1. High resolution radar data and products over the Continental United States
National Severe Storms Laboratory
Norman OK, USA

2. Evolution of WDSS 1993-1998 1995-2000 2003 2005 Single-radar
SCIT, MDA, TDA
Now part of RPG
Single-radar with multi-sensor input
NSE inputs
Scheduled for ORPG-8
2003
Multi-radar multi-sensor over regional domain
(1000km x 1000 km)
Gridded products
Shipped to select WFOs
Used in Storm Pred. Center
Product gen. for AWIPS?
2005
Multi-radar multi-sensor over CONUS
CONUS 1km grids
Available on the Internet
Used in SPC
18 September 2018

3. What products? How often?
Gridded hail products
Reflectivity at constant temperature levels and layer averages
Low-level and mid-level shear and rotation tracks
Short-term forecast fields
Lightning Density
More …
Spatial Resolution:
0.01 deg x 0.01 deg [x 1km] resolution
Approximately 1km x 1km throughout Continental United States.
1km in height
Temporal resolution:
2D reflectivity mosaics every 2 minutes
3D and derived products every 5 minutes
18 September 2018

4. How does it work? The process for creating 2D composites:
Ingest Level-II radar data tilt by tilt
QC reflectivity data (Lak06, JAM, review)
Create virtual volume composites
Merge composites from all the CONUS radars (Lak06, WF, accepted)
2nd level of QC -- using satellite and surface temperature data.
18 September 2018

5. Virtual volume composite
In a traditional composite,
Process volume-by-volume.
Take maximum of all tilts.
Need to wait for end of volume.
In a virtual volume composite:
Process tilt-by-tilt.
Keep a running volume.
Replace older data each time.
Take maximum of most current tilts.
No need to wait for end of volume scan.
A virtual volume provides more timely data.
at19.5
at0.5
18 September 2018

6. Why do QC? On a single-radar product, users may:
want to see clear-air returns.
tolerate more clutter
tolerate test patterns, etc.
On a multi-radar product, clutter and clear-air returns are distracting.
18 September 2018

7. Impact of QC
raw
With QC’ed composites
Left: What we would get if directly combined raw (virtual volume) reflectivity composite data
Clear-air return, sun strobes, test patterns
Right: combining QCed virtual volume reflectivity composite
The QC is performed radar-by-radar
Takes into account terrain, texture and vertical structure.
18 September 2018

8. Second level of QC The radar QC is conservative
Doesn’t always remove non-precipitation echo
Especially if it is biological i.e. moving.
A second level of QC looks at satellite and surface temperature and retains echo where there is likely to be clouds.
Bad data (bloom)
No clouds
18 September 2018

9. What do we do with the composite?
The 2D radar mosaic is created every 2 minutes at 1km resolution.
Converted to Grib2 and sent to the SPC.
Put on the Internet:
Snapshots with map background
Converted to Geotiff
Loadable with Google Earth or any GIS software.
Google Earth does real-time loading
Talk in IIPS on Tuesday
Not 24x7
The software is licensed by some private companies
They run it on their own machines.
They take care of 24x7 reliability.
18 September 2018

10. 2D vs 3D The 2D composite is cheap to create Need to compute in 3D
5 dual-Xeon machines with 6 GB RAM
But always provides an underestimate of true values.
Need to compute in 3D
Height of dBZ value important!
Can incorporate NSE information by height
A lot more products!
The 3D products need:
5 dual-Xeon with 6 GB RAM
2 dual-Xeon with 16 GB RAM
64-bit architecture
composite from 2D: dBZ
composite from 3D: dBZ
18 September 2018

11. The 3D flow Not just reflectivity.
Compute shear (Smith05) and low-level shear.
Process lightning
18 September 2018

12. 3D processing Combine QC’ed reflectivity in 3D Combine AzShear in 3D
Compute hail diagnosis and layer averages.
Compute storm motion from composite.
Use it to advect storms for short-term forecast.
18 September 2018

13. Example products
Extracted from the real-time generation on Jan. 11, 2006
The day I created this presentation!
We haven’t run the CONUS system in Spring yet, so the severe weather products may be underwhelming.
18 September 2018

14. Reflectivity products
Composite from 2D
Composite from 3D
Height of Max Ref
Which radars?
18 September 2018

15. Azimuthal shear products
30 minute rotation tracks
Azimuthal shear 0-3km MSL
18 September 2018

16. Severe weather diagnosis
Also:
Probability of Severe Hail
Maximum Expected Hail Size
VIL_Density
VIL_of_the_day
Other echo top dBZ levels
Reflectivity at temp. levels
VIL
Convection
Echo top (18 dBZ)
18 September 2018

17. Short-term forecast Reflectivity at T=0 Clusters
Reflectivity at T=30 (forecast)
Southward motion
18 September 2018

18. Precipitation estimates
Instantaneous precip rate
Ref closest to ground
Just the 88D algorithm on CONUS
Uses hybrid scan reflectivity
Convective/stratiform segregration based on presence of hail
88D Z/R relationships.
Not multi-sensor
QPESUMS-II under development at NSSL.
2hr precip accum
18 September 2018

19. What do we do with these products?
The 3D products are created every 5 minutes
1km resolution (0.01deg x 0.01deg x 1km)
Converted to Grib2 and sent to the SPC.
Put on the Internet (not all of them):
Snapshots with map background
Converted to Geotiff
Loadable with Google Earth or any GIS software.
Google Earth does real-time loading
Talk in IIPS on Tuesday
Looking for the NWS to pick this up!
18 September 2018