Wednesday, September 17, 2014

New LRC Winter Pattern Projected To Be Snowy

Long range climate models are in agreement that the month of October may feature above-normal precipitation in the North and East US, which could play into a very snowy pattern later on in the winter LRC cycles.

What we'll do first is analyze four precipitation forecasts, each one slightly different from the other based on their initialization and model foundations, from the CFS model. Shown above is the first member of the CFS suite, showing precipitation accumulated over the next 45 days. The end of this forecast period puts us at the very end of October, on Halloween night.

In this forecast, we see a swath of substantial precipitation values extending from the Plains into the Upper Midwest, giving the Great Lakes some of those wet conditions as well. A very dry forecast is noted in the southern Midwest, Ohio Valley, and into the Gulf Coast. We then see somewhat-dry conditions into the Mid-Atlantic, with wet conditions again present in the Northeast.

The next 45-day precipitation forecast from the CFS ensemble members shows a pretty similar story across the board as the first forecast image. In this new projection, we see what appears to be a swath of wetter-than-normal conditions extending from the Southern Plains and into the Midwest, once again hitting the Upper Midwest and Great Lakes the hardest. In a twist, we now see the Eastern Seaboard receiving similarly-heavy precipitation totals, quite a difference from the first ensemble member. Overall, once again, it appears a wet end to September and most of October would be expected for the Upper Midwest.

This third ensemble member from the CFS once again retains a similar projection as the first two members for the next 45 days, but differs in the East. For the Central US, heavy precipitation values are displaced across most of the Midwest and west-central Great Lakes, extending back into the Plains. In this forecast, the Mid-Atlantic is dry, in a similarity to the first ensemble member. The Northeast then appears very wet, all in all looking like a combination of the dry scenario from the first member and wet scenario from the second member.

This fourth member I specifically saved for last, since it appears to be most radical with its forecast in the Midwest (that should be taken as a caveat as well). In this final forecast member, we see very heavy precipitation values over the month of October and late September in the entire Midwest and most of the Great Lakes, stretching down south into the Plains, and even hitting the Ohio Valley in the process. The Eastern Seaboard is forecasted to be predominantly dry, save for the New England region. This could mean that the wet-East projection from the second member we analyzed may be a false forecast, but that's not something we'll investigate right now.

So, why should we care what these four members say about precipitation in the next month and a half?

Because we could be staring right at our winter precipitation pattern.

Something I've discussed on here more than a few times is the concept of the Lezak Recurring Cycle, or LRC. The LRC was developed by meteorologist Gary Lezak, and discusses the idea that weather patterns which develop in October leave a 'footprint' of sorts that is repeated in a regular interval, between 40-60 days through the winter and following spring. In other words, the weather patterns that develop in October repeat themselves for the better chunk of the next year.

So, if we take the four members above to be true (which is NOT something I'd advise to do; I'm showing them in collaboration with additional forecasts below), the Upper Midwest, Midwest, Great Lakes, Plains, and other parts of the East could be in for a very snowy winter.

In the image above, we see an average of precipitation anomalies over the month of October, compiled from eight global forecasting models. In this graphic, we see a familiar trend. The Plains are projected to receive above normal precipitation, leading directly into the Midwest and Great Lakes, as well as the New England area. Does this look familiar? Because it's nearly identical to some of the projections we were viewing earlier in this post.

Based on the average of these eight global model projections, as well as the four CFS ensemble members we dissected earlier, it's safe to say the current trend favors a very wet October for the Midwest (particularly the Upper Midwest), portions of the Great Lakes, Plains, and Northeast. If these projections end up verifying (again, there are many long range caveats associated with this), then the aforementioned areas may want to prepare for a pretty snowy winter, so long as the LRC cooperates.

Since we don't have as many projections for temperature as we do for precipitation, I won't discuss temperature projections for the LRC in-depth right now. However, based on the average of the eight climate models, October could be a warm month, which might then transfer over into a warm winter. I personally don't agree with the diagnosis for now, but the possibility will be re-examined later on this fall.



Anonymous said...

Oh God I hope not! I hope it changes this fall!!

Thank you Andrew for keeping us posted! Much appreciated! But, gota get the very cold & snowy out of my area!!

Joe DeRosa said...

This is in agreement with all the model data I have seen so far. The same blocking patterns are in place, thanks to the warm Gulf of Alaska, and warmer than normal ocean temps near Greenland. The real kicker is going to be the combination of some degree of El NiƱo condition, which will produce higher precipitation rates in the Southeast, with a polar airmass. I agree that the overall LRC will be snowy, but the greatest change from prior Winters will be felt in the mid-South and possibly the deep-South

Christopher Ebie said...

Very interesting. Thanks Andrew.

Unknown said...

dude last year you went for WARM winter...

Then you went for strong possibly super strong El Nino developing for this Spring and Summer of 2014

now you using the CFS in OCT to mean something ? REALLY?

take a look at SEPT OCT 2013 and see how warm and dry those months were. Indeed many forecasters last autumn saw the warm dry Sept oct and assumed it meant something for the winter.

BearCub said...

I remember the Mid-Atlantic States having a warm fall last year. The real cold did not settle in until after Christmas. With the climate/solar changes evolving, I am not sure tried and trusted patterns still apply..

Frank-o said...

In the image that you show that is a average of precipitation anomalies for the month of October.....What I see is a classic La-Nina set up for the East Coast... as we are now well on our way to a El-Nino winter, this is most unsettling....

Frank-o said...

Andrew: I would like to point out that October and November are the "Dry" months in North Carolina. So basing anything on the the LRC, for that time frame, I for one would not put any stock in. WHY? Because as I said Oct & Nov are the dry months here. We get very little rain at all in the fall months....And.... We all ways get cold and snow here in the winter regardless.....

Andrew said...

Unknown: You are mistaken- my winter forecast for last year had a cold outlook for much of the country, which verified well.
Additionally, the Central/East US observed neutral to above-average precipitation during the month of October 2013, with an exception made to the Southeast.

I would advise examining the statements you're making before posting them- this is merely a proposal for what could happen.

BearCub: Last year was certainly the exception in terms of temperatures in October. I'd be surprised if we saw another collapse in this technique this year, however.

Frank-o: Fair point, though that changes when one of the ensemble members puts the East US in heavy precipitation in October, while others do not. Guess it'll be a wait-and-see sort of deal, as most of these theories are.

Frank-o said...

Yes Andrew... at least one of the ensemble members, does put the East US in heavy precipitation in October..and that in 40 to 60 days "could" be the fruit of a Huge El-Nino "type" low coming out of the gulf to just plaster the Gulf coast states of Ga, S.C. and N.C. Fingers Crossed!!! ..But what concerns me is..the other 3 put us exactly where we are in a "normal" October...
Yes!!!! Andrew.....I do see your point and this gives me even more to watch for! Thanks so much for your in-put!! Great Job as per your usual!

Anonymous said...

Last winter the very cold weather arrived in MN at the very end of Dec., and the very, very cold weather arrived around Jan. 6th if I recall correctly. Looking forward to a repeat.

Anonymous said...

Thanks for the update. Hope we get a Halloween Snow Storm like 1991. I'll throw a booya party in my garage and invite the neighbors.