Long-track Tornado over southwestern Manitoba

July 27th, 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 (rated a high-end EF-2) touched down near Pierson, Manitoba at around 0130 UTC on 28 July or 8:30 pm local time on 27 July (Press Report) and persisted until about 0355 UTC or 10:55 pm local time (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 evident in the fluctuation of the coldest cloud-top IR brightness temperatures (the coldest of which was -69º C, darker black color enhancement, 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, warm and humid air was surging northward into far southern Saskatchewan and Manitoba (surface analyses). GOES sounder derived product images (available from this site) 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]

Wildfires continue in the interior of Alaska

July 25th, 2015

GOES-15 visible (top) and shortwave IR (bottom) images [click to play animation]

GOES-15 visible (top) and shortwave IR (bottom) images [click to play animation]

Wildfires continued to burn across parts of the interior of Alaska during the 22-25 July 2015 period, as is shown in GOES-15 (GOES-West) 0.63 µm visible channel and 3.9 µm shortwave IR images (above; click to play animation; also available as an MP4 movie file). Also of interest is: (1) the diurnal change of intensity and areal coverage of the fire hot spots (darker black to red pixels on the shortwave IR images), with the fires dying down at night, and (2) the change in direction of smoke transport, from westward on 22 July to eastward on 24 July. The switch in smoke transport direction was the result of changing winds associated with a broad area of low pressure moving across Alaska during that period (surface analyses).

A more detailed view of the fire hot spots was provided by 375-meter resolution (mapped onto a 1-km AWIPS grid) Suomi NPP VIIRS 3.74 µm shortwave IR images (below; click to play animation).

Suomi NPP VIIRS shortwave IR images [click to play animation]

Suomi NPP VIIRS shortwave IR images [click to play animation]

Many of the fires were burning in the general vicinity of the Utopia Creek, Indian Mountain airport (station identifier PAIM); a time series of surface observation from that site (below) showed that visibility was 1 mile or less due to smoke at times on 25 July.

Time series of surface observation from Utopia Creek, Indian Mountain airport [click to enlarge]

Time series of surface observation from Utopia Creek, Indian Mountain airport [click to enlarge]

Daily composites of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images viewed using the SSEC RealEarth web map server are shown below.

Suomi NPP VIIRS true-color images [click to enlarge]

Suomi NPP VIIRS true-color images [click to enlarge]

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]

Flooding Rains in southern California

July 20th, 2015
GOES-15 Infrared Water Vapor (6.5 µm) Images  (click to play animation)

GOES-15 Infrared Water Vapor (6.5 µm) Images (click to play animation)

Unusual rains causing flooding and mudslides hit southern California (San Diego in particular) on 18-19 July 2015. The two-day rain total (1.69″) at Lindbergh Field broke the monthly record for July (previous record, 1.29″) and exceeded the January-April 2015 rainfall (the typical wet season) at the station. The San Diego Padres had their first July rainout ever, and the Anaheim Angels had their first rainout since 1995! What caused the rains? The water vapor imagery, above, shows the three systems that contributed. Pacific Hurricane Dolores (Track) was declared post-tropical off the coast of Baja California at 0300 UTC on 19 July. Farther to the west, Pacific Tropical Storm Enrique was declared post-tropical at 0300 on 18 July. High pressure aloft was helping support a Gulf Surge, a surge of moisture up the Gulf of California towards the desert southwest. Two animations of MIMIC Total Precipitable Water, below, show the surge and also show that moisture associated with main circulation of Dolores remains mostly offshore until late on the 19th, after the heavy rains had ended.

MIMIC Total Precipitable Water, 0000 UTC on 15 July through 0000 UTC on 18 July 2015 (click to enlarge)

MIMIC Total Precipitable Water, 0000 UTC on 15 July through 0000 UTC on 18 July 2015 (click to enlarge)

MIMIC Total Precipitable Water, 0000 UTC on 18 July through 0000 UTC on 21 July 2015  (click to enlarge)

MIMIC Total Precipitable Water, 0000 UTC on 18 July through 0000 UTC on 21 July 2015 (click to enlarge)

The Blended Precipitable Water Product (data collected from this site), below, also shows evidence of a Gulf Surge of moisture moving northward through the Gulf of California in the few days preceding the rains.

NESDIS Blended Total Precipitable Water (left) and Percent of Normal (right), 1200 UTC on 15 July through 1200 UTC on 20 July 2015 (click to animate)

NESDIS Blended Total Precipitable Water (left) and Percent of Normal (right), 1200 UTC on 15 July through 1200 UTC on 20 July 2015 (click to animate)

The animation of 10.7 µm imagery, below, suggests that the precipitation on Saturday the 18th was associated more with the Gulf Surge of moisture (which surge was likely influenced both by the large scale synoptic flow and by the circulation of Dolores); precipitation on Sunday the 19th seems more directly influenced by Dolores.

GOES-15 Infrared (10.7 µm) Images  (click to play animation)

GOES-15 Infrared (10.7 µm) Images (click to play animation)

What part did the upper-level outflow jets from the two tropical cyclones play in this event? Consider the water vapor animation below, zoomed in from the larger-scale view at the top of this post. Outflow from Enrique moves from the southwest part of the domain towards the southern California coast (the low-level circulation of Enrique are at the southwest edge of the domain), moving inland as convection develops on Saturday 18 July 2015. The Total Precipitable Water imagery suggests that convection starts as the leading edge of the Gulf Surge arrives; water vapor imagery suggests a tie to Enrique.

GOES-15 Infrared Water Vapor (6.5 µm) Images  (click to play animation)

GOES-15 Infrared Water Vapor (6.5 µm) Images (click to play animation)

GOES-15 Visible Imagery, below, from Saturday the 18th and from Saturday the 19th suggest rain on 19 July was more directly tied to the circulation of Dolores. On both days, the convective nature of the precipitation is apparent, with numerous overshooting tops present. Convection on Sunday the 19th started over higher terrain first, and then was joined by tropical convection moving in from the ocean.

GOES-15 Visible (0.65 µm) Images, 1300 UTC 18 July through 0300 UTC 19 July 2015  (click to play animation)

GOES-15 Visible (0.65 µm) Images (click to play animation)

GOES-15 Visible (0.65 µm) Images, 1300 UTC 19 July through 0300 UTC 20 July 2015  (click to play animation)

GOES-15 Visible (0.65 µm) Images (click to play animation)

As might be expected, the San Diego sounding (source) shows deep tropical moisture late on the 18th and late on the 19th as the heavy rains occurred. The precipitable water value of 2.10″ at 0000 UTC on 20 July was a top 5 value for July (Source). The rains caused two spikes in the flow of the San Diego River (Link, courtesy Alex Tardy, NWS San Diego).

Stuve plots of radiosonde data at 72293, 0000 and 1200 UTC 19 July and 0000 UTC 20 July 2015  (click to enlarge)

Stuve plots of radiosonde data at 72293, 0000 and 1200 UTC 19 July and 0000 UTC 20 July 2015 (click to enlarge)

The convection over San Diego produced many lightning strikes on Saturday, as shown on the map below, courtesy of Alex Tardy, NWS San Diego.

Lightning Strikes for the 24 hours ending 2 PM PDT on Saturday 18 July 2015 (click to enlarge)

Lightning Strikes for the 24 hours ending 2 PM PDT on Saturday 18 July 2015 (click to enlarge)