Latest temperature (min, max, mean) forecast for Heathrow

Recent observations
YYYYMMDD     OBS   Min   Max  Mean
20120510     OBS  14.1  17.1  15.6
20120511     OBS  10.7  16.5  13.6
20120512     OBS   4.6  15.7  10.1
20120513     OBS   4.9  17.3  11.1
20120514     OBS   6.4  12.5   9.4
20120515     OBS   5.0  12.4   8.7
20120516     OBS   3.1  14.9   9.0
20120517     OBS   6.6  15.5  11.1
20120518     OBS   9.2  16.2  12.7
20120519     OBS  11.4  17.4  14.4
20120520     OBS   8.7  11.9  10.3
Latest forecasts
                                  Confidence EnsembleSpread
YYYYMMDD     DAY   Min   Max  Mean Min Max   Min   Max
20120521     000   9.   17.   13.  Hi  -     0.3   0.9
20120522     001  11.   22.   17.  Hi  -     0.2   0.2
20120523     002  14.   23.   19.  Hi  -     0.5   0.1
20120524     003  16.   24.   20.  -   -     1.0   0.9
20120525     004  17.   22.   20.  -   -     1.2   1.0
20120526     005  12.   19.   15.  -   -     1.0   0.9
20120527     006  11.   19.   15.  -   -     1.3   1.0
20120528     007  11.   20.   15.  -   Lo    1.2   1.1
20120529     008  11.   20.   16.  Lo  Lo    1.9   1.2
20120530     009  12.   19.   15.  Lo  Lo    2.1   3.3
20120531     010  11.   18.   15.  Lo  Lo    2.8   3.2
20120601     011  11.   17.   14.  Lo  Lo    3.6   2.9
20120602     012   9.   17.   13.  Lo  Lo    3.6   2.6
20120603     013   9.   17.   13.  Lo  Lo    2.9   3.4
20120604     014  10.   18.   14.  Lo  -     2.9   2.7
20120605     015  11.   18.   15.  -   -     3.2   3.6

-99.9 denotes missing data

For forecasts:

• 'Hi' - denotes that recent forecast errors for the specified forecast length (column 'DAY') have had a standard deviation over the past 30 days of less than 1.5C,
• '- ' - as 'Hi' but in the range 1.5C to 3C.
• 'Lo' - as 'Hi' but greater than 3C.
• The values in the 'Ensemble Spread' columns indicate the standard deviation of the spread of the forecasts between the ensembles. Thus, a value of 1.0 indicates that approximately 2/3rds of the ensemble members lie in the range -1.0C to +1.0C about the mean of the ensemble forecasts.
• The larger the value of the 'Ensemble Spread' the greater the uncertainty of the forecast as the ensemble members have a larger variation for the forecast for the day shown.