WX DEVS AND A WX DIVERSION AT ZZZ ARPT CAUSE EMB140 CREW TO DECLARE A LOW FUEL EMER.

Narrative

ENRTE REROUTING INTO ZZZ1 DUE TO WX/LCL TSTMS. ATC REROUTED US FARTHER S AND W THAN EXPECTED. I MADE FREQUENT CONTACT WITH DISPATCH AND ADVISED OF NEW ROUTINGS AND FUEL ON BOARD. DISPATCH INDICATED ZZZ1 NO LONGER NEEDED AN ALTERNATE DUE TO IMPROVED WX CONDITIONS SO WE ELECTED TO PROCEED WITH THE APCH PHASE OF OUR FLT. ON SHORT FINAL AT APPROX 1500 FT; ZZZ1 ATC TWR INDICATED A NEW WINDSHEAR ALERT IN ALL QUADRANTS OF THE FIELD AND ASKED US OUR INTENTIONS. WE ELECTED TO DO A MISSED APCH AND WE WERE VECTORED TO THE W AWAY FROM THE BAD WX. WE ASKED ATC IF OUR ORIGINAL ALTERNATE OF ZZZ2 WAS AVAILABLE AND THEY INDICATED ZZZ2 HAD A STRONG STORM 2 - 2.5 MI N MOVING S AT RAPID RATE. WE ASKED IF ZZZ3 WAS AVAILABLE BUT WAS TOLD A STRONG STORM WAS OVERHEAD THAT ARPT. AFTER PUTTING IN ZZZ4 AND ZZZ5 INTO OUR FMS; WE DETERMINED WE HAD INSUFFICIENT FUEL TO SAFELY PROCEED TO EITHER OF THOSE DESTS. AT THAT POINT I DECLARED A FUEL EMER AND ASKED ZZZ1 APCH THE WX CONDITIONS AT ZZZ. THE WX AT ZZZ WAS ACCEPTABLE AND AFTER REVIEWING OUR RWY PERFORMANCE CRITERIA; TOLD ATC WE WANTED TO DIVERT TO ZZZ. WE LANDED AT ZZZ WITHOUT INCIDENT.