Narrative:

Was inbound from east to bozeman. Had received WX 20 mins prior to incident and WX was VFR. 8 mi southeast of airport lost ground contact and called tower. Tower said WX still VFR, but ceiling and visibility decreasing. Tower said visibility to east was lower. Unsure of terrain, I climbed and asked for an IFR clearance to airport. Bozeman tower handed me off to ZLC and I then received clearance for ILS to runway 12 and proceeded uneventfully to a full stop landing. Tower later told me that field had gone from good VFR to IFR in less than 5 mins. After landing, I contacted ZLC and explained what had happened. Bozeman had traffic on ground waiting for IFR departure until I was able to get clearance and land. I would have declared an emergency if I had any icing and it may have been a good idea anyway.

Related reports:

Google
 

Original NASA ASRS Text

Title: A C210 PLT EXPERIENCES AN ABRUPT CHANGE IN THE WX AS HE NEARS HIS DEST REQUIRING HIM TO OBTAIN AN IFR CLRNC FOR THE APCH.

Narrative: WAS INBOUND FROM E TO BOZEMAN. HAD RECEIVED WX 20 MINS PRIOR TO INCIDENT AND WX WAS VFR. 8 MI SE OF ARPT LOST GND CONTACT AND CALLED TWR. TWR SAID WX STILL VFR, BUT CEILING AND VISIBILITY DECREASING. TWR SAID VISIBILITY TO E WAS LOWER. UNSURE OF TERRAIN, I CLBED AND ASKED FOR AN IFR CLRNC TO ARPT. BOZEMAN TWR HANDED ME OFF TO ZLC AND I THEN RECEIVED CLRNC FOR ILS TO RWY 12 AND PROCEEDED UNEVENTFULLY TO A FULL STOP LNDG. TWR LATER TOLD ME THAT FIELD HAD GONE FROM GOOD VFR TO IFR IN LESS THAN 5 MINS. AFTER LNDG, I CONTACTED ZLC AND EXPLAINED WHAT HAD HAPPENED. BOZEMAN HAD TFC ON GND WAITING FOR IFR DEP UNTIL I WAS ABLE TO GET CLRNC AND LAND. I WOULD HAVE DECLARED AN EMER IF I HAD ANY ICING AND IT MAY HAVE BEEN A GOOD IDEA ANYWAY.

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.