Combat weather forecasters fight ‘fog of war’

[SR-25]

1/13/2005 - KARSHI-KHANABAD AIR BASE, Uzbekistan (AFPN) -- It rolls in when it wants to, covers everything in its path and makes visibility so poor you can barely see your hand in front of your face. It is what some here call “the fog of war.”

This fog, however, is the real thing. It is a fog so thick it makes missions for Operation Enduring Freedom here sometimes difficult. But there is a weapon against it -- up-to-the-minute weather forecasts and predictions by 416th Expeditionary Operations Support Squadron weather flight Airmen.

“Uzbekistan is a semi-arid, plains-type desert,” said Capt. Kristopher Long, operational meteorologist in charge of the flight here. “As a result, it gets very little rainfall in a typical year. However, from last December to right now, we are approximately 500 percent above normal in rainfall. And the trend looks like it will continue through January and February.

“One consequence of more rain, besides mud and standing water, is that is brings more low clouds and fog with it,” Captain Long said. “This makes life a little more difficult for the aircrews flying in and out of here.”

Fog, by definition, is simply a cloud that forms at the surface, Captain Long said.

“Fog can appear at an airfield in two ways -- it can form directly on the airfield where forecasters call it ‘radiational fog,’ or it can form somewhere else and move on to the airfield, which is called ‘advection fog,’” he said.

The level of the dense advection fog is a particularly troublesome weather problem at this base, Captain Long said, because it significantly impedes airfield operations.

The forecasters built a unique theory on the K-2 fog based on many factors. The theory was built by Captain Long and his team of weather technicians who include Tech. Sgt. Troy Walker, who recently returned to the United States, and Staff Sgts. John Radford and Bobby Baum.

Captain Long said the theory states that about one to two days after a cold front passes through K-2, the winds at and near the surface shift.

“If this (shift) occurs at late afternoon or later in the night, and our (sky is) clearing or losing clouds, then the environment becomes favorable for fog formation, especially if it rained significantly as the front came through,” Captain Long said. “At the same time, up in the snow-covered mountains, a dense fog will begin to form because the air is being cooled at the higher altitude and snow covered ground.

“When that cooled air gets cold enough, it becomes saturated and fog forms,” the captain said.

The winds flowing out of the mountains then grab the fog and pull the fog toward the base, he said.

“Usually this happens well after sunset, but sometimes it occurs just as the sun is setting, and we are able to see it form in the mountains with our weather satellite imagery,” he said.

Captain Long said the dense fog he described can drop airfield visibility to less than one-quarter of a mile in less than 15 minutes.

“Obviously the fog creates many problems for aircraft trying to land or takeoff, so forecasting the fog accurately is extremely important,” he said.

To combat the fog, Captain Long said the forecasters refine their forecasts based on the knowledge and experience they have built in their time here in Uzbekistan along with their recorded climatology.

So far, the base has had eight major advection fog events since October and had several dozen advection fog events recorded from 2002 to 2004, Captain Long said.

“Each event has given us more information and clues as to the behavior and characteristics of the fog,” he said.

Captain Long said the team also uses computer-model forecasts and satellite imagery.

“Mostly our computer models don't foresee these dense advection fog events perfectly,” he said. “But one computer model in particular has been able to somewhat accurately predict the fog. More importantly, our aircrews have been really terrific (letting) us know when the weather starts changing.”

Through forward observations, prior experience and the computer models and satellite imagery, the forecasters have been able to refine their advection fog theory, he said.

With the weather team's effort, Captain Long said OEF missions are less hindered, and, he hopes, mission success is that much higher.


http://www.af.mil/news/story.asp?storyID=123009600