The National Hurricane Center announced that they will issue watches and warnings for tropical storms 48 hours out, instead of the previous 36 hours out. See the notice at http://www.noaanews.noaa.gov/stories2010/20100105_nhc.html. The NHC states that this is possible due to an increase in forecast accuracy. While I’m sure this has some bearing on it, also wonder about other reasons and unstated impacts.
That extra 12 hours is good to enable more warning time to inform the public to take the appropriate action. It allows communities to muster the appropriate resource and contact the right people. More advance notice also forces the local communities to be better prepared for landfall should reduce impact to critical infrastructure. However, when the forecast changes to point elsewhere, it also gives an “out” to the emergency manager for spending lot of money on non-event. The EM can state that the NHC warned them and it wasn’t the EM’s fault that it was inaccurate States will need to get on the ball in working with FEMA.
The NHC gives more warning time so the States have fewer excuses if and when they fail. This extra time provides ample time for the State to plan and request pre- and post-disaster assistance from FEMA. Now FEMA can sit back little bit to force the State to be more proactive and less reactive in their near-term. An older disaster response planning general ballpark rule is 50 mile variance for every 12 hours out of storm. This provides variance of nearly 200 miles at 48 hours out. That’s lot of coast line to cover with watch or warning. That’s also lot more communities preparing for landfall – and spending money to do so. Resources will need to be spread across larger area. Mutual aid will no longer come from nearby communities as they are dedicated to their own local preparedness actions. Assistance will need to come from farther distance away.
I’d be interested in seeing the NHC rerun the forecast models with this new accuracy. I’d like to follow storm developing to compare the old model to the new model. How much more accurate are the models? How many more communities would be placed under hurricane watch or warning but didn’t experience landfall? The NHC’s 12-hour forecast shift from 36 hours to 48 hours really has lot of trickle down impact. Many agencies and organizations make their plans based on the valuable information the NHC provides. FEMA, FEMA’s contractors, non-governmental organizations and others will all need more resources to perform pre-landfall work across larger watch and warning area.