a multiscale analysis of the 23 24 november 2004 southeast united states tornado outbreak
Download
Skip this Video
Download Presentation
A Multiscale Analysis of the 23-24 November 2004 Southeast United States Tornado Outbreak

Loading in 2 Seconds...

play fullscreen
1 / 42

A Multiscale Analysis of the 23-24 November 2004 Southeast United States Tornado Outbreak - PowerPoint PPT Presentation


  • 219 Views
  • Uploaded on

A Multiscale Analysis of the 23-24 November 2004 Southeast United States Tornado Outbreak. Alicia C. Wasula. Event Summary. 23/1700 UTC – 24/1300 UTC (nocturnal) 80 Tornadoes (17 F2 or greater) 3 Fatalities / 38 Injuries 45% tornadoes close to Gulf coast (south of 32 N). Motivation.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' A Multiscale Analysis of the 23-24 November 2004 Southeast United States Tornado Outbreak' - vida


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
a multiscale analysis of the 23 24 november 2004 southeast united states tornado outbreak

A Multiscale Analysis of the 23-24 November 2004 Southeast United States Tornado Outbreak

Alicia C. Wasula

event summary
Event Summary
  • 23/1700 UTC – 24/1300 UTC (nocturnal)
  • 80 Tornadoes (17 F2 or greater)
  • 3 Fatalities / 38 Injuries
  • 45% tornadoes close to Gulf coast (south of 32 N)
motivation
Motivation
  • Examine tornado episode from synoptic/mesoscale perspective to look for similarities/differences to composite Gulf coast tornado episode
slide5

CAPE vs. Shear for Cold Season Tornado Cases

0-2 km positive mean shear (x 10-3 s-1)

Convective Available Potential Energy (CAPE, J/kg)

Johns et al. 1993

slide6

CAPE vs. Shear for Warm Season Tornado Cases

0-2 km positive mean shear (x 10-3 s-1)

Convective Available Potential Energy (CAPE, J/kg)

Johns et al. 1993

slide7

Tornado Episode Composites

  • NCEP/NCAR 2.5x 2.5 Reanalysis dataset
  • All tornado episodes 1950-2001
  • ‘Episode-relative’ composite
  • Grouped by start time: 0000-0600, 0600-1200, 1200-1800, 1800-0000 UTC
  • Will show 0600-1200 UTC only
slide8

200 hPa height (m), isotachs (m s-1)

500 hPa hgt (m), avor. (x 10-5 s-1), vort. adv. (x 10-10 s-2)

slide9

1000 hPa height (m), 1000-500 thck. (dam), 700 hPa RH (%)

850 hPa hgt (m), temp (C), temp. adv. (x 10-5 C s-1)

slide10

850 hPa winds, e (K), 850-500 lapse rate (C)

700 hPa height (m), vertical motion (x 10-3 hPa s-1)

slide11

Summary: Composites

  • Strong signal in spite of large sample size:
    • ULJ entrance region at 200 hPa
    • Vigorous upstream trough at 500 hPa
    • Southwesterly LLJ at 850 hPa
    • Low-level e ridge
  • Surface composites show 1st tornado occurs:
    • At strongest T
    • On northern edge of moisture surge/southerly flow
    • Dew point anomalies > +8 C
slide15

SLP, 1000-500 THCK

500 hPa HGHT, AVOR

22 November 2004 0000 UTC

850 hPa HGHT, e, ISOTACHS

200 hPa HGHT, ISOTACHS

slide16

SLP, 1000-500 THCK

500 hPa HGHT, AVOR

22 November 2004 1200 UTC

850 hPa HGHT, e, ISOTACHS

200 hPa HGHT, ISOTACHS

slide17

SLP, 1000-500 THCK

500 hPa HGHT, AVOR

23 November 2004 0000 UTC

850 hPa HGHT, e, ISOTACHS

200 hPa HGHT, ISOTACHS

slide18

SLP, 1000-500 THCK

500 hPa HGHT, AVOR

23 November 2004 1200 UTC

850 hPa HGHT, e, ISOTACHS

200 hPa HGHT, ISOTACHS

slide19

SLP, 1000-500 THCK

500 hPa HGHT, AVOR

23 November 2004 1800 UTC

850 hPa HGHT, e, ISOTACHS

200 hPa HGHT, ISOTACHS

slide20

SLP, 1000-500 THCK

500 hPa HGHT, AVOR

24 November 2004 0000 UTC

850 hPa HGHT, e, ISOTACHS

200 hPa HGHT, ISOTACHS

slide21

SLP, 1000-500 THCK

500 hPa HGHT, AVOR

24 November 2004 0600 UTC

850 hPa HGHT, e, ISOTACHS

200 hPa HGHT, ISOTACHS

slide22

SLP, 1000-500 THCK

500 hPa HGHT, AVOR

24 November 2004 1200 UTC

850 hPa HGHT, e, ISOTACHS

200 hPa HGHT, ISOTACHS

slide23

CAPE 1847 J/kg

LI -7

0-6 km shear 38 kt

0-2 km shear 18 kt

SWEAT 400

JAN

23/2100 UTC

slide24

CAPE 1648 J/kg

LI -6

0-6 km shear 58 kt

0-2 km shear 16 kt

SWEAT 464

JAN

24/0000 UTC

slide25

CAPE 81 J/kg

LI 3

0-6 km shear 39 kt

0-2 km shear 22 kt

SWEAT 225

JAN

24/1200 UTC

slide26

CAPE 1794 J/kg

LI -6

0-6 km shear 54 kt

0-2 km shear 4 kt

SWEAT 279

LIX

24/0000 UTC

slide27

CAPE 2087 J/kg

LI -7

0-6 km shear 40 kt

0-2 km shear 12 kt

SWEAT 332

LIX

24/0600 UTC

slide28

CAPE 2986 J/kg

LI -10

0-6 km shear 32 kt

0-2 km shear 10 kt

SWEAT 513

LCH

23/1800 UTC

slide29

CAPE 2412 J/kg

LI -8

0-6 km shear 42 kt

0-2 km shear 9 kt

SWEAT 353

LCH

24/0000 UTC

slide30

Surface Analysis

24 November 2004

0000 UTC

slide33

Surface Analysis

24 November 2004

0600 UTC

slide37

Surface Analysis

24 November 2004

1200 UTC

conclusions
Conclusions
  • Tornado episode occurred:
    • In presence of strong synoptic-scale forcing for ascent (in warm sector)
    • LLJ strength increased overnight
    • Surface winds stayed south or southeast as surface low rapidly deepened to the north
    • Ample moisture and instability
conclusions1
Conclusions
  • Case study shows similarities to composite tornado episode
    • Strong shear/ULJ/LLJ
    • Deepening surface cyclone
    • Ample low-level moisture (esp. close to coast)
    • Surface winds ‘back’ with time ahead of surface low
  • Difference:
    • Mesoscale thermal gradient?
future work
Future Work
  • Question:
    • Did isallobaric effects help to keep flow in warm sector southerly/southeasterly and allow warm moist Gulf air to remain in place close to coast?
  • Why did LLJ increase in strength so rapidly?
    • Dynamically driven?
ad