One of the long range predictors used in our winter discussions is now hinting at the possibility of an intense, winter-like cold blast to start October.
The image above shows the 500mb geopotential height forecast across the Alaska and Bering Sea regions. This forecast was produced by the ECMWF model, and is valid for Friday morning, September 12th. In this image, we can see a very strong upper level low in the Bering Sea, centered just north of the westernmost Aleutian Islands.
By observing trends in the Bering Sea, weather conditions in the US can be predicted 17 to 21 days in advance. For instance, if the Bering Sea experiences a deep storm system, cold weather may be expected 2.5 to 3 weeks later. The same goes for high pressure in the Bering Sea. If we extrapolate the image above, valid on September 12th, we might expect a strong upper level low (and resultant cold blast) in the US around September 29th to October 3rd, and possibly further. This long range predictor has had great success in its use across the meteorological community, and if the ECMWF forecast verifies, its success could be something that we'd be frowning upon.
If the ECMWF outlook above verifies, indications are that a very strong upper level low would push into the United States and remain there, possibly for a number of days. If this occurred, much of the nation could reasonably expect to go under significantly-below normal temperatures, with snowfall not out of the question. The availability of cold air in Canada after this week's upcoming cold blast only magnifies that possibility.
It's still unknown as to where this upper level low would originate from, but in the spirit of including all possibilities, I suppose there's at least a slight chance that this upper level low may originate as a sheared-off piece of the polar vortex. Then again, it's certainly possible the storm forms as a rapidly-strengthening storm system in the Plains, dragging cold air down behind it. The point is, we just don't know yet.
What we do know is that if the ECMWF forecast does come true, millions across the country should begin watching for frosts, freezes, and general anomalously cold weather to end September and begin October.
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| Plymouth State Click to enlarge |
By observing trends in the Bering Sea, weather conditions in the US can be predicted 17 to 21 days in advance. For instance, if the Bering Sea experiences a deep storm system, cold weather may be expected 2.5 to 3 weeks later. The same goes for high pressure in the Bering Sea. If we extrapolate the image above, valid on September 12th, we might expect a strong upper level low (and resultant cold blast) in the US around September 29th to October 3rd, and possibly further. This long range predictor has had great success in its use across the meteorological community, and if the ECMWF forecast verifies, its success could be something that we'd be frowning upon.
If the ECMWF outlook above verifies, indications are that a very strong upper level low would push into the United States and remain there, possibly for a number of days. If this occurred, much of the nation could reasonably expect to go under significantly-below normal temperatures, with snowfall not out of the question. The availability of cold air in Canada after this week's upcoming cold blast only magnifies that possibility.
It's still unknown as to where this upper level low would originate from, but in the spirit of including all possibilities, I suppose there's at least a slight chance that this upper level low may originate as a sheared-off piece of the polar vortex. Then again, it's certainly possible the storm forms as a rapidly-strengthening storm system in the Plains, dragging cold air down behind it. The point is, we just don't know yet.
What we do know is that if the ECMWF forecast does come true, millions across the country should begin watching for frosts, freezes, and general anomalously cold weather to end September and begin October.
