The trend continues on 00z
Originally Posted by: White Meadows
...and that applies to the ensemble suite too. There's been a gradual rise in the number of sub -10C 850s, but they're very much glancing blows rather than a deep Beast-type setup. Nonetheless, with low pressure close by that 850 level will be hundreds of feet closer to the surface than with an easterly.
At a ground temperature of 3C, 850hPa is around 4900 feet at 1025hPa sea-level pressure. At (say) 990hPa, it's 4000 feet - and that makes a hell of a difference. It's why we're seeing so many runs with snow despite what looks to be on the face of it less than exciting amounts of deep cold air around.
(Click for full size).
Further up, the SSW is of course ongoing. Last night's ECM run extended it until T+216, which is noon on the 20th. This extension, which was hinted at the day before, will just add further impetus towards the pattern change in my view. However, until it goes back to normal (and subsequently flushes down to the lower layers) it's still rather uncertain as to the longer-term effects. I wouldn't be surprised to eventually see a Scandinavian High and easterlies, though that may be a few weeks away yet.
As an aside, it's wonderful to be seeing all this with over half of the meteorological winter remaining!
Edited by user
12 January 2019 06:05:28
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