The wintry weather caused by the Beast from the East has resulted in some unfamiliar codes in weather reports.
The METAR for Birmingham includes the word SNOCLO – meaning the runway is closed due to snow.
The METAR for East Midlands includes a string R09/6503// which is a SNOWTAM. It decodes as “on Runway 09, deposit type 6 = slush exists, 5 = 25-50% of the runway is covered; 03 = 3 mm deep; // braking action has not been determined”. If you were flying regularly in these conditions, you would probably download a SNOWTAM decoder app’s.
As always the temperature and dew point are given, in this case M02/M05. Even at sub-zero temperatures there is some water vapour in the air. When the air is cooled to -5 degrees it will form a solid phase, snow! Sometimes a negative dew-point is called the snow or frost point. Even in sub-zero temperatures, it is possible for the air to be unstable and for CB’s to form, although they will generally be less dramatic as the total amount of water vapour held in the air is less.
The TAF for Lakenheath includes the string of letters TXM00/0120Z TNM04/0204Z. This is normally omitted in temperate climates but you’ll often see it in Scandinavia and Russia. TX = max temperature (0 degrees on the 1st at 2000Z), and TN = min temperature (-4 degrees on the 2nd at 0400Z).