High resolution radar data and products over the Continental United States

Valliappa.Lakshmanan@noaa.govNational Severe Storms Laboratory

Norman OK, USAhttp://www.wdssii.org/

April 19, 2023 lakshman@ou.edu 2

Evolution of WDSS

1993-1998

Single-radar SCIT, MDA, TDA

Now part of RPG

1995-2000

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

April 19, 2023 lakshman@ou.edu 3

What products? How often?

Products: 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

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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.

April 19, 2023 lakshman@ou.edu 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

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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.

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Impact of QC

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.

With QC’ed compositesraw

April 19, 2023 lakshman@ou.edu 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

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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

http://wdssii.nssl.noaa.gov Not 24x7

The software is licensed by some private companies They run it on their own machines. They take care of 24x7 reliability.

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2D vs 3D

The 2D composite is cheap to create

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: 45 dBZ composite from 3D: 50 dBZ

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The 3D flow

Not just reflectivity.

Compute shear (Smith05) and low-level shear.

Process lightning

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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.

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Example products

Extracted from the real-time generation on Jan. 11, 2006The day I created this presentation!We haven’t run the CONUS system in

Spring yet, so the severe weather products may be underwhelming.

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Reflectivity products

Composite from 2D Composite from 3D

Height of Max Ref Which radars?

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Azimuthal shear products

Azimuthal shear 0-3km MSL 30 minute rotation tracks

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Severe weather diagnosis

Reflectivity at temp. levels

Echo top (18 dBZ)

VIL

Convection

Also:

Probability of Severe Hail

Maximum Expected Hail Size

VIL_Density

VIL_of_the_day

Other echo top dBZ levels

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Short-term forecast

Reflectivity at T=0 Clusters

Reflectivity at T=30 (forecast) Southward motion

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Precipitation estimates

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.

Ref closest to ground

2hr precip accum

Instantaneous precip rate

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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

http://wdssii.nssl.noaa.gov

Looking for the NWS to pick this up!