aggiegeog

Chances for a winter weather event are increasing for late Friday into Saturday morning across northern Texas. A lot depends on the track of the SW low. If it stays up along the Red River then likely just a bit of backside flurries. If it passes south of I-20 then rain likely transitions through all precip types starting late Friday.

The NAM is starting to show what i expect on Friday. A vigorous upper low will cross the state behind the cold front which will generate a surface low over E TX or NW LA. This will lead to a changeover to wintery precip on the backside of the precip. We can also expect some decent rain totals ahead of the changeover. I still see potential for Saturday into Christmas Eve also. We are heading into a very cold and active 2 to 3 weeks.

Ensembles sure indicate something. Looks like we start the outbreak thus weekend with some marginal wintery threats then unsettled late next week. We will then likely see a big storm to finally kick the Arctic outbreak out around New Years.

Despite what individual op runs show I am becoming very optimistic about the chances for winter precip anytime between Friday and early Jan, likely multiple rounds four areas north of I-20 and maybe a round south of there also. We have a solid -EPO and an active STJ both are set in place for at least the next couple weeks and likely longer.

Yep, you cannot complain about how things are working out so far. A tricky forecast for Friday and Saturday but no scenario is anything like what looks possible as of late last week.

I think the N Plains will end up below average as the PNA shifts back to its expected mode of slightly negative with a consistent -EPO.

For North Texas this weekend I think significant precip amounts are very likely, the question is will it be 29 or 60. I can see the Canadian scenario of cold west of I-35 with a wam sector over SE TX.

The cold will be easier to keep if the Arctic Circle sgidta south to the Northern Plains as shown on recent models. Those 1050, 1060 or even 1070 highs will bring cold at the surface SE ridge or not.

Latest models showing the first front on Friday not being real cold so now wintery precip. Then the real cold comes down over the weekend with a massive high pressure dome. With high pressure like that single digits and def teens are very likely for lows. Not much of any precip the extreme cold. Though remember that it takes very little too produce light snow at those temps.

Agreed that we still have a bit of time for things to change, but at this point the models have been very consistent for a week and the threat is becoming greater and greater with every model cycle. This is a Harvey-esque situation where we know about the event well ahead of rime but the true scope becomes clearer as the event nears. Also remember that this event is likely to start next weekend and rounds of precip will continue every few days through at least early January with Arctic air being continually reinforced during that time frame. People had trouble comprehending the possibility of widespread 30"rain totals a week before Harvey also. You cannot deny when all models op and ens show very similar outcomes run after run.

18Z GFS with a scary run. Widespread areas of Texas modeled to get over 3 inches of liquid in sub freezing air.

It shows a historic winter storm for N TX. Just remember this is just one model run, 9 days out from the potential event, so it is far from a forecast.

12Z Euro is wow and it transitions things to snow early enough for much of it to fall as white stuff though all types are likely. Pretty much over a half foot of various precip types along I-20 across the state.

My issue is the models have been very consistent with this event. The ensembles have not wavered and the operational runs, especially the GFS, have been incredibly consistent. Personally I have never seen the models show this strong of a signal, this far in advance (the GFS has been on this for a week without wavering significantly). I will be watching the NAM intently starting on Tuesday as it is the best model for Arctic air masses.

Neither have done great on the big events, though the GFS sure has been consistent on the upcoming storm. The SOI crash lends credence to a big time STJ which we have lacked so far this fall and winter.

I fully respect the NWS and the FTW office in particular is typically great, but the probability chart they put out regarding the winter storm threat being very low is as reckless or even more so than some nobody trying to hype the storm. This storm needs to be taken as seriously as if there was a hurricane being modeled to hit within a week.

If the 12Z plays out then we are really set up for something special as you stated. Extrapolate that out to Christmas and beyond we will be in a winter wonderland.

There is great agreement between the GFS and Euro along with their ensembles on a -EPO/-PNA pattern locking in starting late next week. Still too far out for to be confident in timing of precip or temp profiles to determine precip types. Overrunning events with Arctic air entrenched at the surface will tend to be freezing rain events, but we will wait to see how things play out with each individual system.

06Z GFS shows up to a foot of precip through its run over ETX much falling post Arctic fromt. Now I do believe that reality will prove colder than it shows along with being drier.

Finally the GFS goes back to normal and loses its consistency. Still has the very cold air, but the flow very different with an east based trough and almost little precip with a NW flow.

We are now within 10 days of a potentially historic Arctic outbreak. I don't think I could dream up more ideal conditions than what the GFS had been showing for the last 4 days and now we are in the range of the other global models. GFS now shows the NPO ridge inn the GoA reaching into the 590s at 500 mb. That is levels we see in July here. That will likely lead to 1060s mb highs in MT around New Year's. This will also bring precip as we will be on the southern periphery of the upper trough.

18Z GFS is similar to previous runs through early Sunday then it yanks the energy back over the SW and hold it there for a few days before ejecting on Tuesday. This would allow for significant snows and rains over NM and W TX and maybe into E AZ where they are extremely dry.

I feel ya, I am trying to determine a travel plan to get to the mountains after Christmas. I want no part of driving in an ice storm or blizzard. A few inches of powder I can handle, but that does not appear to be what we are looking at.

I have been expecting the phasing, hope it intensifies more still. Here in E TX we will need an intense upper low for us to have any shot at snow early next week.

I noticed that. The northern Mexican mountains are having a great December.