A weak, isolated tornado developed in southwestern Minnesota during the afternoon of 11 August 2010. GOES-15 imagery, above, shows the development of modest cumulus convection that spawned the tornado. The 5-minute time-step in the imagery is similar to that that will be available routinely from the ABI on GOES-R; the loop was taken as part of the GOES-15 science test as described here. (GOES-15 data are available at the SSEC Geostationary Satellite Image Browser) Although the tornadic event was a meteorological surprise (the convective outlook from the Storm Prediction Center, for example, did not foresee convection in the area), several satellite-based products diagnosed the instability that was present in the atmosphere. For example, the CIMSS NearCasting Tool (which tool uses the 3 water vapor channels on the GOES-13 Sounder to predict the 0-6 hours evolution of the theta-e destribution in the troposphere) showed a region of enhanced convective instability over southern Minnesota (see image below). In addition, GOES-13 Sounder estimates of Lifted Index (see the bottom two panels of the linked-to image) show southern Minnesota at the northern edge of unstable air.

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Recent news articles (such as this one) have noted the unusual warmth present in the surface waters of the Great Lakes. Clear skies over the western Great Lakes on Sunday 8 August allowed MODIS instruments to measure sea surface temperatures, and the warm temperatures are plain to see. These warm temperatures have persisted for some time, and 5-day plots for the Buoy in central Lake Michigan (buoy 45007), northern Lake Michigan (buoy 45002), and the center of Lake Superior (buoy 45001) all confirm the MODIS readings: unusual warmth in the Lakes. In fact, many of the lake surface temperature readings are near the top of the 4th quartile in the statistical distribution (see data here for buoy 45001 and here for buoy 45007).

Data from the AVHRR on board the NOAA series of satellites show similarly warm temperatures. Here is an afternoon image from NOAA-19 from 8 August.

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POES AVHRR visible, IR, and IR + severe weather reports

A large Mesoscale Convective System (MCS) initially developed over Nebraska and quickly grew in size as it propagated eastward across the Missouri River Valley region of the north-central US on 08 August 2010. AWIPS images of 1-km resolution POES AVHRR 0.63 µm visible and 10.8 µm IR channel data (above) revealed an impressive back-sheared anvil structure, along with well-defined overshooting tops and very cold cloud top IR brightness temperatures (as cold as -91º C). SPC storm reports showed a number of hail an damaging winds associated with this MCS, as well as one tornado.

An alternative view of the storm can be seen using a false color Red/Green/Blue (RGB) image using POES AVHRR channels 1, 2, and 4 (below).

POES AVHRR Red/Green/Blue (RGB) false color image

On the back-sheared portion of the anvil, note how warm the IR brightness temperatures were on the AVHRR 10.8 µm IR image — due to the very thin nature of the cirrus shield, radiation from the warm ground below contributed to the IR brightness temperatures being warmer than -20º C on that portion of the cirrus shield. However, the more accurate AVHRR Cloud Top Temperature (CTT) product (below) gave a much more accurate CTT of -40 to -50º C.

POES AVHRR 10.8 µm IR image + AVHRR Cloud Top Temperature product

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(Click image for larger version)

GOES-15 is observing from a vantage point above the Equator at 89.5 W and GOES-13 is observing from a vantage point above the Equator at 75 W. The two satellites therefore have slightly different perspectives of cloud scenes over the southeast United States. These different perspectives can be exploited to yield stereoscopic views of cloud development, as shown above. Crossed eyes will yield a third image that shows three dimensions so that vertical cloud structures can be discerned. Note in particular the abundant cirrus in the image over the southeast United States.

A short tutorial on cross-eyed stereoscopy is here. Example images — non-meteorological — can be found here.

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