LMA Assessment

Earth-Sun System DivisionNational Aeronautics and Space Administration

SPoRT SAC Nov 21-22, 2005

LMA AssessmentLMA Assessment

Dennis Buechler



Total Lightning Impacts Decision MakingTotal Lightning Impacts Decision Making• Has directly contributed to several

correct severe warning decisions at HUN and OHX.

• “…the LMA density map gives you a great overall view of where storms with intensifying updrafts are located. So it gives you a good map of where to concentrate attention.”

• “I believe the flash density rates were the primary factor in holding off on a warning.”

• Data archived by WFO

• Used in Warning Event Simulator for office training and research



• Web based LMA survey

developed for the WFOs

• Completed after an event in which the LMA data was used

• Survey also available at other WFOs (OHX, BMX, FWD)

Operational EvaluationsOperational Evaluations





LMA Benchmarking: ResultsLMA Benchmarking: ResultsNovember 2003 through November 2005November 2003 through November 2005

• 28 surveys filled out by HUN and OHX, none yet from BMX: 1 in 2003, 8 in 2004, 19 in 2005

• Severe Weather Scenarios • Large Hail• Tornadoes• Straight Line Winds• Cells Embedded in Lines• Supercells• Microburst-producing single pulse summer

TRW



LMA Benchmarking:LMA Benchmarking:OHX (Nashville) ResultsOHX (Nashville) Results

• 5 Surveys in 2005

• All indicated the data useful identifying cells with strongest updrafts- helped forecaster identify storms needing more attention

• LMA data used to verify other data- radar, eye-witness reports- used by forecasters in the warning decision

• 2 reports: warning lead time increased by 2-3 min

• Forecasters gaining confidence in using the data



LMA Benchmarking:LMA Benchmarking:HUN (Huntsville) ResultsHUN (Huntsville) Results

• 23 Surveys completed; 19 used in analysis• 1 case: problems with data• 3 cases: data not updating properly

• In 11 cases there was a positive impact - increased warning lead time of 1-9 min

• In remaining 8 cases, either no impact on warning decision or forecaster warned based on other available data

• In 2005, 9 of 12 surveys indicated improvement in lead time with LMA



LMA Benchmarking: Interim ResultsLMA Benchmarking: Interim ResultsRankings on Scale of 1-10Rankings on Scale of 1-10

Warning VariableAll Surveys

LMA+ impact=13/24

1.8-2.4 min

Severe Storms88 warnings, 16 surveys

2.2-2.9 min

Tornado50 Warnings, 8 surveys

1.1-1.4 min

Reflectivity Signatures

8.8 8.6 (1) 9.3 (2)

LMA Total Lightning

6.5 6.8 (2) 5.8 (5)

Near storm Environment

5.6 4.9 (3) 7.1 (3)

Strong Rotation 5.3 3.1 (7) 9.5 (1)

Eyewitness Report 4.8 3.8 (5) 6.9 (4)

NLDN CGs 4.0 3.8 (4) 4.4 (7)

Boundaries 3.8 3.4 (6) 4.5 (6)

TVS 2.3 1.4 (8) 4.1 (8)

Previous SVR WX 1.4 0.3 (9) 3.5 (9)



Greatest LMA impact in operationsGreatest LMA impact in operations

• Low to moderate severe events• At greater distances from the radar• Sub radar interval cell information• Detecting initial cloud to ground strikes

– Local case studies have shown lead times on the order of several (3-5) minutes

– Increased lead times for TAF updates and Airport Weather Warnings



Date Storm Type Event/Wx

5/6/03 Supercells W/T/FF

5/1/04 Squall Line W/T

8/20/04 Multicell W/T

10/18/04 Supercell T

12/10/04 Low top Hailstorm

H

2/21/05 Supercells H

7/2/05 Multicell Null

7/27/05 Multicell W

WES Cases for Training and ResearchWES Cases for Training and Research

Selected archived WES cases of different types of weather events (including a null case) for use in training and further research.

T – Tornado

W – Strong Winds

FF – Flash Flood

H – Large Hail

Null – No SVR



SummarySummary

• Surveys and forecaster feedback indicate that LMA data is useful:

• Improved situational awareness

• Improved forecast confidence

• Longer estimated warning lead times

• Surveys useful in reviewing events

• Surveys valuable for choosing case studies

• Encourages feedback

Documents

LMA Assessment