MESOSCALE STUDIES OF INSTABILITY PATTERNS AND WINDS IN THE TROPICS.
Semi-annual rept. no. 13, 1 Jun-31 Dec 66,
MIAMI UNIV FLA RADAR METEOROLOGICAL LAB
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The report summarizes additional work on the extremely heavy South Florida rainstorm that produced more than twenty-one inches of rain in twelve hours on 14 October 1965. Although a tremendous amount of moisture converged into the area at 850 mb with relatively large vertical motions and attending divergence aloft, repeated attention was also drawn to that part of the atmosphere near the melting level. Moisture analysis revealed that the transport of water vapor in the 700-500 mb layer was important for the timing and perhaps severity of the event. A moist tongue at this level could be tracked into the area from the western Caribbean. A radar analysis of the storm was made using both non-contoured and contoured radar data. It was observed that enhanced analysis and forecast capability resulted from the use of contoured video. Without it, small-scale organization and location of the heaviest rain would never have been realized. Frequency distributions of video contoured by 26 db attenuation correlated extremely well with the isohyetal analysis. A quantized warning system was suggested to assist the forecaster in heavy rainfall situations. An evening radar angel pattern was found to be useful in character-typing the atmosphere. It was observed that rainfall the next day was inversely proportional to radius of the pattern. When this particular pattern formed, lines of weather moving toward Miami would tend to break up there. A synopsis of South Florida angels observed from a review of 7000 ft of radar film is presented and illustrated.