the 40th Anniversary
June 2012 marks the 40 year anniversary of Hurricane Agnes, one of the most costly natural disasters in
Pennsylvania history. Nationwide, there were 122 deaths attributed to Agnes, 50 in the state of
Pennsylvania. Total damages from the storm reached over $3 billion dollars nationwide, with over $2
billion dollars in losses occurring in the Susquehanna River basin. It has been estimated that damage from Agnes (if adjusted to 2012 dollars) would be around $16.5 billion dollars. Hurricane Agnes was the nations' most costly natural disaster at the time.
Devastating floods occurred across the Mid-Atlantic region resulting from the remnants of Hurricane Agnes in late June of 1972. Hurricane Agnes came onshore over the Florida Panhandle during the afternoon of June 19th. The storm weakened to tropical depression status over the Carolinas, only to
re-intensify to tropical storm strength as it reached the Virginia coast on the 21st. The storm then moved North, weakening to extra-tropical strength as it passed just west of New York city before
recurving to the West across Central New York state. The storm then looped back to the East, crossing Northern Pennsylvania before dissipating.
The slow moving remnants of the storm moved across Pennsylvania and dropped generally between 7 and
10 inches of rain across the region, although there were some local reports of nearly 18 inches of rain.
Eight to 12 inch amounts were also common across Virginia, with 2 to 6 inch amounts across the southern tier
of New York. The heavy rain of Agnes followed a relatively wet May, in which 3 to 4 inches of rain fell across the area.
Rainfall amounts across Central Pennsylvania for the four day period from June 20th through
June 24th ranged in general from 8 to 10 inches. Isolated amounts however approached 18 inches.
The heaviest rain (12 to 16 inches) fell in a corridor from Williamsport South through Harrisburg and
York. The heaviest reported 24 hour rainfall was recorded at Harrisburg, where 12.53 inches fell
between 8 pm on June 21st through 8 pm on June 22nd. Other rainfall totals (June 20-24) include:
HARRISBURG 15 INCHES
WILLIAMSPORT 12 INCHES
YORK 16 INCHES
LEWISTOWN 12 INCHES
STATE COLLEGE 8.5 INCHES
TIOGA 8 INCHES
BRADFORD 8 INCHES
ALTOONA 9 INCHES
JOHNSTOWN 7 INCHES
Many record river crests were achieved along the Susquehanna and Juniata rivers, as well as
their tributaries. Most of the previous records were established back in March of 1936, when heavy
rainfall on a deep snowpack produced record flooding. Some more notable river crests due to Agnes
SITE RIVER OR TRIBUTARY CREST FLOOD STAGE
BLOOMSBURG SUSQUEHANNA 31.20 19.00
DANVILLE SUSQUEHANNA 32.32 20.00
SUNBURY SUSQUEHANNA 35.80 24.00
HARRISBURG SUSQUEHANNA 32.57 17.00
MARIETTA SUSQUEHANNA 64.54 49.00
SINNEMAHONING SINNEMAHONING CR 19.50 17.00
RENOVO WEST BRANCH SUSQ 26.56 16.00
LOCK HAVEN WEST BRANCH SUSQ 31.30 21.00
JERSEY SHORE WEST BRANCH SUSQ 38.40 26.00
WILLIAMSPORT WEST BRANCH SUSQ 34.75 20.00
MILTON WEST BRANCH SUSQ 34.55 19.00
LEWISBURG WEST BRANCH SUSQ 34.23 18.00
CEDAR RUN PINE CREEK 16.00 12.00
BEECH CR STATION BALD EAGLE CREEK 12.29 11.00
LOYALSOCKVILLE LOYALSOCK CREEK 14.74 12.00
WILLIAMSBURG JUNIATA 18.38 12.00
HUNTINGDON JUNIATA 20.03 12.00
MAPLETON DEPOT JUNIATA 33.07 20.00
LEWISTOWN JUNIATA 42.10 23.00
NEWPORT JUNIATA 33.97 20.00
CAMP HILL YELLOW BREECHES CR 18.33 7.00
HOGESTOWN CONODOGUINET CREEK 17.01 8.00
LANCASTER CONESTOGA CREEK 27.80 11.00
HARPERS TAVERN SWATARA CREEK 23.72 9.00
SHERMANSDALE SHERMAN CREEK 18.09 9.00
PENNS CR STATION PENNS CREEK 14.85 8.00
ADVANCES IN THE NATIONAL WEATHER SERVICE SINCE AGNES
The National Weather Service has made great strides since the early 1970s in computer technology,
data collection and warning services. Information from automated rain and stream gauges are now available to forecasters. In addition, many more gauges have been added to the data network.
A national doppler radar network is in place to accurately track storms
and estimate the precipitation they produce. Round-the-clock satellite coverage is now available to all forecast offices, providing additional precipitation estimates. Additionally, forecasters can now disseminate warnings and advisories in real-time to Pennsylvania county emergency management officials via direct communication links.
More recently, the Advanced Hydrologic Prediction Services (AHPS)
has been implemented to provide river observations, flood outlooks, drought products and water supply guidance. This
improved capability builds on the traditional expertise and responsibility of the National Weather Service
flood forecasting program. AHPS forecasts also provide information about forecast uncertainties which can be beneficial to the users. These longer range products include probabilistic information mostly in graphical format to describe the likelihood of various hydrologic scenarios.