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I I I I I I ,I I I I 'I I I I I I I I I .!l...~ a dry mid-level layer providing an explosive updraft scenario particles would be rapidly accelerating through the warm part of the updraft aiding the growth process through collision. Perhaps only 1.5 km is needed in type of vertical setting for the establishment of the warm coalescence precipitation mechanism to produce rainfall. In the subtropics and tropics the atmosphere is very moist rich through deep layers unless a marine inversion is prevalent. In this moist environment the updrafts are usually much slower in the warm portion of the updraft and perhaps a greater depth of updraft is needed for the collision growth process to maximize. Another example is presented in Figure 2 of a more tropical updraft noted at Victoria, Texas at OOOOGMT on November 16,1987. This updraft was used in a QPF laboratory by Ken Cl\lwford of the Oklahoma Climatological Survey for a heavy rainfall case study at the NWS 4th Conference on Heavy Precipitation Conference held in Scottsdale Arizona in September 1994. In this case the depth of the warm layer is 4.0 !an and the application of Equation (1) with a RWL of 3.5 km and a PWI of 1.05 inches is 2.40 inches per hour. Other nearby sounding exhibited PWI's of up to 1.50" resulting in an hourly rate of 2.93"lhour. One additional approximation can be made to arrive at an estimated peak 30 minute rainfall in the 60 minute period by taking the peak 60 minute rainfall times 0.70. Thus for the Denver sounding the peak 60 minute rain of 2.27 inches times 0.70 results in a peak 30-minute rainfall of 1.59"/30 min. In the Victoria example the calculation is made by taking the peak 60 minute rainfall of 2.40" times 0.70 which results in a peak 30minute rainfall of 1.68 inches. In effect the application of Equation 1 has resulted in an approximation of both the peak hourly and peak 30 minute convective rainfall in the core of the thunderstorm ingesting the sub-cloud layer air into its updraft. The use of this equation in operational settings has been proven time and again. The peak 30-minute rainfall is especially applicable to fast-moving "train-echo" situations frequently encountered on the plains and along the Gulf Coast. It is also useful in other train- line echo situations such as those recently experienced in the California floods of January 1995 in Orange and Los Angeles Counties. For interest table 1 is presented with a listing of significant regional flash floods, the depth of the warm layer (PF in this early paper), the average warmth of tile updraft parcel relative to the ambient atmosphere (Deln and the depth in km of the updraft from the cloud base to equilibrium point (DelZ). Some conditions for the Maddox composite soundings are also presented for comparison purposes. The last section of the paper will present a case study of how the QCP2 can be used in an operational setting for a case of flash flooding the Phoenix, Arizona metro area in Maricopa County. This case was offered to the author by Steve Waters of the Flood Control District of Maricopa County. Arizona at the recent NWS 4th Heavy Precipitation Conference. 3