Explosive LOW brings real threat of damaging winds Sun – Mon: are you ready?

October 26, 2013 — Leave a comment

WEATHER WARNING (but with a note that some models are downplaying this in latest runs 🙂

The explosive LOW arrives Sunday night on the back of the parent LOW moving across today.  There is a risk of significant disruption, albeit there is also a risk of NO disruption as the LOW trails further north or south and some model runs are downgrading the storm inland to 60mph max which is blowy but not as severe… in any case check forecasts regularly for updates. It’s a very tight little low so changes in track will make an enormous difference to your experience on the ground from “oh, is that all?” to something more akin to “OMG!”.  In any case, the advice is to avoid unnecessary travel if at all possible and expect disruption to all forms of transport due to high winds in the SE and heavy rain further north. The strongest winds are located in the southern part of England and Wales.

Here is an outline of what we can expect in the SE and Reigate in particular.

The relative overnight calm will continue through the small hours until after breakfast when winds will slowly pick up, with gusts over 30mph.  Bands of squally, sometimes heavy showers will pass over during the morning. More rain and gusty winds will continue through Sunday pm making it a miserable afternoon with temps barely exceeding 14c and feeling more like 9c.

The highest winds exceeding gusts of 50-60mph arrive in the SE and Reigate around midnight on Monday and the winds quickly increase thereafter.

High winds with gusts exceeding 50mph will be a feature of Monday morning from 0300hrs through to around lunchtime when they will die down quickly.

Heavy rain will arrive with the highest winds overnight but become lighter through Monday daylight hours.

A NASTY STING IN THE TAIL? RED LINE ON MAP SHOWS POTENTIAL FOR 90-100MPH SUDDEN GUSTS IN AREA AT RISK FROM STINGJET: UPDATE: the 99mph winds at Needles were an example of stingjet winds

THERE IS A RISK OF VERY STRONG DAMAGING GUSTS IN THE SE FROM 09:00hrs – 12:00hrs Monday, ESPECIALLY NEAR THE COAST AND IN THE FURTHEST SE CORNER i.e. Sussex and Kent; but everywhere below the red line on the map is especially at risk from this atmospheric phenomenon discovered after the 1987 storm and only observed and studied retrospectively a few times. A stingjet is a newly discovered feature which can develop in rapidly forming storms such as this.  It is when cool dry air sinks from high in the troposphere and can accelerate winds wrapping around the back of an intense LOW, in this case to potentially over 90mph inland and even 100mph+ gusts are a slight possibility over the coast.  There is a risk of such winds occuring anywhere along the coast of Southern England and inland towards the RED line drawn on the map above.  These gusts are like a giant fist from the sky and can flatten whole forests and take off rooves as they did in 1987.  if one occurs it will be one of the rare occasions when it has been modelled.  The characteristic tell-tale of a stingjet is a loop or hook in the wind field or water vapour satellite photo.  Weathermen will be keenly looking for real-time evidence of this throughout the storm.  A hook-like feature on the high resolution model from NMM seems to suggest a stingjet-like formation.  You can see the hook travelling along the zone of highest winds on the animation below (courtesy of NMM netweather). Read below to see what sensible precautions you should make tomorrow.  OK, so this is not a hurricane and is not anywhere near the force of Sandy or Katrina but hurricane force winds MIGHT be embedded within the maelstrom, so we ought to make sensible preparations to avoid unnecessary damage.

PREPARATIONS:

  • secure anything that can blow around e.g. bird feeders, bins, toys
  • cut back any loose branches and trees: store these in a garage
  • check where your car is parked … avoid parking under suspect trees
  • check roof tiles and chimney pots
  • make sure your pets are safe overnight
  • clear loose and clogged drains and gutters
  • ensure all outside doors and windows are shut and secure
  • locate torches and check they WORK in case of power cuts
  • charge your phone in case of power cuts

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