coastal gravity wave event of 24 april 2010 national weather association annual national conference,...

Coastal Gravity Wave Event of 24 April 2010Coastal Gravity Wave Event of 24 April 2010  

National Weather Association Annual National Conference, National Weather Association Annual National Conference, Tucson, AZTucson, AZ

2-7 October 20102-7 October 2010  

Scott Overpeck, Chris McKinney, and Kent ProchazkaScott Overpeck, Chris McKinney, and Kent ProchazkaNOAA/National Weather Service Houston/Galveston, TXNOAA/National Weather Service Houston/Galveston, TX

OverviewOverview

The goal of this study is to document the passing of mesoscale gravity waves that propagated along the Upper Texas Coast during the early morning hours of 24 April 2010. Pressure changes of 5-7 hPa were observed with the passing of the waves, and high winds of 60 knots caused damage to house roofs and snapped power poles.

Synoptic Environment for Gravity Waves.Possible source region of the Gravity Waves on April 24.IR and Water Vapor Satellite Imagery, Radar reflectivity and base velocity showing the Gravity Wave passage.Corresponding pressure and wind data from 5 observation sites along the Upper Texas Coast.Summary of the event.

Synoptic Environment – Koch and O’Handley Synoptic Environment – Koch and O’Handley (1997)(1997)

Synoptic Environment – 24 April 2010 Synoptic Environment – 24 April 2010

Synoptic Environment – 24 April 2010Synoptic Environment – 24 April 2010

IR Satellite Image – 0315 UTC, 24 April 2010IR Satellite Image – 0315 UTC, 24 April 2010

IR Satellite Image – 0631 UTC, 24 April 2010IR Satellite Image – 0631 UTC, 24 April 2010

IR Satellite Image – 0915 UTC, 24 April 2010IR Satellite Image – 0915 UTC, 24 April 2010

Water Vapor Satellite Image – 0345 UTC, 24 April 2010Water Vapor Satellite Image – 0345 UTC, 24 April 2010

Water Vapor Satellite Image – 0631 UTC, 24 April 2010Water Vapor Satellite Image – 0631 UTC, 24 April 2010

Water Vapor Satellite Image – 0915 UTC, 24 April 2010Water Vapor Satellite Image – 0915 UTC, 24 April 2010

Radar Image – 0525 UTC, 24 April 2010Radar Image – 0525 UTC, 24 April 2010

Pressure and Wind ObservationPressure and Wind Observation

Pressure and Wind ObservationPressure and Wind Observation

Radar Image – 0609 UTC, 24 April 2010Radar Image – 0609 UTC, 24 April 2010

Radar Image – 0652 UTC, 24 April 2010Radar Image – 0652 UTC, 24 April 2010

Pressure and Wind ObservationPressure and Wind Observation

Radar Image – 0723 UTC, 24 April 2010Radar Image – 0723 UTC, 24 April 2010

Pressure and Wind ObservationPressure and Wind Observation

Radar Image – 0812 UTC, 24 April 2010Radar Image – 0812 UTC, 24 April 2010

Pressure and Wind ObservationPressure and Wind Observation

Gravity Wave SummaryGravity Wave Summary

SitePeriod (hours)

Pressure Change (MB)

Minimum Pressure (MB)

Maximum Sustained Wind (KNOTS)

Peak Wind Gust (KNOTS)

Angleton (KLBX) 3 2.4 998.3 20 26Freeport (USCG 8772447) 3.3 5.9 996.1 35 43

Scholes Field (KGLS) 3.25 7.1 995.1 45 60Pleasure Pier (GPST2, 8771510) 3.2 6.7 994.5 36 43Sabine Pass North (SBPT2, 8770570) 2.7 7 996.6 32 42Average 3.1 6.7 995.6 37 47

Gravity Wave CharacteristicsFreeport to KGLS

KGLS to Sabine Pass

Freeport to Sabine Pass

Average Period (Hours) 3.275 2.975 3Wave Velocity (Knots) 65 52 55Wavelength (Nautical Miles) 213 155 165

The gravity wave most likely had a period of about 3 hours, a wavelength between 155-215 NM, and a velocity of 52-65 knots.The average pressure change was 6.7 hPa with a minimum pressure of 995.6 hPa and wind speeds of 37 knots (gusts of 47 knots).

Questions? Comments?Questions? Comments?

Coastal Gravity Wave Event of 24 April 2010Coastal Gravity Wave Event of 24 April 2010  

National Weather Association Annual National Conference, National Weather Association Annual National Conference, Tucson, AZTucson, AZ

2-7 October 20102-7 October 2010  

Scott Overpeck, Chris McKinney, and Kent ProchazkaScott Overpeck, Chris McKinney, and Kent ProchazkaNOAA/National Weather Service Houston/Galveston, TXNOAA/National Weather Service Houston/Galveston, TX

E-mail: scott.overpeck@noaa.govE-mail: scott.overpeck@noaa.gov