Gravity wave over Indiana, Ohio, and Michigan

September 15th, 2008 |
GOES-13 visible images

GOES-13 visible images

Blog reader Michael Lawson wrote:

Hi, I am a meteorologist working with Meridian Environmental Technology in Grand Forks, ND. A co-worker noticed a gravity wave feature in the visible over northern Indiana/northwest Ohio during the afternoon of September 15, 2008. Clouds moving into the feature would dissipate then reform once they propagated through the other side. Thought it would make an interesting topic!

Thanks for the tip, Michael. GOES-13 visible imagery (above) did indeed show the wave as it propagated northwestward (against the ambient flow) across northern Indiana/Ohio into southern Lower Michigan on 15 September 2008.

The dissipation of the stratocumulus cloud field with the passage of the wave might be explained by examining the rawinsonde data from Wilmington, Ohio (below) — note the presence of very dry air aloft, which could have been briefly mixed downward as the wave moved through (similar to what was seen with an apparent hydraulic jump over lower Michigan and southern Ontario on 08 May 2008).

Wilmington OH rawinsonde data

Wilmington OH rawinsonde data

Remnants of Hurricane Ike

September 14th, 2008 |
GOES-12 visible images + surface reports

AWIPS images of the GOES-12 visible channel + surface reports

The remnants of Hurricane Ike moved rapidly northeastward across the Ohio River Valley region on 14 September 2008. AWIPS images of the GOES-12 visible channel (above) with an overlay of METAR surface reports showed that a large number of locations reported very strong wind gusts just to the south of the cluster of convection that marked the core of Ike’s remnants. Winds gusted to 43 knots (49 mph) at Pahucah, Kentucky (KPAH) at 14 UTC, 49 knots (56 mph) at Evansville, Indiana (KEVV) at 16 UTC, 65 knots (75 mph) at Lousiville, Kentucky (KSDF) at 18 UTC, 64 knots (74 mph) at Cincinnati, Ohio (KCVG) at 20 UTC, and 57 knots (66 mph) at Port Columbus, Ohio (KCMH) at 21 UTC. The highest unofficial wind gust reported was 73 knots (84 mph) at West Chester, Ohio (NWS WIlmington, Ohio summary).

An animation of a mosaic of US radar reflectivity (105-MB QuickTime movie, courtesy of the UW-Madison Department of Atmospheric and Oceanic Sciences) allows one to follow the progression of the remnants of Ike after the hurricane made landfall along the Texas coast. A large swath of heavy rain resulted, with a maximum amount of 11.02 inches reported in La Porte County, Indiana. In addition, an unusual tropical-type tornado outbreak occurred on 13 September in southern Michigan — a total of 5 tornado touchdowns occurred, producing significant damage in Paw Paw and Plymouth.

Hurricane Ike makes landfall

September 13th, 2008 |
GOES-12 and GOES-13 IR images

GOES-12 and GOES-13 10.7 µm IR images

Hurricane Ike (satellite montage) made landfall as a Category 2 storm during the early hours of 13 September 2008. The comparison of GOES-12 and GOES-13 10.7 µm IR images (above) is a good demonstration of the value of the larger batteries on-board the GOES-13 (and newer) satellites — these larger batteries allow the satellites to operate through the Spring and Fall season “eclipse” periods (when the satellite is in the Earth’s shadow, and the solar panels cannot generate the power necessary to operate the GOES imager and GOES sounder instrument packages). Note that a strong spiral band was in the process of intensifying and moving inland along the far northeastern Texas and far southwestern Louisiana coastlines  during the GOES-12 eclipse period — the evolution of this feature was easily followed using the GOES-13 imagery.

MODIS IR images

AWIPS images of the MODIS 11.0 µm IR channel

A sequence of AWIPS images of the 1-km resolution MODIS 11.0 µm IR channel data (above) showed better details of the cloud features than could be seen using the 4-km resolution GOES IR imagery above.

A closer view using an AWIPS image of the MODIS 3.7 µm shortwave IR channel (below) uses a color enhancement designed to highlight some of the warmer features in the eye region –  some eyewall mesovortex structure was indicated on radar reflectivity data around the time that the eye was approaching the coast.

AWIPS image of the MODIS 3.7 µm IR channel + surface reports

AWIPS image of the MODIS 3.7 µm IR channel + surface reports

Interestingly, the landfall of Hurricane Ike marked the first time on record that 6 consecutively-named tropical cyclones (Dolly, Edouard, Fay, Gustav, Hanna, Ike) have made landfall in the US.

Hurricane Ike

September 12th, 2008 |
GOES-11 SRSO visible images

GOES-11 SRSO visible images

GOES-11 continued in Super Rapid Scan Operations (SRSO) mode on 11 September 2008, with visible imagery (above) showing additional convective bursts around the eye of the storm.

GOES-12 water vapor channel imagery (below) revealed an interesting series of middle- to upper-tropospheric “gravity waves” propagating radially outward away from Ike, moving inland over the Gulf Coast states.

GOES-12 water vapor images

GOES-12 water vapor images

A comparison of AWIPS MODIS images on 12 September 2008 (below) displayed Category 2 Hurricane Ike as the large storm approached the Texas coast. MODIS IR cloud top brightness temperatures at 16:58 UTC were as cold as -84º C (purple enhancement).

AWIPS images of the MODIS visible, IR, cirrus, and water vapor channels

AWIPS images of the MODIS visible, IR, cirrus, and water vapor channels

An oblique view of a MODIS true color image using Google Earth (below; courtesy of Liam Gumley, CIMSS) shows that the clouds associated with Hurricane Ike covered a good deal of the Gulf of Mexico on 12 September.

MODIS true color  image (viewed using Google Earth)

MODIS true color image (viewed using Google Earth)