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SYNOPTIC METEOROLOGY LABORATORYSYNOPTIC METEOROLOGY LABORATORY

The Dallas and Fort WorthThe Dallas and Fort Worth Storms of May 5, 1995Storms of May 5, 1995

BY: Brent Crisp, Phil Grigsby, Thomas Jones, Devon Lucie,BY: Brent Crisp, Phil Grigsby, Thomas Jones, Devon Lucie, Tim Love, Andrew Reader, and Matt SattlerTim Love, Andrew Reader, and Matt Sattler

Presentation OutlinePresentation Outline

Synoptic OverviewSynoptic Overview- Satellite imagery- Satellite imagery- Upper air maps- Upper air maps- Soundings- Soundings- Composite Map- Composite Map

Radar SummaryRadar Summary- Reflectivity Products - Reflectivity Products and cross sectionsand cross sections- Velocity Products- Velocity Products and cross sectionsand cross sections- VIL Products- VIL Products- Hail Trends- Hail Trends- Total Precip. Products- Total Precip. Products

Mesoscale SummaryMesoscale Summary- Surface analysis- Surface analysis - 850 mb features- 850 mb features- Shear analysis- Shear analysis- Radar products- Radar products- Storm Wrap-up- Storm Wrap-up

Synoptic Overview of theSynoptic Overview of the

Dallas and Fort WorthDallas and Fort Worth

Storms of May 5, 1995Storms of May 5, 1995

Water Vapor Loop: May 5 1815Z to May 6 0615ZWater Vapor Loop: May 5 1815Z to May 6 0615Z

Dallas/Ft WorthDallas/Ft WorthAreaArea

Visible Satellite Loop: May 5 1815Z to May 5 2302ZVisible Satellite Loop: May 5 1815Z to May 5 2302Z

250 mb Heights and Observations250 mb Heights and Observations


• • Diffluent FlowDiffluent Flow Over the Southern Plains Over the Southern Plains



500 mb Shortwave500 mb Shortwave

500 mb Vorticity Contours500 mb Vorticity Contours

Weak Vort MaxWeak Vort Max12 s^-112 s^-1



Strong Flow from the Gulf, Bringing in Moistureat 850mb

850 mb Dew point Temperatures850 mb Dew point Temperatures

10°-16°C Dew Points10°-16°C Dew Pointsat 850mbat 850mb

5:00 p.m. Surface Analysis5:00 p.m. Surface Analysis

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Soundings from DFWSoundings from DFW

12Z May 512Z May 5 00Z May 600Z May 6

Lifted Indices at 00Z May 6Lifted Indices at 00Z May 6

Precipitable Water at 00Z May 6Precipitable Water at 00Z May 6

Composite MapComposite Map

• • 250 mb diffluent 250 mb diffluent flowflow



• • 500 mb shortwave500 mb shortwave




• • 850 mb dew point850 mb dew point temperatures 10° -temperatures 10° - 16° C16° C




• • 850 mb dew point850 mb dew point temperaturestemperatures

• • low-level jet low-level jet





• • low-level jetlow-level jet

• • stationary frontstationary front





• • low-level jetlow-level jet

• • stationary frontstationary front

• • precipitable waterprecipitable water values from 1.5-2.0values from 1.5-2.0 inchesinches

Radar Summary of theRadar Summary of the



Base Reflectivity Loop from 6:04 p.m. to 8:59 p.m.Base Reflectivity Loop from 6:04 p.m. to 8:59 p.m.

Dallas Co.Dallas Co.Tarrant Co.Tarrant Co.Parker Co.Parker Co.

Base Velocity Loop from 6:04 p.m. to 8:59 p.m.Base Velocity Loop from 6:04 p.m. to 8:59 p.m.

• • 6:00 p.m DFW RADAR6:00 p.m DFW RADAR

• • Supercell located in SW Supercell located in SW Parker CountyParker County

• • Squall line extends fromSquall line extends from Young to Eastern CountyYoung to Eastern County

• • Reflectivity max at Reflectivity max at 60 dBz’s60 dBz’s

Base Reflectivity Cross SectionBase Reflectivity Cross Section

• • 6:00 p.m. DFW6:00 p.m. DFW radarradar

• • South to North South to North cross sectioncross section

• • Bounded Weak Bounded Weak Echo RegionEcho Region

• • Hail CoreHail Core


6:00 p.m. VIL Product from DFW6:00 p.m. VIL Product from DFW

• • Max VIL Max VIL 70-75 Kg/m^2 70-75 Kg/m^2

Location of Location of SupercellSupercell

• • 6:45 p.m. DFW radar6:45 p.m. DFW radar

• • Supercell located in SE Supercell located in SE Parker County about to Parker County about to enter FTW metroenter FTW metro

• • Squall line beginning toSquall line beginning to bow west of the bow west of the supercellsupercell

• • Max Reflectivity ofMax Reflectivity of 75 dBz’s75 dBz’s



• • South to NorthSouth to North cross sectioncross section

• • More pronouncedMore pronounced Bounded Weak Bounded Weak Echo RegionEcho Region

• • Hail CoreHail Core





• • Base Velocity Base Velocity productproduct

• • Strongest mesoStrongest meso WNW of radar siteWNW of radar site

strong mesostrong meso

Base Velocity Cross SectionBase Velocity Cross Section


• • West to EastWest to East cross sectioncross section

• • Meso evidentMeso evident within the Super-within the Super- cellcell

• • Isentropic liftIsentropic lift

• • Hail and severe hailHail and severe hail probabilities at 100 %probabilities at 100 %

• • Max hail size constant atMax hail size constant at 3+ inches 3+ inches • • Slightly decreasing VIL Slightly decreasing VIL valuesvalues

6:00 p.m. - 6:45 p.m. Hail Trends6:00 p.m. - 6:45 p.m. Hail Trends


• • Supercell located inSupercell located in Tarrant CountyTarrant County

• • Time of largest hail Time of largest hail fallingfalling

• • Supercell is caught bySupercell is caught by the squall linethe squall line

• • Max Reflectivity ofMax Reflectivity of 67 dBz’s67 dBz’s




• • Hail Core lesseningHail Core lessening

• • Lower dBz’s aloftLower dBz’s aloft




6:30 p.m. - 7:30 p.m. Hail Trends6:30 p.m. - 7:30 p.m. Hail Trends

• • Hail and severe hailHail and severe hail probabilities rapidly probabilities rapidly decrease after 7:20 p.m.decrease after 7:20 p.m.

• • Max hail size from 3+ Max hail size from 3+ inches to less than an inch.inches to less than an inch.

• • Decreasing VIL valuesDecreasing VIL values


• • Heavy precip threatHeavy precip threat beginningbeginning

• • Supercell is consumedSupercell is consumed by the squall lineby the squall line

• • Large area of reflectivity Large area of reflectivity greater than 50 dBzgreater than 50 dBz


• • West to EastWest to East cross sectioncross section

• • Strong upliftingStrong uplifting within the squall-within the squall- line.line.

Base Velocity Cross SectionBase Velocity Cross Section

One Hour Precip from 8:00 to 9:00 p.m.One Hour Precip from 8:00 to 9:00 p.m.

Approx. 3 inchesApprox. 3 inchesof rain in one hourof rain in one hour

One Hour Precip Loop from 8:04 to 8:50 p.m.One Hour Precip Loop from 8:04 to 8:50 p.m.




• • Very low dBz’s aloftVery low dBz’s aloft


• • 9:00 p.m. total precip9:00 p.m. total precip imageimage

• • Areas received overAreas received over 3.5 inches of rain3.5 inches of rain

3.5 + inches 3.5 + inches of rainof rain

Mesoscale Analysis of theMesoscale Analysis of the



5:00 p.m. Surface Analysis5:00 p.m. Surface Analysis

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Inverted TroughInverted Trough

00Z May 6, 850 mb Moisture Transport00Z May 6, 850 mb Moisture Transport

• • 850 mb moisture850 mb moisture

• • Low-level jetLow-level jet

• • MesoHigh over LAMesoHigh over LA

850 mb Theta-E Chart850 mb Theta-E Chart

• • Theta-E bulgeTheta-E bulge

• • Inverted TroughInverted Trough

Base Reflectivity Loop from 6:04 p.m. to 8:59 p.m.Base Reflectivity Loop from 6:04 p.m. to 8:59 p.m.

1000 mb (green) - 700 mb (blue) shear1000 mb (green) - 700 mb (blue) shear2100Z May 52100Z May 5

• • 7:30 p.m radar image 7:30 p.m radar image

• • Time of largest hailTime of largest hail fallingfalling

• • Strong bow in squall lineStrong bow in squall line approaching supercellapproaching supercell

Vertical Wind Profiler, 7:00 - 8:00p.m.Vertical Wind Profiler, 7:00 - 8:00p.m.

Inflow NotchInflow Notch Heavy Heavy RainsRains

9:10 p.m. Reflectivity Image9:10 p.m. Reflectivity Image

STORM DAMAGE SUMMARYSTORM DAMAGE SUMMARY(FOUR PLAYERS CAUSE MAYHEM)(FOUR PLAYERS CAUSE MAYHEM)

• HAIL UP TO 4” IN DIAMETERHAIL UP TO 4” IN DIAMETER

• WIND REPORTS TO 75 MPHWIND REPORTS TO 75 MPH

• HEAVY RAINFALL RATES CAUSE HEAVY RAINFALL RATES CAUSE DEADLY FLASH FLOODINGDEADLY FLASH FLOODING

• LIGHTNING STRIKESLIGHTNING STRIKES

OFFICIAL HAIL DAMAGEOFFICIAL HAIL DAMAGE

• 80+ REPORTS OF 1” OR SMALLER 80+ REPORTS OF 1” OR SMALLER HAILHAIL

• 8 REPORTS OF 2” - 3” HAIL8 REPORTS OF 2” - 3” HAIL

• 3 REPORTS OF 3 REPORTS OF 4” HAIL4” HAIL

• 90 INJURIES ASSOCIATED WITH HAIL90 INJURIES ASSOCIATED WITH HAIL

• DAMAGE TO BUILDINGS.DAMAGE TO BUILDINGS.

FLASH FLOODINGFLASH FLOODING

• LARGEST CONTRIBUTOR TO LARGEST CONTRIBUTOR TO FATALITIESFATALITIES

• 15 MINUTE RAINFALL AMOUNTS 15 MINUTE RAINFALL AMOUNTS VARYING FROM 1.58” TO 2.24” IN VARYING FROM 1.58” TO 2.24” IN DALLAS METRO AREADALLAS METRO AREA

• INSUFFICIENT DRAINAGE FOR INSUFFICIENT DRAINAGE FOR RAINFALL RATERAINFALL RATE

WIND DAMAGEWIND DAMAGE

• SEVERAL REPORTS IN EXCESS OF 70 SEVERAL REPORTS IN EXCESS OF 70 MPHMPH

• WALL OF LOCAL WAREHOUSE WALL OF LOCAL WAREHOUSE BLOWN INBLOWN IN

MAY 5 - 6 FATALITIESMAY 5 - 6 FATALITIES

• 20 DEATHS TOTAL20 DEATHS TOTAL

• 4 FATALITIES FROM VICTIMS DRIVING 4 FATALITIES FROM VICTIMS DRIVING INTO HIGH WATERINTO HIGH WATER

• 2 FATALITIES WHEN ROOF COLLAPSES2 FATALITIES WHEN ROOF COLLAPSES

• 1 VICTIM STRUCK BY LIGHTNING1 VICTIM STRUCK BY LIGHTNING

• 3 VICTIMS PULLED INTO DRAINAGE 3 VICTIMS PULLED INTO DRAINAGE SYSTEMSYSTEM

AN OUNCE OF PREVENTIONAN OUNCE OF PREVENTION

• 60 - 70 OF HAIL INJURIES OCCURRED 60 - 70 OF HAIL INJURIES OCCURRED AT MAYFESTAT MAYFEST

• MAYFEST OFFICIALS DID NOT MAYFEST OFFICIALS DID NOT CONTACT NWS FOR WEATHER CONTACT NWS FOR WEATHER REPORT PRIOR TO EVENTREPORT PRIOR TO EVENT

• ““WARNINGS WERE ISSUED NEARLY WARNINGS WERE ISSUED NEARLY 25 TO 30 MINUTES” PRIOR TO STORM 25 TO 30 MINUTES” PRIOR TO STORM HITTING MAYFESTHITTING MAYFEST

Questions?Questions?

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