Convective outflow boundaries off the coast of Cuba

June 8th, 2007 |

GOES-12 visible image

A series of low-level convective outflow boundaries was seen moving off the coast of Cuba on 08 June 2007. GOES-12 visible imagery (above; Java animation) shows the narrow convex cloud bands as they propagated across the offshore waters; note how new convection was seen to develop where adjacent outflow boundaries intersected.

Upper Midwest Severe Thunderstorm Outbreak

June 7th, 2007 |
GOES-12 0.65 µm visible images (click to play animation)

GOES-12 0.65 µm visible images (click to play animation)

An outbreak of severe thunderstorms developed across the Upper Midwest states on 07 June 2007SPC storm reports showed widespread tornadoes (including the EF-3 Langlade WI tornado), large hail, and damaging winds over much of the region. GOES-12 0.65 µm visible channel images (above; click to play animation) revealed a large area of boundary layer wave clouds that developed during the morning hours over a good deal of western Wisconsin and extreme northeastern Iowa and southeastern Minnesota.

GOES-12 10.7 µm IR images (below; click to play animation) depicted cloud top brightness temperatures as cold as -69º C / -92º F (dark red enhancement) as the storms intensified during the afternoon. The dynamics associated with this severe weather outbreak were quite strong, with very fast jet stream winds at the 500 hPa and 250 hPa pressure levels. The 1-km resolution MODIS 6.7 µm water vapor imagery indicated a broad area of potential clear air turbulence downwind of the Rocky Mountains, with the characteristic “herringbone signature” extending as far eastward as western Kansas.

GOES-12 10.7 µm IR images (click to play animation)

GOES-12 10.7 µm IR images (click to play animation)

CIMSS employee Derrick Herndon was chasing these storms in central Wisconsin, and took a photo of some very large hail on the ground in Wisconsin Rapids (below). The largest hail listed on the SPC storm reports for that day was 4.25 inches in diameter at Wisconsin Rapids.

Hail near Wisconsin Rapids

Hail near Wisconsin Rapids

An interesting feature seen on MODIS false-color imagery (below) was the southwest-to-northeast oriented swaths of wet ground left in the wake of rainfall from storms moving across portions of northeastern Iowa and southeastern Minnesota. Note the cooler temperatures (60s and 70s F) at locations within the rainfall swaths. The larger rain swath was still evident on the following day, with surface temperature at Preston, Minnesota (station identifier KFKA) remaining 2-3 degrees cooler than surrounding sites.

Aqua MODIS false-color image

Aqua MODIS false-color

2 days later (09 June), the long-track tornado damage path across northeastern Wisconsin was very evident on a Terra MODIS true-color image (below), courtesy of the Environmental Remote Sensing Center.

Terra MODIS true-color image

Terra MODIS true-color image

Super Cyclone Gonu

June 5th, 2007 |
Meteoasat-7 IR images (click to play animation)

Meteosat-7 IR images (click to play animation)

Super Cylone 02A (“Gonu”) intensified rapidly in the Arabian Sea on 03-04 June 2007. EUMETSAT Meteosat-7 InfraRed imagery (above; animated GIF) showed very cold cloud-top IR brightness temperature values (-80º to -88º C, violet to purple enhancement) in the eyewall region during much of the 2-day period. A distinct eye was apparent on the Meteosat-7 IR images, as well as on the Meteosat-7 visible images on 04 June (animated GIF).

An overpass of the NOAA-17 satellite occurred at 17:33 UTC on 04 June; the IR image (below) depicted a detailed radial “banded structure” to the cold brightness temperature field, with a minimum temperature of -89º C (darker purple enhancement). Also note the area of concentric gravity waves south of the eye (within the gray-to-white enhanced area of -75º to -79º C brightness temperatures).

NOAA-17 IR image

NOAA-17 IR image

The CIMSS Advanced Dvorak Technique is a satellite-based method of estimating tropical cyclone intensity; the ADT plot (below) indicates that Gonu intensified very rapidly from late in the day on 03 June (day 2007154) to early in the day on 04 June (day 2007155), reaching Category 5 intensity (with 140 knot wind speeds). This was the first tropical cyclone of Category 5 strength on record in the Arabian Sea.

Gonu ADT plot

Gonu ADT plot

Tropical Storm Barry

June 1st, 2007 |

AWIPS GOES IR image

Tropical Storm Barry formed in the eastern Gulf of Mexico on 01 June 2007 (the first official day of the Atlantic hurricane season). An AWIPS image of the GOES-12 10.7µm IR channel (above; Java animation) showed that some bursts of convection were developing just north of the center of Barry, with cold IR brightness temperature values of -70º to -80º C (black to white enhancement). The tropical cyclone was embedded in an environment of strong southwesterly wind shear in the middle levels and upper levels of the atmosphere, which was not conducive to further strengthening of Barry.

An AWIPS 4-panel comparison of DMSP SSM/I and POES AMSU imagery (below) revealed that rainfall rates near the center of TS Barry were in the 25-35 mm (1.0-1.4 inch) per hour range (orange to red enhancement, upper panels), while total precipitable water values were increasing to 50-60 mm or 2.0-2.4 inches (violet to purple enhancement, lower panels) in the environment surrounding the storm over the eastern Gulf of Mexico. Note that the times displayed on the AWIPS DMSP and POES images do not necessarily correspond to the actual time of the satellite overpass for the particular region being viewed.

AWIPS DMSP / POES rainfall rate / PW