AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) revealed the formation of a mesoscale vortex over far northwestern Wisconsin during the day on 26 March 2013. Overlays of MADIS 1-hour interval atmospheric motion vectors (below) showed that the satellite-derived winds were indicating some degree of cyclonic flow into the western portion of the mesovortex.

A comparison of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images (below) showed that the cloud elements comprising the mesoscale vortex appeared convective in nature, with many exhibiting IR cloud top brightness temperatures of -20º C or colder (light blue color enhancement). The morning rawinsonde data from Minneapolis, Minnesota indicated that a very unstable layer was present just above the surface between 950 and 750 hPa — so with a convective temperature of only 36º F the convective elements were quick to develop once surface temperatures began to warm after sunrise.

===== 27 April Update =====

During the following overnight hours, the cyclonic swirl signature of the mesoscale vortex could still be seen over northwestern Wisconsin at 07:53 UTC or 2:53 AM local time on the Suomi NPP VIIRS IR brightness temperature difference “fog/stratus product” (below). Due to ample illumination by a full Moon,  a “night-time visible image” provided by the corresponding 0.7 µm Day/Night Band (DNB) showed that city lights could still be seen through the low cloud deck; other features of interest on the DNB image included ice in Green Bay and a few areas along the south shore of Lake Superior, and the southern extent of the snow cover from far eastern South Dakota into southern Minnesota.

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McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) revealed the formation of an eye-like signature that suggests the formation of a warm seclusion off the US East Coast on 25 March 2013.

AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data at 18:16 UTC (below) showed the early stages of the development of the cloud-free core of the warm seclusion. Strong convective squalls were developing along the occluded frontal zone in the eastern portion of the satellite scene.

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AWIPS images of GOES-13 10.7 µm IR channel data (above; click image to play animation) showed a band of strong to severe thunderstorms that moved eastward across central Florida during the afternoon hours on 24 March 2013. These storms produced a few reports of hail up to 1.0 inch in diameter, as well as a number of damaging wind reports which included a gust to 75 knots or 86 mph at Orlando International Airport at 18:40 UTC or 2:40 PM local time (SPC storm reports).

1-km resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR images with overlays of surface METAR reports and SPC storm reports (below) revealed that there was a cluster of overshooting tops with cloud-top IR brightness temperature values as cold as -67º C (darker red color enhancment) that appearaed to be associated with the reports of high wind gusts at the surface.

A comparison of a 1-km resolution Suomi NPP VIIRS 11.45 µm IR image with the corresponding 4-km resolution GOES-13 10.7 µm IR image (below) demonstrated the advantage of higher spatial resolution for aiding in the identification of the location and magnitude of the coldest cloud-top IR brightness temperatures (-67º C with VIIRS, vs -60º C with GOES). In addition, the effect of parallax was evident on the GOES-13 IR image, with features being displaced to the northwest.

GOES-13 sounder Lifted Index (LI) and Total Precipitable Water (TPW) derived product images (below) indicated that moisture (TPW values as high as 45 mm or 1.78 inches) and instability (LI values as low as -10.4º C) were in place in the pre-convective environment across central Florida at 16:00 UTC or 12:00 PM local time.

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Strong winds associated with a cold frontal passage created large areas of blowing dust across parts of New Mexico and Texas on 23 March 2013. The maximum wind gusts were as high as 82 mph in New Mexico and 77 mph in Texas. A comparison of McIDAS-V images of Suomi NPP VIIRS 0.672 µm visible band and 1.378 µm near-IR “cirrus” band images (above) demonstrated the utility of the near-IR imagery for more accurately displaying the areal coverage of the airborne dust that might not be entirely apparent on the standard visible channel imagery. The strength of the 1.375 µm spectral band is the detection of particles that are efficient scatterers of light (such as cirrus ice crystals, volcanic ash, haze, and dust) — so in this case the dense plumes of blowing dust showed up very well, especially in comparison to the corresponding visible image. Note that a 1.38 µm “Cirrus” band will be available with the ABI instrument on the upcoming GOES-R satellite.

For additional information and images of this event, see the NWS Lubbock TX news story and the Wide World of SPoRT blog. This webapp allows you to fade between 4 different visible/near IR channels from MODIS for this case.

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