A.
Product
Description- NDFDClimate is
a computer application that creates images of forecast and climatological
parameters for the continental U.S. from two different digital data sets. The first data set is the NDFD (National
Digital Forecast Database) weather forecast grids produced by the NOAA National
Weather Service (NWS) and the second data set is PRISM (Parameter-elevation
Regressions on Independent Slopes Model), an expert system that uses point
climatological temperature data and a digital elevation model (DEM) to generate
gridded estimates of climate parameters. The NOAA National Weather
Service (NWS) National Digital Forecast Database (NDFD) contains digital
forecast grids of sensible weather elements such as temperature, wind, and
precipitation in a mosaic from collaborating field offices across the U.S. for
forecasts out to seven days. Daily digital climatology grids of maximum and
minimum temperature are created using Parameter-elevation
Regressions on Independent Slopes Model (PRISM; Daly et al. 1994)
method. NDFDClimate grids produced include: PRISM derived normal daily maximum and minimum temperatures, NDFD
derived forecasted heating and cooling degree days through day 6, NDFD
forecasted daily minimum and maximum temperature anomalies derived from PRISM
daily climate fields through day six, NDFD derived five day total of forecast
heating and cooling degree days, NDFD 60 hour total of liquid equivalent QPF,
NDFD forecasted number of hours the temperature is above or below a defined
temperature through day three, NDFD forecasted 24- and 48-hour forecast
temperature changes from forecast issue time.
B.
Purpose- National Oceanic and Atmospheric
Administration's (NOAA) National Weather Service (NWS) is the official United
States governmental voice for issuing warnings during life threatening weather
situations. The mission also states "NWS data and products form a national
information database and infrastructure which can be used by other governmental
agencies, the private sector, the public, and the global community." In
order to complete its mission, the NWS relies on partnerships (e.g., the media
and commercial weather companies) to distribute their observations, forecasts,
and warning information. Technology and innovation have provided new
information exchange pathways, including the Internet. NWS partners, as well as
the general public, are becoming increasingly sophisticated and have new
requirements for NWS' weather, water, and climate information. Users are
demanding faster access to information that is more accurate, easier to
understand, and provided in new formats. NDFDClimate provides a new format for displaying climate
data. NDFDClimate information can then be used to protect property from
forecasted anomalous weather events.
C.
Audience- The target audience for these experimental
graphical products is the general public. The product will be available to the
general public using the Internet.
D.
Presentation
Format - These images will
be displayed on a web page (http:// )
with a table organized by the valid time (or month-day) of each forecast
product listed in Table1. Animation loops are also available under 'loop' for
most graphics. These images have contours and color fill that make the images
easy to interpret. These images include the difference between the daily max
and min temperature forecast and climatology, derived forecasts images from the
NDFD grids, and current NDFD temperature and precipitation and forecasts images
with enhanced color curves.
E.
Feedback Method We are always seeking to improve our products
based on user feedback. Comments regarding NDFDClimate forecast and climatology
images should be sent to:
NOAA National Weather Service
ATTN: Christopher Mello
Federal Facilities Building Hopkins Airport
Cleveland, OH 44135
Or, e-mail the author at: Christopher.Mello@noaa.gov.
A link to a summary of comments is included
on the web page.
Experimental feedback Period: December 15, 2005 through December 15, 2006
Part II Technical
Description
a. Format and Science
PRISM is an expert system that uses point climatological
temperature data and a digital elevation model (DEM) to generate gridded
estimates of climate parameters (Daly et al. 1994). Temperature changes over
flat terrain are easily estimated using linear interpolation between official
National Climatic Data Center (NCDC) climate points. However, mountainous
regions presented the biggest challenge in creating these climate grids due to
the potential of great temperature changes over short horizontal distances.
Fortunately, PRISM is well suited to mountainous regions.
PRISM recognizes that topography is an important climatic
unit and elevation is a primary driver of many climate parameters. The PRISM
system determines climate element values at grid cells by calculating linear regression relationships between the
climate element and elevation. Each grid cell estimate is determined from a
separate multiple linear regression using data from Automated Surface
Observing Systems (ASOS) locations, the
nation's primary surface weather observing network and
local national weather service mesonet stations. Data from in the multiple linear regressions is weighted based on
five factors: distance, elevation, vertical layer, topographic facet, and
coastal proximity. The horizontal
resolution of PRISM data is 5 km across the continental U.S. Topographic facet, or topographic
orientation, is primarily used for precipitation. Rain shadows and upslope enhancement are estimated using
regression formulas based on wind flow divided into eight compass points and
changes in elevation. Vertical layer refers
to two layers: the boundary layer and the free atmosphere above the boundary
layer. By separating into two layers, it became possible to identify
temperature inversions in high mountain valleys also using regression.
Temperature data from PRISM consist of weekly averages of
daily maximum and minimum temperature fields for the period 1971 to 2000. Interpolation between consecutive weekly
data points was performed through a linear regression to obtain daily values
throughout the year. It was assumed that the rate of change of daily high and
low temperature during each week is constant.
Quality control was performed by comparing the derived daily normal maximum and minimum
temperatures from NDFDClimate to the official data from the NCDC at 7 ER sites.
All official NCDC daily normal maximum and minimum temperatures and daily NDFD
maximum and minimum temperature forecasts are rounded to the nearest °F. Seven official climate sites in the
Eastern Region were examined: Cleveland, OH; Toledo, OH; Erie, PA;
Youngstown, OH, Syracuse, NY; Richmond,
VA and Greenville, SC, and each site had a mean absolute error near 0.25 °F for both the normal daily maximum and
minimum temperature. For all seven
sites, the highest daily absolute error was less than 1°F for both the normal maximum and minimum
temperature.
In addition to the images, a point and click
feature is available using the same data sets discussed above using freely
available graphical software GNU plot for selected cities. By clicking on a
selected city, a new pop up image in a graphical format is launched. These
images are NDFD High/Low Temperature forecasts along with a graph of normal
high and low temperatures for the same date of the forecast. GNU plot produces
network graphic products files (PNG).
All software included in NDFDClimate is free to download
(see Mello and LaPlante 2005 for more information) and redistribute as long as
no modifications to the source code are made.
b. Product Availability
The CLE WFO office located in Cleveland, Ohio will run NDFDClimate. The domain will include the entire Eastern Region of the NWS http://www.erh.noaa.gov/. The images will be created at 10 past each hour and posted to the world wide web for public viewing. All images can be accessed through one web page. A link to the web page can be found on the Cleveland National Weather Service homepage at http://www.erh.noaa.gov/er/cle/.
(2) References
Daly, C., R.P. Neilson, and D.L. Phillips, 1994. A Statistical-Topographic Model for Mapping Climatological Precipitation over Mountainous Terrain. J. Appl. Meteor., 33, 140-158.
Mello, C. and R. LaPlante, 2005. NDFDClimate. NOAA/National Weather Service Eastern Region Technical Attachment, Bohemia, NY, 2005-04, pp.