Texas Fall 2013

[orangeblood]

Todays 12Z European Model goes to the extreme option, bringing some 55 deg F below normal temps across parts of Colorado next Friday. Lower levels winds coming straight out of the Arctic all the way to the Texas Coast, pretty unbelievable model run.



Lower Level wind/Temps

[Rgv20]

12zGFS Ensembles Means are pretty impressive with the negative temperature anomalies in the 10-15 day...Interesting days ahead for model watching!

[BigB0882]

I'm going to need the models to shunt that Eastward just a little!! SELA is just missing out on the cold, it looks like.

[somethingfunny]

A NEW ARCTIC HIGH HAS BEGUN TO DEVELOP ACROSS INTERIOR ALASKA AND
YUKON TERRITORY. IN THE MIDDAY DARKNESS...ARCTIC VILLAGE IN ALASKA
(PARC) IS CURRENTLY AT -35F. THIS FRIGID AIR WILL INTENSIFY AND
DEEPEN THE REMAINDER OF THE WEEK...EVENTUALLY SPILLING DOWN THE
HIGH TERRAIN EAST OF THE NORTHERN ROCKIES. THE LEADING FRONT WILL
CROSS SOUTH OF THE 49TH PARALLEL ON MONDAY AND CONTINUE BARRELING
SOUTH. THIS EARLY IN THE SEASON...THERE ARE TYPICALLY LONG
INTERLUDES BETWEEN ARCTIC INTRUSIONS. EVEN IF THESE THAWS ARE
BRIEF...THERE USUALLY IS NOT ENOUGH SNOWPACK TO PREVENT
CONSIDERABLE MODERATION OF THE SUBSEQUENT ARCTIC AIR MASS.
HOWEVER...THIS NEXT ARCTIC INTRUSION WILL ENCOUNTER THE MOST
EXPANSIVE SNOW COVER ACROSS THE LOWER 48 THIS EARLY IN THE SEASON
IN MORE THAN A DECADE. THE FRONT WOULD LIKELY ARRIVE IN NORTH
TEXAS NEAR THE END OF THE CURRENT 7-DAY FORECAST. POSTFRONTAL
TEMPERATURES WILL BE INTRODUCED WITH THE THURSDAY MORNING FORECAST
PACKAGE. AT THIS TIME...GUIDANCE IS RATHER UNIMPRESSED...BUT OUR
INCLINATION IS THAT THIS NEXT ARCTIC BLAST WILL BE STRONGER THAN
PROGGED.

25

[Ntxw]

I'm going to need the models to shunt that Eastward just a little!! SELA is just missing out on the cold, it looks like.

You won't miss the cold, it's just that the southeast is being fought back by the SE ridge thanks to -PNA. Cold will likely bleed from the plains but won't be as potent to the east as long as the ridge is there, if it is weaker the colder you will be.

What the models have changed to is instead of pushing the ridge back up to the north (arctic, retrogression) it is progressing it towards the NW coast. This makes much more sense given the pattern we have seen and the + Gulf of Alaska anomalies. That is a much colder scenario vs the prior.

[Ntxw]

An important feature to watch. There is a flare of thunderstorms across the international dateline that will/is linking up to the westerlies. This is a feature to watch as it will be system #1 associated with the incoming Arctic front.

[Rgv20]

Joe Bastardi posted this graphic on twitter....12zECMWF Ensemble Control Run 11-15 Temperature Anomalies

[BigB0882]

Can someone explain temperature anomalies? For example, that graph shows Baton Rouge around the -10 range. Does that means temperatures will be about 10 degrees below normal? So if our high is typically 65 then a high of about 55?

What were the temperature anomalies for this latest event? I would say that our highs were much more than 10 degrees below normal, more like 20 but I don't remember seeing these graphs before hand. I know often time the temps are a lot colder than progged so that map could be very telling if it is being conservative.

[orangeblood]

That's about as cold a 5 stay stretch as you'll ever find on a model run. To give you an idea of what kind of precip is associated with this Euro Control Run, just to wet Portastorm's appetite

[Texas Snowman]

:uarrow: That's about as cold a 5 stay stretch as you'll ever find on a model run. To give you an idea of what kind of precip is associated with this Euro Control Run, just for to wet Portastorm's appetite

http://models.weatherbell.com/ecmwf/201 ... nus_54.png

Wxman57 is going to love December!

[Ntxw]

Can someone explain temperature anomalies? For example, that graph shows Baton Rouge around the -10 range. Does that means temperatures will be about 10 degrees below normal? So if our high is typically 65 then a high of about 55?

What were the temperature anomalies for this latest event? I would say that our highs were much more than 10 degrees below normal, more like 20 but I don't remember seeing these graphs before hand. I know often time the temps are a lot colder than progged so that map could be very telling if it is being conservative.

Baton Rouge's most recent cold snap was between -12 to -14 over 3/4 days averaging about -13. If you look at the maps it's about the same span on the charts.

[TeamPlayersBlue]

Those maps are in CELCIUS though

[BigB0882]

Those maps are in CELCIUS though

Oh, the anomalies are in Celsius? That makes a huge difference. So -10 would be equal to about 18 F difference. No wonder people see this as being so cold. And again, aren't the models often conservative on the cold temps?

[Ntxw]

Folks the latest EPO continues to plunge to almost -2SD's. All guidance including ensembles are remarkably similar heading it into 4-5SD's below. The Pacific Ocean is going hog-wild and will be dealing us the big hand.

[orangeblood]

Those maps are in CELCIUS though

Yes, so some of those purples are 50 plus degrees F below normal

[BigB0882]

Now I just need the models to begin moving that cold East a little in future runs. I want the COLD. We have had no winter for too many years in a row. I will settle for a record cold Fall!

What is crazy is the snow cover will be great so if this sets up again then the next cold batch could be even more potent.

Of course, if this even happens. I have been fooled too many times over the last few winters. lol

[Portastorm]

Folks the latest EPO continues to plunge to almost -2SD's. All guidance including ensembles are remarkably similar heading it into 4-5SD's below. The Pacific Ocean is going hog-wild and will be dealing us the big hand.

Indeed. That is what will drive this pattern in the next 30 days. The Pacific rules the roost as you, Ntxw, and orangeblood have been wisely pointing out to us for weeks. Here's hoping for several wintry weather episodes before the pattern relaxes probably in early January.

Man, I do love those Euro ensembles which orangeblood posted a few posts back. They've got me rummaging through my closet for the kicking shoes!

[Ntxw]

Indeed. That is what will drive this pattern in the next 30 days. The Pacific rules the roost as you, Ntxw, and orangeblood have been wisely pointing out to us for weeks. Here's hoping for several wintry weather episodes before the pattern relaxes probably in early January.

Man, I do love those Euro ensembles which orangeblood posted a few posts back. They've got me rummaging through my closet for the kicking shoes!

Definitely, last year and this year has turned my understanding of indices a complete 180! It's striking that 2012/13 featured a predominant -AO yet because of the +EPO we were flushed with the PAC jet and a semi Alaskan vortex. This year a predominant +AO yet a great Pacific was able to mask it, everyone else was warm but not us in NA. Don't even get me started with 2011/12...

I think we need a better understanding of the EPO and how there are different variations such as in a previous post about retrograding -EPO and progressing one. There are big differences!

[Snowman67]

The forecast discussion of the Bismark, ND NWS office gives some insight as to the origin of the upcoming cold air intrusion into the U.S.

"ONE THING THAT IS MORE CERTAIN IS THE INTRUSION OF COLD AIR. A
VERY COLD AIRMASS IS SETTING UP ACROSS EASTERN SIBERIA AND IS
PROGGED TO ENTER EASTERN ALASKA AND FROM THERE MAKE A BEELINE
TOWARD THE CENTRAL CONTINENTAL USA. THIS COULD POTENTIALLY BE THE
COLDEST AIR WE HAVE SEEN YET WITH 850MB TEMPS AROUND -25."

[Portastorm]

At 6 am Central time on Thanksgiving morning, here's an impressive map. Surface temps. Looks like at least 80% of the CONUS is at or below freezing. As I write this, it's 31 degrees at the Portastorm Weather Center.



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