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January Forecast Discussion


REDMK6GLI

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Its a week away. Gfs has beaten the Euro already many times this winter. Gfs has been inching closer and stronger to the coast with every run.

you dont want that to happen - unless you want a cold rain... 

 

I still think this goes OTS for the most part with minimal impacts - a more wound up storm, and it's rain - I'll take OTS

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yup this one looks like even with the perfect track its rain in january...what a disaster of a winter

Not that this is likely as it has no support , but that`s rain 1st and the GFS evolves into that . That's the perfect track .Again not likely but that's what it showed .

post-7472-0-84217300-1420899850_thumb.jp

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Bluewave, you may already know this but just in case. The euro weeklies are an extension of the previous 0z euro ensemble run. Identical through d15. So week 2 being bad goes along with d11-15 not doing so hot on the ensembles lately. The GEFS has been sniffing out the shifts faster lately. Just like this cold shot we're having now. GEFS started showing it days before the EC. 

 

Now we have another model war emerging with the GEFS digging the +pna/-epo idea while the Euro ens is favoring the coldest anomalies and lowest heights in the western half of the conus (although today's 12z run shifted more towards the GEFS idea). It will be another test of the d11-15 between the 2. 

 

My biggest issue with the weeklies is that if the regular ensembles blow the d10-15 period, week 3 is already going to fail more often then not. 

 

 

Strongly agree. The weeklies have been atrocious this winter, mainly because (IMO) the pattern has been quite changeable over the past few months. Since November 1st, we've experienced a few different regimes, from -AO / -EPO in November to +EPO / +AO / +NAO in December, and now -EPO / +AO / +NAO so far in January. Long-term guidance performs with a higher skill in stable patterns like we experienced last winter: generally a similar -EPO / +NAO / Fluctuating AO type regime for the majority of the meteorological winter. This month, the GEFS has been leading the ECMWF with respect to Pacific pattern and tropical forcing. And now the longer term look that the GEFS has been indicating for several days is beginning to appear on the ECMWF ensembles for beyond the 20th-21st. While the ECMWF performs better than the GFS overall, that doesn't preclude periods in which the inverse is true, as we've seen recently. The two models are starting to converge in the longer term, but the weeklies from Thursday night were still based off of an ensemble mean run which was still correcting closer to the GEFS in the D10-15 period.

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Everyone might want to start watching that tricky moisture slug 84-96 hours when we are under the next arctic high, weak subtle disturbance at 500mb mostly impacting the MA and NC region but it gets close.

That's the SW to watch. 96 to 108 it's off the EC a little further N and we snow .

It's draw back is this is the SW that wrecks the trailer.

Doug saw that too . Worth watching.

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That is not the original coastal that most models have now lost, thats the wave we mention above, the GGEM goes insane with it and has a big storm just missing us at 90 hours...it would probably be snow but I don't buy it with no other models having it yet

Ah, thanks. Well, if a big snow storm did miss us, it would certainly fit the pattern of this rather boring winter.

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The AO should fall from strongly positive soon but not a clear negative signal just yet. The EPO is also poised to return after the thaw and the MJO might enter a more favorable phase or at least in the COD, which isn't a bad thing.

Still no reason to fully give up on this winter yet.

MJO is definetly going into more favorable phases and the COD

 

http://www.kylemacritchie.com/real-time-maps/realtime-mjo/

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The AO should fall from strongly positive soon but not a clear negative signal just yet. The EPO is also poised to return after the thaw and the MJO might enter a more favorable phase or at least in the COD, which isn't a bad thing.

Still no reason to fully give up on this winter yet.

Please help me understand in which regions we should be looking to determine the current and future states of the following indices: AO, NAO, PNA, EPO, WPO. Also, please tell me what is the MJO and give me a summary of how it can be used during a weak El Niño winter to forecast wintry weather. While you're at it, I'd like you to explain ENSO numbers to me. And the difference between El Niño and La Niña.
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Poor Run-to-Run Continuity Can Undermine Forecasts (even the best ones)...

 

Back on December 26, I noted in Message #70 in response to another message in which the CPC forecast had been cited favoring a warmer than normal outcome along much of the East Coast for the January 3-9, 2015 period, that such an outcome was not a "slam dunk," as the guidance had been experiencing less than normal run-to-run continuity in the medium- and extended-range. I noted that the GFS ensembles were suggesting caution and even showing the arrival of "some Arctic air."

 

Indeed, the Arctic air arrived, resulting in NYC having its first consecutive winters with a minimum temperature below 10° in ten years.

 

A comparison of the CPC probabilistic idea and the temperature anomalies is below.

 

January3to92015_Temperature_Anomalies.jp

 

In sum, uncertainty should garner a measure of respect in discussions, especially during times when the guidance is showing inconsistent solutions. One should at least know that there is a lot of risk during such times and that things are not necessarily cast in proverbial stone.

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I have noticed that the new GFS is scoring as high as the ECMWF at day 10 recently. The ensembles are also on

track for an upgrade this week along with the operational. So maybe they will help increase the skill in 6-10

and 8-14 day forecasts.

 

attachicon.gifcor_day10_HGT_P500_G2NHX.png

This is very good news. I'm especially excited about the upgrade to the GFS ensembles. The better tools we have, the better insight we can gain.

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This is very good news. I'm especially excited about the upgrade to the GFS ensembles. The better tools we have, the better insight we can gain.

 

I found the details on the upgraded  ensembles in this recent story:

 

http://www.noaanews.noaa.gov/stories2015/20150105_supercomputer.html

 

in January will begin running an upgraded version of theGlobal Forecast System (GFS) with greater resolution that extends further out in time – the new GFS will increase resolution from 27km to 13km out to 10 days and 55km to 33km for 11 to 16 days. In addition, theGlobal Ensemble Forecast System (GEFS) will be upgraded by increasing the number of vertical levels from 42 to 64 and increasing the horizontal resolution from 55km to 27km out to eight days and 70km to 33km from days nine to 16.

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