Narrative:

Bos to lhr on track U at XX45Z. At a point approximately 80 NM east of 47n50w we detected a line of thunderstorms directly on our route. Requested from ATC permission to deviate up to 25 NM north of course for WX. Request was denied. Exercising captain's authority/authorized I declared an emergency at which time we were cleared as requested. Encountered continuous moderate turbulence and were back on course 20 mins later. In the clear at 43W. Notified ATC back on track. Notified dispatch. Remainder of flight uneventful.

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Original NASA ASRS Text

Title: EA30 CAPT USED EMER AUTH TO AVOID TSTM ACTIVITY DIRECTLY AHEAD IN HIS PATH.

Narrative: BOS TO LHR ON TRACK U AT XX45Z. AT A POINT APPROX 80 NM E OF 47N50W WE DETECTED A LINE OF TSTMS DIRECTLY ON OUR RTE. REQUESTED FROM ATC PERMISSION TO DEVIATE UP TO 25 NM N OF COURSE FOR WX. REQUEST WAS DENIED. EXERCISING CAPT'S AUTH I DECLARED AN EMER AT WHICH TIME WE WERE CLRED AS REQUESTED. ENCOUNTERED CONTINUOUS MODERATE TURB AND WERE BACK ON COURSE 20 MINS LATER. IN THE CLR AT 43W. NOTIFIED ATC BACK ON TRACK. NOTIFIED DISPATCH. REMAINDER OF FLT UNEVENTFUL.

Data retrieved from NASA's ASRS site as of July 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.