FFMP Plays Life Saving Role in Pennsylvania

Early in the afternoon of Wednesday, May 12, a thunderstorm developed over Miller and Shaver Mountains south of Tunkhannock Pennsylvania in Wyoming County. The thunderstorm was nearly stationary and at times had rainfall rates over 4 inches per hour. Rainfall totals exceeded 6 inches in just a few hours times and caused massive flash flooding of the Moneypenny Creek which is along Thurston Hollow Road in Eaton township.

Figure 1. Storm Total Precipiation

Storm Total Precipitation or STP is a map of estimated storm total precipitation accumulation continuously updated since the last one-hour break over the entire scope. This product is used to locate flood potential over urban or rural areas, estimate total basin runoff and provide rainfall data 24 hours a day.

In this case, the image shows a range of 2 1/2 inches (dark green) to a maximum of 6 to 7 inches (dark blue square near the center of the image) near the location that the flooding occurred.

The flash flood warning was issued at 1:37 p.m.Flash flooding began on some roads around 2:13 p.m. The major flash flood on Moneypenny Creek was about 60 minutes after the warning was issued according to Gene Dziak, Wyoming County Emergency Manager. The detailed warning message and its lead time allowed Gene Dziak, to take protective action by barricading roads and diverting school buses out of the affected area.

According to Mr. Dziak, "The warning information that NWS Binghamton provided us was priceless!!" I am very impressed with the specificity of the warning message and the lead time that allowed me to better coordinate my response to this disaster."

There were no injuries or deaths related to this flash flood. This is a credit to the strong partnership between the National Weather Service in Binghamton and the Wyoming County Emergency Management Agency. NWS Binghamton issued this flash flood warning for southeastern Wyoming County about 1 hour before the flood hit that specifically mentioned Moneypenny Creek. The NWS in Binghamton used new technology known as FFMP (short for Flash Flood and Monitoring Program) to produce a very specific flash flood warning. There is no doubt that the warning message and the coordinated response from the Wyoming County Emergency Management Agency saved lives and prevented injuries and further property damage in this area.

The power of water is evident in the photographs (Courtesy of Charles Rigdon) as the water carved a swath of damage and  scattered debris along Thurston Hollow Road which was totally devastated. Total damages estimates have exceeded 500,000 dollars to this area.  (Images courtesy of Charles Rigdon)

Figure 2. Flash Flood damage to Thurston Hollow Road>

Figure 3. Water running cross Thurston Hollow Road

Figure 4. Trees across Thurston Hollow Road

Figure 5. Another picture of damage across Thurston Hollow Road

Figure 6. Another picture of trees and parts of a fence across Thurston Hollow Road

Figure 7. Schematic of how thunderstorms can produce flash flooding

The most common cause of flash flooding in spring and summer is a slow-moving or stationary thunderstorm that dumps heavy rain relentlessly on a small, localized region. This is especially true when the jet stream is often very weak or north of our area. The jet stream is a current of air high up in our atmosphere, which "steers" weather systems long, including thunderstorms. When the jet stream is weak or well north of the region, thunderstorms that form often have very weak steering currents and move slowly, producing flash floods. The hills and mountains of our region often are the breeding grounds for these slow-moving thunderstorms.

As winds rise up the mountains, the air cools and condenses forming clouds, and, when the conditions are right, the clouds can develop into thunderstorms. With weak steering currents aloft, these thunderstorms often remain stationary on a hill or mountainside. This often has disastrous consequences since many small streams and creeks flow down our mountains and hills.