Narrative:

I was on a VFR flight from laramie, wy, to grand junction, co. I had received a WX briefing at XA30 am from casper FSS. It described the WX as clear with slight to moderate turbulence. I filed the VFR plan and left laramie en route to grand junction, co. Around eagle, there were several scattered clouds but much higher than the terrain. I went towards the clouds. It appeared they were dropping very rapidly. I started executing a 180 and found myself in the clouds as they dropped in the sky as if someone pulled the plug. As I completed my 180, I found myself in the clouds thinking I would quickly fly out of them, but I did not. The plane began to be buffeted by WX and ice began building on the plane. At that time, I decided I needed to declare an emergency as there are several 13000 to 14000 ft peaks and I was at 12500 ft. ZDV picked me up on their radar and directed me to an airport and I landed in glenwood springs, co. I believe what caused the problem was the unstable WX mass. I have flown this route many times and have never seen the WX react as quickly as it did. I believe when I started my turn, I was well clear of the clouds and would be in a situation which could have been progressed safely. The WX changed too quickly resulting in having to declare the emergency.

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Original NASA ASRS Text

Title: SMA ENCOUNTERS WX AND DURING 180 TURN BECOMES SURROUNDED BY CLOUDS. DECLARES EMER DUE HIGHER TERRAIN IN AREA. VECTORED TO ARPT.

Narrative: I WAS ON A VFR FLT FROM LARAMIE, WY, TO GRAND JUNCTION, CO. I HAD RECEIVED A WX BRIEFING AT XA30 AM FROM CASPER FSS. IT DESCRIBED THE WX AS CLR WITH SLIGHT TO MODERATE TURB. I FILED THE VFR PLAN AND LEFT LARAMIE ENRTE TO GRAND JUNCTION, CO. AROUND EAGLE, THERE WERE SEVERAL SCATTERED CLOUDS BUT MUCH HIGHER THAN THE TERRAIN. I WENT TOWARDS THE CLOUDS. IT APPEARED THEY WERE DROPPING VERY RAPIDLY. I STARTED EXECUTING A 180 AND FOUND MYSELF IN THE CLOUDS AS THEY DROPPED IN THE SKY AS IF SOMEONE PULLED THE PLUG. AS I COMPLETED MY 180, I FOUND MYSELF IN THE CLOUDS THINKING I WOULD QUICKLY FLY OUT OF THEM, BUT I DID NOT. THE PLANE BEGAN TO BE BUFFETED BY WX AND ICE BEGAN BUILDING ON THE PLANE. AT THAT TIME, I DECIDED I NEEDED TO DECLARE AN EMER AS THERE ARE SEVERAL 13000 TO 14000 FT PEAKS AND I WAS AT 12500 FT. ZDV PICKED ME UP ON THEIR RADAR AND DIRECTED ME TO AN ARPT AND I LANDED IN GLENWOOD SPRINGS, CO. I BELIEVE WHAT CAUSED THE PROBLEM WAS THE UNSTABLE WX MASS. I HAVE FLOWN THIS RTE MANY TIMES AND HAVE NEVER SEEN THE WX REACT AS QUICKLY AS IT DID. I BELIEVE WHEN I STARTED MY TURN, I WAS WELL CLR OF THE CLOUDS AND WOULD BE IN A SITUATION WHICH COULD HAVE BEEN PROGRESSED SAFELY. THE WX CHANGED TOO QUICKLY RESULTING IN HAVING TO DECLARE THE EMER.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.