Archives For sleet


WEATHER ALERT FOR UK AND REIGATE:

Saturday am: heavy snow falling across our region: check twitter for updates.  A major wintry weather event is unfolding tomorrow and over the weekend across the UK.  This could bring potentially hazardous weather Friday through Sunday almost anywhere in the UK so if you are travelling please take care and check weather warnings for your destination. Reigate remains comparatively sheltered throughout but even here we have the threat of seriously miserable and cold weather with an evil mix of heavy rain, cold winds and sleet turning to snow over this weekend.  Snow amounts and depths for us still uncertain though.

Cold Polar Easterly winds will increasingly undercut and push back the advancing warm air brought in by a vigorous depression out west in the Atlantic. Where these air masses meet is essentially where the heaviest rain and snow will fall: the fronts move north on Friday and then move south on Saturday as the cold air wins out over the warm: it is the move south on Saturday which could bring some SNOW to Reigate. The SW is due to get torrential rain, whilst anywhere north of the M4, especially on high ground, could see heavy snow and drifting in high winds. Reigate remains comparatively sheltered throughout this episode BUT if you are travelling anywhere else do heed weather warnings.
Whilst Reigate will escape the worst of all this, we are due to have a pretty cold, windy, very wet and sleety and at times snowy weekend weather wise!
Friday sees fronts crossing the country and bringing increasing rain to Reigate during the day. Overnight into Saturday might see this rain turning increasingly icy and sleety. Wind chill 0°C to -4°C.
Saturday will be a truly horrible day with temperatures falling throughout. Cold winds (feeling -5°C) and heavy rain will turn increasingly sleety and turn to snow anytime but with greatest risk in the afternoon.  By the afternoon, however, the heaviest precipitation should be dying out over Reigate so any snowfall should be light by that stage.  Saturday could see totals over 20mm of precipitation (mostly in the morning as rain); snow lying could amount from 0cm to a few cm especially on the Downs by evening. Any snow conditions will be worse to the north of the region and over high ground.
Sunday sees even colder weather and a threat of further snowfall from nearby fronts to the south.  Still uncertainty around this so keep watching forecasts. Wind chill -8°C so feeling very cold indeed.  Drier later though.
The rest of the week looks cold, frosty and dry with gradual recovery of temperatures and the hint of more spring-like temperatures next weekend!
Take care this weekend if you are travelling anywhere in the UK: floods in the SW, blizzards and snow up North. If you don’t need to travel, you should probably wait until Sunday or Monday when things have calmed down.

What a difference a year makes: check out the daffodil pictures: taken one year apart!

update Friday pm: much as stated above with main snow zone staying north of London for longer on some models: filthy horrible day mostly sleet icy rain Sat; poss light snow later pm as cold air arrives; cold wind; colder on sunday and into next week. Cold and frosty next week. #notspring 

How much colder is it 100 metres above you, right now? We tested this today by driving up the North Downs which stand 100 metres above Reigate, Surrey town centre.  A Kestrel 3500 was used to collect the data from the hill and temperatures were given a good while to stabilize.  The RGS weather station sits at the foot of the same hill at 96 metres. So, the (rather un-scientific!) results at 2.15pm were as follows:

Reigate 96m: Temp 3.1ºC; dew point 2.5ºC
Reigate Hill 200m: Temp 2.1ºC; dew point 1.5ºC

So Reigate Hill is a whole degree colder than the town, the wind chill was -1C. This was noticeable also in the heavy sleet on the hill.
The decrease in temperature with height is called “lapse rate” and it, usually, continues to drop for another 10,000 metres, the top of the troposhere (“weather atmosphere”). The 1C drop per 100 metres today is a steep lapse rate. We would normally expect around 0.6C drop per 100m, called the environmental lapse rate. The freezing level is currently only 300 metres above Reigate town centre and, with temperatures falling tonight the freezing level will almost certainly arrive at the surface.  The clouds were interesting: thick nimbostratus formed a solid cloud base at 300 metres; amazing shreds of fractus cloud formed on the stiff SE wind blowing up the hill.  Fractus or thicker Pannus clouds are those whispy shreds which appear under rain clouds and indicate deteriorating weather.

Sleet and you shall find” is the likely scenario for Monday in Reigate! Deep and crisp and even snow is not looking on the cards for us on Monday despite it snowing almost everywhere else right now (see map) and despite low temperatures overnight and tomorrow morning.
Light snow might lay for a while am but temperatures are due to creep above freezing for Monday as a warm front pushes “warmer” air across the region. This will deliver sleety rain on a southerly wind rather than snow through the morning. Nevertheless, snow is notoriously tricky to forecast and the cold front following closely behind might still deliver moderate snow showers as temperatures fall Monday pm and overnight to Tuesday heading in on an increasingly brisk and cold Northerly / NE.  Why is snow so difficult to forecast accurately?  There are good reasons for this… but this is a question to tackle later.  Meanwhile, latest model runs suggest cold will hang on for at least a week, snow still very much on the cards… so perhaps “ask and it will be given to you” might still hold true for snow lovers? (Matthew 7:7)