The Functionality of a New Radar Software Package: GRLevel2 Analyst Edition

Ted KellerSenior Meteorologist

KOLR/KSFX-TVSpringfield, Missouri

I’m from Springfield, MissouriMuch of our “skyline” is due to this guy

Missouri State University

Perhaps many of you may be more familiar with Branson, Missouri

This Presentation

• Why I decided to give this talk• Review of AE software capabilities• Using AE in real-time• Considerations for using AE on air• Establishment of a radar resource or

dialog program (via a web site?)

My Radar Experience

• WSR-57C (first hook echo)• Kavorus RADAC• WSI 1010N (level 3, NIDS)• Baron FasTrac Millennium

The NIDS Years

• Useful for quick diagnostic; storm attributes

• NIDS images poor quality; hard to “see” many features

• Storm attributes delayed from images• Storm attributes not perfect• The whole NIDS set up discouraged any

detailed analysis

Why This Talk?

• I’m excited! AE has opened a whole new world of radar analysis

• I come from background with no live radar experience

• I’m certainly no radar expert but I believe I represent many of you with similar backgrounds and experiences

• AE has improved severe weather coverage!

GR2 Analyst Edition (AE)

• AE reads Level II data from the NWS 88D radar (real-time or archived)

• It was designed as a volume-rendering tool allowing users to view radar data in three dimensions plus time (4D)

• AE is also a very slick 2D radar viewer with lots of useful features

GR2 Analyst Edition (AE)

• AE uses hail detection algorithms patterned after those developed by the National Severe Storms Lab (NSSL)

• The environmental data used by the algorithms can be entered by hand or automatically input using RUC objective analysis data

• AE generates two hail parameters: – POSH, Probability of Significant Hail– MEHS, Maximum Estimated Hail Size

GR2 Analyst Edition (AE)

• The user can input storm motion vectors used in the calculation of storm relative velocity (SRV)

• AE calculates vertically integrated liquid (VIL) density (VILD)

• VILD takes the entire storm height into consideration and uses all reflectivity (including hail) in its calculation

AE 2D Fields• Base reflectivity (BR)• Base Velocity (BV)• Storm Relative Velocity (SRV)• Spectrum Width (SW)• Echo Top (ET)• Vertically Integrated Liquid (VIL)• Vertically Integrated Liquid Density (VILD)• Probability of Significant Hail (POSH)• Maximum Expected Hail Size (MEHS)

2D Features

• Elevation scan selection• Derived products• Screen markers• Storm motion vector• 2D “slice”• Placefiles and shapefiles• Exporting images

Place and Shape Files

Note: the radar data is level 3 in this example

The Volume Rendering Engine

• Allows storms to be viewed in three dimensions

• Two modes:– Lit Surface, uses

an alpha table to produce semi-transparent dBZ surfaces

– Isosurface, users can step through dBZ levels

• Four viewable fields:– Base reflectivity– Base velocity– Storm relative velocity– Spectrum width

Lit Surface Example

• Solid 50 dBZ surface (red)• Semi-transparent 45 dBZ “shell” (gold)

What is this?

Isosurface Example

An externally produced animation showingsuccessive layers of dBZ being stripped away

3D Alpha Table• Users can select which dBZ levels are visible

and their degree of transparency by manipulating an alpha color table

Solid above 50 dBZ

“shell” at about 45 dBZ

Strong Tornado

Where Are the Attributes?

• At present, there are none in AE• The issues are what to offer and how to

display it, not whether it should be done• Velocity data: noisy data subject to

aliasing issues

Current Cut-In Policy

• Definite:– At least one live cut-in for all tornado warnings

• Subjective:– “Preemptive Strike”: a cut-in for a storm likely

to become tornadic – Ongoing coverage of tornado warnings that

fall short of “wall-to-wall”– Most severe thunderstorm warnings are not

covered with a cut-in

Preemptive/Ongoing Tornado Coverage

• Just using AE in 2D with Level II data is a huge improvement!!

• In 3D, features such as BWER’s are plain to see

• What about the “tornado finger”? (“fickle finger of fate”)

• AE definitely aids the decision making process

Noteworthy 3D Features

• Tornado tube• Hail cores• Bounded Weak Echo Regions (BWER’s)• Overhangs• Triple Backscatter• Overshooting Tops

An Example of a Three Body

Scatter Spike

(TBSS)

Non-Tornadic Storms

• Cut-in decision based on general storm intensity, weighed heavily by population density!

• Can AE provide enough detailed storm information to justify more cut-ins for non-tornadic events?

Finding Hail Cores in 4D

• AE makes it easier to visualize developing and descending hail cores using the volume rendering engine

• AE also has sophisticated hail probability and estimated hail size algorithms

Extreme Hail Cores

Hail Size - MEHS

Tennis Ball (2.5”) sized hail near Moody, MOAE estimated 2.76” 4 minutes before the reported time of the hail

Using AE On-Air

• It should first be stated that AE in its present form was not designed specifically for on-air use

• If future builds lean in this direction, there are only two considerations:– Would AE add meteorological value?– How does it look? Is it understandable?

Just the Facts

• I tend to lean toward the “Joe Friday” approach to live cut-ins meaning I believe the public is best served by clear graphics which state what, where and when

• On the other hand, this is TV and where would we be without a certain level of enthusiasm for new products and visualization techniques?

How Does it Look? Is it Understandable?

• AE has done a great job giving the user graphical options to make the product look fantastic!

• Will viewers understand what they are looking at? Perhaps.– Need accurate geographical reference points– Must be selective about what to show and

careful in your explanation• For stations already committed to 3D radar

views, AE is an improvement!

Would AE Add Meteorological Value?

• This is a tougher question• A few candidates:

– Timing of hail core descent– Tornadic signatures– Other undiscovered signatures

Future Investigations and Projects

• Database of hail size verification• New 3D structures or signatures?• New 3D velocity structures or signatures• Convincing management to invest in a

stand alone computer for proper on-air testing

• Establishing a radar resource web site

Helical Flow

• Example of twisted inbound/outbound couplet in 3D velocity data• New signatures here? I don’t know, I’ve never seen images like this before,

real-time or otherwise.

Level 2 Radar Data(not a comprehensive list!)

• Allison House (placefiles and data)• University of Iowa (non-commercial)• National Climate Data Center (archive

only)