Narrative:

Night IMC weather. I was the PF. Last of 4 legs with no ACARS functions at all. Dispatch had filed us with no alternate and the paperwork was forecasting no severe weather and no needed alternate. My first officer looked at the radar on his iphone app and points out that there is a thunderstorm of considerable size and intensity ahead. Our forecast and dispatch agree that weather will not be an issue on the approach. I figured it would dissipate somewhat as the forecast was showing no significant weather. What wasn't clear to me was that when we looked at the iphone app the weather looked as though it was headed right for our destination. We took off with the idea that we would have to deviate around weather. Dispatch has also planned extra gas for that. Enroute we had to make some minor heading changes and I suggested that we try FL370 to get above the weather. We climb to FL370. My first officer says that he doesn't like weather and I can tell he is uncomfortable with flying through this weather. As we approach the main line of weather I realize that we won't be able to top the weather. I ask ATC what route he suggests and also asked if we could get the weather for our destination. The controller gives us the weather and best route which he said was to go north 030 around the weather. We turn to 030. We are deviating around the worst and I still plan to go around the front and land at our destination or a nearby alternate if that doesn't work. I believe that both the first officer and I notice the IAS comparator flag at the same moment. The first officer's side airspeed readings were low compared to mine. We figured we were picking up ice and needed to descend. I was simultaneously changing the aircraft heading towards a 060 as we were coming around the backside of the worst of it. My first officer requested a descent from ATC. It was around this time that the ice got bad. My first officer got his flashlight out and it covered the windows; and within a minute or so my airspeed dropped off. I began a rapid descent at this point. I was initially very concerned (it was like looking at a watch in reverse). I was trying to get the airspeed up with more descent and more power. As the aircraft wind noise become louder than I was used to; I noticed that the ailerons shook for about 5 seconds (left and right) I realized that I was approaching this all wrong (I [now] thought we were over speeding). I glanced at the standby and the airspeed showed about 280 knots (I believe that was wrong; indicating slow and it didn't show the red arc). I also glanced at the tat (-50) and sat (-38). About now the first officer said; 'do you want to declare an emergency'; and I said 'yes'. He had good knowledge of ZZZ as an alternate and its location relative to us. We changed our destination to ZZZ and declared an emergency. Airspeed was now about 100 knots and went to a red X (I believe). The first officer said his side also was showing the same. There were definitely red items across the pfd. I had disconnected the autopilot and began to adjust using pitch and power. I brought the aircraft [nose to] the horizon and used power to maintain the descent. I then noticed that the altimeter had frozen or close to it. I kept the descent going as I have heard of other people that needed to get to lower altitude and then everything becomes unfrozen; and that's what happened; around FL250. We made a quick approach into ZZZ and landed safely. Aircraft potential for overspeed although not known. I think we encountered severe ice between FL300-370 which is rare. ACARS needs to be operational for dispatch into severe weather. It appears as if dispatch weather reports were old and needed to have been updated. Suspected super cooled rain in night IMC.

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Original NASA ASRS Text

Title: EMB145 Captain reports encountering severe icing conditions at FL370 while avoiding a thunderstorm that results in loss of airspeed indication. A descent is initiated with power up due to confusing indications; until wind noise and aileron shake indicated an overspeed was occurring. Pitch and power is used to reduce to a safe flying speed and the descent is continued until airspeed returns to normal.

Narrative: NIGHT IMC weather. I was the PF. Last of 4 legs with no ACARS functions at all. Dispatch had filed us with no Alternate and the paperwork was forecasting no severe weather and no needed Alternate. My First Officer looked at the radar on his iPhone app and points out that there is a thunderstorm of considerable size and intensity ahead. Our forecast and Dispatch agree that weather will not be an issue on the approach. I figured it would dissipate somewhat as the forecast was showing NO significant weather. What wasn't clear to me was that when we looked at the iPhone app the weather looked as though it was headed right for our destination. We took off with the idea that we would have to deviate around weather. Dispatch has also planned EXTRA gas for that. Enroute we had to make some minor heading changes and I suggested that we try FL370 to get above the weather. We climb to FL370. My First Officer says that he doesn't like weather and I can tell he is uncomfortable with flying through this weather. As we approach the main line of weather I realize that we won't be able to top the weather. I ask ATC what route he suggests and also asked if we could get the weather for our destination. The Controller gives us the weather and best route which he said was to go North 030 around the weather. We turn to 030. We are deviating around the worst and I still plan to go around the front and land at our destination or a nearby alternate if that doesn't work. I believe that both the First Officer and I notice the IAS comparator flag at the same moment. The First Officer's side airspeed readings were low compared to mine. We figured we were picking up ice and needed to descend. I was simultaneously changing the aircraft heading towards a 060 as we were coming around the backside of the worst of it. My First Officer requested a descent from ATC. It was around this time that the ice got bad. My First Officer got his flashlight out and it covered the windows; and within a minute or so my airspeed dropped off. I began a rapid descent at this point. I was initially very concerned (it was like looking at a watch in reverse). I was trying to get the airspeed up with more descent and more power. As the aircraft wind noise become louder than I was used to; I noticed that the ailerons shook for about 5 seconds (left and right) I realized that I was approaching this all wrong (I [now] thought we were over speeding). I glanced at the Standby and the Airspeed showed about 280 knots (I believe that was wrong; indicating slow and it didn't show the red arc). I also glanced at the TAT (-50) and SAT (-38). About now the First Officer said; 'do you want to declare an emergency'; and I said 'yes'. He had good knowledge of ZZZ as an Alternate and its location relative to us. We changed our destination to ZZZ and declared an emergency. Airspeed was now about 100 knots and went to a red X (I believe). The First Officer said his side also was showing the same. There were definitely RED items across the PFD. I had disconnected the autopilot and began to adjust using pitch and power. I brought the aircraft [nose to] the horizon and used power to maintain the descent. I then noticed that the altimeter had frozen or close to it. I kept the descent going as I have heard of other people that needed to get to lower altitude and then everything becomes unfrozen; and that's what happened; around FL250. We made a quick approach into ZZZ and landed safely. Aircraft potential for overspeed although not known. I think we encountered severe ICE between FL300-370 which is rare. ACARS needs to be operational for dispatch into severe weather. It appears as if Dispatch weather reports were old and needed to have been updated. Suspected super cooled rain in night IMC.

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.