*************Whether Idle's Winter forecast************
Issued 21st December 2016. Valid until 23rd March 2017.
Headline - Varied. Mild start Colder Finish. Dry in England. Stormy at times, especially so in Scotland.
Methodolgy: SSTs, Ice cover, Experience and Gut Feeling.
SSTs: https://www.fnmoc.navy.mil/ncoda_web/dynamic/ncoda_1440x721_global_anom.gif
The SST anomaly shows that the North Atlantic GIN sea area and Arctic Ocean are much warmer than the LTA. Between 1 and 7c warmer. This means northerlies from the Arctic will lack their usual cold bite.
An area of ocean off Newfoundland ... anomalies on the left and SST actual on the right>
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The water to the north is much colder, and the water to the south much warmer than usual - the thermal gradient is extreme and likely to produce storm after storm this winter which will ride east towards Europe on the jet. The water is 20c different temperature in the space of 70 miles. Astonishing.
Ice:
http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/
Shows the current 11.8million km, about 1.3million km 2 less than the LTA for 20 December, and the least sea Ice recorded at this time (its been the same all autumn) since measurements began. We are about 3 weeks "behind "the curve. This will blunt the depth of any cold that arrives from the North.
Gut feeling indicates to me the Ice and SST situation will be influential early on (20 Dec-20 Jan).
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Dates provided are for guidance only 😉.....
Broad scenario -21 Dec - 20 January - generally zonal. Mild the cool then mild as pM air alternates with tM air. Windier and wetter towards NW. More settled and drier towards SE. Mid latitude high will at times deflect storm systems to the N and W of the UK, at other times the storms will affect Scotland. Excellent month for generation of wind power in N and W of UK. Possibly exceptionally dry in SE. Lowland snow fleeting and non-disruptive, some frost and fog in the south.
21 January - 24 January brief easterly type cold, frosty with wintry showers on prone coasts. Storminess resumes by around January 26th, possible transitional snowfall.
27 January - 5 February - Stormy, unsettled. (This time also affecting areas further S). By turn of the month, finally pressure drops over southern and eastern Europe. Cooler, unsettled, wetter for south. Windy, wintry showers on northern Hills. Wind between WSW and NW.
7 February - 14 February - Drier and colder period. Frost. Isolated snow flurries. Easterly winds with Anticyclonic conditions also.
15-23 February- More mobile and westerly. Average temperature and rainfall.
23 February - March 12. COLDEST period of the winter. Winds swinging NW then N then NE then E with northern blocking. Snow in upland areas and possibly more generally in N and E.
March 13-23. Anticyclonic, dry, pleasantly mild at times in S and E.
Notes :I expect the sea ice and temperature anomalies will be much closer to LTAs by late winter, resulting in our best shot at snow in the latter third of winter (ie 20 Feb - 23 March).
The big pattern change that will allow the cooler 2nd half will be the lowering of pressure over eastern Europe as potent storm systems penetrate from west to east. NB potentially very wet and windy in NW from 21 Dec- mid February.
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Whether Idle 21st December 2016.