Narrative:

Approaching denver; we noticed rapid developing convective activity across entire front range. From about 80NM away I was painting a cell just off the departure end of 17R; which we had planned to use for landing. Dispatch did not file an alternate for us; as the forecast did not require one. Our arrival fuel was computed to be around 7.0. This included 2.0 contingency fuel. As we approached den; I realized that weather was going to be critical and sent an ACARS to dispatch requesting an alternate. He gave us cos with a fuel burn of 1500 pounds. During the descent; the first officer briefed the applicable QRH severe weather avoidance matrix. Approach control began vectoring us for runway 26. Severe weather was within 5 miles of the field; but the overhang of the one cell extended out beyond grasp on the approach. Based on our fuel; I briefed the first officer that if we had to go-around that an immediate divert to cos would occur. As we descended between fuzzz and grasp; den tower advised us that all runways except 26 were reporting microburst warnings. A flight ahead of us had just touched down and reported +/- 10 knots on the approach; I manually changed vapp by adding an additional 10 knots. Approaching grasp; we configured to flaps 3 and contacted the tower. We had already captured the glideslope and localizer outside of grasp. We started to get some large raindrops to strike the windscreen from the overhang thousands of feet above us and started picking up some light chop. At about the same time; the aircraft pitched up to maintain the glideslope; as it felt as if the aircraft was beginning to sink. Airspeed dropped to vls and the speed trend arrow showed a decrease to below vls. We got the low energy warning audio of 'speed; speed; speed'; and the first officer pushed the power levels from clm to mct. With hardly any performance change; the first officer selected toga and then back to mct as the aircraft began to accelerate. We both decided to execute a go-around as the approach was now approaching unstable. Although; we did not get either a reactive windshear or predictive windshear caution or warning I reported a windshear to tower of -15 KTS at 7000 MSL. I requested an immediate diversion to cos. On approach to 17L at cos; tower issued a windshear warning for an adjacent runway. After taxiing to the cos ramp; winds and convective activity approached the field with winds gusting to 47 KTS. Appeared to be entering a microburst/windshear from severe convective activity approaching den IAP.

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Original NASA ASRS Text

Title: An A319 crew executed a go-around on short final to DEN because of increasing windshear and microburst activity. The flight proceeded to its alternate where windshear activity was also increasing.

Narrative: Approaching Denver; we noticed rapid developing convective activity across entire front range. From about 80NM away I was painting a cell just off the departure end of 17R; which we had planned to use for landing. Dispatch did not file an alternate for us; as the forecast did not require one. Our arrival fuel was computed to be around 7.0. This included 2.0 contingency fuel. As we approached DEN; I realized that weather was going to be critical and sent an ACARS to Dispatch requesting an alternate. He gave us COS with a fuel burn of 1500 LBS. During the descent; the First Officer briefed the applicable QRH severe weather avoidance matrix. Approach Control began vectoring us for Runway 26. Severe weather was within 5 miles of the field; but the overhang of the one cell extended out beyond GRASP on the approach. Based on our fuel; I briefed the First Officer that if we had to go-around that an immediate divert to COS would occur. As we descended between FUZZZ and GRASP; DEN Tower advised us that all runways except 26 were reporting microburst warnings. A flight ahead of us had just touched down and reported +/- 10 knots on the approach; I manually changed VAPP by adding an additional 10 knots. Approaching GRASP; we configured to Flaps 3 and contacted the tower. We had already captured the glideslope and LOC outside of GRASP. We started to get some large raindrops to strike the windscreen from the overhang thousands of feet above us and started picking up some light chop. At about the same time; the aircraft pitched up to maintain the glideslope; as it felt as if the aircraft was beginning to sink. Airspeed dropped to Vls and the speed trend arrow showed a decrease to below Vls. We got the low energy warning audio of 'speed; speed; speed'; and the First Officer pushed the power levels from CLM to MCT. With hardly any performance change; the First Officer selected TOGA and then back to MCT as the aircraft began to accelerate. We both decided to execute a go-around as the approach was now approaching unstable. Although; we did not get either a reactive windshear or predictive windshear caution or warning I reported a windshear to tower of -15 KTS at 7000 MSL. I requested an immediate diversion to COS. On approach to 17L at COS; Tower issued a windshear warning for an adjacent runway. After taxiing to the COS ramp; winds and convective activity approached the field with winds gusting to 47 KTS. Appeared to be entering a microburst/windshear from severe convective activity approaching DEN IAP.

Data retrieved from NASA's ASRS site as of April 2012 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.