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FINAL FORECAST FOR NOVEMBER 2017
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Issued: Tuesday 31st October 2017
Contact: simon@weatherweb.net
HEADLINES
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+ A quieter month than recently
+ Drier than average for many
+ Cool to average temperatures
+ Potential for cold later
FACTORS AFFECTING NOVEMBER 2017 GUIDANCE
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+ La Nina is now becoming more pronounced, although it still weak
+ Early snow cover in Canada and Russia lowering temperatures
+ Negative Artic Oscillation allows for cooler air to slip south
+ QBO (Quasi-Biennial Oscillation is easterly)
+ Low solar activity leads to increase tendency for blocking conditions
UNCERTAINTIES - WHAT COULD GO WRONG?
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+ Models may have overplayed high pressure signals
+ Warm Atlantic may enhance convection and hence allow conditions to be stormier
+ La Nina may not intensify as expected
OVERVIEW
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November 2017 is expected to experienced more settled conditions since the weather broke in mid July. All indications are that higher pressure will try to build into the country.
This high pressure will be bringing some days of dry weather but also a risk of overnight frosts, mist and fog.
The far north and far south are likely to be more unsettled on certain days, especially northern Scotland due to the proximity of lower pressure here.
Towards the end of the month conditions may be notably cooler or even cold as high pressure becomes a stronger feature.
BREAKDOWN
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1st to 7th
A rather slack flow through the opening week of November with mainly light winds across most southern parts of the UK and Ireland. This brings much dry weather with a risk of overnight slight frosts and more widespread ground frosts on some nights.
Note that it is not expected to be completely dry and there will be some rain around especially towards the weekend.
Further north the flow tends towards more showers and is likely to turn more north to northwesterly bringing cooler conditions to all.
8th to 14th
Pressure again stays on the high side during the week although there is the risk of some rain and stronger winds tending to affect more western parts of the UK and Ireland early in the week.
Higher pressure then starts to build again with conditions becoming drier once more, although it may be that some showers affect southeast England.
Mist and fog as well as overnight frosts could increase in number as the week progresses.
15th to 21st
There are indications of pressure beginning to build more strongly after the middle of the month.
It may become chilly with a more northwesterly and a few showers to the far north. These showers could be turning wintry over the hills of Scotland.
We also need to watch for lower pressure to the south and the risk of some rain affecting the far south of England, bringing chilly conditions here.
For most it should be mostly dry with some mist or fog patches developing overnight together with frosts. Days should be dry although increasingly cool.
22nd to 30th
The end of November again remains under higher pressure conditions.
Generally dry and rather cool with mist, fog and frosts overnight.
Days are likely to be dry although cloud amounts and sunshine will be dependent on wind direction and the exact position of the high.
Should the high remain in position there is the chance of some cold days with temperature struggling to rise.
At this stage temperatures overall are expected to be close to or just below average overall.
PROBABILITIES
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Temperature
- Very warm 10%
- Warm 20%
- Average 25%
- Cool 25%
- Cold 20%
Rainfall
- Very Wet 10%
- Wet 15%
- Average 25%
- Dry 30%
- Very Dry 20%
CONFIDENCE
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Confidence in this forecast is considered to be moderate.
