P9.112 A Storm-Scale Analysis of the 29 May 2013 Tornado Event

across East-Central New York

Thomas A. Wasula, Brian J. Frugis, Ian R. Lee & Luigi F. Meccariello

NOAA/National Weather Service, Albany, NY

Synoptic Overview Tornado Climatology

1980-2014Storm-Scale Analysis

2 29 May 2013

5

2a

Summary• 3 tornadoes in the ALY forecast area (one long path EF2 tornado of 13 miles in

Montgomery and Schenectady Counties)

• Moderate CAPE – High Shear pre-convective environment for supercells & bows

• Along strong low-level theta-e gradient, severe convection migrated along in the

Mohawk River Valley, Capital Region into the Berkshires of Massachusetts

• Mini-squall line merged with a hook echo, and a bow echo (or wall of wind) formed

• Applied collaborative research from CSTAR for tornado warning decision (Vr – R

Shear Study)

• First Dual Pol EF2 TDS in Eastern Region (debris ball up to 6-8 kft AGL)

• 2100 UTC 29 May 2013 HRRR captured MCS and bow echo well

• Maximum sustained winds from the damage survey was 125 mph (EF2) with the

Montgomery-Schenectady County Tornado

1800 UTC & 2100 UTC WPC SFC Analysis

1980-2012 Tornado Distribution by County Warning Area

Note: Numbers can be skewed since several reports from one

tornado case are entered in separately in StormData

Motivation

- EF2 Tornadoes in the Albany Forecast

Area are rare (80% are EF0/EF1)

- CSTAR IV - V Goals (2010 – Present)

(1) To examine severe weather cases

with application of the new (April

2012) dual polarization radar data

(differential reflectivity, correlation

coefficient, and specific differential

phase)

(2) Expand ALY Tornado Vr-R Shear

Climatology from 1998-2000 in

COMET partners project

CSTAR Grant #: NA01NWS4680002

Outline- Tornado Climatology

- Brief Synoptic Overview

- Mesoscale Analysis: SPC Rapid

Refresh

- Review of Correlation Coefficient with

Tornadic Debris Signatures

- Storm-scale Analysis with new V-R

Shear Nomogram

May 29, 2013 Tornadoes

Number of Tornadoes by time in EST

Note: Most occur between 12:00-20:00 EST

EF1/EF2 tornado in Montgomery

and Schenectady Counties & EF1

in Saratoga County

EF1 Tornado in mountainous Schoharie Co.

EF1 damage in Scotch Bush,

Montgomery County, NY

EF2 damage in Mariaville, Schenectady

County, NY

NWS at Albany Forecast Area

1200 UTC 500 hPa Heights, Winds & Temps

1200 UTC 250 hPa Heights, Isotachs & Temps

V-R Shear Nomogram(CSTAR IV Research)

Mesoscale Analysis

Nomogram: Gate to Gate Shear vs. Mesocyclone

Rotational Velocity for 41 ALY Cases (2003-13)

Vm= 108 kts and S = 0.526 S-1 for Schenectady

County EF2 Tornado

Area of focus is the Mohawk River Valley, Capital Region, Northern

Catskills, Taconics, and Berkshires

Tornadic Debris Signature (TDS) Review

Image Courtesy of WDTB

Base REF

(High Z)

Strong Relative

Velocity (Strong

rotational Signature)

Differential

Reflectivity

(ZDR~0dB)

Correlation

Coefficient

(usually<0.80)

0000 UTC 30 May 2013 ALY Sounding

• TDS indicates debris being lofted such as shingles, siding,

insulation, leaves and other debris

• The EF2 tornado on 29 May 2013 had an impressive TDS

which is shown in the Storm-Scale Analysis

RR SBCAPE (J kg-1) & SBCIN (J kg-1) RR Effective Bulk Shear (kts)

2300 UTC 29 May 2013

www.spc.noaa.gov

500-1500 J kg-1

40-50 kts

www.spc.noaa.gov

SFC-1 km Shear Vectors (kts) SFC Theta-e (K) & Advection

0

5

10

15

20

25

30

19

80

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81

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82

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83

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84

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86

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87

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89

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90

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91

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96

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97

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99

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20

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20

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20

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20

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20

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20

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20

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20

14

# of Tornadoes per Year for NYS

0

2

4

6

8

10

12

14

Year

19

81

19

82

19

83

19

84

19

85

19

86

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87

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88

19

89

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90

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91

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92

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94

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95

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96

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97

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98

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99

20

00

20

01

20

02

20

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20

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20

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20

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20

07

20

08

20

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20

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20

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20

13

20

14

# of Tornadoes Per Year in CWA ALY

0

10

20

30

40

50

60

70

80

90

100

# of Tornadoes per Month in NYS

0

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10

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20

25

30

35

# of Tornadoes Per Month in CWA ALY

0

20

40

60

80

100

120

140

160

EF0/F0 EF1/F1 EF2/F2 EF3/F3 EF4/F4 EF5/F5

# of Tornadoes By Intensity in NYS

0

5

10

15

20

25

30

35

40

45

50

EF0/F0 EF1/F1 EF2/F2 EF3/F3 EF4/F4 EF5/F5

# of Tornadoes By Intensity in CWA ALY

0

2

4

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8

10

12

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16

18

# of Tornadoes Per Hour in CWA ALY

Mariaville Lake EF2 damage

(Photos from ALY Damage Survey Team)

A

B

0.5° Base REF & SRM: Developing tornado/hook echo in reflectivity data and mesocyclonic velocity couplet with TVS (Vr = 39.6 kts over a distance 0.5 nm with

S = 0.0406 s-1). Line A – B is part of the cross-section through the hook echo . The BWER is shown in the RCS and the SRM cross-section shows the mesocyclone well.

2242 UTC 29 May 2013

Vm= 98.8 kts

2247 UTC 29 May 2013 2252 UTC 29 May 2013

Tornado Warning issued at 2245 UTC. Classic Hook Echo with bow echo

approaching. Nrot = 1.36 well above mean and median values (0.90; 0.81) for

tornadoes in local study . GR2analyst Guide: Nrot > 1.0 (significant) > 2.5 (extreme)

0.5° KENX SRM shows classic low-level mesocyclone with a TVS. Vr = 48 kts with

S=0.0526s-1 at a distance of 15 nm from the KENX RDA, and a beam height of 1.5 kft

AGL. The x-section shows a classic meso with a tornadic circulation with Vm=108 kts.

Descending RIJ

Vr = 48 kts

Vm = 108 kts

2257 UTC 29 May 2013

Nrot = 1.36

KENX 0.5˚Base REF and SRM: The orange polygon is the TOR Warning issued at

2245 UTC. The line A-B is the cross-section for the ZDR and CC images to the

right. The SRM data continued to show an impressive tornado on the ground with a

Vr = 38 kts at a distance of 14 nm from the RDA and S = 0.0406 s-1

The 4 lowest tilts from the radar are shown with depressed Correlation Coefficient

(CC) values to 6.2 kft AGL in the 3.4° elevation slice with a corresponding CC value =

0.685. The TDS shows up well through x-sections of the storm with the low-level ZDR

at 0 to -0.3 dB, and the CC values below 0.8 up to around 8 kft AGL.

0.5°

3.4°2.4°

1.5°

A

B

2257 UTC 2316 UTC

2 tornadoes on the

ground at the same

time in the ALY CWA

KENX radar shows

MCS evolved into a

line echo wave pattern

with a book end vortex

2100 UTC HRRR

captured bow

echo moving

across eastern

NY fro 0000 UTC