Bayesian Investor Blog

Why did many people decide not to leave New Orleans in advance of Katrina? Part of the problem may have been that they relied on storytellers rather than weather experts.
NBC’s Brian Williams reports on his blog NBC’s reaction to this weather alert:

URGENT – WEATHER MESSAGE
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1011 AM CDT SUN AUG 28 2005
…DEVASTATING DAMAGE EXPECTED…
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 HALF OF WELL CONSTRUCTED HOMES WILL HAVE ROOF AND WALL
FAILURE. ALL GABLED ROOFS WILL FAIL…ALL WOOD FRAMED LOW RISING
APARTMENT BUILDINGS WILL BE DESTROYED. … WATER SHORTAGES WILL MAKE
HUMAN SUFFERING INCREDIBLE BY MODERN STANDARDS.

Williams says “The wording and contents were so incendiary that our folks were concerned that it wasn’t real”, and implies that he and others at NBC translated this into something less scary for their viewers.
My most memorable experience with hurricane forecasts was with hurricane Gloria in 1985 when I was in Block Island (off Rhode Island). I recall a TV weather forecast that winds might reach 135 to 175 mph, and marine weather radio forecasts of 50 to 70 knot sustained winds with gusts to 90 knots (i.e. less than 105 mph). The marine radio forecasts seem to be more direct relays of what the weather service puts out, and it was fairly simple for me to determine that the TV forecast was bogus (the marine radio forecasts proved pretty accurate).
So it’s easy to imagine that people are aware that TV forecasts have a habit of overstating the threat from storms, and thought they could infer expert forecasts from TV forecasts by assuming a simple pattern of exaggeration, when it may be that the storytellers have a more complex model of how viewers’ behavior should be manipulated by biasing their reports. Do people actually rely on TV reports rather than more direct and reliable sources of expert opinion when accurate forecasts are important? If so, is it because they use weather forecasts mainly as entertainment or a catalyst for smalltalk at parties, and don’t want to be aware of the flaws?
And of course there was the problem of key government leaders failing to believe the expert forecast: (from The Agitator) [then] FEMA Director Brown:

Saturday and Sunday, we thought it was a typical hurricane
situation — not to say it wasn’t going to be bad, but that the
water would drain away fairly quickly. Then the levees broke and
(we had) this lawlessness. That almost stopped our
efforts…Katrina was much larger than we expected.