Where is the Thanksgiving Day storm?

For about 3 weeks (look back in the past three posts) I had discussed a possible storm around (several days before to after) Thanksgiving.  In the blog I did last Friday (click here) I talked about the anomalously strong jet stream extended across the Pacific and how it would likely amplify (buckle). That process is starting to happen as of late Sunday night.

I had a feeling that with this buckling that there would be major cyclogenesis (deep low developing) somewhere from the central part of the country to the east coast.  It often is impossible to predict this location much in advance, until a pattern is established and starts to cycle.

On the following satellite image, you can't see the storm that brought rain and much warmer air to the snow battered Buffalo, NY area.  Another weaker small storm (denoted by the L) was moving through Illinois and will bring additional precipitation to western New York.  The two lines with arrows indicates the positioning of two branches of the westerlies (jet stream).  The one in red is the result of the buckling of the extended jet stream noted above.  The second blue one is the polar extension of the jet stream.  The two X's represent energy in the flow that will become the first of two storms.

It now appears that this buckling will result in several storms instead of just one major one.  The first will bring heavy snow and wind to the western Great Lakes late today and tonight (24th).  The second will amplify into the Mississippi Valley and eventually deepen and move up the east coast.  If you look at the Weather Prediction Center's precipitation forecast of precipitation for the next 7 days there is a swath of heavy precipitation on the east coast.  That leaves the High Plains region without much of anything!

WPC precipitation forecast

Early on it appeared pretty likely that Arctic air would make a return visit late this month behind these potential systems.  The cold air is in place behind a strong cold front, but it now appears that much of this cold air will move southeast instead of south.

Map of the current location of the Arctic air and fronts.


It is amazing that the various numerical weather prediction computer models have been all over the place regarding impacts from the evolution of this pattern.  One in particular from the European weather center (ECMWF - it's generally the most accurate) had been indicating possible snow across the central plains for Thanksgiving.  Now it is indicating very mild conditions for Thursday and Friday.  Another model that goes 6 to 8 weeks into the future was indicating a very cold stretch of 7-9 days, starting Thursday.  But it too has backed off considerably.

Another long range computer model's output showing the cold for Dodge City....

Thankfully the above forecast output is not likely to verify - at least this time.

I think the story line is that until the pattern starts to repeat and cycle, it will be tough to have much lead time on any systems.

More later...