Huff Storm Coefficients

Similar to the SCS Rainfall pattern is the Huff Dimensionless Storm Coefficients. The Huff distributions are used by the State of Illinois and are represented in a tabular form. Storms are grouped in four (4) categories depending on whether the rainfall peak occurred in the 1st through 4th quarter of the storm duration (referred to as quartile). The 1st quartile curves are associated with short duration events, roughly 62% of the precipitation whereas the 4th quartile curve represents longer duration storms where the rainfall is more evenly distributed over the entire storm duration. It has been suggested that the 3rd quartile distributions are suitable for the Pacific seaboard.

Dimensionless Huff Storm Coefficients
t/td	Pt/Ptotal for quartile
	1st Quartile	2nd Quartile	3rd Quartile	4th Quartile
0.00	0.000	0.000	0.000	0.000
0.05	0.063	0.015	0.020	0.020
0.10	0.178	0.031	0.040	0.040
0.15	0.333	0.070	0.072	0.055
0.20	0.500	0.125	0.100	0.070
0.25	0.620	0.208	0.122	0.085
0.30	0.705	0.305	0.140	0.100
0.35	0.760	0.420	0.155	0.115
0.40	0.798	0.525	0.180	0.135
0.45	0.830	0.630	0.215	0.155
0.50	0.855	0.725	0.280	0.185
0.55	0.880	0.805	0.395	0.215
0.60	0.898	0.860	0.535	0.245
0.65	0.915	0.900	0.690	0.290
0.70	0.930	0.930	0.790	0.350
0.75	0.944	0.948	0.875	0.435
0.80	0.958	0.962	0.935	0.545
0.85	0.971	0.974	0.965	0.740
0.90	0.983	0.985	0.985	0.940
0.95	0.994	0.993	0.995	0.975
1.00	1.000	1.000	1.000	1.000