FORECASTING UPPER AIR SYSTEMS

To prepare surface and upper air prognostic charts, we must first make predictions of the weather systems for these charts. Inasmuch as the current surface and upper air charts reveal the current state of the weather, so should the prognostic charts accurately reveal the future state of the weather.

Preparing upper air and surface prognostic charts dictates that the Aerographers Mate first begin with the upper levels and then translate the prognosis downward to the surface. The two are so interrelated that consideration of the elements on one should not be made independently of the other.

Prognostic charts are constructed at the Fleet Numerical Meteorology and Oceanography Center (FNMOC). The resultant products are transmitted over their respective facsimile networks.

Overseas Meteorology and Oceanography (METOC) units also construct and transmit prognostic charts. We are all too often inclined to take these products at face value. Since these prognostic charts are generally for large areas, this practice could lead to an erroneous forecast.

It is important that you, the Aerographers Mate, not only understand the methods by which prognostic charts are constructed, but you should also understand their limitations as well. In this chapter we will discuss some of the more common methods and rules for forecasting upper air features. In the following chapter, methods and techniques for progging upper air charts will be considered. These methods can be used in constructing your own prognostic charts where data are not available and/or to check on the prognostic charts made by other sources.

Before you read this chapter, you may find it beneficial to review the AG2 TRAMAN, NAVEDTRA 10370, volume 1, unit 8, which discusses upper air analysis concepts.

GENERAL PROGNOSTIC CONSIDERATIONS

LEARNING OBJECTIVES: Evaluate features on upper level charts, and be familiar with the various meteorological products available to the forecaster in preparing upper level prognostic charts.

The forecaster must consider all applicable forecasting rules, draw upon experience, and consult all available objective aids to produce the best possible forecast from available data.

Forecasters should examine all aspects of the weather picture from both the surface and aloft before issuing their forecasts. Some conditions are deemed less important, while others are emphasized.

Forecasters must depend heavily upon their knowledge and experience as similar conditions yield similar consequences. Some forecasters may decide to discard a parameter, such as surface pressure, because through their experience, or the experience of others, they may decide that it is not a decisive factor.

An objective system of forecasting certain atmospheric parameters may often exceed the skill of an experienced forecaster. However, the objective process should not necessarily y take precedence over a subjective method, but rather the two should be used together to arrive at the most accurate forecast.

Methods and procedures used in the analysis of upper air charts were covered in the AG2 TRAMAN, volume 1. Accurately drawn analyses provide the forecaster with the most important tool in constructing an upper air prognostic chart. Such information as windspeed and direction, temperature, dew point depression, and heights are readily available for the forecaster to integrate into any objective method for producing a prognostic chart.

FNMOC provides a large number of charts for dissemination to shore and fleet units. These include analysis and prognostic charts ranging from subsurface oceanographic charts to depictions of the troposphere, as well as a number of specialized charts. A complete listing of the these charts is  contained in The Numerical Environmental Products Manual, volume III (Environmental Products), FLENUMMETOCCENINST 3145.2.

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