Maximum Daytime Temperature from partial thickness (1000-850 hPa)

Maximum Daytime Temperature from partial thickness (1000-850 hPa) - C&P method

Partial thickness (1000-850 hPa)

Date period

Cloud class

Max Temperature : °C

*Max temp range for cloud classes with selected thickness and date period:*
Cloud Class	Max Temp °C
0 :
1 :
2 :
3 :

Callen and Prescott method:

This is an empirical technique based on the maximum temperatures observed at Gatwick and the 1000-850 hPa thickness values at midday at Crawley.

Three steps are involved:

Obtain the 1000-850 hPa thickness value (gpm).
Obtain the temperature adjustment for the time of year and cloud class from the graph.
Apply this correction to the uncorrected maximum temperature from thickness values to obtain T_max

The relationship between 1000-850 hPa thickness values (h) and the unadjusted maximum temperature (T_u) is given by:
$$T_u = -192.65 + 0.156h$$

*Cloud Class definitions and adjustment curves:*
Cloud Class	Definition
0	C_L + C_M ≤ 3/8, C_H ≤ 5/8 or any fog confined to dawn period
1	C_L + C_M + C_H = 4/8-6/8 or any fog clearing slowly during morning
2	C_L + C_M ≥ 6/8 or any fog clearing before noon
3	Predominantly overcast with precipitation (not including very slight drizzle) or persistent fog

*Unadjusted maximum temperature (°C) from thickness (gpm):*
	0	1	2	3	4	5	6	7	8	9
1220	-2.3	-2.2	-2.0	-1.9	-1.7	-1.6	-1.4	-1.2	-1.1	-0.9
1230	-0.8	-0.6	-0.5	-0.3	-0.1	0.0	0.2	0.3	0.5	0.6
1240	0.8	0.9	1.1	1.3	1.4	1.6	1.7	1.9	2.0	2.2
1250	2.3	2.5	2.7	2.8	3.0	3.1	3.3	3.4	3.6	3.8
1260	3.9	4.1	4.2	4.4	4.5	4.7	4.8	5.0	5.2	5.3
1270	5.5	5.6	5.8	5.9	6.1	6.3	6.4	6.6	6.7	6.9
1280	7.0	7.2	7.3	7.5	7.7	7.8	8.0	8.1	8.3	8.4
1290	8.6	8.7	8.9	9.1	9.2	9.4	9.5	9.7	9.8	10.0
1300	10.2	10.3	10.5	10.6	10.8	10.9	11.1	11.2	11.4	11.6
1310	11.7	11.9	12.0	12.2	12.3	12.5	12.6	12.8	13.0	13.1
1320	13.3	13.4	13.6	13.7	13.9	14.1	14.2	14.4	14.5	14.7
1330	14.8	15.0	15.1	15.3	15.5	15.6	15.8	15.9	16.1	16.2
1340	16.4	16.5	16.7	16.9	17.0	17.2	17.3	17.5	17.6	17.8
1350	18.0	18.1	18.3	18.4	18.6	18.7	18.9	19.0	19.2	19.4
1360	19.5	19.7	19.8	20.0	20.1	20.3	20.4	20.6	20.8	20.9
1370	21.1	21.2	21.4	21.5	21.7	21.9	22.0	22.2	22.3	22.5
1380	22.6	22.8	22.9	23.1	23.3	23.4	23.6	23.7	23.9	24.0
1390	24.2	24.3	24.5	24.7	24.8	25.0	25.1	25.3	25.4	25.6
1400	25.8	25.9	26.1	26.2	26.4	26.5	26.7	26.8	27.0	27.2
1410	27.3	27.5	27.6	27.8	27.9	28.1	28.2	28.4	28.6	28.7
1420	28.9	29.0	29.2	29.3	29.5	29.7	29.8	30.0	30.1	30.3
1430	30.4	30.6	30.7	30.9	31.1	31.2	31.4	31.5	31.7	31.8
1440	32.0	32.1	32.3	32.5	32.6	32.8	32.9	33.1	33.2	33.4
1450	33.6	33.7	33.9	34.0	34.2	34.3	34.5	34.6	34.8	35.0
1460	35.1	35.3	35.4	35.6	35.7	35.9	36.0	36.2	36.4	36.5
1470	36.7	36.8	37.0	37.1	37.3	37.5	37.6	37.8	37.9	38.1
1480	38.2	38.4	38.5	38.7	38.9	39.0	39.2	39.3	39.5	39.6
1490	39.8	39.9	40.1	40.3	40.4	40.6	40.7	40.9	41.0	41.2
1500	41.4	41.5	41.7	41.8	42.0	42.1	42.3	42.4	42.6	42.8