December-Wet/Stormy New Years Eve Ahead

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December-Wet/Stormy New Years Eve Ahead

Post by txflagwaver » Sat Nov 17, 2012 9:39 am

Well...we know Thanksgiving is going to be a bust as far as cold weather goes.
Do we have anything to look forward to :?: Are we going to have Winter :?:

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Re: December Weather - What can we expect?

Post by srainhoutx » Sat Nov 17, 2012 4:45 pm

There are 'hints' of a big pattern change showing up via the long range guidance and the 12Z Euro is beginning to sniff out that pattern change as we head toward the last week of November/early December. There is a lot of chatter concerning a fairly significant cold snap around the first week of December. As mentioned in the November thread, a cross polar flow and significant increase in snow cover in our source regions of NW Canada and Siberia with a splitting Polar Vortex dropping S into Canada could bring that building cold air S into the Lower 48 into areas E of the Rockies. That said the zonal split flow of late does appear to be on its last leg once we get beyond Thanksgiving. We will see.
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11172012 12Z Euro 12zeuro500mbHeightAnomalyNH240.gif
11172012 12Z Euro 12zeurohourly850mbTempAnomalyNA240.gif
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Re: December Weather - What can we expect?

Post by srainhoutx » Tue Nov 20, 2012 11:32 am

While this is still way out in the 12Z GFS Operational la la land, it does give a hint of some potential near first week of December. We will see.
11202012 12Z GFS 12zgfs500mbHGHTNH336.gif
11202012 12Z GFS 12zgfs850mbTAnomalyNA348.gif
11202012 12Z GFS 12zgfs250mbWindsHeightsNA336.gif
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Re: December Weather - What can we expect?

Post by srainhoutx » Wed Nov 21, 2012 5:23 pm

Just so everyone has something to dream about when it's warm on Thangiving Day... :mrgreen: ;)
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11212012 18Z GFS 18zgfs850mbTSLPp12_county384.gif
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Re: December Weather - What can we expect?

Post by srainhoutx » Fri Nov 23, 2012 11:22 am

After several day of flip flopping via all the operational guidance and the cold air staying put across Canada, some changes are still brewing as we look to December. The Pacific has not been cooperating, but a more favorable pattern for the cold weather lovers appear to be in the works. It is very common for the GFS and the Euro to become 'confused' and send mixed signals. Some of the pattern 'drivers' this year are already beginning to develop. We are seeing some warming of the stratosphere across the Polar Regions and the polar vortex will likely split. Of course we do not know exactly where the polar vortex will set up shop over Canada after that split, but there are strong indications of a tanking NAO or Greenland Blocking ridge of high pressure that may move E toward the Davis Straights. Also a more favorable MJO appears to be shaping up next week which in time tends to develop a +PNA ridge in the NE Pacific. If we see that active MJO progress E, then the sub tropic jet becomes more active as increased convection migrates toward the Western Mexican Coast. The very long range operations GFS has been hinting of this pattern so that will be something to watch in the coming week. We have to remember that climo suggests our first freeze usually happens near the 8th of December. Hopefully we will begin to see some storminess develop to our W and increase the moisture across the Lone Star State in the weeks ahead. Fingers crossed that with some luck and a good pattern we won't have to wait too much longer for the chatter to pick up and we'll move beyond this rather quiet/boring weather stretch we have been in since September.
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Re: December Weather - What can we expect?

Post by wxman57 » Sat Nov 24, 2012 7:46 am

The first week or so of December is looking pretty good as far as I can see - no evidence of any extreme cold in our area, though the models are indicating building cold in western Canada.

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Re: December Weather - What can we expect?

Post by srainhoutx » Sat Nov 24, 2012 11:46 am

Nice storm brewing across the Plains the first week of December via the 12Z GFS output. Also noting a +PNA developing that continues to build and a very deep Central US trough showing up in the long range as well. Interesting to see the GFS trending 'wetter' over that past couple of days.
11242012 12Z GFS 12zgfs500mbHeightAnomalyNA240.gif
11242012 12Z GFS 12zgfsday6-10240.gif
11242012 12Z GFS 12zgfs500mbHeightAnomalyNH348.gif
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Re: December Weather - What can we expect?

Post by srainhoutx » Tue Nov 27, 2012 10:56 am

The first week or so of December is looking a bit warmish but there are some fairly good hints that the zonal flow and the flood of moisture over the Pacific will be ending. The long range GFS has been sniffing a Pacific Ridge building and a rather impressive dome of Arctic High Pressure (near 1050+) developing near the Arctic. Perhaps a piece of that cold Arctic air will break off and head S during the second week of December near the 12th, +/- a couple of days. We will see.
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11272012 12Z GFS 12zgfs500mbHGHTNA288.gif
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Re: December Weather - What can we expect?

Post by Belmer » Tue Nov 27, 2012 11:20 am

I just can't trust it, Srain! I will take it three days at a time, not more than that. Models seemed to go crazy on cold air for the end of November to early part of December and now reality is that highs will be in the mid to upper 70s, even approaching 80s by the first of next week. Now we will have to wait till mid December to possibly get our shot of cold air? Nope. Just not buying it.

This could be because Joe Bastardi had to speak up in October saying, "November will be the coldest month across the U.S. in quite some time". Well that obviously didn't happen. Last week he mentioned on twitter that, "Hope everyone is ready for a very cold month of December across the mid and eastern US".
Of course, take those quotes how you want. They weren't word for word like that. But pretty darn close. I need to stop listening to that man! :x
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Re: December Weather - What can we expect?

Post by srainhoutx » Tue Nov 27, 2012 12:23 pm

Belmer wrote:I just can't trust it, Srain! I will take it three days at a time, not more than that. Models seemed to go crazy on cold air for the end of November to early part of December and now reality is that highs will be in the mid to upper 70s, even approaching 80s by the first of next week. Now we will have to wait till mid December to possibly get our shot of cold air? Nope. Just not buying it.

This could be because Joe Bastardi had to speak up in October saying, "November will be the coldest month across the U.S. in quite some time". Well that obviously didn't happen. Last week he mentioned on twitter that, "Hope everyone is ready for a very cold month of December across the mid and eastern US".
Of course, take those quotes how you want. They weren't word for word like that. But pretty darn close. I need to stop listening to that man! :x

That's a wise approach. As we have seen this year alone, many a forecaster has eaten a lot of 'crow' whether it is was long range forecasting of cold/wintry weather/rain/tropics/...etc...;) What I do see in the longer range are fairly good indicators that a -AO/-NOA regime with a relaxing EPO lending to a +PNA as the N Pacific calms down in about a week to 10 days. Add to that a SSW (Sudden Stratospheric Warming) event that is underway already with the Polar Vortex in Eurasia leading to a PV split that should drop into Canada near the 5th to 7th of December. There is a lot of snow building across Western Canada and indications are the Rockies and Plains will begin to get some snow cover after the first week of December. Our source regions are primed and ready. Now can they deliver the goods is the $64,000 question.
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11272012 12Z GFS Ensembles 12zgfsensembles500mbHeightAnomalyNH300.gif
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