WDAY: The News Leader

Published February 07, 2011, 08:33 AM

Special flight helps determine how much moisture is in the snow

Fargo, ND (WDAY TV) - It's the most important number that will determine the extent of our spring flood: moisture content. Today, the first numbers from our region, from a special flight, in a special plane. WDAY-6 Stormtracker meteorologist Daryl Ritchison was the only person from our area on that flight today.

By: Daryl Ritchison, WDAY

It is not a matter of "if" it will flood this spring, but how high will the water go. A lot of factors will determine how high rivers will eventually go, but none of them is more important than how much moisture is in the snow.

Trying to get an accurate picture of the moisture content of the snow can be difficult. Although, we have numerous weather observers taking weekly snow samples, their data represent just a tiny percentage of the area.

To gather data more efficiently, The National Oceanic and Atmospheric Administration (NOAA) uses this modified airplane to measure the Snow Water Equivalency or SWE contained within the snow. Within the airplane is a highly specialized "black box".

Lt. Paul Hemmick, NOAA Pilot: “It is a passive gamma detection system, so we are not sending out any from it, so it is just sitting here and we are collecting ambient radiation.”

The pilots will fly a predetermined flight line, anywhere from 10 to 20 miles long at only 500 feet above the ground, turn on the black box, and start collecting this natural background radiation. The black box will then analyze the data and give them an instant calculation of the average water content of the snow.

Of the several flight lines flown today, the highest SWE was from Devils Lake to Church's Ferry where 11.4 centimeters of water was detected. That is the equivalent of 4.5 inches of rain ready to melt. All the runs made on the flight today measured over 3" of water.

Byte: Lt. Paul Hemmick, NOAA Pilot: “We are tasked to support the North Central River Forecast Center and the Missouri Basin River Forecast Center. Not only do they use the data, but decision makers all a across the country use out data.”

These data are also posted on the web for anyone to see. Today's flight was one of many that will be taking place during the upcoming flood season.