Narrative:

We departed ZZZ with good weather forecasted for slc with no alternate needed. We were planned with 600 lbs taxi fuel and :23 (1471lbs) contingency fuel. The flight was uneventful until we began the descent to slc. We were being vectored north around the airport to get around a storm that was over the airport. As we broke out north of the airport; I looked down and saw it raining on the east side with more storms east of the airport. We were on downwind vectors for 16L and had just been cleared for the approach when ATC said aircraft were reporting a loss of 20 KIAS on final and were going around. I told the first officer to tell them we will be discontinuing the approach and would like to hold for a bit. We were still doing alright on fuel then and had 3800lbs on board. I figured we had 10-15 minutes before we had to do an approach to slc or divert. The ppos direct page in the FMS also looked good at that point so I was focused on whether or not we could hold long enough to get into slc. ATC said the storm was passing at slc and the winds were 16 kts and steady with no low level windshear alerts. They asked if we would like to do an approach and we decided to give it a shot. The first officer and I decided that we would try a single approach and if we go missed to go to ZZZ1. We setup for the approach; intercepted final; and started configuring flaps. ATC advised heavy precipitation between us and the runway. Given the weather on the field we decided to give it one try. We were on the glideslope at 190 KIAS with flaps 2 passing through 7500 MSL when it seems we might have encountered a microburst. I don't know if that's what it was; but within 5 seconds our indicated airspeed rapidly increased to 234 KIAS and stayed there. I would have normally broken off the approach immediately; but we were high enough off the ground that I could get stable by 1000 AGL and I also expected the speed increase to immediately subside. We were both caught completely off guard when the airspeed didn't go back to normal; but actually kept increasing. At that point; I told ATC that we were going missed and going to ZZZ1 as I disconnected ap/at and turned out to the right and started climbing. At this point it was easier for me as ca to work the radios rather than my first officer (PF). I was then verbally requesting mode changes to match what I was flying and requested ap/at back on to lighten the workload. Even though there was a flap overspeed; I elected to call for flaps to be retracted due to our fuel status and not knowing if there would be a delay getting into ZZZ1 with other aircraft being diverted there. I felt it would be less risky to retract the flaps than continue flying with flaps at 2 and burning extra fuel.we then told ATC we were diverting and got setup and briefed for it. I had my first officer type a message to dispatch that we were diverting and the fob. I called fas and made a quick PA to passengers. We landed in ZZZ1 uneventfully and I left the flaps at landing configuration until maintenance could look at them in case they were damaged. If you go through the replay interval by interval you can see our ground speed significantly decrease almost 20 kts from one interval to the next. A 200 ft climb occurred at the same time. I'm sure quality assurance data will show more detail; but it shows that we had a sudden increase in headwinds.

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Original NASA ASRS Text

Title: EMB-175 Captain reported diverting after encountering a microburst while on approach to SLC.

Narrative: We departed ZZZ with good weather forecasted for SLC with no alternate needed. We were planned with 600 lbs taxi fuel and :23 (1471lbs) contingency fuel. The flight was uneventful until we began the descent to SLC. We were being vectored north around the airport to get around a storm that was over the airport. As we broke out north of the airport; I looked down and saw it raining on the east side with more storms east of the airport. We were on downwind vectors for 16L and had just been cleared for the approach when ATC said aircraft were reporting a loss of 20 KIAS on final and were going around. I told the FO to tell them we will be discontinuing the approach and would like to hold for a bit. We were still doing alright on fuel then and had 3800lbs on board. I figured we had 10-15 minutes before we had to do an approach to SLC or divert. The PPOS Direct page in the FMS also looked good at that point so I was focused on whether or not we could hold long enough to get into SLC. ATC said the storm was passing at SLC and the winds were 16 kts and steady with no Low Level Windshear alerts. They asked if we would like to do an approach and we decided to give it a shot. The FO and I decided that we would try a single approach and if we go missed to go to ZZZ1. We setup for the approach; intercepted final; and started configuring flaps. ATC advised heavy precipitation between us and the runway. Given the weather on the field we decided to give it one try. We were on the glideslope at 190 KIAS with flaps 2 passing through 7500 MSL when it seems we might have encountered a microburst. I don't know if that's what it was; but within 5 seconds our indicated airspeed rapidly increased to 234 KIAS and stayed there. I would have normally broken off the approach immediately; but we were high enough off the ground that I could get stable by 1000 AGL and I also expected the speed increase to immediately subside. We were both caught completely off guard when the airspeed didn't go back to normal; but actually kept increasing. At that point; I told ATC that we were going missed and going to ZZZ1 as I disconnected AP/AT and turned out to the right and started climbing. At this point it was easier for me as CA to work the radios rather than my FO (PF). I was then verbally requesting mode changes to match what I was flying and requested AP/AT back on to lighten the workload. Even though there was a flap overspeed; I elected to call for flaps to be retracted due to our fuel status and not knowing if there would be a delay getting into ZZZ1 with other aircraft being diverted there. I felt it would be less risky to retract the flaps than continue flying with flaps at 2 and burning extra fuel.We then told ATC we were diverting and got setup and briefed for it. I had my FO type a message to dispatch that we were diverting and the FOB. I called FAs and made a quick PA to passengers. We landed in ZZZ1 uneventfully and I left the flaps at landing configuration until Maintenance could look at them in case they were damaged. If you go through the replay interval by interval you can see our ground speed significantly decrease almost 20 kts from one interval to the next. A 200 ft climb occurred at the same time. I'm sure quality assurance data will show more detail; but it shows that we had a sudden increase in headwinds.

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.