets a good snow for DFW. But there is hope now. It was looking hopeless last week. I am enjoying looking at the NYC snow today via webcam. I don't often do that, but with 20 inches forecasted, want to check out those rates.

[txtwister78]

Looks like more ice than snow for DFW though. Like usual. But, some snow at the end maybe. Really only one of the GFS ensembles there gets a good snow for DFW. But there is hope now. It was looking hopeless last week. I am enjoying looking at the NYC snow today via webcam. I don't often do that, but with 20 inches forecasted, want to check out those rates.

Typically these are mostly ice scenarios. Shallow arctic air that drains down and moisture out of the SW overrides it. Sometimes you don't want too much moisture either (depending on the strength of the arctic HP to our north) because that can actually warm temps a few degrees and leave you with a cold rain (assuming you're rooting for ice). I know we all would rather see a big snowstorm.

[Portastorm]

It's looking (at least to me) like the initial Arctic blast will definitely be focused to our northeast. Hopefully it's part of a process where the pattern retrogrades some so that additional highs coming out of Canada will be more on a north-south trajectory as compared to northwest-southeast. If Texas is going to get in on the action, it looks like our first chance might be in about 8-10 days.

[Cpv17]

It's looking (at least to me) like the initial Arctic blast will definitely be focused to our northeast. Hopefully it's part of a process where the pattern retrogrades some so that additional highs coming out of Canada will be more on a north-south trajectory as compared to northwest-southeast. If Texas is going to get in on the action, it looks like our first chance might be in about 8-10 days.

I don’t think the models have a good handle on this. That big of an amount of cold air shouldn’t have much of a problem pushing south. It’s like it hits a wall around Kansas and then moves straight east from there.

[Iceresistance]

12z Euro similar to 12z Canadian except more Ice & farther east in Oklahoma (Wwwwwwwhhhhhhhhhyyyyyyy Do IIIIIIIIIIIIIIIIIIIII get more snow than Texas? )

[txtwister78]

You can definitely see on the ICON (FWIW) where the model makes zero sense in terms of the progression of the cold air. Look at 15z image/temps and then compare it to 18z/21z where it actually tries to warm temps and "block"/blunt the cold air advancing south. Lol. Yeah that's not happening in that scenario. You can argue the strength of the arctic high depicted on this particular model, but at the very minimum these outbreaks typically have a huge bust potential in terms of temps despite the fact that I do agree the coldest air will probably remain to our NE with this first intrusion.

[starsfan65]

You can definitely see on the ICON (FWIW) where the model makes zero sense in terms of the progression of the cold air. Look at 15z image/temps and then compare it at noon where it actually tries to warm up a few degrees and "block"/blunt the cold air advancing south. Lol. Yeah that's not happening in that scenario. You can argue the strength of the arctic high depicted on this particular model, but at the very minimum these outbreaks typically have a huge bust potential in terms of temps despite the fact that I do agree the coldest air will probably remain to our NE with this first intrusion.

https://www.tropicaltidbits.com/analysis/models/icon/2021020112/icon_T2m_us_50.png
https://www.tropicaltidbits.com/analysis/models/icon/2021020112/icon_T2m_us_51.png

You think this model is wrong?

[txtwister78]

You can definitely see on the ICON (FWIW) where the model makes zero sense in terms of the progression of the cold air. Look at 15z image/temps and then compare it at noon where it actually tries to warm up a few degrees and "block"/blunt the cold air advancing south. Lol. Yeah that's not happening in that scenario. You can argue the strength of the arctic high depicted on this particular model, but at the very minimum these outbreaks typically have a huge bust potential in terms of temps despite the fact that I do agree the coldest air will probably remain to our NE with this first intrusion.

https://www.tropicaltidbits.com/analysis/models/icon/2021020112/icon_T2m_us_50.png
https://www.tropicaltidbits.com/analysis/models/icon/2021020112/icon_T2m_us_51.png

You think this model is wrong?

I think the models (all of them) have a hard time seeing the cold air this far south with outbreaks like this. They don't handle it well. The point I'm making is with that much cold air involved it's not going to stop its progression southward as the ICON showed in its 12z run (it's actually worse at 21z). That doesn't mean we are going to be as cold as those to our east and NE obviously, but I've seen too many bust in temps with these type of outbreaks in the past by the globals.

[bubba hotep]

Growing agreement on a cutoff low dropping into the Pacific off of Cali. That's step 1. Then beyond that the orientation and timing of the trough dropping in over the eastern 2/3s of the country has to be worked out. Then beyond that there are some s/w coming down the backside. Timing of those will be key in determining how far east the cutoff can get before shearing into the base of the trough. Yesterday's 12z Euro was basically the perfect timing of all the moving parts. Today's 12z Euro and CMC offer up different variations of the system. Still a chance timing is off and we don't really get a system and most everything moves through dry.

[txtwister78]

18z GFS flips back and is more bullish with cold shot down into TX Sunday. Prime example of the models flipping back and forth as they try to capture the colder air moving south.

Yes it still has the coldest air off to our NE but at least this run seems more realistic considering the amount of cold air involved in the pattern.

[Texas Snow]

Yesterday the NWS had a Super Bowl Sunday high in the upper 30’s for DFW. Now it’s up 47, which frankly isn’t that cold. Here is their current thinking:

A pair of fast moving disturbances diving through the deep parent
trough will move overhead on Friday and Saturday. The first will
send a weak surface low through the area with a dry weak cold
front accompanying it. The second will send a much colder Arctic
airmass southward into the area late Saturday into Sunday. There
are still quite a few uncertainties with this second front, as
recent guidance has altered the orientation of the upper trough
axis such that the trajectory of the surface high and coldest air
may only skirt the forecast area as a backdoor front rather than a
direct shot of Arctic air. Either way, this should reinforce
below-normal temperatures with highs mainly in the 40s to around
50 on Sunday with most of the area experiencing a freeze
overnight. Without a meaningful moisture source, this system is
largely expected to come through dry within our forecast area.
Another storm system may bring slightly better rain chances during
the second week of February.

-Stalley

[starsfan65]

Yesterday the NWS had a Super Bowl Sunday high in the upper 30’s for DFW. Now it’s up 47, which frankly isn’t that cold. Here is their current thinking:

A pair of fast moving disturbances diving through the deep parent
trough will move overhead on Friday and Saturday. The first will
send a weak surface low through the area with a dry weak cold
front accompanying it. The second will send a much colder Arctic
airmass southward into the area late Saturday into Sunday. There
are still quite a few uncertainties with this second front, as
recent guidance has altered the orientation of the upper trough
axis such that the trajectory of the surface high and coldest air
may only skirt the forecast area as a backdoor front rather than a
direct shot of Arctic air. Either way, this should reinforce
below-normal temperatures with highs mainly in the 40s to around
50 on Sunday with most of the area experiencing a freeze
overnight. Without a meaningful moisture source, this system is
largely expected to come through dry within our forecast area.
Another storm system may bring slightly better rain chances during
the second week of February.

-Stalley

I don't get it.

[Iceresistance]

18z GFS flips back and is more bullish with cold shot down into TX Sunday. Prime example of the models flipping back and forth as they try to capture the colder air moving south.

Yes it still has the coldest air off to our NE but at least this run seems more realistic considering the amount of cold air involved in the pattern.

It's back in the game!

Not much winter precip tho, but it's a start. (Also, what are the GFS ensembles showing?)