The all-caps format of NWS bulletins emerged from the limits of the teletype keyboard, together with standards set by the World Meteorological Organization designed to accommodate nations with widely varying technological capabilities. No capital letters were allowed, and the only punctuation permitted was periods (.), ellipses (…), forward slashes (/), dashes (—), and pluses (+). These conventions went largely unseen by the public until the NWS website was established in the 1990s. Before that point, NWS text products were reformatted by newspapers or read aloud on TV and radio, including NOAA Weather Radio.
The best one in history has to be this one. It was so out of sorts, it has its own WIKI page.
HURRICANE KATRINA...A MOST POWERFUL HURRICANE WITH UNPRECEDENTED
STRENGTH... RIVALING THE INTENSITY OF HURRICANE CAMILLE OF 1969.
MOST OF THE AREA WILL BE UNINHABITABLE FOR WEEKS...PERHAPS LONGER. AT
LEAST ONE HALF OF WELL CONSTRUCTED HOMES WILL HAVE ROOF AND WALL
FAILURE. ALL GABLED ROOFS WILL FAIL...LEAVING THOSE HOMES SEVERELY
DAMAGED OR DESTROYED.