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February 2013 weather in Reigate. Highest temp 11.6C; lowest temp -2.5C; rainfall total 42.6mm.

Also winter 2012-2013 summary available above too.

FULL update of RGS weather data available on the DATA page here!

 

The very cold upper atmospheric pool of air which put Reigate in the freezer this half term (-11ºC at 1500m, -35ºC at 5000m!) is moving off South… to be replaced by warmer air aloft moving in from the North (-1°C at 1500, -25ºC at 5000m).  Watch the video below to see the warm air moving in from the north and pushing the cold air south.  This is rather upside-down to what we would normally expect and is being caused by warm air being squeezed through by an active jetstream in the Atlantic: this is feeding warmer air into the HIGH pressure sitting atop the UK currently.  Reigate weather will be dominated by the HIGH pressure during this week making things mostly dry but, as we are located on the edge of the high pressure weak fronts will be able to influence our weather as they nudge across the Channel early in the week and bring light snow turning to drizzle through Monday and maybe more light rain on Tuesday. Temperatures remain uninspiring at 5°C.


Cloud is spreading from the East tonight associated with the cold easterly winds approaching tomorrow but the sky will hopefully remain clear over Reigate for a siting of the International Space Station this evening. The ISS will make a visible pass over Reigate at 18:57hrs this evening moving from west to east across the sky in just over 2 minutes. Where do we look? Start by looking due west and then nudge a few degrees to the north. The ISS will make an appearance some 40′ above the horizon near Andromeda at 18:57:04 hours. It will ascend to a position almost vertically above our head when it will be only 260 miles away. It is brightly illuminated by the sun and will disappear into the shadow of the Earth as it moves down across the eastern horizon. The ISS is orbitting at over 17,000 mph and takes about 1hr30mins to orbit the Earth.

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The “Russian ice bear” is escaping again and will arrive in Reigate from Tuesday!  A HIGH pressure developing over Scandinavia and a LOW over Europe will open the cage and let the Russian ice bear gallop across Northern Europe and arrive freezing and growling in the UK from mid-week.  Expect cold easterly winds on the back of the bear.  The frigid continental interior, where the bear lives, has had the whole winter to cool down: the source region is now -10ºC and frequently lower. (View the Urals meteorite shower youtube clips again to get an idea of how cold the source region of this air mass is!) There is the potential for some of the coldest temperatures of this winter yet to be recorded in the SE as the bear bites back.  The week looks mostly dry but snow showers are also possible, especially further east.  The easterly winds warm up on their journey west and also pick up some moisture from the Baltic and comparatively warm North Sea; any warming causes instability (a tendency for air to rise and form cloud and rain/snow) and snow showers are therefore possible on the east coast, some of these could reach further inland on the strong easterly winds forecast.  Whilst the duration of this cold snap is not certain, the end of this sort of episode often sees westerly winds return with substantial snow on the leading edge of fronts.  How and when the bear returns to it’s cage remains uncertain,  but it will be prowling around Reigate from Wednesday on wards this week.

This will be no help at all … but the most widely used weather models are completely at odds over half term weather forecasts next week. The GFS (US) system shows warmer, unsettled Atlantic westerlies blowing back through on a perky jetstream and places a HIGH to the south of the UK bringing in milder SW winds for a time. The ECM model (European) has completely the opposite and fixes a HIGH over the NE and puts the UK firmly back in the fridge with a fierce easterly: snow again for the east. The GEFS model run sits on the fence and puts us somehere in between the two other scenarios. This illustrates how each model has slight in-built bias and it is up to experienced meteorologists to pick the one that works best in each type of weather flow.  It also shows how forecast models for more than 200 hours into the future are sometimes unreliable, can only be used to show broad patterns of developing weather and should be used with caution. Meanwhile, the remainder of this week looks drier (except for Thursday!) for Reigate, a warm front brings sleet then rain on Thursday and a HIGH should build in bringing drier and BRIGHTER weather Friday and into the weekend.  Bring back the sun…Reigate last saw the sun on Monday 9 Feb at 8.30am.

Today illustrated how observing changing cloud types can help predict an approaching front and rain. If you look up, you can often have a good shot at forecasting the weather several hours away. Today, a warm front approaching Reigate rapidly from the west was heralded by a series of cloud formations. In case you missed the drama, here is a round up of the best bits:

A bright blue sky and a frosty calm morning quickly gave way to a milky sky with the appearance of high cirrus cloud building into a thicker blanket of milky cloud called cirrostratus. These indicate increasing moisture in the upper atmosphere, which is often a sign of deteriorating weather and frontal rain approaching. A “halo” might appear around the sun with thickening cirrostratus: again, a sign of deteriorating conditions aloft. Cirrostratus clouds continued to thicken and lower into a blanket of middle altitude clouds called altostratus. These turn the sun into a fading white disc. Altostratus clouds are rarely thick enough to cause rainfall. As the front approaches low level stratus clouds appeared scudding above Reigate Hill in the 50mph winds aloft. Persistent rainfall started in Reigate mid-afternoon when thicker featureless nimbostratus clouds moved overhead, marking the arrival of the front proper. The temperature rose throughout the day, from 0°C at 8am to 10°C by 10pm, another indication of an approaching warm front.  The front travelled 200 miles in about 4 hours, a 50mph race across the UK and, despite the gathering wind and gloom, brought a wonderful lesson in meteorology, hope you had a moment to enjoy it!

An unusual winter pressure pattern is building in the early part of next week: a HIGH over Spain and NW Africa and deep LOWS over the Atlantic to the NW of the UK will combine to create what some meteorologists call the “blowtorch”. The relative position of HIGH and LOW pressure will funnel Tropical air from the Azores direct to Reigate possibly raising temperatures to 12°C on Tuesday (the big map shows temps for today, Saturday). This effect is sometimes called the “BLOWTORCH” (or hairdryer) because it can bring unseasonably high temperatures and melt snow rapidly across NW Europe (this blowtorch could reach as far as Russia where snowfall has been extreme). Reigate snow will be long gone by Tuesday but the warming effect could still be marked and a big contrast to a week ago when Tuesday temperatures fell to -6°C. Don’t break out the flip-flops just yet! Unfortunately, the blowtorch is unlikely to last more than a day or two at most and, in any case, it will be accompanied by rain and wind which might make it feel fairly unremarkable! Watch the video clip below which shows temperatures rising across the continent and the cold being beaten back as BLOWTORCH blasts through Europe!