charles.ross@noaa.gov warning program

National Weather Service Flood Forecasting and Warning Program

Charles RossService Hydrologist

NWS State College, PAMarch 16th, 2021

charles.ross@noaa.gov

Harrisburg, City Island, March 1963

National Weather ServiceWater PredictionsforLife Decisions

Thanks For attending !

Topics covered today• PA Weather/Hydrology Review• NWS Hydrologic Program Overview• Real time river and flood mapping and information on the web• Flood Safety Week Coming Up

Let’s keep this interactive and laid back• Ask questions!!• Comments welcome

National Weather ServiceWater PredictionsforLife Decisions

PA Weather Classified as a humid continental climate

• Hot and humid summers, cold winters

Precipitation is fairly spaced out throughout the year• July wettest, February snowiest

It can flood any time of the year• Heavy rain from thunderstorms, tropics, stalled fronts• Snowmelt / Ice can contribute• Seasonal factors: Frozen ground, greenup, saturation, etc

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

Poll Question 1 What was the wettest year on record for

Pennsylvania?

A. 1972B. 2011C. 1996D. 2018

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

PA Hydrology

National Weather ServiceWater PredictionsforLife Decisions

Poll Question 2 Which has the largest mean annual flow?

A. Delaware River at Trenton (Philadelphia area)B. Susquehanna River at HarrisburgC. Ohio River at Sewickley (Pittsburgh area)

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

Types of Flooding in PA● Flash Flooding - A rapid and extreme flow of high water into a normally dry

area, or a rapid water level rise in a stream or creek○ Mostly from heavy rain in the spring and summer○ Tropical storms○ Ice Jams in winter○ Dam Break (rare, but can happen)

● River Flooding - Occurs when river levels rise and overflow their banks or the edges of a river or stream and inundate areas that are normally dry.○ Very common in Pennsylvania

National Weather ServiceWater PredictionsforLife Decisions

Our Office in State College

National Weather ServiceWater PredictionsforLife Decisions

NWS Offices Nationwide

National Weather ServiceWater PredictionsforLife Decisions

NWS River Forecast Centers

National Weather ServiceWater PredictionsforLife Decisions

National Water Center

National Weather ServiceWater PredictionsforLife Decisions

NWS Data on the Web

National Weather ServiceWater PredictionsforLife Decisions

River Gage Data

AHPS is the source

water.weather.gov

National Weather ServiceWater PredictionsforLife Decisions

River Forecast Centers

Two RFCs service Pennsylvania:-Ohio River Forecast Center● https://www.weather.gov/ohrfc/● Ohio River Basin

-Middle Atlantic River Forecast Center● https://www.weather.gov/marfc/● Susquehanna and Delaware Basins

National Weather ServiceWater PredictionsforLife Decisions

National Water Model● 4 components to this national model

○ Analysis○ Short Range 18-hour forecast○ Medium Range○ Long Range

● 2.7 million stream reaches! ● 3.6 million water miles● 700x spatial density of forecasts provided

today● PA centric link

National Weather ServiceWater PredictionsforLife Decisions

Interesting NWS Hydro Links

● Flood Inundation Mapping ○ Overview Video○ https://water.weather.gov/ahps/inundation.php

● NOAA Atlas 14 Precipitation Frequency Estimates○ Historical frequency of heavy rain events○ https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html

● 1-stop Gage Analysis page○ Edit the URL below to enter NWSLID or USGS gage number○ https://www.weather.gov/source/aprfc/gageAnalysis.html?site=harp1

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

Flood Safety Week Is Next Week

● NWS Planning a big push on flood safety this year○ Daily Social Media posts on our Facebook and Twitter Page

■ https://www.facebook.com/NWSStateCollege/■ https://twitter.com/NWSStateCollege

○ Two livestream virtual lectures on Pennsylvania flood safety■ Monday, March 22, at 7PM: https://attendee.gotowebinar.com/register/6920019834983037710

■ Wednesday, March 24, at 11AM: https://attendee.gotowebinar.com/register/7633099305084184078

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

National Weather ServiceWater PredictionsforLife Decisions

Thank you for attending!

Contact Info:Charles RossService Hydrologist, NWS State College PAcharles.ross@noaa.gov(814) 954-6387