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yellow Warnings have been issued for the United Kingdom

Snowdonia

Weather hazards over 300m on Wed 01 Jul 2015

High risk

Strong sunlight
The UV levels will be high, with little cloud to mitigate against this.

Medium risk

No medium risks
none

Low risk

Persistent extensive hill fog
Risk of some hill fog during the evening.
Thunderstorms
Risk of an isolated thunderstorm through the day.

No risk

Blizzards
none
Heavy snow
none
Storm force winds
none
Gales
none
Severe chill effect
none
Heavy persistent rain
none

Wed 01 Jul 2015

After a dry and warm night, strong sunshine will lift temperatures quickly through the morning. This strong sun has the potential to spark off localised torrential downpours with an accompanying risk of both hail and thunder. A hot day, with the high UV levels and high humidity worth considering when planning activities. While remaining warm, becoming generally cloudy into the evening, with hill fog closing in.

Time
0000 to 0300 0300 to 0600 0600 to 0900 0900 to 1200 1200 to 1500 1500 to 1800 1800 to 2100 2100 to 2400
Weather
Cloudy Partly cloudy night Sunny intervals Sunny intervals Sunny intervals Sunny intervals Sunny day Partly cloudy night
Precipitation probability
0% 0% 20% 30% 40% 20% 0% 0%

Visibility

Good, locally poor in heavy or thundery showers. Very poor by late evening as hill fog closes in.

Hill Fog

Becoming extensive on southwest-facing ground during the evening at 400m.

Max wind above 500m

Southerly 25 to 30 mph at first.

Temperature

Valleys:
Plus 16 becoming 27 Celsius.
800m:
Plus 15 becoming 18 Celsius.
Freezing level:
Well above the summits.

Thu 02 Jul 2015

A muggy night with low cloud giving a little drizzle in places. Becoming brighter through the morning with cloud bases lifting and breaking to allow some warm sunshine once again, though not the very high temperatures of Wednesday. A fine and dry evening to follow with some pleasant late sunshine.

Visibility

Moderate to poor at first. Becoming very good or excellent by afternoon.

Hill Fog

Broken bases 400 m at first gradually lifting and breaking above the summits by midday.

Max wind above 500m

Southwesterly 25 mph.

Temperature

Valleys:
Plus 14 becoming 22 Celsius.
800m:
Plus 10 becoming 14 Celsius.
Freezing level:
Well above the summits

Fri 03 Jul 2015

Probably a fresher start than of late, leading into another largely dry and sunny day. Becoming warm or very warm later in the day, with higher humidity returning on a southeasterly breeze, this perhaps triggering late showers.

Sat 04 Jul 2015

Overnight showers or thunderstorms, some locally very heavy, will clear east. Then broken cloud and fresher conditions will follow from the west, along with sunshine and a few showers. Light southwesterly winds.

Sun 05 Jul 2015

Dry overnight. Some cloud developing through the day could give a few light showers. Temperatures still on the warm side of average, Winds should be light.

Issued at: 1554 on Tue 30 Jun 2015