Long-track Tornado over southwestern Manitoba

July 28th, 2015

Color-enhanced Infrared (10.7 µm) imagery from GOES-15 (left) and GOES-13 (right), times as indicated  [click to play animation]

Color-enhanced Infrared (10.7 µm) imagery from GOES-15 (left) and GOES-13 (right), times as indicated [click to play animation]

A strong tornado touched down near Pierson, Manitoba at around 0120 UTC on 28 July (Press Report) and persisted until about 0400 UTC (near Virden Manitoba). The animation above shows GOES-15 (left) and GOES-13 (right) Infrared imagery from 0000 UTC through 0430 UTC. The strong storm lifting northward over southwestern Manitoba is apparent, with an enhanced-V signature especially noticeable in the GOES-13 imagery.

A closer view of the tornadic supercell is shown below, with overlays of surface reports (metric units). The pulsing nature of the overshooting tops is apparent in the fluctuation of the coldest cloud-top IR brightness temperatures (the coldest of which was -69º C on the 0300 UTC GOES-15 and 0315 UTC GOES-13 images). There are different apparent positions of the storms based on the satellite that views them because of parallax shifts. Such shifts are especially pronounced at higher latitudes with very tall storms.

GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared images, with surface reports [click to play animation]

GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared images, with surface reports [click to play animation]

A 1-km resolution Terra MODIS 11.0 µm Infrared image at 0331 UTC is shown below; the minimum cloud-top IR brightness temperature was -73º C.

Terra MODIS 11.0 µm Infrared image [click to enlarge]

Terra MODIS 11.0 µm Infrared image [click to enlarge]

GOES-13 Visible (0.63 µm) imagery, times as indicated  [click to play animation]

GOES-13 Visible (0.63 µm) imagery, times as indicated [click to play animation]

Visible imagery from GOES-13 (above) and GOES-15 (below) showed the overshooting tops associated with the tornadic thunderstorm, as well as the rapidly expanding cirrus shield.

GOES-15 Visible (0.62 µm) imagery, times as indicated  [click to play animation]

GOES-15 Visible (0.62 µm) imagery, times as indicated [click to play animation]

A closer view of the tornadic supercell from GOES-15 vs GOES-13 is shown below, with overlays of surface reports (metric units). The overshooting tops are again apparent on the images, along with an above-anvil plume (which is easier seen on the GOES-13 images, due to a more favorable forward-scattering viewing geometry). The robust convective development was first seen on the 2030 UTC images, in the vicinity of the Saskatchewan/Manitoba/North Dakota border region.

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images, with surface reports [click to play animation]

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images, with surface reports [click to play animation]

As an area of low pressure was deepening over eastern Montana (surface analyses), GOES sounder derived product images of Convective Available Potential Energy (CAPE), Lifted Index, and Total Precipitable Water (below) showed that the environment across southern Manitoba was becoming increasingly unstable and moist leading up to the time of convective initiation.

GOES sounder CAPE derived product images [click to play animation]

GOES sounder CAPE derived product images [click to play animation]

GOES sounder Lifted Index derived product images [click to play animation]

GOES sounder Lifted Index derived product images [click to play animation]

GOES sounder Total Precipitable Water derived product images [click to play animation]

GOES sounder Total Precipitable Water derived product images [click to play animation]

Reynolds Creek Fire in Glacier National Park, Montana

July 23rd, 2015

GOES-15 (left) and GOES-13 (right) visible and shorwave IR images [click to play animation]

GOES-15 (left) and GOES-13 (right) visible and shorwave IR images [click to play animation]

Shown above (click image to play animation; also available as an MP4 movie file) is a 4-panel comparison of GOES-15 (GOES-West, left panels) and GOES-13 (GOES-East, right panels) 0.63 µm visible channel images (top) and 3.9 µm shortwave IR images (bottom) which showed the development of the the long smoke plume and the fire hot spot (dark black to red shortwave IR pixels)  associated with the Reynolds Creek Fire (InciWeb | Wildfire Today) which began to burn in the eastern portion of the Glacier National Park in Montana around 2145 UTC or 3:43 pm local time on 21 July 2015. A Red Flag Warning was in effect for the region, due to the combination of warm temperature with low relative humidity, and strong southwesterly winds (gusting to 30 mph at Cut Bank and 29 mph at Browning).

Another sequence of GOES-15 visible channel images is shown below (click image to play animation; also available as a MP4 movie file). Another smaller smoke plume can be seen originating from a fire in far southeastern British Columbia.

GOES-15 visible channel images [click to play animation]

GOES-15 visible channel images [click to play animation]

As it continued to burn into the following night; a comparison of Suomi NPP VIIRS 3.74 µm shortwave IR and 0.8 µm Day/Night Band images at 0958 UTC or 3:58 am local time (below) revealed the hot spot (yellow to red to black pixels) and the bright glow of the fire.

Suomi NPP VIIRS shortwave IR and Day/Night Band images [click to enlarge]

Suomi NPP VIIRS shortwave IR and Day/Night Band images [click to enlarge]

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Suomi NPP VIIRS 3.74 µm shortwave IR images [click to enlarge]

Suomi NPP VIIRS 3.74 µm shortwave IR images [click to enlarge]

On the following day (22 July), consecutive afternoon (1944 and 2122 UTC) Suomi NPP VIIRS 3.74 µm shortwave IR channel images (above) revealed changes in the shape and areal coverage of the fire hot spot (dark black pixels); the corresponding VIIRS Red/Green/Blue (RGB) true-color images (below) still showed a smoke plume, though is was not as large as that seen on the GOES visible imagery from the previous day.

Suomi NPP VIIRS true-color RGB images

Suomi NPP VIIRS true-color RGB images

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On 23 July, daytime (1925 and 2104 UTC) Suomi NPP VIIRS 3.74 µm shortwave IR and true-color RGB images (below) continued to display large fire hot spots and a smoke plume drifting toward the east-northeast. The size of the Reynolds Creek Fire was estimated to have increased to 4000 acres.

Suomi NPP VIIRS 3.74 µm shortwave IR and true-color RGB images [click to enlarge]

Suomi NPP VIIRS 3.74 µm shortwave IR and true-color RGB images [click to enlarge]

Severe thunderstorms causing damaging winds across Missouri and Arkansas

July 14th, 2015
GOES-13 sounder CAPE derived product images (click to play animation)

GOES-13 sounder CAPE derived product images (click to play animation)

GOES-13 sounder Convective Available Potential Energy (CAPE) derived product images (above; click to play animation) showed a large cluster of of severe thunderstorms that developed in eastern Kansas and moved southeastward across southern Missouri into northern Arkansas during the day on 14 July 2015. Due to strong surface heating and ample low-level moisture ahead of the storms, the atmosphere became quite unstable with GOES sounder CAPE values reaching the 5800-6000 J/kg range (lighter violet color enhancement) by 16 UTC. A long swath of damaging winds (SPC storm reports) was produced by these storms.

The visible and infrared images below show snapshots of this severe convective cluster at 3 different times, using high-resolution data from instruments on polar-orbiting satellites: Terra MODIS at 1657 UTC, Suomi NPP VIIRS at 1851 UTC, and POES AVHRR at 1916 UTC. The coldest cloud-top IR brightness temperatures were -83º C on the MODIS image, -86º C on the VIIRS image, and -87º C on the AVHRR image.

Terra MODIS 0.65 µm visible channel and 11.0 µm IR channel images (with SPC storm reports) at 1657 UTC [click to enlarge]

Terra MODIS 0.65 µm visible channel and 11.0 µm IR channel images (with SPC storm reports) at 1657 UTC [click to enlarge]

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images (with SPC storm reports) at 1851 UTC [click to enlarge]

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images (with SPC storm reports) at 1851 UTC [click to enlarge]

POES AVHRR 0.86 µm visible channel and 12.0 µm IR channel images (with SPC storm reports) at 1916 UTC [click to enlarge]

POES AVHRR 0.86 µm visible channel and 12.0 µm IR channel images (with SPC storm reports) at 1916 UTC [click to enlarge]

Strong Convection over the Upper Midwest

July 13th, 2015
MODIS 11 µm infrared imagery and GOES Sounder DPI Lifted Index, 0400 UTC (Click to enlarge)

MODIS 11 µm infrared imagery and GOES Sounder DPI Lifted Index, 0400 UTC 13 July 2015 (click to enlarge)

A strong mesoscale convective system (MCS) moving southeastward through the Upper Midwest from late 12 July 2015 into early morning 13 July caused numerous severe wind reports across Minnesota and Wisconsin. This MCS was forecast to drop southeastward and continue to produce severe weather during the day on 13 July 2015 (Storm Prediction Center outlook). The toggle above shows the 0420 UTC Terra MODIS 11.0 µm image and the 0400 UTC GOES-13 Sounder DPI Lifted Index product (which is available in realtime here). As the MCS moved over southern Wisconsin, the coldest cloud-top IR brightness temperature on the 0826 UTC MODIS 11.0 µm IR image was -85º C. The strong system continued to move southeastward as very unstable air as diagnosed by the Sounder fed into it (click here for 850-mb RAOB plots). The 0746 UTC Suomi NPP VIIRS 11.45 µm IR image, below, also toggled with a GOES-13 Sounder Lifted Index product, showed a similar story: very strong convection downwind of a source of strong instability. The GOES Sounder can also diagnose Convective Available Potential Energy (CAPE), with values from 5000-6000 J/kg seen over southern Minnesota and eastern Iowa.

Suomi NPP VIIRS 11.45 µm infrared imagery and GOES Sounder DPI Lifted Index, 0746/0800 UTC (Click to enlarge)

Suomi NPP VIIRS 11.45 µm infrared imagery and GOES Sounder DPI Lifted Index, 0746/0800 UTC 13 July 2015 (click to enlarge)

The Suomi NPP VIIRS Day/Night Band, below, which is a source of visible imagery at night, depicted signatures of the active lightning that accompanied this system: numerous along-scan bright streaks over southern Wisconsin were caused by lightning illuminating the cloud as the VIIRS instruments scanned the cloud top. This toggle showed a comparison of Day/Night Band and 11.45 µm Infrared imagery.

Suomi NPP VIIRS Day/Night Band 0.70 µm visible imagery 0746 UTC (Click to enlarge)

Suomi NPP VIIRS Day/Night Band 0.70 µm visible imagery 0746 UTC 13 July 2015 (click to enlarge)

A closer view comparing the 0746 UTC VIIRS IR and Day/Night Band images, below, includes overlays of METAR reports and both 15-minute and 1-hour cloud-to-ground lightning strikes. The coldest VIIRS cloud-top IR brightness temperature was -78º C.

Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band images, with overlays of METAR surface reports and cloud-to-ground lightning strikes (click to enlarge)

Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band images, with overlays of METAR surface reports and cloud-to-ground lightning strikes (click to enlarge)

At 0805 UTC, the coldest CLAVR-x POES AVHRR Cloud Top Temperature value was -81º C, with maximum Cloud Top Height values of 15 km along the southwestern portion of the MCS.

POES AVHRR Cloud Top Temperature and Cloud Top Height products at 0805 UTC (click to enlarge)

POES AVHRR Cloud Top Temperature and Cloud Top Height products at 0805 UTC (click to enlarge)

This image of Radar Composites of the main line of storms was produced by Greg Carbin of SPC and was posted on Facebook on 13 July 2015.