Computer models have transformed weather forecasting in the last 50 years, but you may have noticed that sometimes they get it wrong.
As good as computers are in forecasting weather several days in advance, they are handicapped by one overwhelming weakness: It is extremely difficult to figure out precisely what's going on in the atmosphere now.
The models are only as good as the observations fed into them, and the world is full of data blind spots, especially over the oceans.
One of the biggest and most-dangerous data voids is over the North Pacific, the storm factory of the United States. Weather moves west to east, and the West Coast often gets blind-sided by storms that eventually wor their way across the country.
Obviously, it's impossible to send weather balloons into the atmosphere over the Pacific, so the goverment is going after the problem in the other direction. It is sending high altitude aircraft to drop instrument packs that take readings all the way through the atmosphere.
The instrument "bombs," a little bigger than paper-towel dowel, send back readings of temperature, winds and other data, from the jet stream winds howling at 150 m.p.h. per hours, 8 miles up, on down to the Pacific surface.
Those jet winds, 4 to 9 miles in the atmosphere, act as the great highways that carry storms, and their tremendous winds also detonate those storms. The jet stream has quite an amazing history that will be sharing with our readers in the weeks to come.
The flights by the National Oceanic and Atmospheric Administration have close encounters with those jet stream winds. The planes take off every few days and drop 20 to 30 instrument packs over an eight-hour period.
The idea is to identify trouble spots where storms are forming, and in about an hour, a NOAA plane is heading for just such a region north of the Hawaiian islands where a trouble-maker is taking shape.
The data it gathers will be fed almost immediately to computer models all over the world, including the ones that will generate forecasts for Philadelphia. Chances are that the system they are studying today will have some impact on the East Coast early next week.
Inquirer photographer Larry Kesterson and I will be accompanying the crew and, if all goes well, we'll be filing live reports.