Narrative:

I and my student were on a routine local training flight out of ZZZ1; doing some pattern work at ZZZ2. There were isolated showers in the area; as is typical of south fl WX; and I decided to leave early as a nearby area of rain seemed to be intensifying. We attempted to fly the most direct route from ZZZ2 to ZZZ1; which would take us on a s-southwesterly course. As we flew through ZZZ3 class B airspace; we found it necessary to alter our course a bit to the east to circumnav a developing area of heavy rain. As we continued south; it became apparent that what appeared earlier to be isolated cells was a developing line of thunderstorms that we could not get through to return to ZZZ1; as it had filled in to our west and nnw. At this point; the WX appeared clear enough to the south that we attempted to reach nearby ZZZ4. We were at this point in contact with ZZZ and had discussed that we were diverting around some WX and may need to skirt through the northwest section of their airspace en route to ZZZ4. This was approved. However; the WX quickly deteriorated and we were unable to make it there either; nor was returning north an option due to the developing line. ZZZ tower attempted to assist us with reaching ZZZ5 a nearby private airport to their southeast; to see if we could land there. However; at this point we had an estimated 30 mins of fuel. Though it was more than sufficient to reach ZZZ1; it was not enough to go all the way to ZZZ5 (which we were advised did not have services) and then make it safely back to either ZZZ1 or ZZZ4 (the nearest airports with services). Given the rapidly deteriorating WX; our minimal fuel situation; and our close proximity to ZZZ; I determined that ZZZ was our safest landing option. I declared an emergency based on our minimal fuel; received a transponder code from their tower; and tower approved my landing on a taxiway adjacent to the tower. We remained on base for a short time to monitor the WX until it cleared enough to safely allow a direct-to flight back to ZZZ1.

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Original NASA ASRS Text

Title: A HELICOPTER INSTRUCTOR. AND STUDENT LANDED AT A MILITARY ARPT AFTER DECLARING AN EMER BECAUSE OF LOW FUEL AND TSTMS.

Narrative: I AND MY STUDENT WERE ON A ROUTINE LCL TRAINING FLT OUT OF ZZZ1; DOING SOME PATTERN WORK AT ZZZ2. THERE WERE ISOLATED SHOWERS IN THE AREA; AS IS TYPICAL OF S FL WX; AND I DECIDED TO LEAVE EARLY AS A NEARBY AREA OF RAIN SEEMED TO BE INTENSIFYING. WE ATTEMPTED TO FLY THE MOST DIRECT RTE FROM ZZZ2 TO ZZZ1; WHICH WOULD TAKE US ON A S-SOUTHWESTERLY COURSE. AS WE FLEW THROUGH ZZZ3 CLASS B AIRSPACE; WE FOUND IT NECESSARY TO ALTER OUR COURSE A BIT TO THE E TO CIRCUMNAV A DEVELOPING AREA OF HVY RAIN. AS WE CONTINUED S; IT BECAME APPARENT THAT WHAT APPEARED EARLIER TO BE ISOLATED CELLS WAS A DEVELOPING LINE OF TSTMS THAT WE COULD NOT GET THROUGH TO RETURN TO ZZZ1; AS IT HAD FILLED IN TO OUR W AND NNW. AT THIS POINT; THE WX APPEARED CLR ENOUGH TO THE S THAT WE ATTEMPTED TO REACH NEARBY ZZZ4. WE WERE AT THIS POINT IN CONTACT WITH ZZZ AND HAD DISCUSSED THAT WE WERE DIVERTING AROUND SOME WX AND MAY NEED TO SKIRT THROUGH THE NW SECTION OF THEIR AIRSPACE ENRTE TO ZZZ4. THIS WAS APPROVED. HOWEVER; THE WX QUICKLY DETERIORATED AND WE WERE UNABLE TO MAKE IT THERE EITHER; NOR WAS RETURNING N AN OPTION DUE TO THE DEVELOPING LINE. ZZZ TWR ATTEMPTED TO ASSIST US WITH REACHING ZZZ5 A NEARBY PVT ARPT TO THEIR SE; TO SEE IF WE COULD LAND THERE. HOWEVER; AT THIS POINT WE HAD AN ESTIMATED 30 MINS OF FUEL. THOUGH IT WAS MORE THAN SUFFICIENT TO REACH ZZZ1; IT WAS NOT ENOUGH TO GO ALL THE WAY TO ZZZ5 (WHICH WE WERE ADVISED DID NOT HAVE SVCS) AND THEN MAKE IT SAFELY BACK TO EITHER ZZZ1 OR ZZZ4 (THE NEAREST ARPTS WITH SVCS). GIVEN THE RAPIDLY DETERIORATING WX; OUR MINIMAL FUEL SIT; AND OUR CLOSE PROX TO ZZZ; I DETERMINED THAT ZZZ WAS OUR SAFEST LNDG OPTION. I DECLARED AN EMER BASED ON OUR MINIMAL FUEL; RECEIVED A XPONDER CODE FROM THEIR TWR; AND TWR APPROVED MY LNDG ON A TXWY ADJACENT TO THE TWR. WE REMAINED ON BASE FOR A SHORT TIME TO MONITOR THE WX UNTIL IT CLRED ENOUGH TO SAFELY ALLOW A DIRECT-TO FLT BACK TO ZZZ1.

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