Winter 2010-11 for the Southern Plains

[Portastorm]

:lol: One run didn't count. But you are right Portastorm, you called it buddy.

No, YOU called it! Don't be so modest.

Anyhow, it's going to be real fun to track this system in the days ahead. This will be our first "play" so to speak of the fall/winter season. We may only have a few of these this winter so it's time to enjoy the modeling, satellites, conjecture, et al. Let the games begin!!

[kb75007]

:uarrow:

It certainly can not be ruled out, IMO. The 'wrinkle' started showing itself with the 00Z yesterday runs and with todays output, you can almost sense a move toward biting on a stronger/slower progression of the Upper Air feature coming through Thanksgiving Day/night. I suspect there will be some model watching in the days ahead.

Hey, didn't I point this out this 'wrinkle' last weekend based on one of the Euro model runs?! In fact, a certain unnamed S2K mod who has a username referencing a certain large city in southeast Texas saw this before any of us did ... guess who?

Sorry, but what is this "wrinkle" you guys are talking about!? Help me out!

[Portastorm]

There could be some upper level energy lagging behind the main cold front. That has the potential to create some overrunning precipitation which would fall through a very cold layer of air. It is not out of the question to think that some parts of north Texas or the Panhandle could see a frozen precip threat. I would still put the odds at slim for this to happen but it is a possibility should the modeling verify.

But we have some very good pro mets who post on here and they have been opining from time to time. Watch their comments!

[kb75007]

I see Fox 4 has dropped there high for thursday a couple degrees and put some precip in the forecast.

[srainhoutx]

I see Fox 4 has dropped there high for thursday a couple degrees and put some precip in the forecast.

Perhaps you could put your genaral location in your profile. You'll find that our Mets will provide some great information if they know where you are located.

[kb75007]

I see Fox 4 has dropped there high for thursday a couple degrees and put some precip in the forecast.

Perhaps you could put your genaral location in your profile. You'll find that our Mets will provide some great information if they know where you are located.

Okay thanks did it!

[Ntxw]

The model mayhem continues! EC is even slower than before and a bit less cold. GFS sort of does the same thing but faster. Talk about headache! EC still has a low holding back, so still expect cloudy, chilly weather!

[wall_cloud]

The models continue to show their confusion in handling the timing of this feature. The 21/00z runs of the gfs/ecmwf/gem show the slower trend with the main shortwave swinging around the base of the trof late Thursday. While this may very well be how this system plays out, I am a little concerned that the models continue to handle strong cold fronts with a slow bias. Taking at look at the current surface analysis. Very cold temperatures exist across the northern Plains (a few subzero readings in portions of MT). Farther south, a retreating warm front exists over portions of the central High Plains. The baroclinicity along this boundary was not captured by the 00z models which under played the cold air over western KS and the relatively warm air in the warm sector. My concern is that this strong baroclinic zone to the south (which will weaken with time) may lead to stronger (than the models suggest) winds aloft as an upper level jet forms to restore the thermal wind balance. These strong winds aloft may help shove any discernible shortwave trofs out slightly faster than the models currently want to. I threw out the 00Z GFS/ECMWF for now and went with the slightly faster 18Z DGEX solution. This bastardized NAM/GFS concoction shows the stronger north winds behind the front and slightly faster timing that I would expect. I sure hope that I'm on the right track as this timing would bring the front into my area before temps really get a chance to warm up. That sure makes max temp forecasting a lot easier! This may be way off base but I guess only time will tell.

Not that the climatology will have one ounce of bearing on the evolution of the longwave pattern over the next several days but a slower solution does mean we (in west central TX) would be looking at an early morning fropa as opposed to one during the afternoon. This is more in line with what we typically see.

[Portastorm]

wall_cloud, thanks as always for your insights. It appears that you and your colleagues have some real challenges ahead in forecasting how Thanksgiving day plays out with the fropa. In its morning AFD, the NWSFO EWX used the word "conundrum" about Thursday!

[srainhoutx]

Interesting write up, wall_cloud and I agree. My thinking is the Arctic Boundary may well be as much as 24 hours faster than currently progged. My past experience of watching these type of set ups tells me that the models are under estimating the dense shallow nature of the cold air and are keeping the energy too long in the SW. Could I be wrong? Certainly! I also am becoming concerned about the severe weather parameters across N and Eastern TX and point E as well. Interesting days ahead.


The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For official information, please refer to NWS products.

[Portastorm]

Larry Cosgrove has a good read here on the week ahead and beyond:

http://www.examiner.com/weather-in-houston/weatheramerica-newsletter-saturday-november-20-2010-at-5-00-p-m-ct

[Portastorm]

The 12z Euro is less than impressed with this "polar front."

http://www.meteo.psu.edu/~gadomski/ECMWF0.5_12z/ecmwfloop.html

[srainhoutx]

Beyond our Thanksgiving front, I'd keep on eye on the 30th through December 5th/6th +/- a couple of days. A mighty big winter storm keeps showing up.

[Extremeweatherguy]

12z ECWMF valid 6am Thanksgiving morning:


not all the fronts on this map are depicted, only the ones important to my discussion

I have added the approximate location of the surface front (which will precede the 850mb front), to give an idea of where it thinks the cold air will be by that point. If this run is correct, then the surface front will be through Oklahoma and most of the N. Texas metro areas by sunrise on Thanksgiving day, with central and SE Texas still on the warm side.

This is a very fast moving punch of colder air though, and 24 hours later the front is already reaching the east coast of the USA! The great lakes region and upper Mississippi valley region look very cold Friday, and some nice lake effect bands will likely set up in that region. For the southern plains, the ECMWF drops the 1030mb surface high into west-central Texas, bringing chilly air into much of the region. However, it definitely looks like just a glancing blow compared to what could have happened if the coldest "punch" of air was directed more toward the south rather than east. None the less, the chilliest readings of the season are still likely for the entire southern plains region Thursday through Saturday, with it obviously colder and colder the further north you go.

6am Friday morning:


not all the fronts on this map are depicted, only the ones important to my discussion

Of course, everything stated and shown above is dependent on the ECMWF being correct, which may not be the case. As many have pointed out, cold airmasses can sometimes drop southward down the plains much more quickly than the models forecast. If this is the case, then the front might actually be much further into Texas by Thanksgiving morning.

[Ntxw]

Second half of the 18z GFS is crazy. Only the 18z (not believable) but apparently the mad hatter has taken control of it. Keeps the pattern chilly and bombs a phantom storm in the southern plains swinging it through the gulf coast up the east coast as a nor'easter, and frigid in it's wake for early Dec. Too far out to believe, however the Euro has shown signs of another cold intrusion the week after Thanksgiving.

Models are still trending a bit slower for the frontal passage on Thanksgiving.

[kb75007]

So on Thanksgiving day im guessing the temperatures are going to drop throughout the day? Whats the latest on the front?

[Ntxw]

So on Thanksgiving day im guessing the temperatures are going to drop throughout the day? Whats the latest on the front?

Current trend says front arrives early on Thursday accompanied with some light, chilly rain throughout the day for North Texas.

There is a series of storms laying groundwork for snow up north before the arctic front arrives, perhaps ripening things for the future.

[kb75007]

So on Thanksgiving day im guessing the temperatures are going to drop throughout the day? Whats the latest on the front?

Current trend says front arrives early on Thursday accompanied with some light, chilly rain throughout the day for North Texas.

Is it possible any of it will be frozen precipitation? I just noticed on the NBC news website (Dallas) that the high for Thanksgiving was 41 with a chance of rain.

[Ntxw]

So on Thanksgiving day im guessing the temperatures are going to drop throughout the day? Whats the latest on the front?

Current trend says front arrives early on Thursday accompanied with some light, chilly rain throughout the day for North Texas.

Is it possible any of it will be frozen precipitation? I just noticed on the NBC news website (Dallas) that the high for Thanksgiving was 41 with a chance of rain.

At this time it looks unlikely. If the arctic air is colder than predicted and moves further/faster south than progged, there is a slight chance with overrunning precip but don't expect anything like that right now.

[kb75007]

What about anywhere in Oklahoma?