Circulation

Well the first thing to say is that low’s are not at all unusual in August. Remember the Fasnet storm of 13 August 1979? Tomorrow’s low has a forecast central pressure of 983 hPahPa A Hectopascal is the SI unit of pressure and identical to the Millibar for midday and is situated close to Birmingham. Below is a graphic of charts drawn using reanalysis data from 1948 so you can make your own minds up. The one that immediately stands out to me is the chart for the 2nd of August 1986, with a GIGI Gale Index of 38. Remember this chart uses reanalysis data in a coarse 2.5°x2.5° grid of MSLPMSLP Mean sea level pressure is the pressure at sea level, or, when measured at a given elevation on land, the station pressure reduced to sea level assuming an isothermal layer at the station temperature. values so contours may well be lower.

It just so happens that I have this chart, but as you can see the low close to Tiree is already a filling feature, with a minimum central pressure of 988 hPa at 06 UTCUTC Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT)., and can’t match the forecast depth of tomorrow’s low. So tomorrow’s low looks very unusual, and is likely the deepest low to affect the UKUK The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. on this date in over 75 years!