Henry Lind's Weather Watch
by Henry Lind

Weather Watch

A Daily Gazette news blog
Weather events in our region and why they happen

Hitting the (bench) mark

By Henry Lind
Monday, March 24, 2014

Many, many factors are involved with the science and decision making that goes into the daily forecasts which are generated by meteorologists. Computer models are perhaps the most powerful tool at their disposal, and there are several models which are consulted hourly to help define the various weather patterns in both the near and more distant future.

All of the models are built on two fundamental items — current observations of things like temperature, barometric pressure, wind speed and direction and such. The second component is historical records — what has happened in the past when these conditions have been present. The combination is a mathematical model with which computers produce simulated conditions in the upcoming hours — the forecast. It might not surprise you that like many other situations, different models predict different solutions and the role of the human forecaster is to evaluate the differences and apply logic to best make a prediction. It is fairly easy to get weather observations on land from the many reporting stations, and the models will begin on solid footing using that information. At sea, the number of observations are few — limited to buoys, ship traffic and some satellite data. As a result, the forecasting ability of the models for an offshore storm at less precise.

Using the human intervention piece of the puzzle for storms along the Atlantic coast, forecasters have adopted an imaginary point in the water which they refer to as “the benchmark”. It is located a few hundred miles east of New Jersey at 40 degrees north latitude and 70 degrees west longitude. History has shown that coastal storms which pass to the east of that point tend to provide less of an impact to inland portions of New England and New York, and those which pass to the west of the benchmark will likely extend their impact as far as the Hudson River. The consensus of the models for the upcoming storm predicts it to pass near or slightly east of the bench, which provides the basis for a minimal amount of snow for our area. Of course, unforeseen changes may well alter that outcome, and it is important for us to understand that fact. Regardless of the outcome, future models will incorporate all of the upcoming details to help refine future efforts.

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