Uncertainty and forecasting headaches around Wednesday's low pressure

It's already been wet and windy for NW UK but it is developments during Tuesday night which are making forecasters twitchy. It could just be a spell of autumnal wet and windy weather on Wednesday.

Uncertainty and forecasting headaches around Wednesday's low pressure

Issued: 4th October 2022 09:58
Updated: 4th October 2022 10:53

The rain over western Scotland is already causing some disruption. This same frontal boundary will shift southeastwards but then wave back in from the Atlantic. Along this front, another low pressure centre will develop during Tuesday night. This should bring more heavy rain to western areas and strong winds, even gales. There is still uncertainty about how the low will develop, which in turn, affects where will see the heaviest rain and strongest winds on Wednesday morning. Further travel disruption is possible with a lot of surface water and spray on the roads and speed restrictions already announced by Network Rail on routes through northern Britain. There is still the possibility of very strong winds but this seems less likely.

UKV rain and wind Weds am

UKV solution for Wednesday 7am with heavy rain and high gusts over north Wales and NW England, Pennines

The trees are still in near-full leaf and so strong winds can cause more problems at this time of year. They certainly sound noisy in the fresh, gusty SW winds today.

The main forecast models have come together more this morning. The deterministic solution shows heavy rain over Ireland, Northern Ireland and parts of Scotland on Tuesday night. That heavy rain then affects more of Scotland by Wednesday morning and the cold front hits NW England, Wales and SW England around dawn. That frontal band will move eastwards over England during Wednesday morning. There will be strong and gusty winds around this developing wave over the UK and then the low centre continues to deepen out over the North Sea.

Ensemble forecast from Netweather Extra

Part of the GEFS ensemble suite showing pressure pattern by Weds morning

Within the ensemble forecast suite, there are still some solutions which show a deep low centre affecting the UK with severe gales, even storm force winds. Yesterday the UKV showed such winds passing over the Western Isles and Orkney. It has come into line today with the less developed wave. So, a tricky morning at the UK Met Office as they decide on the public service warnings. The overriding forecast theme seems to show a midweek spell of wet and windy weather which is likely to cause some impacts on Wednesday morning. Not much more than some autumnal heavy rain and strong winds. However, there are still outlying hints that it could be a more serious event with high impacts and dangerous winds by early Wednesday and that small collection can not be just ignored. If there was a stronger signal for the deeper low, it would probably be named Storm Antoni by now with an Amber warning.

We have the deep trough in the mid North Atlantic, the strong jet core and the waving front. If you imagine the jet core like a flume at the swimming pool, a tube that you go into and come out of, the area to the left of the exit is where rapid development takes place. This 'yet to form' low centre moving over the UK tonight and early Wednesday will probably manage to stay away from that area which would then keep the shallower low solution.

At the moment there is too much uncertainty and the Met Office forecasters will be waiting on the latest model run, and then will need time to analyse and discuss this morning. Next will be issuing any new warnings or updates to the existing broad yellow wind warning. This was issued yesterday for Tuesday night/Wednesday and maybe then discussing Storm Name number one with Met Eireann and Dutch KMNI.

We’ll await the updates late morning on Tuesday. Meanwhile more discussion and chat in the Netweather community forum. 

Tags: UK Weather  Severe Weather

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