A great arctic outbreak is potentially near
Posted: Thu Jan 10, 2008 5:15 pm
For days, the numerical guidance has continued to trend stronger for strong ridge amplification near 150W in response to a strong trough amplification near 170E in the Pacific. The tropical forcing potentially influencing this amplification has finally moved into a position that would seem to support the latest numerial guidance.
In the meantime, anomalous cold in AK (1-2+SD cold), will likely be tapped by the aforementioned amplification. Some of the great arctic outbreaks have developed from similar synoptic evolutions. One of the keys to this potential event will be the anomalous nature of the source region and the current climatological norms, which are near the bottom of the annual temperature curve.
Additionally, the positioning of the ridge axis along 150W will likely lead to a nationwide cold west to east. There are trends for undercutting of this Eastern Pacific ridge, which makes sense. So quite a bit of snow/ice the last week in jan for many southern locations could be in order which could tend to "initially" limit the southern penetration of the cold.
To speculate beyond the model guidance, one would expect one or several short waves to amplify and eventually push the cold into the deep south. Further, while the guidance is certainly non supportive for blocking in the North Atlantic, one might further speculate that North Atlantic blocking could initiate in late Jan or more likely February.
Looking at this season thus far, it has been colder than most seasons the last 10 years, which is not saying very much. But more interestingly, the anomalous nature of the temperature pattern continues. From a very warm October, to a very cold early December, to a brief, but potent and highly anomalous cold shot in the Southeast near New Year's to the incredible mild spell we have seen recently. It now seems a 2SD event in on the way.
Looking at the NOAA 8-14 day forecast from today, Thursday, Jan 10th, is somewhat bewildering as it seem much too warm. The numerical guidance continues to trend quicker and stronger with the cold moving into the country and when one considers the source region, quite an event may be on the way.
In the meantime, anomalous cold in AK (1-2+SD cold), will likely be tapped by the aforementioned amplification. Some of the great arctic outbreaks have developed from similar synoptic evolutions. One of the keys to this potential event will be the anomalous nature of the source region and the current climatological norms, which are near the bottom of the annual temperature curve.
Additionally, the positioning of the ridge axis along 150W will likely lead to a nationwide cold west to east. There are trends for undercutting of this Eastern Pacific ridge, which makes sense. So quite a bit of snow/ice the last week in jan for many southern locations could be in order which could tend to "initially" limit the southern penetration of the cold.
To speculate beyond the model guidance, one would expect one or several short waves to amplify and eventually push the cold into the deep south. Further, while the guidance is certainly non supportive for blocking in the North Atlantic, one might further speculate that North Atlantic blocking could initiate in late Jan or more likely February.
Looking at this season thus far, it has been colder than most seasons the last 10 years, which is not saying very much. But more interestingly, the anomalous nature of the temperature pattern continues. From a very warm October, to a very cold early December, to a brief, but potent and highly anomalous cold shot in the Southeast near New Year's to the incredible mild spell we have seen recently. It now seems a 2SD event in on the way.
Looking at the NOAA 8-14 day forecast from today, Thursday, Jan 10th, is somewhat bewildering as it seem much too warm. The numerical guidance continues to trend quicker and stronger with the cold moving into the country and when one considers the source region, quite an event may be on the way.
