Narrative:

The terminal aerodrome forecast (taf) was calling for 5SM tsra BKN030CB beginning just before our ETA. The most current meteorological report (metar) was reporting thunderstorms in the vicinity already. After looking at a current radar report for the area I determined that the storms were scattered enough that we would likely be able to find a way through; and that forecast weather conditions at the field did not warrant an alternate airport. Our dispatcher had given us extra fuel (hold: 1116 pounds = 30 minutes and contingency: 556 pounds = 15 minutes) in preparation for issues that the weather may produce. I briefed our flight attendant and passengers of the forecasted weather; and told our flight attendant that she could expect to finish her landing preparations and take her jumpseat early as directed by the flight deck once we got closer. The flight was uneventful until about 80 nm from [the airport] roughly 20 minutes from landing. I called our flight attendant and asked her to take her jumpseat early as we would be encountering the weather in about 10 minutes. The current automated terminal information system (ATIS) upon our descent was calling for winds 190 at 8 kts; visibility 10 sm; thunderstorms in the vicinity; few clouds at 2;400 ft AGL; broken cumulonimbus at 4;700 ft AGL; broken clouds at 9000 ft AGL; lightning all quadrants and runway 23 in use. We were looking at the radar depiction and could see the storm cells as we were in visual conditions at the time. The thunderstorms had seemed to form at horse shoe shape around the airport with little to no precipitation northeast of the field; and leaving the airport in the middle of the 'horse shoe' in what seemed to be borderline VFR conditions. However the cells to the west; south; and east were depicting heavy to extreme precipitation. After checking on with approach control we requested a 060 heading to stay away from the precipitation as we formulated a plan. Approach cleared us to 10;000 ft MSL and told us to 'pedal fast' as speed was what would allow us to beat the storm closing in on the airport. We maintained 280 knots for turbulence penetration for as long as practical. After a few minutes the controller pointed out an adequate gap in the east side of the storms that we could fly through and be in position for the RNAV. We allowed ATC to vector us through the gap; which was mostly clear and only produced some light turbulence at times. At this point we were getting close to the approach course (roughly 25nm to 30nm) from the airport so I instructed my first officer to begin slowing the aircraft in preparation for a descent and approach. He began slowly decelerating towards 200 knots. At this point storm cells to the west of the field had shifted almost over the airport reducing our likelihood of being able to land. A band of extreme precipitation had begun moving over our approach course. ATC asked if we wanted to continue and I said yes; as we were now surrounded by thunderstorm cells and even a missed approach would have resulted in going through one. My reasoning being that if we had to fly through the heavy to extreme precipitation anyway we should try the approach. We were descending onto the approach course and my first officer had commanded for flaps 8 and 20 with landing gear down and full flight spoilers deployed. The aircraft weighed roughly 46;800 pounds at that point. As we decelerated we began getting uncomfortably close to our minimum spoiler speed for that configuration so we retracted the flight spoilers. We finished configuring the aircraft with flaps 30 and 45 and set the speed bug to our final vref plus 5kts for any abnormal wind conditions. As we neared the final approach fix it became evident that we were still too high for our approach (roughly 3;000 ft MSL with a final approach altitude of 2;300 ft MSL). At that moment the tower informed us that the visibility at the airport had just dropped to 2;400 ft RVR; which was belowour minimums of 1 3/8 sm. I asked the tower to repeat the RVR just to be sure and at that exact moment the storm produced a downdraft on the aircraft. The plane was fully configured for landing; descending at roughly 1;000 feet per minute; and airspeed indicated approximately vref +7kts; however the upset of the aircraft produced a split second activation of the stick shaker which disengaged the autopilot. All of this occurred in a span of about 10 seconds. I immediately called for the missed approach and we began the procedure. We were at an altitude of roughly 2;700 ft MSL (1;900 ft AGL) and had just passed the final approach fix when this happened. We had already begun our climb back through 3;000 ft MSL when I informed ATC we were missed approach. ATC instructed us to fly runway heading and maintain 4;000 ft MSL however by the time this clearance was issued we were almost at 4;000 ft MSL. I selected 4000 in the altitude selector; but due to the high energy climb and the aircraft being hand flown we leveled off at 4;300 ft MSL; the first officer promptly corrected the altitude. ATC vectored us out with very little turbulence. We then made the decision to divert to allow the storms to pass [the airport] and we could take on more fuel. The divert was executed without event. After waiting; we flew the plane and passengers [back to the original destination].the biggest factor to this issue was a complacent attitude; or invulnerability. My attitude was that I have worked many flights when there are scattered thunderstorms in the vicinity. We always seem to find a way through and make an approach; and if the storm is too severe then the airport typically closes or approach control issues holding instructions. I made a decision to find a gap in the storm with the expectation that favorable conditions at the field would remain. I honestly didn't expect these storm cells to move so quickly over the field and expected we would be able to execute a visual approach once we had managed to get past the line of storms south of the field; initially ATC seemed to think the same. I made a poor decision to continue the approach when conditions started deteriorating and we were in a difficult position to set up a stabilized approach. However I do feel the decision to execute a missed approach was made with still plenty of safety margin given our altitude. It is my opinion that the quick burst of stick shaker activation was a result of the shifting wind in the storm as we were at a low angle of attack with the aircraft fully configured for the speed we were flying. I also feel that the divert decision; while we still had plenty of fuel; was the safest course of action. This was a humbling experience for me as a captain. I lacked a healthy respect for the speed at which conditions were changing. In the future I will request holding and try to ensure that if we find a way in through a gap in a storm; then we have a more viable way out if conditions worsen.

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Original NASA ASRS Text

Title: CRJ200 Flight Crew reported encountering thunderstorms during descent and approach; resulting in a missed approach and divert to an alternate airport.

Narrative: The terminal aerodrome forecast (TAF) was calling for 5SM TSRA BKN030CB beginning just before our ETA. The most current meteorological report (METAR) was reporting thunderstorms in the vicinity already. After looking at a current radar report for the area I determined that the storms were scattered enough that we would likely be able to find a way through; and that forecast weather conditions at the field did not warrant an alternate airport. Our dispatcher had given us extra fuel (Hold: 1116 pounds = 30 minutes and Contingency: 556 pounds = 15 minutes) in preparation for issues that the weather may produce. I briefed our flight attendant and passengers of the forecasted weather; and told our flight attendant that she could expect to finish her landing preparations and take her jumpseat early as directed by the flight deck once we got closer. The flight was uneventful until about 80 nm from [the airport] roughly 20 minutes from landing. I called our flight attendant and asked her to take her jumpseat early as we would be encountering the weather in about 10 minutes. The current automated terminal information system (ATIS) upon our descent was calling for winds 190 at 8 kts; visibility 10 sm; thunderstorms in the vicinity; few clouds at 2;400 ft AGL; broken cumulonimbus at 4;700 ft AGL; broken clouds at 9000 ft AGL; lightning all quadrants and runway 23 in use. We were looking at the radar depiction and could see the storm cells as we were in visual conditions at the time. The thunderstorms had seemed to form at horse shoe shape around the airport with little to no precipitation northeast of the field; and leaving the airport in the middle of the 'horse shoe' in what seemed to be borderline VFR conditions. However the cells to the west; south; and east were depicting heavy to extreme precipitation. After checking on with approach control we requested a 060 heading to stay away from the precipitation as we formulated a plan. Approach cleared us to 10;000 ft MSL and told us to 'pedal fast' as speed was what would allow us to beat the storm closing in on the airport. We maintained 280 knots for turbulence penetration for as long as practical. After a few minutes the controller pointed out an adequate gap in the east side of the storms that we could fly through and be in position for the RNAV. We allowed ATC to vector us through the gap; which was mostly clear and only produced some light turbulence at times. At this point we were getting close to the approach course (roughly 25nm to 30nm) from the airport so I instructed my first officer to begin slowing the aircraft in preparation for a descent and approach. He began slowly decelerating towards 200 knots. At this point storm cells to the west of the field had shifted almost over the airport reducing our likelihood of being able to land. A band of extreme precipitation had begun moving over our approach course. ATC asked if we wanted to continue and I said yes; as we were now surrounded by thunderstorm cells and even a missed approach would have resulted in going through one. My reasoning being that if we had to fly through the heavy to extreme precipitation anyway we should try the approach. We were descending onto the approach course and my first officer had commanded for flaps 8 and 20 with landing gear down and full flight spoilers deployed. The aircraft weighed roughly 46;800 pounds at that point. As we decelerated we began getting uncomfortably close to our minimum spoiler speed for that configuration so we retracted the flight spoilers. We finished configuring the aircraft with flaps 30 and 45 and set the speed bug to our final Vref plus 5kts for any abnormal wind conditions. As we neared the final approach fix it became evident that we were still too high for our approach (roughly 3;000 ft MSL with a final approach altitude of 2;300 ft MSL). At that moment the tower informed us that the visibility at the airport had just dropped to 2;400 ft RVR; which was belowour minimums of 1 3/8 sm. I asked the tower to repeat the RVR just to be sure and at that exact moment the storm produced a downdraft on the aircraft. The plane was fully configured for landing; descending at roughly 1;000 feet per minute; and airspeed indicated approximately Vref +7kts; however the upset of the aircraft produced a split second activation of the stick shaker which disengaged the autopilot. All of this occurred in a span of about 10 seconds. I immediately called for the missed approach and we began the procedure. We were at an altitude of roughly 2;700 ft MSL (1;900 ft AGL) and had just passed the final approach fix when this happened. We had already begun our climb back through 3;000 ft MSL when I informed ATC we were missed approach. ATC instructed us to fly runway heading and maintain 4;000 ft MSL however by the time this clearance was issued we were almost at 4;000 ft MSL. I selected 4000 in the altitude selector; but due to the high energy climb and the aircraft being hand flown we leveled off at 4;300 ft MSL; the first officer promptly corrected the altitude. ATC vectored us out with very little turbulence. We then made the decision to divert to allow the storms to pass [the airport] and we could take on more fuel. The divert was executed without event. After waiting; we flew the plane and passengers [back to the original destination].The biggest factor to this issue was a complacent attitude; or invulnerability. My attitude was that I have worked many flights when there are scattered thunderstorms in the vicinity. We always seem to find a way through and make an approach; and if the storm is too severe then the airport typically closes or approach control issues holding instructions. I made a decision to find a gap in the storm with the expectation that favorable conditions at the field would remain. I honestly didn't expect these storm cells to move so quickly over the field and expected we would be able to execute a visual approach once we had managed to get past the line of storms south of the field; initially ATC seemed to think the same. I made a poor decision to continue the approach when conditions started deteriorating and we were in a difficult position to set up a stabilized approach. However I do feel the decision to execute a missed approach was made with still plenty of safety margin given our altitude. It is my opinion that the quick burst of stick shaker activation was a result of the shifting wind in the storm as we were at a low angle of attack with the aircraft fully configured for the speed we were flying. I also feel that the divert decision; while we still had plenty of fuel; was the safest course of action. This was a humbling experience for me as a captain. I lacked a healthy respect for the speed at which conditions were changing. In the future I will request holding and try to ensure that if we find a way in through a gap in a storm; then we have a more viable way out if conditions worsen.

Data retrieved from NASA's ASRS site 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.