Notice - January 9, 2013

Hello, everyone-

I have been a thorough and dedicated weather blog for the past few years, and have managed to keep a good balance of my life and this blog. However, there is business that requires my complete and undivided attention for a while.

That said, I will not be posting anything from January 10 - January 12, 2013. I will resume posting January 13, 2013.

Andrew

Third Stratospheric Warming In Sight; Fourth Warming Incoming?

The long range GFS model has consistently been putting a third sudden stratospheric warming in the forecast, with the upper stratosphere forecast to experience unusually warm temperature anomalies over Canada and the New England area.

The presence of a third sudden stratospheric warming after a significant warming that ended several days ago and an incredible ongoing SSW (link) would surely penetrate the inner core of the polar vortex, pushing it further and further to the breaking point, a.k.a. collapse. I have been heralding such a collapse for weeks now, and I am not backing down with its potential. While the collapse may be pushed back a bit, I am confident that a collapse (the Arctic Circle is no longer dominated by the polar vortex) is imminent in at least some parts of the stratosphere.

Let's turn our attention to the next potential Fourth SSW. This one has me very excited, because it could feature a prolonged warming event, which would only further enhance the vortex's collapse, possibly into oblivion if we're lucky, keyword "if".

This is a forecast image of the Madden-Julian Oscillation, composed of several forecast models and ensembles. The Madden-Julian Oscillation, known as the MJO, involves placement of wind anomalies and convection from the Indian Ocean, across the Pacific and into the Caribbean. Phase 1 starts in the Atlantic and Indian oceans, and transitions east from the Indian Ocean from Phases 1 to 8, as seen in the image on the left. I am in to finding correlations between certain indices, and this is no exception. Upon some hard research, I found data suggesting that a sudden stratospheric warming can be predicted days- even weeks- in advance just by using the MJO. Here's a quick rundown of MJO phase to possible SSW in days:

Phases 2, 3: 25-36 Days
Phases 4, 6, 7: 13-24 Days
Phase 7, 8: 12 Days

So, if we use that MJO forecast graphic, we see the models going from Phase 5 to Phase 7, which is roughly a 13-24 day lag time from MJO phase to SSW. But here's the catch: the models start to circle in Phases 6 to 7, meaning the convection in the image on the left stays in the areas just east (and inside) of Micronesia. What this ALSO means is the potential for a prolonged stratospheric warming event starting in the next 13-24 days and continuing for as many days as the MJO can stay in the designated Phases.

This is all very exciting, but a major caveat is that the MJO does not necessarily always provoke sudden stratospheric warmings- it helps them along, so to speak. In this environment, an SSW would be easy to establish.

Andrew

Snow Prospects Dim For Next Several Days

The prospects for accumulating snow over much of the nation are unusually low for the next several days, and there is one big factor causing this: the Negative PNA.

The image above depicts the typical atmospheric set-up in a negative Pacific North American (PNA) phase. We see high pressure build in the Gulf of Alaska, causing a depression of pressure to form in the Rockies. This then brings cold air to the region, as well as the North Plains. However, high pressure then forms in the Southeast and East Coast due to the presence of low pressure in the West. This high pressure redirects the storm track to favor precipitation along the Gulf Coast or in the Northern Plains. We already saw this pattern earlier this winter, and now it's returning.

This 500 millibar height anomaly forecast for the next 6 to 10 days clearly shows a defined negative PNA pattern, with high pressure in the Gulf of Alaska, low pressure in the Rockies and high pressure in the Southeast. However, because the high pressure in the Gulf of Alaska is so unusually strong, the low pressure in the Rockies also strengthens and expands, meaning the cold would then push into much of the Plains and parts of the Midwest (i.e. Iowa, Missouri). The storm track would then also push east, meaning any storms that took the southern route would affect the Midwest and Ohio Valley. But Mother Nature prefers to leave the United States snowless, as model forecasts have the North Plains storm track on overdrive and the Gulf Coast/Ohio Valley storm track running on empty.

There is some hope, though:

This is the Day 10 forecast from the ECMWF model's ensembles, commonly called the EPS. The EPS shows the majority of the polar vortex collapsing into the Northeast in a fashion that would inspire frigid temperatures and a very windy period in the entire East US. A negative North Atlantic Oscillation (NAO) is present with high pressure over Greenland, and a positive PNA appears with high pressure on the West Coast. I'm not too keen on buying into this idea at the moment, as other forecasts have the PNA in negative territory for a while to come.

Please do not ask if your area will receive snow, this is a general overview, not a precise snowfall timing forecast.

Andrew

Announcements for January 9, 2013

Announcements:

The reason I have not been posting about the snow is because of the scope of the warming stratosphere and it's forthcoming implications, there's just no winter storms to track. I'll bring up the snow topic on a post later today.

Where Could The Polar Vortex End Up?

The latest ECMWF model forecast from Europe is showing the polar vortex (what makes the Arctic as cold as it is, not including the presence of a tundra landscape) sitting over Nova Scotia, Canada and the Canadian Maritimes. This solution would bring incredible cold and wind to the Maritimes, while a negative NAO rages, high pressure builds over the Arctic and a sliver of energy still remaining in Canada tries to build the vortex back up. What an incredible solution this would be if it verified.

But the truth is, models are horrible at handling pattern changes, so it's best we turn to ensemble forecasts.

The top image shows the ECMWF Ensemble prediction system, commonly called the ECMWF EPS (or just EPS for short) forecast at 10 days, and the GFS Ensembles (GEFS) are shown on the bottom, also valid 10 days out. These forecasts are showing 500 millibar height anomalies, where low pressure is shown in cool colors and high pressure in warm colors. Both ensemble sets agree on the polar vortex dropping down into Canada enough to bring the North US some serious cold, but nothing historic (nothing historic has been expected thus far- just serious, harsh cold). I feel like this will be a long-lasting event, with the sudden stratospheric warming's effects lasting for a couple weeks. This means, rather than one big cold shock, it appears possible that waves of cold will penetrate the nation, each wave spreading more and more cold around.

This is still a while away and the models remain without a consensus, so I will be updating you on the possibilities as this forecast time comes closer.

Andrew