Strong Storm in the Mediterranean

November 19th, 2013 |
Meteosat-10 10.8 µm infrared channel images (click to play animation)

Meteosat-10 10.8 µm infrared channel images (click to play animation)

Cyclone Cleopatra moved through the central Mediterranean Sea, causing flooding in Italy and Sardinia (BBC News Link) with northeastern Sardinia particularly hard hit. The infrared imagery from Meteosat-10, above, and the water vapor imagery, below, shows the slow movement of the entire system within the Mediterranean basin, as well as the strong thunderstorms over Sardinia later in the day on 18 November. Note in the Infrared animation that the minor eruption of Etna, on Sicily, is apparent (as documented here).

Meteosat-10 6.2 µm water vapor channel images (click to play animation)

Meteosat-10 6.2 µm water vapor channel images (click to play animation)

A higher-resolution view centered on Sardinia, below, shows the redevelopment of strong thunderstorms (inferred by cold cloud tops on the IR imagery) over Sardinia ending after 1800 UTC on 18 November as dry air swept north. The visible imagery (bottom) is also testimony to the training aspect of this convection. (Hat tip to Byron Grisham at NOAA/OSPO for alerting us about this noteworthy storm)

Meteosat-10 10.8 µm infrared channel images (click to play animation)

Meteosat-10 10.8 µm infrared channel images (click to play animation)

Meteosat-10 0.7 µm visible channel images (click to play animation)

Meteosat-10 0.7 µm visible channel images (click to play animation)

Ice forming in Hudson Bay, Canada

November 19th, 2013 |
Suomi NPP VIIRS 0.64 µm visible channel images

Suomi NPP VIIRS 0.64 µm visible channel images

AWIPS II images of 375-meter resolution Suomi NPP VIIRS 0.64 µm visible channel data (above) showed the growth of new ice immediately offshore in the northwestern portion of Hudson Bay, Canada during the 17 November19 November 2013 time period. The northwesterly flow of cold arctic air in the Arviat, Nunavut (station identifier CYEK) region was also producing well-defined cloud streets over the open waters of Hudson Bay.

The corresponding false-color “Snow Cloud Discrimination” Red/Green/Blue (RGB) images (below) confirmed that the brighter white nearshore features seen on the visible images were ice — ice and snow cover appear as shades of red on the RGB images, in contrast to supercooled water droplet clouds which appear as varying shades of white.

Suomi NPP VIIRS "Snow Cloud DIscrimination" false-color RGB images

Suomi NPP VIIRS “Snow Cloud DIscrimination” false-color RGB images

On 18 November, a significant amount of young pack ice motion can be seen in the 104-minute period between the 17:16 UTC and 19:00 UTC VIIRS visible images (below).

Suomi NPP VIIRS 0.64 µm visible channel images

Suomi NPP VIIRS 0.64 µm visible channel images

Daily “stage of development” ice analyses from the Canadian Ice Service are shown below.

Canadian Ice Service daily ice analysis for northern Hudson Bay (17, 18, 19 November)

Canadian Ice Service daily ice analysis for northern Hudson Bay (17, 18, and 19 November)

Satellite Views of an Historic Severe Weather Outbreak

November 17th, 2013 |
MODIS Visible (0.68 µm) and Infrared (11 µm) imagery from 1634 UTC 17 November overlain with hourly severe reports from 1700 and 1800 UTC (click to enlarge)

MODIS Visible (0.68 µm) and Infrared (11 µm) imagery from 1634 UTC 17 November overlain with hourly severe reports from 1700 and 1800 UTC (click to enlarge)

A late-season tornadic outbreak occurred on Sunday November 17th over the Upper Midwest. The animation above shows MODIS Imagery — visible and 11 µm just as the severe weather was erupting over Illinois. Two different sets of severe weather reports are overlain: those within an hour of the image, and those an hour after the image. The convection over central Illinois has just started to produce severe weather, and it intensified after the imagery (as seen by the blossoming in areal coverage of severe weather reports).

GOES-13 Enhanced Infrared (10.8 µm) imagery 17 November, times as indicated (click image to animate)

GOES-13 Enhanced Infrared (10.8 µm) imagery 17 November, times as indicated (click image to animate)

An animation of GOES-13 10.7 µm imagery (in RSO mode during the day), above, (also available here, on YouTube) shows the storms. The storm tops were not particularly cold (unsurprising given the date), but severe weather signatures (enhanced Vs, for example), can be discerned. Storm reports from SPC suggest that the strongest tornado, in Washington (in Tazewell County), was on the ground at 1700 UTC. The 1655, 1702 and 1710 UTC images shows a strong cell, but not one with particularly cold tops. An animation of these 3 images is shown below. The storm is relatively small compared to GOES-13 resolution. Note also that the storm appears to be north of Tazewell County because of parallax errors.

GOES-13 Enhanced Infrared (10.8 µm) imagery 17 November, times as indicated (click image to animate) Washington is in far northern Tazewell County, which County is outlined in White

GOES-13 Enhanced Infrared (10.8 µm) imagery 17 November, times as indicated (click image to animate) Washington is in far northern Tazewell County, which County is outlined in White

The large-scale environment was unusually moist and unstable for November. Total Precipitable Water exceeded 200% of normal over much of the upper midwest (link), and an animation of GOES-13 Sounder imagery of DPI Lifted Index (link) showed instability, albeit in between holes in the cloud (the extensive cloud shields suggest that solar heating played little role in this outbreak). The 1700 UTC GOES DPI Lifted Index image is below. Lifted Indices below -5 are common throughout Illinois. (GOES-13 Sounder data continues to have missing data points, as noted here and here)

GOES-13 Sounder DPI Values of Lifted Index, 1700 UTC on 17 November (click image to enlarge)

GOES-13 Sounder DPI Values of Lifted Index, 1700 UTC on 17 November (click image to enlarge)

Suomi/NPP also viewed the storms, but after they had moved east of Illinois. A toggle between VIIRS Visible, 11.35 µm and 1.61 µm imagery, below, shows isolated supercells pushing through the cirrus shield.

Suomi/NPP Visible (0.65 µm), Infrared (11.45 µm) and 1.61 µm imagery from 1913 UTC 17 November (click to enlarge)

Suomi/NPP Visible (0.65 µm), Infrared (11.45 µm) and 1.61 µm imagery from 1913 UTC 17 November (click to enlarge)

Suomi/NPP sees the Mt. Etna eruption

November 17th, 2013 |
Suomi/NPP Imagery of Mt. Etna, including the Day/Night Band, I05 (11 µm) and M13 (3.9 µm) (click to play animation)

Suomi/NPP Imagery of Mt. Etna, including the Day/Night Band, I05 (11 µm) and M13 (3.9 µm) (click to play animation)

Mt. Etna, on Sicily in the Mediterranean Sea, erupted early in the morning on Nov 17th just before a Suomi/NPP overpass. The VIIRS Day/Night Band gives a clear view of the volcanic plume (and the light emitted by the lava in the caldera); thermal channels show a distinct hot spot: 360 K in the 11 micron channel, and 523 K in the 3.9 micron channel! (Imagery courtesy Will Straka, UW-Madison/CIMSS)