Narrative:

We left with a basically clear forecast for ZZZ and no alternate. After takeoff; the ACARS failed; and we notified dispatch via radio of the ACARS failure and provided our out/off times. Shortly before descent into ZZZ; dispatch advised us of a just-revised forecast for ZZZ showing the possibility of some small buildups. ATC initially informed us of a small buildup southeast of the field; then later said the nearest buildup was 15 mi away. An approach was begun to ZZZ; and on final we received notice of some windshear reports; shortly followed by a microburst alert with a 40 KT loss over the runway. A go around was accomplished due to this alert. Since we had initially dispatched with no alternate fuel; I could see that we might end up landing close to our reserve fuel; so as a precaution I declared an emergency for fuel and diverted to nearby ZZZ2. An uneventful visual approach and landing were accomplished at ZZZ2 and the emergency was terminated on taxi-in. As ZZZ2 is not a regular station; a brief delay was encountered while locating all necessary flight forms and pubs. After consulting with dispatch; loads; duty chief; and local contract maintenance; all necessary flight forms and pubs were located and an MEL item was addressed. We then uneventfully departed ZZZ2 for ZZZ. We landed in ZZZ2 above reserve fuel; but I felt the declaration of emergency and diversion to ZZZ2 was appropriate at the time due to the uncertainty of the rapidly changing and unforecast WX; lack of ACARS information; and the short time in which to make decisions and land the aircraft.

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Original NASA ASRS Text

Title: MD80 CREW DIVERTS IN VFR CONDITIONS TO NEARBY ALTERNATE DUE TO MICRO BURST ALERTS AT DESTINATION AND LOW FUEL.

Narrative: WE LEFT WITH A BASICALLY CLR FORECAST FOR ZZZ AND NO ALTERNATE. AFTER TKOF; THE ACARS FAILED; AND WE NOTIFIED DISPATCH VIA RADIO OF THE ACARS FAILURE AND PROVIDED OUR OUT/OFF TIMES. SHORTLY BEFORE DSCNT INTO ZZZ; DISPATCH ADVISED US OF A JUST-REVISED FORECAST FOR ZZZ SHOWING THE POSSIBILITY OF SOME SMALL BUILDUPS. ATC INITIALLY INFORMED US OF A SMALL BUILDUP SE OF THE FIELD; THEN LATER SAID THE NEAREST BUILDUP WAS 15 MI AWAY. AN APCH WAS BEGUN TO ZZZ; AND ON FINAL WE RECEIVED NOTICE OF SOME WINDSHEAR RPTS; SHORTLY FOLLOWED BY A MICROBURST ALERT WITH A 40 KT LOSS OVER THE RWY. A GAR WAS ACCOMPLISHED DUE TO THIS ALERT. SINCE WE HAD INITIALLY DISPATCHED WITH NO ALTERNATE FUEL; I COULD SEE THAT WE MIGHT END UP LNDG CLOSE TO OUR RESERVE FUEL; SO AS A PRECAUTION I DECLARED AN EMER FOR FUEL AND DIVERTED TO NEARBY ZZZ2. AN UNEVENTFUL VISUAL APCH AND LNDG WERE ACCOMPLISHED AT ZZZ2 AND THE EMER WAS TERMINATED ON TAXI-IN. AS ZZZ2 IS NOT A REGULAR STATION; A BRIEF DELAY WAS ENCOUNTERED WHILE LOCATING ALL NECESSARY FLT FORMS AND PUBS. AFTER CONSULTING WITH DISPATCH; LOADS; DUTY CHIEF; AND LCL CONTRACT MAINT; ALL NECESSARY FLT FORMS AND PUBS WERE LOCATED AND AN MEL ITEM WAS ADDRESSED. WE THEN UNEVENTFULLY DEPARTED ZZZ2 FOR ZZZ. WE LANDED IN ZZZ2 ABOVE RESERVE FUEL; BUT I FELT THE DECLARATION OF EMER AND DIVERSION TO ZZZ2 WAS APPROPRIATE AT THE TIME DUE TO THE UNCERTAINTY OF THE RAPIDLY CHANGING AND UNFORECAST WX; LACK OF ACARS INFO; AND THE SHORT TIME IN WHICH TO MAKE DECISIONS AND LAND THE ACFT.

Data retrieved from NASA's ASRS site as of January 2009 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.