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OCR for page 51
5
Conclusions and Recommendations
CONCLUSIONS
Based on an intensive 6-month study, the NEXRAD Pane} of the NWSMC arrived at a strong
overall conclusion that weather services on a national basis will be substantially improved under the
currently planned NEXRAD network. The panel's conclusions were as follows:
.
The NEXRAD radars generally meet or exceed their technical design specifications in
all respects relevant to the detection of weather phenomena and are substantially
superior to the radars they are replacing. Therefore, there is no degradation of radar-
detection coverage, but always improvement, when a NEXRAD is located at or near the
site of one of the old radars. Indeed, the introduction of NEXRAD radars will
significantly improve overall storm detection and warning performance and will
substantially improve weather services on a national basis.
Compared to coverage by the old network, the NEXRAD network will provide greater
coverage at the 10, 000-ft level over the contiguous United States.
For the detection of specific weather phenomena, that is, supercelis, mini-supercelIs,
macrobursts, lake-effect snow, and stratiform snow, the NEXRAD coverage is generally
much greater than it was for the old system; for hurricanes, the NEXRAD coverage is
complete over the area of risk.
Digital signal and data processing will permit the production and display of a wide
variety of automated weather products which, in turn, will improve the forecasters'
ability to rapidly assimilate and use the available data, not only from their NEXRAD
but also from neighboring NEXRAD sites.
The NEXRAD's Doppler feature and other technical characteristics allow for greatly
increased capability for short-term forecasting ("nowcasting") ofthunderstorm initiation;
detection of damaging winds, such as macrobursts and wind shear; and detection of the
mesocyclones that are often associated with tornadoes and other severe storm hazards.
Despite the fact that NEXRAD provides overall network superiority, in areas where the
old radar site is relatively distant from the replacement NEXRAD, there may be some
degradation in NEXRAD detection coverage. Examples of areas of concern include
northern Alabama, northern Indiana, northwestern North Dakota, northwestern
Pennsylvania, and southeastern Tennessee.
The regions of degraded coverage will increase for most weather phenomena if 15 of
the DoD NEXRADs that are currently operating in the network are not operated and
maintained as pan of the national network. Operation of any of these radars with stan
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52
Assessment of NEXRAD Coverage
cards and availability less than those of NWS-operated units will effectively degrade
coverage. Principal areas of concern include portions of DoD NEXRAD coverage areas
in Alabama, Georgia, Mississippi, and Texas.
In the national NEXRAD network, there will be four NEXRADs (i.e., Yuma, Arizona;
Key West, Florida; Caribou, Maine; and Cedar City, Utah) without a nearby WFO. The
reliability of the NEXRAD and the dependability of services derived from it, as well
as communications, forecast office staffing, and warning and forecast dissemination, all
become even more important when forecasters are remote from the radar site.
Weather services are influenced by the full complement of observations and products
available to the forecaster, as well as by cooperative spotter networks and the skills of
experienced forecasters. The performance of this composite system is the critical
element in assessing whether areas that have degraded radar-detection coverage will also
have a degraded quality of weather services. Such assessments need to include a much
more in-depth technical analysis for these areas and locations where there are radar
coverage concerns than has been the case to date.
.
.
following:
RECOMMENDATIONS
Based on its analyses and on the conclusions derived from them, the pane! recommends the
1.
3.
4.
5.
_
Where the pane! has identified specific geographic areas where degradation of radar-
detection coverage may occur, the National Weather Service should examine each
potentially vulnerable area to determine whether such degradation would result in
degradation of associated weather services.
2. The procedures and criteria for decommissioning old radars are specified in existing
National Weather Service documentation; these should be rigorously applied, especially
in vulnerable areas. Additional criteria/procedures proposed by the pane! (described in
Chapter 4, under "Assessment Criteria and Procedures") should be followed in assessing
the degradation of service and determining corrective actions. These assessment
processes should be incorporated into official National Weather Service guidelines and
procedures and used in conjunction with the requirements in P.~. 102-567.
The National Oceanic and Atmospheric Administration should take immediate steps to
ensure that the 15 NEXRADs under the control of the Department of Defense, which
are needed to avoid degraded coverage, function as fully committed elements of the
national weather radar network, operating with the same standards, quality, and avail
ability as the National Weather Service-operated NEXRADs.
The National Weather Service should ensure that maintenance for, operation of, and
communication with NEXRADs that are not located near a Weather Forecast Office are
in full accordance with network standards. In addition, responsibilities for weather
services to the area covered by these NEXRADs should be unambiguously assigned to
a specific Weather Forecast Office to ensure high-quality weather services for that area.
Staffing and communications capability should be commensurate with each Weather
Forecast Off~ce's service area's responsibilities.
The storm-detection and warning performance of the composite national weather system,
as a function of range from a NEXRAD, should receive an in-depth independent
technical assessment that considers region-specific issues. This assessment should evalu
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Conclusions and Recommendations
53
6.
ate the warnings and reported events on a per-unit-area basis, as well as the traditional
National Weather Service verification statistics. The assessment should include further
testing in the Modernization and Associated Restructuring Demonstration in addition to
tests at diverse geographic locations.
The adequacy of NEXRAD coverage with respect to the "no degradation of service"
requirement should be reexamined in an independent study after all National Weather
Service NEXRADs are commissioned.
Representative terms from entire chapter:
weather services
