during the early 90s, the nws installed a network of powerful doppler weather radars, aka nexrad

The Status of the Weather Radar Acquisition for the Washington Coast

Cliff Mass Department of Atmospheric Sciences

University of Washington

During the early 90s,

the NWS installed a network of powerful Doppler Weather

radars, akaNEXRADWSR88D

NWS Radar Sites

But there was a major problem in the Pacific Northwest...

The two NW radars (Camano Island, WA and Portland, OR) were placed east of the Olympics and Coastal Mountains and thus the radar beams were generally blocked before they reached the coast.

Radar coverage for the lowest beam (.5 degree elevation angle) for the current network. Red areas indicate no coverage below 8000 m (25,000 ft). Radar coverage calculations byKen Westrick

The right diagram indicates the effective coverage of theWeather Service radars for all elevation angles at 10,000 ft above mean sea level, with hatching indicatingsubstantial blockage.

Northwest Coastal Radar Problem• The Pacific Northwest has the worst coastal

radar coverage of any region of the lower 48-states.

• There is virtually no radar coverage for the lower atmosphere over the coastal zone and the near-shore waters.

• Such poor coverage exists for a region of often intense storms AND a great deal of military, shipping, fishing and other marine traffic.

The Obvious Answer:Secure Additional Radars for the

Coast!

Now With Two New Radars

Coverage for Lowest Elevation Angle (.5 degrees)

We Got A Taste of the Value of a Coastal Weather Radar During

the IMPROVE Field Program in January-February 2001

Westport S-Pol Radar (January-February 2001)

Reflectivity from S-Pol radar at Westport 0031 UTC 2 Feb 2001 at 0.5 degree elevation

dBZ

Years in the Wilderness

• For roughly ten years a number of local meteorologists called for the acquisition of additional coastal weather radars, with one positioned on the central Washington Coast.

• This went nowhere until three things happened in 2007 and 2008.

The First: The Big Storm of December 2-4, 2007

Dec. 2-3, 200720 inches in two days over coastal

terrain of SW Washington

The results: massive

landslides and river flooding

Pictures courtesy of WSDOT

Hurricane-Force Gusts for Nearly 24h Along the Coast

Second: Growing Support for the Coastal Radar

• Northwest Weather Modeling Consortium• Friends of Gray’s Harbor• Crab Industry, Fishers, and Oystermen• Audubon Society• Port Blakely Tree Farms• Cities and Counties• Puget Sound Clean Air Agency• Editorials in major local papers

The Third: Senator Maria Cantwell

Senator Cantwell Not Only Appreciated the Importance of a Coastal Radar But Secured the

Funding

• 2 million dollars of stimulus funding• 7 million dollars in the 2009-2010 budget

Current Status• The National Weather Service is now committed to

installing and operating the radar.• It will be a powerful S-band (10-cm wavelength)

Doppler radar like the current NEXRAD units.• It will be a be a dual-polarized radar, which the

current radars are not.• (Dual-pol radars allow determination of precipitation

type and better estimates of intensity.)

Where will the radar be located?• Using stimulus funds, the National Weather

Service hired SRI International to do a site survey.• The University of Washington (Socorro Medina)

did an independent analysis and provided it to SRI.

• A draft siting report is out with possible locations, with one recommended. It will be released in March.

I am limited on what I can reveal, but…

Some hints!

• The sites are in Gray’s Harbor County, within 10 miles of the coast.

Some Locations Examined by the UW

Beam blockage at 0.0° elevation angle for different radar locations(using ~1 km resolution terrain and a 30 m tower)

LangleyHill –Site 12

ScarHill –

Site 19

SaddleHill –

Site 23

N. CentralPark -Site 6

Beam blockage at 0.5° elevation angle for different radar locations(using ~1 km resolution terrain and a 30 m tower)

LangleyHill –Site 12

ScarHill –

Site 19

SaddleHill –

Site 23

N. CentralPark -Site 6

Beam blockage at 1.0° elevation angle for different radar locations(using ~1 km resolution terrain and a 30 m tower)

LangleyHill –Site 12

ScarHill –

Site 19

SaddleHill –

Site 23

N. CentralPark -Site 6

Beam blockage at 1.5° elevation angle for different radar locations(using ~1 km resolution terrain and a 30 m tower)

LangleyHill –Site 12

ScarHill –

Site 19

SaddleHill –

Site 23

N. CentralPark -Site 6

Beam blockage at 2.0° elevation angle for different radar locations(using ~1 km resolution terrain and a 30 m tower)

LangleyHill –Site 12

ScarHill –

Site 19

SaddleHill –

Site 23

N. CentralPark -Site 6

Radar Siting

• There will be a one-month public comment period, with public notices, after the SRI report is released sometime this month.

• With the community’s input, the land can be leased or purchased, and site preparation can begin.

Next Step: Acquisition of the radar

• First, the radar specifications must be determined.

• Then, bids must be acquired, followed by purchase.

• There is some issues right now about the specs– zero degree scans and RHIs.

The Issues

• Zero degree scans can allow you to see considerably further and get more information at low levels.

• Range-Height Indicator (RHI) scans allow one to get details on the height of the freezing level, mountain precipitation, and offshore structures.

Distance-Height Diagram for Zero Degree and Standard 88-D Elevation Angles

Note the absence of low-level coverage of the standard .5 degree elevation angle at greater distances (more than 100 km out). The zero degree angle provides a major improvement in coverage at long ranges

in the critical lower atmosphere.

No coverage at .5 degree

Examples of RHIsExample from IMPROVE 1: SPOL at Westport looking to the W

Example from IMPROVE 1: SPOL at Westport looking to the E

Zero Degree and RHI

• Local NWS offices, NWS Western region, and UW want it, Oklahoma radar folks are hesitant.

What do Oklahoma folks know about marine and mountain weather?

Timetable

• Current NWS plans is for the radar to be installed in late 2012 and operational on January 1, 2013

• Looking at the specific timetable, this seems highly conservative.

• Hopefully, the unit can be operational far earlier.

The End