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March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul...
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![Page 1: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/1.jpg)
March 14, 2001 Bow Echo in Southeast
Texas – AMid-Altitude Radial Convergence Case
StudyPaul Lewis II
![Page 2: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/2.jpg)
Objectives
1. Brief overview of Mid-Altitude Radial Convergence (MARC)
2. Summary of the synoptic and meso-scale pattern for March 14, 2001
3. How the MARC signature analysis can be utilized to pinpoint warnings
4. Questions or comments?
![Page 3: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/3.jpg)
• A MARC analysis is a tool that can be utilized with other severe weather analysis techniques
• The MARC signature can help pinpoint locations of strongest surface winds
• Useful in understanding the model of a bow echo that generates damaging downbursts
MARC Overview
![Page 4: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/4.jpg)
MARC Overview
• From Gary Schmocker & Ron Przybylinski at WFO St. Louis:– “The MARC velocity signature is a Doppler
radar-velocity based precursor towards forecasting the initial onset of damaging straight-line winds in a linear Quasi Linear Convective System (QLCS) or bowing convective system.”
– http://www.crh.noaa.gov/lsx/?n=marc_signature
![Page 5: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/5.jpg)
• More from Schmocker & Przybylinski:– MARC signature = Vmaxin + Vmaxout
– Look for MARC signature of 24 m/s (~50 kts) along 3 to 6 radials
– Enhanced wind damage possible with a local area of enhanced radial convergence of 35 to 40 m/s (70 to 80 knots) within the larger MARC signature
MARC Overview
![Page 6: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/6.jpg)
MARC Overview
• From Gary Schmocker & Ron Przybylinski - WFO St. Louis and Yeong-Jer Lin – SLU
• See: http://www.crh.noaa.gov/lsx/science/marc/newmarc.php
![Page 7: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/7.jpg)
MARC Overview
• From Gary Schmocker & Ron Przybylinski - WFO St. Louis and Yeong-Jer Lin – SLU
• See: http://www.crh.noaa.gov/lsx/science/marc/newmarc.php
![Page 8: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/8.jpg)
Summary of the Synoptic and Meso-Scale Pattern for March 14, 2001
• 2 bow echoes affected SE Texas
• 1st produced damage west of Houston (mobile home example)
• 2nd moved over the radar site. . .Focus of this case study
Paul Lewis NWS HGX
![Page 9: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/9.jpg)
Meso/Synoptic Scale Overview
• Ongoing convection from the previous day: Soundings a worked over air mass but with a downburst potential
![Page 10: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/10.jpg)
SoundingsCRP at 12 UTC 14 March 2001
Low-Level Jet forming?
![Page 11: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/11.jpg)
Soundings LCH at 12 UTC 14 March 2001
One item stuck out
after the post-storm
analysis: DCAPE!
Low-Level Jet? – No!
![Page 12: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/12.jpg)
Station LI KI PW CAPE CIN DCAPE 700-500 LR
CRP 3.1 23.3 1.16 NA NA 1110 -6.8
FWD 4.7 31.7 0.93 NA NA 501 -5.5
LCH 7.5 14.7 0.99 NA NA 1163 -4.9
SHV 10.2 15.1 0.77 NA NA 901 -5.1
12 UTC 14 March 2001
Thermodynamic Parameters
• Downdraft CAPE (DCAPE) – An indicator of downburst strength potential
• DCAPE computed by RAOB using the “density weighted 6 km method”
• DCAPE reference: Gilmore, M. S., and Wicker, L. J., 1997: The influence of midtropospheric dryness on supercell morphology and evolution. Mon. Wea. Rev., 126, 943–958.
![Page 13: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/13.jpg)
• Ongoing convection from the previous day: Soundings a worked over air mass but with a downburst potential
• Active pattern with an approaching upper trough
• Increasing low-level moisture
• Increasing instability
Meso/Synoptic Scale Overview
![Page 14: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/14.jpg)
Developing Diffluent Flow Aloft12 UTC 3/14 250 mb 00 UTC 3/15 250 mb
Images courtesy of the Storm Prediction Center Map Archives http://w1.spc.woc.noaa.gov/obswx/maps/
![Page 15: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/15.jpg)
Approaching Upper Trough12 UTC 3/14 500 mb 00 UTC 3/15 500 mb
Images courtesy of the Storm Prediction Center Map Archives http://w1.spc.woc.noaa.gov/obswx/maps/
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Mid-Level Dry Air Punch12 UTC 3/14 700 mb 00 UTC 3/15 700 mb
Images courtesy of the Storm Prediction Center Map Archives http://w1.spc.woc.noaa.gov/obswx/maps/
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Low-Level Moisture Increase12 UTC 3/14 850 mb 00 UTC 3/15 850 mb
Images courtesy of the Storm Prediction Center Map Archives http://w1.spc.woc.noaa.gov/obswx/maps/
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Low-Level Moisture Increase12 UTC 3/14 925 mb 00 UTC 3/15 925 mb
Images courtesy of the Storm Prediction Center Map Archives http://w1.spc.woc.noaa.gov/obswx/maps/
![Page 19: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/19.jpg)
SoundingsCRP at 00 UTC 15 March 2001
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SoundingsLCH at 00 UTC 15 March 2001
Low-Level Jet – Yes!
![Page 21: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/21.jpg)
Event Evolution
![Page 22: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/22.jpg)
2059 UTC 14 March 2001
Developing bow echo
Previous bow echo
Utilizing MARC to Pinpoint Warnings
• High situational awareness was present during the event due to damage reports received during the 1st bow echo
• MARC analysis was conducted during the post-storm review
![Page 23: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/23.jpg)
• Location of MARC signatures can help pinpoint potential wind damage areas
• County-based warnings were issued during the event– The technique can greatly aid in issuing
modern storm-based warnings– Can be utilized to update warnings (SVS)
Conclusions from Post-Storm Analysis
![Page 24: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/24.jpg)
2.4˚ 5.9˚ 9.3˚
6-Panel Method – Imagine “All Tilt” or “4-Panel”
Developing MARC
![Page 25: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/25.jpg)
Developed MARC Signature at 2208 UTC
2.4˚ 5.9˚ 9.3˚
![Page 26: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/26.jpg)
Developed MARC Signature at 2223 UTC
2.4˚ 5.9˚ 9.3˚• MARC signature is a bit tough
to see – probably better in the AWIPS environment
• Cross sections were seen to be the best way to view the MARC during the post-storm analysis
![Page 27: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/27.jpg)
Cross Section Location
• Following slides are cross sections of Reflectivity and Storm Relative Motion
• The cross sections were taken WSW of the radar site
![Page 28: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/28.jpg)
Cross SectionsNote. . .Radar site to the left – directional sense reversed
2158 UTC 14 March 2001
• Developing MARC signature ~ 18,000 ft & 40 nm WSW HGX
• About 39 knots – 32 minutes before 1st wind damage
![Page 29: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/29.jpg)
Cross SectionsNote. . .Radar site to the left – directional sense reversed
2203 UTC 14 March 2001
• Developed MARC signature ~ 14,000 ft & 40 nm WSW HGX
• About 52 to 65 knots – 27 minutes before 1st wind damage
![Page 30: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/30.jpg)
Cross SectionsNote. . .Radar site to the left – directional sense reversed
2208 UTC 14 March 2001
• MARC signature 12,000 – 14,000 feet & 30 nm WSW HGX
• Around 65 Knots – 22 minutes prior to the 1st wind damage
![Page 31: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/31.jpg)
Cross SectionsNote. . .Radar site to the left – directional sense reversed
2214 UTC 14 March 2001
• MARC signature 8,000 – 14,000 feet & 22 nm WSW HGX
• 78 and 91 knots (16 minutes prior) – SVS to update warning?
![Page 32: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/32.jpg)
Cross SectionsNote. . .Radar site to the left – directional sense reversed
2224 UTC 14 March 2001
• MARC signature > 65 knots (4 minutes prior)
• Last MARC signature before the 1st damaging wind report
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MARC & Damage Locations
• Note the pattern of severe events & MARC locations
• MARC times listed:– 2208 UTC (1608 LST)– 2213 UTC (1613 LST)– 2218 UTC (1618 LST)– 2223 UTC (1623 LST)
![Page 34: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/34.jpg)
Highlighted Wind Reports
Note. . .LST = UTC – 6• 1555 LST – Trees and street signs down in Pearland• 1625 LST – 80 mph est. wind gust in Friendswood• 1630 LST – Wind damage in Alvin• 1636 LST – 62 mph gust at NWS• 1640 LST – Tornado report in Sante Fe• 1645 LST – 65 mph gust at Texas City PD• 1700 LST – Wind damage on Galveston Island
![Page 35: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/35.jpg)
Wind Damage near KHGX
Paul Lewis NWS HGX
Paul Lewis NWS HGX
![Page 36: March 14, 2001 Bow Echo in Southeast Texas – A Mid-Altitude Radial Convergence Case Study Paul Lewis II.](https://reader036.fdocuments.us/reader036/viewer/2022062520/5697bf761a28abf838c80f3a/html5/thumbnails/36.jpg)
Questions or Comments?
Paul LewisNational Weather Service1353 FM 646 Rd WSuite 202Dickinson, TX 77539
e-mail: [email protected]
Sunset view of the backside of 14 March 2001 bow echo at NWS HGX Paul Lewis NWS HGX