Hurricane Sandy by the Numbers…

As you might imagine, the past 7 days here at WDT® have been very demanding! We knew Sandy had characteristics that would brand her a “historic” storm; but just how historic was yet to be determined. With our custom products though, we were able to provide our customers with very specific information prior to landfall. Economic impact by industry, potential damage to residential zones, even details as specific as areas with broad leaf trees that are more susceptible to wind damage are examples of the information we provided.

Our WeatherOps™ team of meteorologists worked 24/7 delivering custom maps and forecasts, expert interviews for television coverage, and 16 separate webinars to participating customers. After the storm made landfall our WeatherOps Forensic Analysis team activated and has drawn a set of post Sandy GIS product layers that depict Rainfall Totals, Extreme Precipitation Index, and Wind Analysis for the entire path of Sandy. You can contact for details.

Over the course of this event, WDT served over 500 million requests for data, amounting to 10 terabytes of data transferred. We sent 1 million alerts to our iMap Weather Radio App customers and our RadarScope App served 1.5 million requests for radar information during the period.   All without a glitch!

Here are a few Sandy-specific stats from the Associated Press we think you will find interesting:

  • 50 – Estimated (and rising) number of people killed in the U.S. from the storm, more than half in the state of New York (22 in New York City alone)
  • $17.6 billion – WDT’s HurrTrax- Hurricane damage model estimated economic impact due to U.S. damage from Sandy
  • 932 – Sandy’s size, in miles, as measured by diameter of tropical storm–force sustained winds at landfall — nearly double the diameter of Hurricanes Isaac and Irene
  • 11.91 – Inches of rain from Sandy recorded in Wildwood Crest, N.J., as of Oct. 30
  • 15 – Hours it took to evacuate 300 patients — including 20 infants from the neonatal intensive care unit from New York’s NYU Langone Hospital using darkened stairwells
  • 2.7 million – Mentions of Sandy on Twitter in the 12 hours before and 12 hours after landfall

We want to thank all of our customers for riding out the storm alongside WDT. We invite you to contact us for notification of future special event coverage and remind you we are here every day to satisfy your custom weather needs, regardless of industry.


Categories: Hurricane, Severe Weather | Leave a comment

Hurricane Irene – The biggest impacts are not going to be winds.

As I write this on Friday afternoon, Hurricane Irene is a Category 2 Hurricane aimed directly at Cape Hatteras, North Carolina. After Irene pummels North Carolina, she will move up the Eastern Seaboard almost paralleling the coast. When Irene gets to the North East it will cause havoc in some of our biggest cities. By that time Irene will “only” be a Cat 1 Hurricane or Tropical Storm, but winds will still be very strong (60-90 mph). It is likely that the biggest impacts will be from storm surges and large waves in some of the most important waterways in the North East, including Chesapeake Bay, Delaware Bay, and the waterways in Atlantic City and New York City.

precip forecast

Precipitation Forecast

Additionally, 10 inches or more rain will fall in some areas on top of already wet ground. This will cause significant flash flooding. WDT has partnered with Metstat to produce a new product, the Forecast Potential Flood Index, just launched today in beta mode. By combining the forecast rainfall amounts with regional climatological values, we can actually characterize the amount of rain expected in terms of how “rare” it is to get such amounts. This makes it much easier to ascertain potential impacts such as flooding than using simple amounts, since what is deemed heavy rain in one part of the country may be typical in another. The attached graphics show the forecasted rainfall amounts from WDT’s advanced, high-resolution numerical weather

"ARI" How Often This Occurs

prediction model along with the Forecast Potential Flood Index derived from those values. The first graphic shows the rainfall expected for the 24 hour period ending Sunday morning, and the second shows the 24 hour period ending Monday morning. This forecast suggests that some portions of New York state will see rainfall amounts that typically only occur once every 500-1000 years!

There is also deep concern that in areas where there has been significant rainfall in the past few weeks plus the additional rainfall from Irene, that tree root systems will not hold up to strong winds, so a big issue will be toppling trees which will lead to widespread power outages.

WDT has recently signed an Agreement with the National Hurricane Center where we are working with them to distribute real-time video from experts at the NHC on an hourly basis during the period leading up to landfalling hurricanes. These experts are describing the latest thinking on Hurricane Irene and updating you every hour. We have these videos on 600+ websites. To find a local media site that is carrying these videos, please go to or go to

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Tropical Storm Don: Drought Buster?

Most of Texas and the western half of Oklahoma our under an “Exceptional Drought” as determined by NOAA. See (Pic 1). If normal rainfall occurred over the state of Texas for the next few years it will still not alleviate this drought. But what is needed is a large slow moving tropical system that dumps a lot of rain on the area.

Could Tropical Storm Don be the answer to their prayers in Texas? Check out the forecasted movement of TS Don in (Pic 2) and follow its movement and forecasts on

It is conceivable that up to 8-10 inches of rainfall could fall over a large area in West Texas as part of TS Don making landfall somewhere between Houston and Brownsville! This will not completely alleviate the drought, but will make a significant dent in it.

US Drought Monitor

(Pic 1) U.S. Drought Monitor

Tropical Storm Don in iMap on

(Pic 2) Tropical Storm Don in iMap on

Categories: Hurricane | Tags: , , , | Leave a comment

The Hurricane Cone of Probability

Although I spent most of my career focusing on severe weather and its detection and nowcasting, I regularly observe how the National Hurricane Center (NHC) communicates threats from hurricanes, drawing corollaries with how severe thunderstorm and tornado threats are transmitted to the public. My impression is that the NHC has spent considerable time over the years working on how to represent hurricane locations to the public.

Cone of Probability for Hurricane Alex 2010

Cone of Probability for Alex (2010)

You may or may not know how the “hurricane cone of probability” produced by NHC is created. The cone represents the probable track of the center of the tropical cyclone and on average 67% (2/3) of the center locations will fall within that cone. They can calculate this cone because they assume that their forecast errors in the past 5 years will be the same as their existing forecasts.

I have always been impressed at how rigorous NHC’s approach is in calculating the probability cone. This is quite different than severe thunderstorm warnings or tornado warnings where local NWS meteorologists “on the fly” have to determine the size and location of the warning.

Of course there are issues in both approaches. If you think about the NHC cone of probability, if 2/3 of the forecasted center locations are within the cone, that means that 1/3 will be outside the cone. And I think that just as much of an issue is that the public interprets the area of the cone as the area where hurricane damage will occur, but that is not the case. NHC is representing where they believe 2/3 of the centers of hurricanes will fall, and hurricane force winds, surges, etc. definitely extend out from the center location by many miles.

On the severe thunderstorm and tornado warning side, the size and location of the polygon is placed in such a way that the meteorologist believes that the hazardous weather will always occur within the polygon. It would be interesting to see statistics on what percent of tornadoes for example occur outside tornado warnings, but my guess is that number will be very small. The biggest issue with tornado warnings is false alarms.

So all in all, communicating information to the public about hazards from hurricanes and severe thunderstorms and tornadoes is a difficult task. Meteorologists producing these warnings and forecasts have to deal with the reality that inherently all forecasts of meteorological events are by their nature not perfect. Thus, in the meteorological community we try to express the hazards to the public by making warnings or cones of probability larger in size and time than will ever actually occur to cover the uncertainty in our capability to forecast these events. Ultimately, progress in science and our capability to collect data on these events will help us reduce the uncertainty, leading to more precise and accurate warnings and forecasts.

Categories: Alerting, Hurricane | Tags: , , , | Leave a comment

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