Stormlab Radar Stormlab Radar SoftwareSoftware

The MUST have radar software for a successful weather The MUST have radar software for a successful weather operationoperation

How to operate Stormlab and InterwarnHow to operate Stormlab and Interwarn

How to interpret Stormlab output…examplesHow to interpret Stormlab output…examples

How to prevent needless activation of the tornado sirens, How to prevent needless activation of the tornado sirens, StormlabStormlab is your 24/7 pre-deployed spotter!is your 24/7 pre-deployed spotter!

© 2009 Fisher

>20NM

<15NM

>20NM

All Storms

Composite produces stormtable & detail picture

Data level

<15NM

Stormlab

Terminal Doppler Radar ORD & MDW

Server choice

For Storm Rel Velocity only…Use the Composite storm table for the storm motion to enter. Either use table value for particular storm if looks good, or average several storm motions to arrive at a value to enter. TOR warning also an option, look at code at bottom of warning.

Do this first before clicking on SRV.

Enter position/spotter data

2 ways to “sample” the warning polygon

Clicking on radar site opens window, shows current watches and

warningsLoop control

buttons

Naperville shows at 4X, road numbers at 8X.

Interwarn

Stormlab/Interwarn computer Stormlab/Interwarn computer configurationconfiguration

#1#1 #1 #2#1 #2

#1 #2 #3#1 #2 #3

ReflectivityReflectivity ** L 2L 2 L 2L 2

VelocityVelocity ** L 2L 2 L 2L 2

Storm Relative Storm Relative Velocity Velocity ** L 2L 2 L 2L 2

VAD WindsVAD Winds ** ** ** PrecipitationPrecipitation ** ** **Composite Composite

Reflectivity+TabReflectivity+Tablele

** * * **

InterwarnInterwarn ** ** **SPC MesoanalysisSPC Mesoanalysis ** ** **

1 PC 2 PC 3 PC

Doppler Weather Radar ConceptsDoppler Weather Radar Concepts

•Radar beam increases in altitude with distance from radar.

•Radar beam increases in size with distance from radar.

•Radar takes 4-5 minutes to complete full scan when in storm/precip mode.

•Reliable doppler wind data limited to about 60-70 nm.

•Radar velocity 100% when parallel, 0% when perpendicular to beam direction.

If R = 60 NM 120 NM 180 NM 240 NM

D = 1 NM 2 NM 3 NM 4 NM

D

D = Beam Width

Radar resolution with respect to beam width / range

.96 Degree Beam Resolution.96 Degree Beam Resolution

100% 100%

0%

0%

When the wind velocity is parallel to the radial, the full component of the wind is measured

When the radial is perpendicular to the the wind,

the radar displays zero velocity - This “zero zone” is

called the “Zero Isodop”.

What percentage of actual wind

will the radar detect?

00 = 100% - Parallel150 = 97%300 = 87%450 = 71%600 = 50%750 = 26%

900 = 0% - Perpendicular

The Zero Isodop “Problem”The Zero Isodop “Problem”

Range 0 120 nm(example)

Weak inbound, weak outbound

Rotation too small to be resolved

Stronger inbound than outbound

Strong inbound, strong outbound

Azimuth 3

Azimuth 2

Azimuth 1

Enlarged image along a radial. Individual “blocks”

represent one sample volume. This graphically

shows the radar resolution.

Rotational couplet identification can be affected by azimuth resolution.

As the diagram shows, the closer a rotation is to the radar the more likely it will be identified correctly. If the rotation is smaller than the 10 beam width (possible at long ranges) then the rotation will be diluted or

averaged by all the velocities in that sample volume. This may cause the couplet to go unidentified until it gets closer to the radar.

Azimuth Resolution ConsiderationsAzimuth Resolution Considerations

Line of tstms moving thru ne IL

Base velocity locates gust front

Lake breeze in precip mode, how it would look if a gustfront coming out of a tstm or shower.

Lake breeze on base velocity

Bowing squall line

Bowing line with Base velocity, inbound winds 50-64

kts

Bowing line on Composite. Note storm motions 45-60

kts

Bowing squall line over N IL

Composite view, note cell motion of 45 & 52 kts

Base velocity, > 55 kts inbound with stronger cells

VAD winds, note 50-60 kts noted 3-6,000 feet as line is within 20 nm of radar

Reflectivity

Book end vortex forms and Inflow jet intensifies

Derecho Aug 4, 2008

Base Velocity

Gustfront

Reflectivity

Storm Relative Motion

Tornadic circulation 2 EF1 tornadoes

Storm Relative Motion

Tornadic circulation EF2 tornado

IA tornado: Mesocyclone & hail symbols, along with pathcast.

IA tornado: Strong inflow and updraft area notch (9,000 ft)

IA tornado: Bounded Weak Echo Region

Extremely strong updraft (16,000 ft)

GA… Nothing special on .5 reflectivity

.5 SRM shows very strong rotation

Note red triangle (Tornado Vortex Signature) + Meso

value of 12

Height of beam above ground vs distance from radar.

Green 10nm

Yellow 15nm

Red 20nm

Joliet tornado 4/20/04 .5° and 3.4°

1800 ft

300 ft

Joliet tornado: .5° and 3.4°

300 ft

1800 ft

Example of level 2 Base Velocity detail. Microburst of 62+ knots which unroofed apartment complex in Carol Stream

April 2007.

1400 ft

One hour rainfall

3 Hour Rainfall

How to evaluate a storm reportHow to evaluate a storm report

Take no report at face value, always question the source of Take no report at face value, always question the source of the reportthe report

The more accurate, reliable, and timely the report, the better the NWS does with its warnings, and the better local communities do with managing their alert and siren systems. Make sure the report is not a recycled one from a few minutes ago.

Every false alert/warning/siren sounding just leads to public inaction on the next storm.

If a storm report is received, try to verify as best as possible:

The exact time and location If estimated or measured (how) If building damage…type of building (structure) and exact damage If tree damage….size of tree and/or branches…type of tree if known If reporting rotation…is it clearly visible and not just clouds moving around If tornado…is there clear ground contact and a connection to the cloud above

If it don’t spin, don’t turn If it don’t spin, don’t turn it in!it in!

Tornadic Supercell Tornadic Supercell “Ingredients”“Ingredients”

Instability (varies, usually CAPE > 1000 J/Kg)

Deep layer shear (0-6km) bulk shear > 35kt

Low level shear (0-1km) SRH > 150 m2/s2

or pre-existing boundary)

Relatively high RH values (in BL and aloft)Sfc Td depressions <12°FSfc Td depressions <12°F

Tornadogenesis: Three Tornadogenesis: Three ingredientsingredients

Development of a persistent, rotating updraft1

Ingestion of enhanced SRH (occasionally, large-scale SRH is sufficient) and development of strong low-level rotation

2

Development of a downdraft partially embedded in the rotation that aids in the transport of rotation to the ground, followed by focusing of that rotation through convergence if the downdraft reaches the ground with some very uncommon properties

3

Tornadogenesis in a Tornadogenesis in a NutshellNutshell

L

Forward Flank Downdraft

Inflow

RFD

June 7, 2008

L

Forward Flank Downdraft

Inflow

RFD

L

“Old” Tornado Becomes Rain-wrapped

LL

TDWR

WSR-88D

Left overold hook

“eye”

New hookdeveloping

Suggested Tornado Siren Suggested Tornado Siren guidelineguideline

Your community is in a NWS tornado Your community is in a NWS tornado warning polygon (extreme e fringe?)warning polygon (extreme e fringe?)

…….OR…..OR…. You have a reliable/verified report of You have a reliable/verified report of

a tornado approaching/in your a tornado approaching/in your community or a verified funnel cloud community or a verified funnel cloud (not cold air type) (not cold air type) andand

You have You have used Stormlabused Stormlab to verify to verify the report. (rotation at 0.5/1.5/2.5)the report. (rotation at 0.5/1.5/2.5)

Summary of How to Use Summary of How to Use StormlabStormlab

Use to verify incoming storm report: Use to verify incoming storm report: does it match radar?does it match radar? Sirens?Sirens?

Use to position or update spottersUse to position or update spotters

Use to time incoming weather: Use to time incoming weather: pathcastpathcast

Use to see what the radar is detecting: : hail, high winds, meso, hail, high winds, meso, TVSTVS

Use to monitor potential: Use to monitor potential: flash flooding, cell mergers, strengthflash flooding, cell mergers, strength

Use to know when threat has ended: Use to know when threat has ended: rain, windrain, wind

Use to see visual display of the: Use to see visual display of the: warning polygonwarning polygon

Use to monitor weather during festivals:Use to monitor weather during festivals: When to shut down? When to shut down?

Be sure to go to Be sure to go to SPCSPC meso page to have an idea what to expect meso page to have an idea what to expect

Use Use Interwarn to monitor: to monitor: warnings, statements, storm reports

Allan FisherAllan Fisher

ALLFISH3@SBCGLOBAL.NETALLFISH3@SBCGLOBAL.NET

630-355-2628630-355-2628