TX Winter Wx Threat # 10---cool/cold and wet?

[cycloneye]

Continue the discussions here.

http://www.storm2k.org/phpbb2/viewtopic ... 33&start=0

Thread #9 above.

[wall_cloud]

While I understand what wall_cloud said and it makes sense, it's hard to believe they'd have numbers this high and even going up on Sunday. I know they have plenty of time to change the forecast, I'm just saying that even if they do drop them by quite a bit, I don't think it's going to be anything bone-chilling, colder than we've seen in many years.

Don't read me wrong, southerngale. I'm not trying to defend anyone's forecast on this particular event. I'm just giving a reason why SOME forecasters are more on the conservative side. I really can't justify temps increasing over the weekend for most of the central and eastern CONUS (but keep in mind that I really have only focused on the Amarillo area). Also, like others have stated, those with little experience will rely on models WAY more than seasoned forecasters. I like to think of myself as being between the two, but my gut tells me we still have room to go down on the weekend temp forecast.

[Furious George]

http://weather.cod.edu/forecast/loop.ecmwf850t.html

Notice the 12Z ECMWF still has the unbelievably cold air just north of the US border, but it no longer wants to drive it far south (or at least by next weekend). If this holds true, I would not be surprised to see seasonable weather next weekend.

[wall_cloud]

well once it dislodges, I really don't see it stopping.

[southerngale]

Gotcha wall_cloud. I don't know what their justification is for increasing temperatures over the weekend because they have yet to mention the possibility of any type of front. I know it's a week out, but they have to know that many people are talking about it...it's all over the news as a "possibility" and just being talked about in general. You'd think they'd at least mention it, even if only to say something like, "some of the guidance shows...yada yada yada...but will wait for further guidance before making any forecast changes, but right now, we're leaning on yada yada yada..." but maybe I'm expecting too much.

[double D]

http://weather.cod.edu/forecast/loop.ecmwf850t.html

Notice the 12Z ECMWF still has the unbelievably cold air just north of the US border, but it no longer wants to drive it far south (or at least by next weekend). If this holds true, I would not be surprised to see seasonable weather next weekend.

It also look like the cold air that does make into the US gets quickly shunted to the east. I wonder if the models are on to something as the GFS shows something similar to the EURO. Also the 500mb flow doesn't look as impressive as it did a couple of days ago. I would not be surprised at all if next weekend ends up being sunny and cool/mild, but not cold. Just my 2 cents, which may not even be worth that much.

[Extremeweatherguy]

http://weather.cod.edu/forecast/loop.ecmwf850t.html

Notice the 12Z ECMWF still has the unbelievably cold air just north of the US border, but it no longer wants to drive it far south (or at least by next weekend). If this holds true, I would not be surprised to see seasonable weather next weekend.

It also look like the cold air that does make into the US gets quickly shunted to the east. I wonder if the models are on to something as the GFS shows something similar to the EURO. Also the 500mb flow doesn't look as impressive as it did a couple of days ago. I would not be surprised at all if next weekend ends up being sunny and cool/mild, but not cold. Just my 2 cents, which may not even be worth that much.

Looks impressive on the 18z GFS: http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_192m.gif

Looks impressive on the 12z EURO as well: http://weather.unisys.com/ecmwf/ecmwf_500p_6d.gif (though not as impressive as the 0z)

However, the Euro only goes out to Saturday right now, so we do not know what it shows beyond that time period. If it follows the GFS, then it very well could show arctic cold by Monday the 5th. We just do not know yet.

[TexasStooge]

Uh-oh! Here we go again with the wintry mix-up!

[JenBayles]

I can't take another one! AAAAAHHHH!!!!!

[aggiecutter]

All the models will have trouble bringing an air mass of that intensity very south because the physics of the model says that's not supposed to happen. If, and I am speaking in the subjunctive, this follows what happened in 83 and 89, and this looks like where it is heading, then chunks of the air mass will break off and come down. There will be 3 or 4 of them and then the motherload will break loose and nothing will stop it. In the interim, while everyone is wondering when and where the brunt of the cold will go, these feeder shots will be more than cold enough to produce snow and ice in the southern plains and Texas. That will probably be the big story mid-week as everyone keeps their eyes on what is happening in Canada. In December of 83, a 20% chance of snow showers turned into 8 inches of snow in Texarkana.This occurred with one of the feeder shots before the main cold came.

[wall_cloud]

All the models will have trouble bringing an air mass of that intensity very south because the physics of the model says that's not supposed to happen. If, and I am speaking in the subjunctive, this follows what happened in 83 and 89, and this looks like where it is heading, then chunks of the air mass will break off and come down. There will be 3 or 4 of them and then the motherload will break loose and nothing will stop it.

Agreed. Even if the model indicates that it won't happen, its not necessarily true. I've seen several instances this season where the GFS picked up on something around 7-10 days out, only to change to a more reasonable solution in the medium range (days 3-5), then abrubtly revert back to the original solution. Once this cold air starts south, it will be difficult to stop it. models also tend to overdo the erosion of the cold dome and warm things up too fast...especially in shallow arctic/modified arctic air like this (at least shallow as it begins to dislodge southward).

[GeneratorPower]

wall_cloud, are you saying this air is shallow?

[TrekkerCC]

All the models will have trouble bringing an air mass of that intensity very south because the physics of the model says that's not supposed to happen. If, and I am speaking in the subjunctive, this follows what happened in 83 and 89, and this looks like where it is heading, then chunks of the air mass will break off and come down. There will be 3 or 4 of them and then the motherload will break loose and nothing will stop it. In the interim, while everyone is wondering when and where the brunt of the cold will go, these feeder shots will be more than cold enough to produce snow and ice in the southern plains and Texas. That will probably be the big story mid-week as everyone keeps their eyes on what is happening in Canada. In December of 83, a 20% chance of snow showers turned into 8 inches of snow in Texarkana.This occurred with one of the feeder shots before the main cold came.

We could have some problems if the feeder shot that comes in on Tuesday is a little bit colder than expected. NWS Ft. Worth Office (at least the day shift) is seemingly on board for some wintry precipitation as it is. It could be a mess if the highs/lows are below the forecast. Even as they are are presented now in the NWS forecast, we could have problems each morning Weds-Fri if the temperatures dip below freezing in North Texas. The NWS Ft. Worth Office night shift may change the forecast back to rain and cancel the Special Weather Statement, but the upcoming week will be very interesting.

[ETXHAMXYL]

I've watched 3 of the Dallas stations and all have it at least in the 40's and have all mentioned several fronts coming in one after the other. One station was showing 50's for Sat. and Sunday after low 40's for the week. One showed the weekend in the lower 40's getting colder on Monday...and one in the 30's getting even colder by Monday. Most of the prec. was from Wed.-Fri. but one mentioned possible snow event early next week if all verifies with temps in the twenties. So they are all over the place but Hey its still a way's out.
I just think after tomorrow it will be cold, colder and even colder each and every day and we all know the prec. will be in there sometime, somewhere...right?

[wall_cloud]

wall_cloud, are you saying this air is shallow?

I didn't state that well, did I? initially it will be shallow...and that is what the models will pick up (or not LOL) first. Also, keep in mind that the MEX numbers use a database that looks for previous events (and does very poorly with unusual and extreme events). It is also set up to trend toward climatology in the days 5-7 due to errors perpetuating through the entire forecast period. They will always underdo the cold air in the statistical guidance in an event such as this.

[Air Force Met]

All the models will have trouble bringing an air mass of that intensity very south because the physics of the model says that's not supposed to happen. If, and I am speaking in the subjunctive, this follows what happened in 83 and 89, and this looks like where it is heading, then chunks of the air mass will break off and come down. There will be 3 or 4 of them and then the motherload will break loose and nothing will stop it. In the interim, while everyone is wondering when and where the brunt of the cold will go, these feeder shots will be more than cold enough to produce snow and ice in the southern plains and Texas. That will probably be the big story mid-week as everyone keeps their eyes on what is happening in Canada. In December of 83, a 20% chance of snow showers turned into 8 inches of snow in Texarkana.This occurred with one of the feeder shots before the main cold came.

There is a big difference b/w 1983/1989 and now. The air was a LOT colder in those years compared to nw...and those years had huge arctic highs. That is what is missing. Right now...there is a 1035 high moving down western Canada...but right now...that's it. There is some cold air sitting up near the pole...-30's and -40s...and that is what the Euro is wrapping into the polar vortex. But...short of a monster high to bring it due south...it is the kind of cold that we get some of...but the bulk of goes into the plains and then east. The air will get brought south form it's source...but it's not all that cold considering where it's coming from. -40 for the north pole in January ain't that cold...and Texas is not known for receiving arctic outbreaks from the north pole. We can get good cold snaps from that source region...but the classic don't come from there...not for us....especially when there isn't a mega-high attached.

[GeneratorPower]

wall_cloud, what do you make of the 204hr GFS? Granted, it's day 9.

[wall_cloud]

its feasable in an arctic air outbreak and dang sure looks cold. However, the GFS past day 5 usually doesn't impress me too much.

[southerngale]

All the models will have trouble bringing an air mass of that intensity very south because the physics of the model says that's not supposed to happen. If, and I am speaking in the subjunctive, this follows what happened in 83 and 89, and this looks like where it is heading, then chunks of the air mass will break off and come down. There will be 3 or 4 of them and then the motherload will break loose and nothing will stop it. In the interim, while everyone is wondering when and where the brunt of the cold will go, these feeder shots will be more than cold enough to produce snow and ice in the southern plains and Texas. That will probably be the big story mid-week as everyone keeps their eyes on what is happening in Canada. In December of 83, a 20% chance of snow showers turned into 8 inches of snow in Texarkana.This occurred with one of the feeder shots before the main cold came.

There is a big difference b/w 1983/1989 and now. The air was a LOT colder in those years compared to nw...and those years had huge arctic highs. That is what is missing. Right now...there is a 1035 high moving down western Canada...but right now...that's it. There is some cold air sitting up near the pole...-30's and -40s...and that is what the Euro is wrapping into the polar vortex. But...short of a monster high to bring it due south...it is the kind of cold that we get some of...but the bulk of goes into the plains and then east. The air will get brought south form it's source...but it's not all that cold considering where it's coming from. -40 for the north pole in January ain't that cold...and Texas is not known for receiving arctic outbreaks from the north pole. We can get good cold snaps from that source region...but the classic don't come from there...not for us....especially when there isn't a mega-high attached.

So, at this time, how cold do you think it WILL get down here? And if what you say is cold enough, do you think there's much chance that some frozen precip will accompany it?

Yup, I'm a hopeless snow romantic.

[Kennethb]

wall_cloud, what do you make of the 204hr GFS? Granted, it's day 9.

come back with the 24 and not the 204 GFS and then we may have something to talk about.