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7
Forecasting and future work
''An intelligence which, for a given instant, could know all the forces by
which nature is animated, and the respective situation of the beings who
compose it, if, moreover, it was suciently vast to submit these data to
analysis, if it could embrace in the same formula the movements of the
greatest bodies in the universe as well as those of the lightest atom—
nothing would be uncertain for it, and the future, like the past, would be
present to its eyes.''
Pierre-Simon Laplace—A Philosophical Essay on Probabilities
7.1 SHORT-RANGE FORECASTING
7.1.1
Ingredients-based forecasting
In the early days of severe weather forecasting in the U. S. in the 1950s and 1960s,
synoptic conditions associated with severe convection in the Great Plains and to
the east were identified. For example, it was noted that a strong low-level south-
erly jet transporting moisture northward from the Gulf of Mexico surmounted by
a more westerly jet aloft were synoptic conditions that seemed to permit the devel-
opment of severe convective storms. This forecasting technique is one of pattern
recognition based on synoptic features. A good example of pattern recognition
forecasting is the use of the idealized synoptic patterns (''Types A-F'') discussed
in the widely used Technical Report 200 for the U. S. Air Weather Service, by
Col. Robert C. Miller, in 1972 and revised in 1975. Since local climatology,
orography, and topography vary significantly across the globe, it is not possible to
formulate a general set of ''forecasting rules'' that will work everywhere: For
example, an easterly wind on the high plains of Colorado, which is indicative
of low-level upslope flow, transporting relatively high-dewpoint air westward, re-
ducing CIN, and increasing vertical shear when the winds aloft have a westerly
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