On many occasions I discuss the great progress we have made in weather forecasting, including winter storms, in recent years. However, that progress is primarily in the 48-hour and less time period. We still have little ability to consistently forecast winter storms five days out or more. Here is a good example.
Just about all of the computer models yesterday and last night show a major winter storm to affect the East the middle of next week. Here is the 5-day precipitation forecast from early this morning:
Using a 10:1 snow to water ratio, Washington, D.C. would have 14″; Richmond, 15″; Philadelphia, 22″; NYC, 21″; Boston 17″. This would be a crippling storm as the models indicate it would be accompanied by high winds.
However, the first of this morning’s computer model forecasts is out and it is a completely different story:
With the exception of Providence and Boston, the path of the storm is too far into the Atlantic for heavy snow to fall in the Northeast. For example, this model is only predicting about 2″ for NYC.
At this point, I don’t know whether either of these is correct or whether the storm will evolve according to some third scenario.
It is often tempting to try to stretch the science beyond what it can reasonably do. I’m happy if I get an accurate forecast of snow amounts a full 24 hours in advance. That gives adequate time to prepare and minimizes unnecessary preparations due to false alarms.
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