1. Pittsburgh Urban Flash Flood May 18, 1999

4. AMBER Time Display Interval 5-minute ABR: Used to compute ABR Rate and to display 2-hour accumulated ABR.5-minute ABR: Used to compute ABR Rate and to display 2-hour accumulated ABR. 15-minute ABR: Used for comparison with IFLOWS rain gage data and to display 6-hour accumulated ABR.15-minute ABR: Used for comparison with IFLOWS rain gage data and to display 6-hour accumulated ABR. 1-hour ABR: Used for history of ABR in a watershed and to display 24-hour accumulated ABR.1-hour ABR: Used for history of ABR in a watershed and to display 24-hour accumulated ABR.

5. Turtle Creek (1) ABR #1108 18May, 1999 1-hour data

6. Turtle Creek (1) ABR #1108 18-19May, 1999 15-minute data

8. Forest Hills Run ABR #5321 18-19May1999 15 min. data

9. Forest Hills Run ABR #5321 18May1999 5 min. data

11. Forest Hills Run in Park looking downstream.

12. Forest Hills Run exits the park under Route 30.

13. Forrest Hills Run underground. Notice new cement in storm drain. Kenmore Avenue Natural creek channel between Taco Bell and house.

14. Dumpster at Vincent’s Pizza washed 1 mile downstream along Electric Ave. Water and mud damage in building.

15. Electric Ave. Road is built on Forrest Hills Run creek bed, buried underground.

16. Forest Hills EMA Reports 2215 UTC - First reports of water in basements.2215 UTC - First reports of water in basements. 2300 - 0100 UTC many cars stranded along Ardmore Boulevard.2300 - 0100 UTC many cars stranded along Ardmore Boulevard. 0056 UTC - 10/homes/20 people evacuated on Kenmore Avenue.0056 UTC - 10/homes/20 people evacuated on Kenmore Avenue.

18. Mon Valley Urban Areas Total population 86,565 Rankin/Braddock 8,256 3.0mi 2Rankin/Braddock 8,256 3.0mi 2 Clairton 12,188 1.3mi 2Clairton 12,188 1.3mi 2 McKeesport 31,012 2.0mi 2McKeesport 31,012 2.0mi 2 Glassport 6,242 1.2mi 2Glassport 6,242 1.2mi 2 Port Vue 5,316 0.9mi 2Port Vue 5,316 0.9mi 2 Wilson/Dravosburg 11,075 0.8mi 2Wilson/Dravosburg 11,075 0.8mi 2 Duquesne 10,094 1.4mi 2Duquesne 10,094 1.4mi 2 Liberty 3,112 2.2mi 2Liberty 3,112 2.2mi 2

19. Port Vue #4032 0.9mi 2 18-19May1999 15 min. data

20. Port Vue #4032 0.9mi 2 18May1999 5 min. data

21. Rankin/Braddock #4028 3.0mi 2 18-19May1999 15 min. data

22. Rankin/Braddock #4028 3.0mi 2 18May1999 5 min. data

23. Liberty #4134 2.2mi 2 18-19May1999 15 min. data

24. Liberty #4028 2.2mi 2 18May1999 5 min. data Liberty #4028 2.2mi 2 18May1999 5 min. data

25. Duquesne #4117 1.4mi 2 18-19May1999 15 min. data

26. Duquesne #4117 1.4mi 2 18May1999 5 min. data

27. Clairton #4029 1.3mi 2 18-19May1999 15 min. data

28. Clairton #4029 1.3mi 2 18May1999 5 min. data Clairton #4029 1.3mi 2 18May1999 5 min. data

29. AMBER’sSlidingTime Window AMBER’s Sliding Time Window AMBER gives the forecaster the option of examining rainfall in any time duration.AMBER gives the forecaster the option of examining rainfall in any time duration. The capability of examining rainfall in a moving time window is a very powerful feature for the flash flood forecaster.The capability of examining rainfall in a moving time window is a very powerful feature for the flash flood forecaster. One inch of rain falling in 15 minutes produces a much large stream response than one inch of rain distributed through 1 hour.One inch of rain falling in 15 minutes produces a much large stream response than one inch of rain distributed through 1 hour.

30. Clairton #4029 1.3mi 2 18May1999 5 min. data

31. Clairton #4029 1.3mi 2 18May1999 5 min. data Clairton #4029 1.3mi 2 18May1999 5 min. data

32. 24 Hour ABR-Rainfall History The history of previous rainfall in a watershed is invaluable in determing flash flood potential.The history of previous rainfall in a watershed is invaluable in determing flash flood potential. The AMBER 24 hour rainfall product can be used to quickly determine the rainfall distribution in any watershed for the past 24 hours.The AMBER 24 hour rainfall product can be used to quickly determine the rainfall distribution in any watershed for the past 24 hours. ABR is displayed in one hour increments.ABR is displayed in one hour increments.

33. Clairton #4029 1.3mi 2 18May1999 1 hour data Clairton #4029 1.3mi 2 18May1999 1 hour data

34. Glassport #4031 1.2mi 2 18-19May1999 15 min. data

35. Glassport #4031 1.2mi 2 18May1999 5 min. data

36. Thompson Run(1) #6398 1.6mi 2 18-19May1999 15 min. data

37. Thompson Run(1) #6398 1.6mi 2 18May1999 5 min. data

38. Thompson Run(2) #6399 3.2mi 2 18-19May1999 15 min. data

39. Thompson Run(2) #6399 3.2mi 2 18May1999 5 min. data

40. Braddock Lock 2 ABR #4332 18-19May1999 15 min. data

41. Braddock Lock 2 ABR #4332 18May1999 5 min. data

42. Conclusions Small watersheds definition is the key to detection of flash flooding.Small watersheds definition is the key to detection of flash flooding. ABR Rate gives early warning for flash flood potential.ABR Rate gives early warning for flash flood potential. Time duration of rainfall display impacts forecaster perception of flash flood threat.Time duration of rainfall display impacts forecaster perception of flash flood threat. User selectable time window needed.User selectable time window needed.