Center records hydrologic data for forecast offices

Will it rain tomorrow?


The team at the Ohio River Forecast Center has the job of supplying that information to
the National Weather Service’s forecast offices, which in turn issue public watches
and warnings.


The 52-year-old center is the oldest of the nation’s 13 river forecast centers.


It monitors conditions for an area of about 200,000 square miles throughout the Ohio
River basin, including the Allegheny River in western New York, the Monongahela River in
West Virginia and the Ohio River from Pittsburgh to Cairo, Ill., where the Ohio flows into
the Mississippi.


“We issue daily forecasts for about 100 points in the Ohio River drainage
basin,” said Tom Adams, development and operations hydrologist for the
center. The center issues river forecasts three days in advance and precipitation
forecasts 24 hours in advance.


“We have automatic data collection from rain gauges and river gauges. There’s
also a network of cooperative observers who provide us with daily rainfall amounts,”
Adams said.


Reports from the automated gauges are received either hourly or every six hours. Most
of the gauges are maintained by the Geological Survey or the Army Corps of Engineers,
although there are some state-funded systems, Adams said.


The center relies heavily on rainfall forecasts from the weather forecast offices,
Adams said.


The rainfall forecasts are further analyzed by meteorologists in the river forecast
offices. “Actually, what we forecast is precipitation,” including snow,
Adams said. “During the winter months we have to forecast temperatures because there
can be a snow melt from rising temperatures,” he said.


The hydrologic information is processed by a Hewlett-Packard Co. 9000 Series 750 server
running HP-UX 10.20. After decoding, the data is stored in an Informix database and a
database within the National Weather Service’s River Forecast System, Adams said.
Hydrologists also receive hourly Doppler radar data from the National Weather
Service’s weather forecast offices.


The radar data goes through two levels of automatic precipitation processing. The data
then goes through a third level of processing, where the team mosaics the radar data it
receives from about 13 weather forecast offices in the region, Adams said.
“That’s combined into a single radar rainfall/precipitation field,” he
said.


The radar data is checked against the center’s rain gauge estimates, Adams said.
“That’s an essential part of the radar precipitation processing because by
estimating precipitation from the radar alone, you don’t get perfect estimates and
there could be biases due to a number of atmospheric causes. So the rain gauges have to be
used throughout the whole radar field,” he said.


After some additional processing, the radar rainfall data is put into hydrologic models
in the River Forecast System, which has been around since the late 1970s, “first on
mainframes, then, as we moved to a workstation environment, to Unix,” Adams said.


In the late 1980s and 1990s, the system was modified to run in the interactive
environment within the X Window System, Adams said. The newer system is referred to as
NWS-RFS-IFP, which stands for The National Weather Service’s River Forecast
System’s Interactive Forecast Program.


The National Weather Service is in the process of modernizing its telecommunications,
computers, software and databases through the Advanced Weather Interactive Processing
System.


In June, the Ohio River Forecast Center received about $3 million worth of new
Hewlett-Packard hardware and software, Adams said.


The center posts information on the Web at http://www.nws.noaa.gov/er/iln/ohrfc.htm.
   

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