Narrative:

I departed fld in light rain. My clearance had been to fly to 30 NM west of fld, then direct msn. The cell I had hoped to avoid with this departure had moved nward into my route, so msn approach approved direct msn. I leveled at 8000' in IMC after some light ice and hail on the climb out. I broke out of the clouds for a moment and saw a narrow but high build up in front of me. I asked for and received permission to deviate to the south of my heading to avoid a cell. As I began my turn I was hit with an updraft hard enough to FLIP down the glare shields on the wind screen. My hands were on the throttles at the time and my hands swung down closing both to the idle position. The vsi showed a climb rate of 1100 FPM with the nose pushed down and the throttles at idle. I shot up to an altitude of approximately 8600'. I was then hit by a downdraft which swung the vsi to a descent of 1000 FPM and lifted a full soda can off the floor of the plane to the level of my shoulder. At this time msn approach called asking if I could now go direct msn. I told them I could and reported the moderate turbulence, and the light rain, ice and some hail encountered on the climb. They reported that they showed no precipitation in my area. The only additional comment I have is that it seems that the newer radars being used by the ATC don't seem to be very good at picking up precipitation. I have heard several controllers mention this while flying in IFR conditions and most have allowed pilots to deviate as need even if nothing is being shown on their scopes. I know that they are intended for control of aircraft and not for WX reporting, but it may be easier for the controller to understand why a pilot asks for a deviation if he can see the WX the pilot is trying to avoid.

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Original NASA ASRS Text

Title: IMC WX ENCOUNTER, SEVERE UP AND DOWN DRAFTS, ALT DEVIATION.

Narrative: I DEPARTED FLD IN LIGHT RAIN. MY CLRNC HAD BEEN TO FLY TO 30 NM W OF FLD, THEN DIRECT MSN. THE CELL I HAD HOPED TO AVOID WITH THIS DEP HAD MOVED NWARD INTO MY ROUTE, SO MSN APCH APPROVED DIRECT MSN. I LEVELED AT 8000' IN IMC AFTER SOME LIGHT ICE AND HAIL ON THE CLB OUT. I BROKE OUT OF THE CLOUDS FOR A MOMENT AND SAW A NARROW BUT HIGH BUILD UP IN FRONT OF ME. I ASKED FOR AND RECEIVED PERMISSION TO DEVIATE TO THE S OF MY HDG TO AVOID A CELL. AS I BEGAN MY TURN I WAS HIT WITH AN UPDRAFT HARD ENOUGH TO FLIP DOWN THE GLARE SHIELDS ON THE WIND SCREEN. MY HANDS WERE ON THE THROTTLES AT THE TIME AND MY HANDS SWUNG DOWN CLOSING BOTH TO THE IDLE POS. THE VSI SHOWED A CLB RATE OF 1100 FPM WITH THE NOSE PUSHED DOWN AND THE THROTTLES AT IDLE. I SHOT UP TO AN ALT OF APPROX 8600'. I WAS THEN HIT BY A DOWNDRAFT WHICH SWUNG THE VSI TO A DSCNT OF 1000 FPM AND LIFTED A FULL SODA CAN OFF THE FLOOR OF THE PLANE TO THE LEVEL OF MY SHOULDER. AT THIS TIME MSN APCH CALLED ASKING IF I COULD NOW GO DIRECT MSN. I TOLD THEM I COULD AND RPTED THE MODERATE TURB, AND THE LIGHT RAIN, ICE AND SOME HAIL ENCOUNTERED ON THE CLB. THEY RPTED THAT THEY SHOWED NO PRECIPITATION IN MY AREA. THE ONLY ADDITIONAL COMMENT I HAVE IS THAT IT SEEMS THAT THE NEWER RADARS BEING USED BY THE ATC DON'T SEEM TO BE VERY GOOD AT PICKING UP PRECIPITATION. I HAVE HEARD SEVERAL CTLRS MENTION THIS WHILE FLYING IN IFR CONDITIONS AND MOST HAVE ALLOWED PLTS TO DEVIATE AS NEED EVEN IF NOTHING IS BEING SHOWN ON THEIR SCOPES. I KNOW THAT THEY ARE INTENDED FOR CTL OF ACFT AND NOT FOR WX RPTING, BUT IT MAY BE EASIER FOR THE CTLR TO UNDERSTAND WHY A PLT ASKS FOR A DEVIATION IF HE CAN SEE THE WX THE PLT IS TRYING TO AVOID.

Data retrieved from NASA's ASRS site as of August 2007 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.