So, how did the meteorological profession do with Irene, a rare hurricane that made landfall in the Northeast United States? Meteorologists almost always do postmortems on major storms because we need to learn from our mistakes so we can do it better next time.
|Arrow indicates the point of landfall as determined by the
National Hurricane Center.
The intensity was overforecast at this point. We were forecasting a category 3 and it was a cat 2 when it made landfall.
Tuesday at 7:19am (roughly four days before landfall), the point of landfall in North Carolina, while slightly far west, was extraordinarily good for four days out. There was still an over forecast by one category but that isn’t bad at all given it is four days out.
Why did the forecast improve? Because the National Weather Service started launching weather balloons at six-hour intervals and NWS and USAF hurricane hunter and high-level aircraft began gathering special data to load into the computer forecast models.
Shortly after 10pm, I
forecast posted the first of a series of genuinely amazing path forecasts.
Things didn’t change much on Wednesday. I wouldn’t change very much of what I posted on Tuesday and Wednesday.
Thursday at noon I posted the two sets of forecasts I’m not proud of. Titled, This Looks Serious, and, Irene: My Concern is Rising, I walked readers through some of the newer computer models that were taking the intensity of Irene up to, perhaps, a category 4. If this had occurred, the results would have been devastating. Irene did intensify aloft but for scientifically unknown reasons the intensification never made it to the ground. Meteorologists just do not have a solid understanding of the processes which cause tropical systems to intensify or weaken.
Throughout the week, I warned of extensive power failures due to toppled trees from wind and wet ground. I posted the map below of forecast rainfall which I predicted would lead to “major flooding.”
Below is the rainfall map from Irene. Unfortunately, the colors are not the same but I believe you’ll agree that 3-4 days out (depending on location), the correlation between the forecast and actual is remarkable.
From this point on, the path, wind, and rainfall forecasts underwent little revision as confidence went up (i.e., the boundary of the “confidence interval” narrowed).
So, how would I rate the quality of the forecasts presented on this blog?
- Path, 5 days to landfall and later: A+
- Intensity: C-
- Forecast of Widespread Power Failures: A
- Forecast of “Major Flooding:” A+
- Forecast of Window Breakage in Manhattan High-Rises: F
ADDITION: Here is another take on the accuracy of the forecast. And, the New York Times has a good article about the weakening that took Irene from the 2 we forecast just southwest of NYC down to the borderline 1 it actually was.
Interactive map of Irene’s path and damage. Total “customers” (homes and businesses) that lost power are 5.8 million. The electric utility industry uses 3.5 people per “customer” so the total number of people without power is just over 20,000,000.
UPDATE 6:50PM: My friend, meteorologist Dr. Cliff Mass, has a completely different take. He does not believe Irene was even a hurricane north of the North Carolina border. As I understand NHC’s reasoning (and I may be incorrect), there were very high winds aloft and over water and they were concerned those would sustain the hurricane.
I present all of this because I want non-meteorologists to understand the complexities of what we are dealing with when it comes to hurricanes and tropical storms.