PC12 captain experiences severe turbulence and heavy rain while attempting to fly through a cold fro...

Narrative:

We had departed for airport ZZZ in IMC conditions associated with a cold front passage. The frontal system was stirring up rain and thunderstorms associated with the convection. Both crew members checked weather together within 10-15 minutes prior to departure and had determined that there was sufficient room for maneuvering as we climbed to our enroute phase. We queried ATC prior to takeoff of our departure clearance to confirm the latest instructions. After departure we climbed to our cruise altitude without incident and began receiving vectors around weather by ATC. Prior to reaching our filed cruise altitude we requested right deviations based on our on-board radar indications. We were asked to expedite to 16;000 before we could receive any deviations. After leveling off at 16;000; we requested the deviations again with no response. Moments later we were asked when we could turn to the left. We replied; not for 10-15 miles. We were instructed; when able proceed to ZZZ VOR. Utilizing on-board as well as nexrad radar we began to inch our way around towards a course to ZZZ VOR when we encountered icing. We had already leveled off at our cruise altitude and we turned our deicing equipment on. Within moments we began to encounter heavy rain; moderate to severe turbulence and we immediately requested vectors to the closest departure from the weather. ATC responded that there were no exits (our radars; both on board as well as nexrad) did not show any signs of such intense weather. Within moments we encountered what felt like a downdraft and severe turbulence causing a stall warning alert; but no pusher activation. We immediately applied full power and reduced aoa; attempting to keep wings level and airspeed within maneuvering limitations. After recovering the aircraft; we [advised ATC] and requested lower altitudes for positive temperatures. We flew the RNAV 11 approach into airport ZZZ1 and landed without issue. We performed a post-flight walk around to check for damage; but could not determine anything. We contacted dispatch; maintenance control; and the duty manager. Be extremely cautious when flying around frontal activity (especially fast moving cold fronts.) consider embedded thunderstorms and keep a close check on go/no-go decisions.

Original NASA ASRS Text

Title: PC12 Captain experiences severe turbulence and heavy rain while attempting to fly through a cold front with thunderstorms. Neither NexRad nor onboard radar displayed the severity of the weather encountered. Once clear the flight diverts to a suitable airport.

Narrative: We had departed for Airport ZZZ in IMC conditions associated with a cold front passage. The frontal system was stirring up rain and thunderstorms associated with the convection. Both crew members checked weather together within 10-15 minutes prior to departure and had determined that there was sufficient room for maneuvering as we climbed to our enroute phase. We queried ATC prior to takeoff of our departure clearance to confirm the latest instructions. After departure we climbed to our cruise altitude without incident and began receiving vectors around weather by ATC. Prior to reaching our filed cruise altitude we requested right deviations based on our on-board radar indications. We were asked to expedite to 16;000 before we could receive any deviations. After leveling off at 16;000; we requested the deviations again with no response. Moments later we were asked when we could turn to the left. We replied; not for 10-15 miles. We were instructed; when able proceed to ZZZ VOR. Utilizing on-board as well as NEXRAD radar we began to inch our way around towards a course to ZZZ VOR when we encountered icing. We had already leveled off at our cruise altitude and we turned our deicing equipment on. Within moments we began to encounter heavy rain; moderate to severe turbulence and we immediately requested vectors to the closest departure from the weather. ATC responded that there were no exits (our radars; both on board as well as NEXRAD) did not show any signs of such intense weather. Within moments we encountered what felt like a downdraft and severe turbulence causing a stall warning alert; but no pusher activation. We immediately applied full power and reduced AOA; attempting to keep wings level and airspeed within maneuvering limitations. After recovering the aircraft; we [advised ATC] and requested lower altitudes for positive temperatures. We flew the RNAV 11 approach into Airport ZZZ1 and landed without issue. We performed a post-flight walk around to check for damage; but could not determine anything. We contacted Dispatch; Maintenance Control; and the Duty Manager. Be extremely cautious when flying around frontal activity (especially fast moving cold fronts.) Consider embedded thunderstorms and keep a close check on go/no-go decisions.

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.

Attributes
ACN	1220782
Time
Date	201411
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	PC-12
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Weather Radar
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Commercial
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence Inflight Event / Encounter Loss Of Aircraft Control

PC12 captain experiences severe turbulence and heavy rain while attempting to fly through a cold front with thunderstorms. Neither nexrad nor onboard radar displayed the severity of the weather encountered. Once clear the flight diverts to a suitable airport.