By AccuWeather.com Meteorologist Tyler Roys.
Storm Hector was named by the Met Office this morning and is currently (as of mid-afternoon) located in the middle of the North Atlantic. It looks disorganized on satellite now, but over the next 24 hours, it will get its act together. The question becomes how strong Hector will become.
This afternoon, at 500mb, it is just a vort max that is racing eastward under a neutral trough towards the British Isles.
As it approaches the British Isles, it will help the trough become negative as a closed low develops. At the surface, this will lead the surface low to take a more northerly turn and in turn avoids crossing Scotland.
The strength of the surface low is related to the trough becoming negative and the vort max becoming robust as it rounds the trough towards the open waters north of Scotland.
The GFS, for comparison sake, only gets the surface low down to 980 mb for early Thursday morning. Again, it is related to the strength of the vort max rounding through the negative trough. Typically, we do not see this kind of storm during the summer time and that can be contributed to the jet stream.
The storm system will be making this left hook northward during the course of Wednesday night. This will bring outbreaks of rain to much of Ireland, northern England and Scotland. The models including the EFI are all highlighting that western coast of Scotland will get some of the heaviest rain. The heaviest rain will come during the evening hours. The models are actually in agreement with how much rain will generally fall across the British Isles.
The GFS is generally forecasting that the heaviest rain will fall across the northwestern coast of Ireland into western Scotland with a max over the western coastal region of Scotland with 1-2 inches.
The ECMWF highlights two areas, the most western coastal region of Ireland and the western coast of Scotland as regions that could get over an inch, with upwards of 2 inches possible in western Scotland. Notice, that much of the rain avoids southern England and the southern Midlands. Any meaningful rainfall will remain across the northern two thirds of the British Isles. This does not bold well for those who are looking for rain as much of southern England has not received a drop of rain so far this month. Granted, after a wet end to May, this is helpful, but now we are moving into the middle of the month with not having received even 0.01 of an inch. This rain coming in could lead to localized flooding in areas that have poor drainage. There could even be some swelling of the banks of small streams and some flash flooding in the streets. This is something to watch in the evening hours.
The bigger story and the reason why it got named is the wind. The EFI for wind gusts highlights much of Ireland, northern Wales, northern England and Scotland with values around .9. This just screams to me that the winds will be unusually gusty and potentially damaging. What is increasing the damaging threat is the time of the year. Trees are in full bloom by now, so when you through in unusually gusty winds, the likelihood for damage increases. Again, we have differences in how strong the winds will be tonight into tomorrow.
The GFS is one of the weakest, with gusts of 40-45 knots (around 50 mph) for northern half of Ireland into northern England and Scotland.
The ECMWF is forecasting peak wind gusts of around 35-40 knots (40-46 mph) for southern Ireland into the Midlands, with gusts of 40-50 knots (46-58 mph) for northern half of Ireland, northern England and Scotland then with a bull's-eye of over 60 knots (69 mph) for the northern coast of Ireland into southern Scotland, including Glasgow and Edinburgh.
The ARPEGE is forecasting that some of the strongest winds will be 50 and 60 mph across Ireland into northern England and southern Scotland. I am not expecting widespread gusts over 50 mph for a prolong period of time, if they do I expect them for an hour to at most 2 hours late Wednesday night into early Thursday morning, essentially when the morning commute will begin.
I suspect that the strongest winds will likely occur across the northern coast of Ireland into southern Scotland and the western coast of Scotland. It is across here that winds could reach around 70 mph. I expect though that the winds will be closer to 50 mph across Ireland, northern England and Scotland. Peak wind gust within this area will be around 65 mph, but as just stated, most people will be closer to 50 mph. Winds will become breezy in London but should fail to reach 40 mph.
The biggest impacts will be from the wind, where I do expect scattered to widespread tree damage, power outages, road closures and transportation delays across northern half of Ireland, western and southern Scotland. Dublin, Manchester (on the line) and Aberdeen will likely endure scattered impacts which include isolated to scattered tree damage, power outages, road closures and transportation delays. Even though it won't be bad in London, there could be some lingering delays in London with transportation, especially with rail and air.
Hector is an unusual and rare late season storm that should not be shrugged off as just another windstorm. Some of the most damaging storms occur out of season and during the summer. The last one occurred in Germany several years ago in July.
Stay weather alert and with AccuWeather.com for the latest in your forecast. If you have a question, please do not hesitate to ask on twitter: Tylertheweather.