An area of organized convection was seen moving rapidly southwestward across the western Atlantic Ocean on 31 May 2011, not far off the East Coast of the US. AWIPS images of GOES-13 6.5 µm “water vapor channel” data (above; click image to play animation) suggested that this area of convection over the Atlantic (which was designated Atlantic Tropical Invest 93L on the morning of 01 June) may have been due to a residual Mesoscale Convective Vortex (MCV) that was created by a large Mesoscale Convective System (MCS) over the Upper Midwest region of the US 2 days earlier (for additional information, see the WeatherMatrix Blog and the Weather Underground WunderBlog). A comparison of a POES AVHRR 0.63 µm visible image at 12:37 UTC with ASCAT scatterometer surface winds about 2 hours later at 14:40 UTC (below) revealed a well-defined cyclonic circulation within the convective cluster on 31 May.

MODIS Sea Surface Temperature (SST) product images (below) indicated that the SST values within the Gulf Stream were in the upper 70s to low 80s F (darker red color enhancement) — and these warm waters may have helped the MCV convection to organize and intensify as it eventually moved southwestward over the Gulf Stream.

The feature could also be followed on the MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) — TPW values remained above 40-45 mm during the entire journey across the western Atlantic Ocean, and peaked at 58 mm at 18:00 UTC on 31 May as the disturbance began to move over the warmer waters of the Gulf Stream.

A sequence of MODIS 11.0 µm IR and POES AVHRR 10.8 µm IR images (below) showed minimum cloud top IR brightness temperature values in the -71º C to -83º C range during the 31 May to 01 June period.

A somewhat similar case was noted back in July 1999, when MCV-related convection moved inland produving large hail, damaging winds, and heavy rain in parts of North Carolina and South Carolina.

CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR, MODIS, and MIMIC TPW images and products available for National Weather Service offices to add to their local AWIPS workstations. The VISIT training lessons “POES and AVHRR Satellite Products in AWIPS”, “MODIS Products in AWIPS“, and “Morphed TPW Detection (MIMIC)” are available to help users understand these products and their applications to weather analysis and forecasting.

[Added, 7 June 2011: An enhanced infrared loop using data from GOES-13 that shows the entire life of the MCV is available here. Note: 34 megabyte file size]

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A major outbreak of severe weather (SPC storm reports) occurred across much of the southern Great Plains region of the US on 24 May 2011. One of the ingredients for this severe weather scenario was the approach of a strong jet stream, which was rounding the base of a broad upper level trough located over the Rocky Mountains. Due to these strong winds, a prominent mountain wave signature was seen on AWIPS images of 4-km resolution GOES-13 6.5 µm and 1-km resolution MODIS 6.7 µm “water vapor channel” data (above). Overlays of the RUC80 model isotachs at the 500 hPa, 400 hPa, 300 hPa, 250 hPa, and Maximum Wind levels showed the magnitude of these jet stream winds.

Strong winds were also found at the surface, and McIDAS images of GOES-13 0.63 µm visible channel data (below; click image to play animation) showed several large plumes of blowing dust (along with some smoke plumes from a few wildfires) which streamed eastward and northeastward behind the dryline that acted as the focus for the development of the severe thunderstorms. The haziness seen across the southeastern half of Texas was due to smoke which had been transported northward from fires burning in the Yucatan Peninsula region of Mexico.

GOES-13 sounder Total Precipitable Water (TPW) derived product images (below) revealed that TPW values in excess of 30 mm or 1.2 inches (yellow color enhancement) began to stream northward from Texas into Oklahoma by 18:00 UTC. This moisture helped to fuel the development and maintenance of the deep convection across the region.

The 12 UTC rawinsonde report from Norman, Oklahoma revealed a classic “loaded gun” type of profile, which would lead to a very unstable airmass once strong surface heating took place during the morning and early afternoon hours. GOES-13 sounder Lifted Index (LI) derived product images (below) showed LI values of -10 to -13 C (red to violet color enhancement) just ahead of the dryline, where the atmosphere had indeed become very unstable.

Once the severe thunderstorms began to form across western Oklahoma after 18:15 UTC, GOES-13 6.5 µm water vapor channel images (below) displayed a pronounced warm/dry signature (orange color enhancement) immediately behind the thunderstorms — a signature of strong subsidence in the wake of the convection.

AWIPS images of 1-km resolution POES AVHRR 0.86 µm visible channel and 12.0 µm IR channel data at 20:32 UTC (below) revealed distinct overshooting tops on the visible image, with corresponding cloud top IR brightness temperatures as cold as -85ºC (violet color enhancement). Note that large swaths of rain-cooled ground could be seen on the IR image, which exhibited a lighter gray appearance immediately behind the thunderstorms.

For more information on this severe weather outbreak, see the National Weather Service websites at Norman OK, Tulsa OK, Dodge City KS,  and Wichita KS.

===== 26 May Update =====

A 250-meter resolution MODIS true color Red-Green-Blue (RGB) image from the SSEC MODIS Today site (above; viewed using Google Earth) revealed one of the 24 May tornado damage tracks (oriented from southwest to northeast) which was located just to the northwest of Oklahoma City. Early in its life cycle, the tornado crossed Interstate 40, overturning a number of vehicles.

A comparison of before (22 May 2011) and after (26 May 2011) MODIS true color images (below) showed that the tornado damage path was not present on the 22 May image,

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McIDAS images of GOES-13 Visible (0.63 µm) data (above) showed the rapid development of a supercell thunderstorm that produced the deadly tornado which struck Joplin, Missouri (station identifier JLN) on 22 May 2011. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO), providing images as frequently as every 5-10 minutes. Very distinct overshooting tops could be seen with this large thunderstorm as it developed in extreme southeastern Kansas and moved eastward ahead of an advancing cold frontal boundary. According to the  National Weather Service Springfield MO damage survey, the Joplin tornado produced EF-5 damage with a path width of 3/4 mile and a path length of 6 miles, and was responsible for 132 deaths and 750 injuries.

The corresponding GOES-13 Infrared (10.7 µm) images are shown below. The Joplin tornado began to move into the city around 22:41 UTC  or 5:41 pm local time (Visible/Infrared image toggle).

A 250-meter resolution MODIS true color Red-Green-Blue (RGB) image from the SSEC MODIS Today site (below; displayed using Google Earth) showed the line of thunderstorms developing from western Missouri into extreme southeastern Kansas.

AWIPS images of GOES-13 Infrared (10.7 µm) data with overlays of the Automated Overshooting Tops Detection product (below) flagged a number of overshooting tops as the storm approached Joplin (KJLN).

A comparison of AWIPS images of the GOES-13 Infrared (10.7 µm) data at 21:25 UTC with overlays of the corresponding Automated Thermal Couplet Detection product and the past hour of SPC storm reports (below) revealed a strong thermal couplet of 12.7º C at that time (about 1 hour and 16 minutes before the Joplin tornado) — note that the location of the thermal couplet indicator is parallax-corrected, moving it just to the southeast of where the cold/warm thermal couplet is seen on the non-parallax-corrected GOES-13 Infrared image. This particular thermal couplet was associated with a west-to-east swath of hail as large as 1.75 inch in diameter that began in far southeastern Kansas at 21:02 UTC, along with a report of wind gusts to 62 mph.

The Overshooting Tops detection and Thermal Couplet detection products are collaborative efforts between researchers at the NASA Langley Research Center and CIMSS. The development, generation, and evaluation of these products are part of the GOES-R Proving Ground effort; there are plans for these products to be operational with data from the ABI instrument on the upcoming GOES-R series.

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Meteosat-9 visible channel images (above) showed the volcanic eruption cloud emanating from the Grímsvötn volcano in Iceland on 21 May 2011 (images courtesy of Dave Santek, SSEC). According to the Icelandic Met Office, at 21:00 UTC the eruption plume had risen to an altitude of over 65,000 ft (~20 km). It is interesting to note that the London VAAC reported

EXTREME LIGHTNING ACTIVITY DETECTED BY ATDNET SYSTEM OF UK METOFFICE, 7000 BETWEEN 1900Z AND 0100Z

The volcanic eruption cloud was even apparent on the very edge of GOES-13 (GOES-East) imagery, as can be seen in an animation of visible channel images (below). The oblique viewing angle from this satellite helped to emphasize the large vertical extent of the eruption cloud.

An animation of Meteosat-9 SEVIRI volcanic ash retrieval product 4-panel images (below) indicated that the initial volcanic cloud was ice-dominated (darker red color enhancement on the false color Red/Green/Blue or RGB images in the upper left panel). Around 22:00 UTC, the signal of an SO2 cloud (green color enhancement) began to appear around the northern and northeastern edges of the eruption cloud — very high values of SO2 were subsequently seen moving northward, using data from the OMI instrument.

A more distinct volcanic ash signal (pink color enhancement on the RGB image) became obvious as time progressed along the southern and southeastern edges of the eruption cloud, and by 06:00 UTC on 22 May the retrieved maximum ash height had reached 7.52 km (with the mean volcanic ash particle effective radius at 11.14 µm). Total volcanic ash mass loading had increased to 44.97 kilotons by 06:00 UTC.

CIMSS participation in GOES-R Proving Ground activities includes the generation of these SEVIRI volcanic ash retrievals, which offers a demonstration of the type of products that will be available for volcanic ash monitoring with the ABI instrument on the future GOES-R satellite.

===== 22 MAY UPDATE =====

Meteosat-9 visible channel images (below; click image to play animation) showed that multiple volcanic eruption clouds were still reaching significant vertical heights, with much of this high-altitude material drifting northward. Another lower-altitude hazy volcanic ash cloud could also be seen spreading out just off the southern coast of Iceland. See the US Air Quality blog for MODIS true color images and OMI SO2 images of the volcanic eruption.

 

 

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