0z GFS VERY intresting

[Air Force Met]

what about the extreme cold in China?

It may...but if it doesn't...you don't get the cold air the GFS is putting out. It is a rare thing to get the cold air like the GFS is forecasting...which my the 18th is subfreezing all the way up. That kind of air in SETX is usually accompanied by a large high pressure originating in AK and coming down the lee-side of the Rockies. This is not that kind of scenario...at least not the way it is currently being forecasted. Anti-cyclogenesis begins up there with some weak highs...then it gets lost...then ridges in from the Pacific and Anti-cyclogenesis begins again over the Rockies and that is what sends down the cold air. This is not the kind of set-up that sends us bitterly cold air all the way up the column...especially when it has been so warm in the plains

Also. why would the GFS consistantly show it being very cold on the 17th and 18th in all of its runs during the last few days if it knew that something was not going to happen to allow that cold air to enter the U.S?

Because models get into feedback loops and when they hook onto an idea...it is sometimes very difficult to spit it out. Remember December? What happened? I am not saying it won't get cold here...I am just saying we are not going to see those GFS numbers. The GFS has numbers below freezing all the way through the column. That is NOT going to happen with the current setup. That is what I am saying. If nothing changes...it will not happen.


Also, the GFS is contridicting your idea of the "no cold air coming to alaska"...it is showing 850mb temps. colder than -20C building into Alaksa over the next week or so, and then down to below -30C by the 23rd...which leads me to believe the coldest shot of air comes later this month (may be around the 25th or 26th).

I did not say no cold air...I said it is not that cold....and in context...I mean for them. Fairbanks and Barrow are both normal. They are really cold. For us to get as cold as forecasted...we need to see places like Fairbanks and the like to be very cold....not normal

Also...take some advice...do not look at the 850 MB temps when looking at Acrtic air. Arctic air is very dense. There is usually a very large inversion above the sfc and depending on the elevation...the sfc temps can be significantly colder than the 850 temps. In teh central plains of Canada you can have sfc temps of -40 and 850 temps of -20. So...don't look at the 850 temps. Also...remember...and this had been stressed by numerous mets here before and I will stress it again...the GFS is terrible with temp forecasting...especially this far out with arctic air in areas where there are not a lot of reporting stations.


I just think that this time we do actually have the chance for some cold air...may be not the teens and may be not 20s for highs, but I still think we see at least 30s for highs and a hard freeze within the next 7-12 days.

Now...I would not disagree with that. I do think a high in the 30's is possible with a low in the mid 20's. The GFS though, at least the 18z run, is ridiculous...keeping us below freezing for almost 48 hours....from 17/18z - 19/18z....roughly. That is NOT happening with the way the GFS control run sees it.

Now the caveat. The ensembles show a pattern that is more condusive for colder air to filter down. Notice how the ridging is a lot more pronounced off the west coast with the flow coming straight from AK down the rockies. That's a better setup. Also the SFC setup is better for dumping cold air southward than is the control GFS.

http://wwwt.emc.ncep.noaa.gov/gmb/ens/t ... 10712.html

http://wwwt.emc.ncep.noaa.gov/gmb/ens/t ... 10712.html

[Portastorm]

Air Force Met ... a question about reading those ensembles ... don't the colors of orange and red mean high variability ... as if some of the runs agree with the modeling and some don't? How does one read that? I can certainly see the Alaska-to-the-Rockies flow to which you refer .... but I'm wondering about the colors on the maps.

[Extremeweatherguy]

what about the extreme cold in China?

It may...but if it doesn't...you don't get the cold air the GFS is putting out. It is a rare thing to get the cold air like the GFS is forecasting...which my the 18th is subfreezing all the way up. That kind of air in SETX is usually accompanied by a large high pressure originating in AK and coming down the lee-side of the Rockies. This is not that kind of scenario...at least not the way it is currently being forecasted. Anti-cyclogenesis begins up there with some weak highs...then it gets lost...then ridges in from the Pacific and Anti-cyclogenesis begins again over the Rockies and that is what sends down the cold air. This is not the kind of set-up that sends us bitterly cold air all the way up the column...especially when it has been so warm in the plains

Also. why would the GFS consistantly show it being very cold on the 17th and 18th in all of its runs during the last few days if it knew that something was not going to happen to allow that cold air to enter the U.S?

Because models get into feedback loops and when they hook onto an idea...it is sometimes very difficult to spit it out. Remember December? What happened? I am not saying it won't get cold here...I am just saying we are not going to see those GFS numbers. The GFS has numbers below freezing all the way through the column. That is NOT going to happen with the current setup. That is what I am saying. If nothing changes...it will not happen.


Also, the GFS is contridicting your idea of the "no cold air coming to alaska"...it is showing 850mb temps. colder than -20C building into Alaksa over the next week or so, and then down to below -30C by the 23rd...which leads me to believe the coldest shot of air comes later this month (may be around the 25th or 26th).

I did not say no cold air...I said it is not that cold....and in context...I mean for them. Fairbanks and Barrow are both normal. They are really cold. For us to get as cold as forecasted...we need to see places like Fairbanks and the like to be very cold....not normal

Also...take some advice...do not look at the 850 MB temps when looking at Acrtic air. Arctic air is very dense. There is usually a very large inversion above the sfc and depending on the elevation...the sfc temps can be significantly colder than the 850 temps. In teh central plains of Canada you can have sfc temps of -40 and 850 temps of -20. So...don't look at the 850 temps. Also...remember...and this had been stressed by numerous mets here before and I will stress it again...the GFS is terrible with temp forecasting...especially this far out with arctic air in areas where there are not a lot of reporting stations.


I just think that this time we do actually have the chance for some cold air...may be not the teens and may be not 20s for highs, but I still think we see at least 30s for highs and a hard freeze within the next 7-12 days.

Now...I would not disagree with that. I do think a high in the 30's is possible with a low in the mid 20's. The GFS though, at least the 18z run, is ridiculous...keeping us below freezing for almost 48 hours....from 17/18z - 19/18z....roughly. That is NOT happening with the way the GFS control run sees it.

Now the caveat. The ensembles show a pattern that is more condusive for colder air to filter down. Notice how the ridging is a lot more pronounced off the west coast with the flow coming straight from AK down the rockies. That's a better setup. Also the SFC setup is better for dumping cold air southward than is the control GFS.

http://wwwt.emc.ncep.noaa.gov/gmb/ens/t ... 10712.html

http://wwwt.emc.ncep.noaa.gov/gmb/ens/t ... 10712.html

Thanks for this long explaination of each of my questions, it was very insightful. But here are a few more that you might have good answers to...Do you think that with the high in the 30s and the low in the middle 20s we could see some ice here in Houston from this cold shot? Also, if the ensembles pattern played out, then COULD it get as cold as the GFS is predicting? And finally, what is the absolute COLDEST scenario you could see playing out with this arctic air? any answer to these would be great.

[Valkhorn]

What about February of 1996? Before the massive arctic outbreak for much of the nation, it was very warm for a while in the Southeastern US.

Plus regarding snowcover, the GFS itself is showing some snowpack being deposited in a few pulses to the Ohio river valley if not further south by the time of day 10 anyways.

Also, if there is a southeast snowstorm, it could very well make a hit at record lows due to the cooling of the lower levels by local snowpack.

So I do think cold, snow, and even freezing rain is possible IF this pans out, and the GFS is making a little sense with the teleconnections anyhow in my opinion.

Things have to balance. We've been so warm, it stands to reason things will swing back around.

[LarryWx]

why would the GFS consistantly show it being very cold on the 17th and 18th in all of its runs during the last few days if it knew that something was not going to happen to allow that cold air to enter the U.S?

Besides the fact that 1/17-18 is still 9-10 days away (still a relative eternity as far as model forecasting confidence is concerned), the GFS has averaged cold biased, especially at longer ranges, since a major change that was implemented on 5/15/2001. The physics behind the GFS allow it to more easily bring down Arctic air than reality verifies. Check the top of the two charts in the following time sensitive image:



Note that the GFS is at -8.0 (based on the last 32 days) in the northern hemisphere, which translates into a significant cold bias. The month-long GFS averages have been
in the negative range every day since I started following this chart several years ago. The warmest recently has been the Canadian with a +4.40.

Does this mean I think it can't get very cold by 1/18? No. Who knows? The GFS may get it right this time. But a lot more often than not, it has verified a good bit too cold when showing very cold coming down into the eastern half of the U.S. without other models in agreement. So, I wouldn't bet on it right now. A very cold day 7+ GFS model run for the eastern U.S. , if it is not backed by the consensus of other models, usually doesn't get me too excited about upcoming cold.

Back during the winter of 2001-02, the GFS brought down record breaking after record breaking Arctic cold into the eastern US and they never verified. That turned
out to be a very warm winter.

[jkt21787]

LOL, this is what the GFS is all about, the 0z run shows NO cold air whatsoever entering the southern portion of the country.

[Brent]

LOL, this is what the GFS is all about, the 0z run shows NO cold air whatsoever entering the southern portion of the country.

[Valkhorn]

Yes, the trend is your friend. The pre 17th 'outbreak' isn't there anymore BUT the front before it is now much colder.

You see the GFS has to get its take on the first front, then it can see the next.

The trend = your friend.

[jkt21787]

Yes, the trend is your friend. The pre 17th 'outbreak' isn't there anymore BUT the front before it is now much colder.

You see the GFS has to get its take on the first front, then it can see the next.

The trend = your friend.

And the cold is in and out in less than 24 hours, much like this last front. Not very noteworthy, IMO, and it just continues the trend of this winter with these very fast moving cold airmasses that are gone in matter of a few days, under fast pacific flow.

[Extremeweatherguy]

LOL, this is what the GFS is all about, the 0z run shows NO cold air whatsoever entering the southern portion of the country.

Yeah but with this being the first run of the last many to show less cold on the 17th...I will not buy into it much.

[Yankeegirl]

Hey, the accuwether site has rain and some ice in the forecast for the 18th and the 19th of Jan. They have changed that from yesterday...

((sings)) Its my Birthday.... Its my Birthday....((sings))

[gboudx]

FWIW, local DFW TV met Steve McCauley began hype of a pattern change on the 10pm segment last night. He showed a graphic with the jet stream setting up to dive from AK down into the plains, then back WSW into eastern NM. This put all of Texas in a cold pattern. He caveated by saying it's still a ways off(mid month), but that it's worth mentioning at this point. Maybe he's tired of forecasting warm, dry and fire danger.

[Extremeweatherguy]

Hey, the accuwether site has rain and some ice in the forecast for the 18th and the 19th of Jan. They have changed that from yesterday...

((sings)) Its my Birthday.... Its my Birthday....((sings))

Yeah I just saw that too! May be your birthday wish will come true!

[Extremeweatherguy]

According to the latest hour by hour accuweather forecast...here is what they are expecting the 18th/19th:

The 18th: They have us waking up in the upper 20s with ice, then by the afternoon it changes over to rain, but then begins to mix with sleet overnight.

The 19th: We wake up around 30 with more ice falling. It again is forecast to turn to rain by afternoon.

***The one thing I wonder about is with such a cold morning a some overnight accumulations of ice as well as the cloud cover...i doubt we would be able to reach the 50 degree mark each day. If this scenario really played out..I wouldn't expect to get much higher than 45.***

[Extremeweatherguy]

Looking in the shorter term...the European and the GFS both show it getting pretty chilly here this weekend...not to the level of what may come next week...but cold enough for a freeze or two.

[ETXHAMXYL]

local DFW TV met Steve McCauley always predicts these big changes but I have yet to see it happen. He's sort of our local JB when it comes to getting hopes up way out and then he never comes out and says GEEZE I guess I should have waited to see the pattern become a trend.
You never See TRoy making such a long range hype over something that may or may not happen weeks out. Harold Taft would be turning in his grave had this met taken over for him.




The trend seems to be DROUGHT & DRY WINDY & WARM....Keep Repeating.

[deltadog03]

local DFW TV met Steve McCauley always predicts these big changes but I have yet to see it happen. He's sort of our local JB when it comes to getting hopes up way out and then he never comes out and says GEEZE I guess I should have waited to see the pattern become a trend.
You never See TRoy making such a long range hype over something that may or may not happen weeks out. Harold Taft would be turning in his grave had this met taken over for him.




The trend seems to be DROUGHT & DRY WINDY & WARM....Keep Repeating.

actually the pattern does look to start breaking down...take a look at the 12z euro for the 168hr....ridge going up in alaska and the block starting to go up over greenland!!!

[Johnny]

I wouldn't quite jump on this scenario just yet because of the pre-christmas disappoinment BUT, this scenario is a bit different. First off...currently the temperatures up in Alaska are trending colder unlike this past December. Secondly we are currently in a warm patter and this is bound to break sooner than later. I don't doubt at all we will have a freeze or two or three. Heck, I got down to 30 degrees here in central Montgomery County yesterday morning!

[gboudx]

Etxhamxyl, in no way was I throwing my hopes behind his forecast; only posting it since there's been discussion here about the pattern changing, and because I happened to be watching Channel 8 and saw him present it. I'll tune in to Kristine this week and see what she says. She nailed the last wintry precip event.

[ETXHAMXYL]

Yeah, I like Kristi K's forecast myself if I can't watch my Boy Troy. Just that this guy is one to blow things up way too early. Have a feeling he isn't very popular with the kids who hope for snow, or the adults either. LOL
Just talked to my sister up in the lower part of Alaska and they haven't had much cold or snow so far this year. She said it was still up in the 40's but suppose to be getting colder soon. So maybe things will start falling into place soon.
This Wind blowing dust and walking on cracking blades of dead grass is getting so depressing...Not to mention the dryness makes my hair crackle each time I brush it.
PLEASE Mother NATURE...hurry up and get out of this Pattern.