40/70 Benchmark Posted November 22, 2022 Share Posted November 22, 2022 I think the main deviation from what I had expected for the month of December when I issued my outlook a couple of weeks ago is that the neg NAO looks a bit more pronounced, which turns this: Into this: NO Note how the more pronounced high latitude blocking earlier in the season helps to relegate any semblance of a se ridge to the southern mid Atlantic, as compared to modest positive anomalies encroaching on the NE in the aforementioned guidance and seasonal forecast composite. While the month appears as though it may be trending a bit cooler due to what may transpire at higher latitudes, all is not lost if this does indeed revert back to a slightly tamer look. The month should not end up as mild as it could otherwise due to the tendency for Canada to remain cold, a la the 1973, 1975 and 2007 dataset mentioned on the seasonal forecast, which will ensure chances for wintery weather during the month across the north, despite the fact that it will not be a frigid month. The month will gradually turn colder as the high latitudes become more disturbed, and while the mid-Atlantic may find snowfall scare, New England should not...especially north and interior. However, coastal areas/lower terrain may have frequent precip type issues during coast storms due warm SSTs. Some elevation events are certainly possible. There will also be southwest flow events/warm air advection events, which will be more fruitful for the coast in terms of snow. A white Christmas is likely across the interior and northern New England, and possible along coastal southern New England. It is very unlikely for at least the lower terrain of the mid Atlantnic. While this is not your prototypical "big dog pattern", they are possible should a worthy wave become pinned beneath the NAO block, a la Jan 2011. Said system would be of the miller B variety and primarily impact from the 40th parallel on north. December Forecast H5 Composite: The real fireworks may come after the new year. 6 1 Link to comment Share on other sites More sharing options...
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