MAJOR COLD COMING TO THE US FEB 5-20

[Tyler]

IMO, I think we'll see something like early December, everyone in the eastern 2/3rds gets to see a bit of much below average temperatures...

[Cumulonimbus]

One thing is for sure, don't, for any reason, trust the GFS!

[bob rulz]

In early December pretty much the entire country saw much below average temperatures at least for a few days, not just the eastern 2/3rds. Maybe the eastern 3/4ths of the country, because I don't live in the eastern 2/3rds and it was very cold.

[TheWeatherService.com]

It's starting to become clear that the start of the major cold should come to the east behind our big storm on Feb 5th.

GFS ensembles are and have been showing mean temps staying below average in the east from Feb 5th to the end of their run at hr 360 (now Feb 17th).

As seen below, the long term Euro and GFS ensembles agree that the coldest time of this period should come hr 192-216 (Feb 9-10th).



With the PNA strongly positive, and a negative NAO/EPO to soon be in place, I see no reason to think otherwise.

Im still confident that the cold should last until the 20th, when the NAO goes positive, and the PNA trough collapses.

[Stephanie]

So we have a "little" window opening for winter to return. Then BRING ON SPRING for good!

[Hybridstorm_November2001]

I still think this airmass will modify quite quickly (quicker than the models show). I still see no cold weather trend, just a bump in the road (a week tops, before things start to warm up again West to East).

[Tyler]

I still think this airmass will modify quite quickly (quicker than the models show). I still see no cold weather trend, just a bump in the road (a week tops, before things start to warm up again West to East).

That is not likely to happen in such an amplified pattern as this one. The AO is going to tank, and the US will be held in a cold pattern for at least 3 or 4 weeks. The airmass will not "modify quickly". This is a bitterly cold airmass from Alaska, and its going to take alot to modify.

If you can not tell by the skyrocketing +PNA, and the -AO, then I have no idea what in the world you are looking at...

[Hybridstorm_November2001]

Honestly it just a gut feeling, the fact it has been such a warm January, and the fact that the models tend to over do things like this. We shall see how it pans out in the end.

[Tyler]

Making the point that becuase January was so warm does not mean that February can not be cold. Also, if anything, models are way UNDERdoing the cold air next week. Models have a hard time with cold arctic airmasses like the one next week, and tend to underdo the extent of the cold. Also, the weather doesn't care what it's done in the past...

[Wacahootaman]

That is not likely to happen in such an amplified pattern as this one. The AO is going to tank, and the US will be held in a cold pattern for at least 3 or 4 weeks. The airmass will not "modify quickly". This is a bitterly cold airmass from Alaska, and its going to take alot to modify.

I sure hope so. We need some hard freezes to kill the skeeters in the woods.

Was working outside a while back in a warm spell and the skeeters were bad. Just babies but still anoying

Best case senario fer skeeters would be a super late freeze in mid march followed by a drought.

An while I am wishing, hope to have a record breaking cool spring and summer in North Florida this year.

[TheWeatherService.com]

This ended up being a decent call. Although this cold period wasnt really "major" by a normal winters standards, it was major compared to what we have seen this winter in late Dec and January.

Just as planned, the pattern changed occurred on February 5th... From there, we saw a few fluxes between warm and cold periods, but the cold ended up dominating most of the country during these 16 days....

Here is a composite of the past 2 weeks across the US (Feb 7-20). I would do Feb 5-20, but the map making site only allows 2 week intervals. For the record, Feb 5-6 was pretty cold throughout the nation.

85% of the entire CONUS is BELOW AVERAGE for temps- (remember this wasnt a prediction for just the east... but the entire US)



I mentioned in my original post that the PNA would most likely stay positive for this time. A +PNA favors a cold SE which is exactly what we saw..



The other place that saw colder weather was in the Midwest. This is the area that benefits the most from a negative NAO in place (which I also mentioned in my original post)



Now lets review what I said in my original post, and how everything played out...

1. The EPO should become a lot less positive, and eventually negative as the MJO passes through a stage that could enhance EPO cooling. Also, climatology says that the EPO cant stay raging positive for much longer. This soon to be drop is starting to come up very well on the MRF index model shown by the CDC's site....

The EPO eventually went negative, but MUCH later then expected. Actually about a week later then expected. The EPO staying positive for the 1st half of this timeframe is the main reason that the entire US didnt see "near record cold". I need to find a way to predict the EPO without relying on models in the future...

2. It has been proven that if strong, the MJO passing through phases 8-1-2 correlates to a very negative NAO setting up. Since the MJO wave looks to stay strong as it passes through these phases, the NAO should continue to drop and reach a severely negative stage by Feb 1st. Again, the index models are picking up on this....

The NAO did end up being negative in this timeframe. The NAO call was a good one.

This means that we can now expect a positive PNA to occur during the month of February. What a +PNA does is it puts a strong trough over the SE while ridging the West.

The PNA did end up being positive in this timeframe, and the SE saw cold because of this.

By Feb 20th, the MJO will enter a phase favorable for a positive NAO to develop, and with the Pacific Jet gaining strength once again, the pattern should change back to seasonal if not eventually warm again across the country.

The MJO stalling for 2 weeks in phase 8 is what killed me on this call...

Overall, I will give myself a B on this Feb 5-20 forecast.[/img]