MODIS true color and false color RGB images from 08/09/10/11 June

The High Park Fire was started by lightning early in the morning on 09 June 2012, approximately 15 miles west of Fort Collins (InciWeb). Daily comparisons of 250-meter resolution MODIS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) are shown for 08 June (the day before the fire started; note the burn scar on the false color image from the Hewlett Fire that burned near that same location back in May 2012), and then after the fire was burning on 09 June, 10 June, and 11 June 2012. The areal extent of the smoke is clearly seen on the true color images, while the false color images show very hot active fires (bright pink on the 09 and 10 June images) or the coverage of the burn scar (the light brown feature seen through the thin veil of smoke on the 11 June image).

AWIPS images of 1-km resolution MODIS 3.7 µm shortwave IR data (below) showed the growth of the fire “hot spot” from 19:42 UTC on 09 June to 09:18 UTC on 10 June. Note how the fire hot spot was seen to grow eastward and then curve southward in the wake of a cold frontal passage that brought strong northerly winds to the region.

MODIS 3.7 µm shortwave IR images from 09/10 June

The curved shape of the fire hot spot was more clearly seen on a 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 3.74 µm shortwave IR image at 08:30 UTC or 2″30 AM local time on 10 June (below). The corresponding 0.7 µm VIIRS Day/Night Band image showed the bright glow of the actively burning fire complex, which was likely accentuated with moonlight reflection off the top of the dense smoke plumes that were rising over the fire source region.

Suomi NPP VIIRS 3.74 µm shortwave IR + 0.7 µm Day/Night Band image

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GOES-13 6.5 µm water vapor channel + CRAS 500 hPa heights (click image to play animation)

AWIPS images of GOES-13 6.5 µm water vapor channel data with overlays of CRAS model 500 hPa geopotential height (above; click image to play animation) showed the circulation of an upper-level low over the western Gulf of Mexico coastal region, with a southwesterly flow of moisture aiding the development of areas of deep convection across the eastern Gulf Coast states during the 08 June – 09 June 2012 period.

MIMIC Total Precipitable Water product (click image to play animation)

Both the MIMIC Total Precipitable Water (TPW) product (above; click image to play animation) and the Blended Total Precipitable Water product (below; click image to play animation) indicated that there was a prolonged plume of high TPW values in excess of 55 mm (2.2 inches) streaming northeastward toward the eastern Gulf Coast region during this time period. In addition, the presence of a quasi-stationary frontal boundary helped to provide a forcing mechanism for enhancing lift and focusing the development and intensification of deep convection.

Blended Total Precipitable Water product (click image to play animation)

A sequence of 1-km resolution MODIS 11.0 µm IR, POES AVHRR 12.0 µm IR, and Suomi NPP VIIRS 11.45 µm IR images (below) showed some of the more well-developed areas of deep convection that moved across the region on 09 June. Very heavy rainfall resulted at some locations on that day, including 13.13 inches being recorded at Pensacola, Florida (their second-highest daily precipitation total on record). A COCORAHS station near Pensacola reported a total of 21.70 inches of rain in the 24 hours ending at 8 AM local time on 10 June. Mobile, Alabama received 5.79 inches of rainfall, setting a new daily record for 09 June.

MODIS 11.0 µm + POES AVHRR 12.0 µm + Suomi NPP VIIRS 11.45 µm IR images

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GOES-13 0.63 µm visible channel images (click image to play animation)

Parts of the north-central US (namely, western and central North Dakota and South Dakota, and far eastern Montana and Wyoming) received upwards of 0.5 to 1.0 inch of rainfall (Radar estimated precipitation | Regional temperature/precipitation data) in association with a slow-moving frontal boundary on 07 June 2012. With moist soil and strong radiational cooling during the following night (overnight lows included 43 F at Williston, North Dakota, 42 F at Hoover, South Dakota, and 38 F at Medicine Lake, Montana), areas of fog and low stratus clouds developed during the pre-dawn hours on 08 June 2012. AWIPS images of 1-km resolution GOES-13 0.63 µm visible channel data (above; click image to play animation) showed that these fog and low stratus cloud features quickly dissipated after sunrise with solar heating and increasing southeasterly winds.

A comparison of 4-km resolution GOES-13 and 375-meter resolution Suomi NPP VIIRS brightness temperature difference (BTD) “fog/stratus product” images just after 09 UTC or 4 AM local time (below) demonstrated the advantage of higher spatial resolution data for (1) depicting the formation of the more subtle valley fog features, and (2) more accurately defining the edges of low stratus cloud features.

GOES-13 vs Suomi NPP VIIRS "fog/stratus product" images

A comparison of the Suomi NPP VIIRS “fog/stratus product” with the corresponding 0.7 µm Day/Night Band (DNB) image (below) showed that with the moon in the waning gibbous phase (75% of full moon), the vertically-thicker low stratus cloud features in the western portion of the satellite scene were more brightly illuminated that the areas of thinner valley fog. It is also interesting to note the widespread bright DNB features associated with natural gas flares and illuminated man camps that are part of the extensive drilling operations across the Bakkan oil shale field (primarily in northwestern North Dakota; MSNBC news story).

Suomi NPP VIIRS "fog/stratus product" and Day/Night Band images

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GOES-12 10.7 µm IR image using Side 1 electronics (left) and Side 2 electronics (right)

At 1645 UTC on 6 June, an Electronics Side Swap occurred for GOES-12 to mitigate the effects of Cycle Slips that were occurring around 0800-1300 UTC each day (See this link for an explanation). No Cycle Slips occurred in the GOES-12 imager data on 7 June; as a result, the images are much cleaner. The image above shows an enhanced 10.7 µm image from June 4 2012 using the Side 1 electronics, which side was plagued by cycle slips, and from June 7 2012 using the Side 2 electronics, which show no cycle slips.

GOES-12 Imager (all channels) for 0945 UTC on June 4th and on June 7th (click image to play animation)

The Cycle Slips affected all bands. Click the image above to see the improvement across all bands between 0945 UTC on 4 June and 0945 UTC on 7 June. Note that there will be slight differences for a given input radiance in the computed brightness temperature for each band for the Side 2 Planck conversion coefficients versus the Side 1 Planck conversion coefficients. Those differences are, for Band 2, 0.0001K for both detectors; for Band 3, -0.0001 K for detector ‘a’, 0.0631 K for detector ‘b’; for Band 4, -0.0001 K for both detectors and for Band 6, 0.0119 K. These differences are much smaller than the instrument noise.

Real-time imagery of GOES-South America imager and sounder data are available here.

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