Train derailment fire in Lac-Mégantic, Quebec

July 6th, 2013 |
GOES-13 3.9 µm shortwave IR images (click image to play animation)

GOES-13 3.9 µm shortwave IR images (click image to play animation)

A large fire resulted from a train derailment in the town of Lac-Mégantic, Quebec at around 05:15 UTC (1:15 AM local time) on 06 July 2013. According to the TSB investigation report and a CBC news story, the 72 rail cars were carrying crude oil. AWIPS images of 4-km resolution GOES-13 3.9 µm shortwave IR images (above; click image to play animation) revealed the fire “hot spot” (black to yellow to red pixels), with a maximum IR brightness temperature value of 36.5º C on the 05:30 UTC image.

The fire hot spot was no longer evident on the GOES-13 3.9 µm shortwave IR images after 06:15 UTC, perhaps because of partial obscuration by the approach of a patch of mid/high altitude clouds from the west — however, a well-defined fire hot spot (with a maximum IR brightness temperature value of 54.5º C) was still evident on a 375-meter resolution (mapped onto a 1-km AWIPS grid) Suomi NPP VIIRS 3.74 µm shortwave IR image at 06:21 UTC (below).

GOES-13 3.9 µm and Suomi NPP VIIRS 3.74 µm shortwave IR images

GOES-13 3.9 µm and Suomi NPP VIIRS 3.74 µm shortwave IR images

In addition to the fire hot spot on seen the VIIRS shortwave IR image, a very large and bright glow from the fire was apparent on the corresponding 0.7 µm VIIRS Day/Night Band image (below).

Suomi NPP VIIRS 3.74 µm shortwave IR and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 3.74 µm shortwave IR and 0.7 µm Day/Night Band images

Hat-tip to Dan St. Jean of the National Weather Service forecast office at Gray/Portland, Maine for the heads-up on this event.

Potential Vorticity (PV) anomaly aiding convective development

July 2nd, 2013 |
GOES-13 0.63 µm visible channel images (click image to play animation)

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

AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the development of pockets of thunderstorms across Iowa, eastern Nebraska, and northwestern Missouri  on 02 July 2013.  Several of these storms produced hail up to 1 inch in diameter (SPC storm reports).

Note the pronounced cyclonic spin across the region of thunderstorm development — this was due to the approach of a compact shortwave trough that was rotating around the western periphery of a larger-scale upper-level trough of low pressure that was centered over the middle Mississippi River valley on that day. This shortwave trough had a nice signature on GOES-13 6.5 µm water vapor channel images (below; click image to play animation).

GOES-13 0.65 µm water channel images (click image to play animation)

GOES-13 0.65 µm water channel images (click image to play animation)

GOES-13 sounder Total Column Ozone product

GOES-13 sounder Total Column Ozone product

In addition, the GOES-13 sounder Total Column Ozone (TCO) product (above; click image to play animation) revealed that a distinct maximum in TCO values (red color enhancement) accompanied this disturbance. NAM40 model overlays of the pressure of the Potential Vorticity (PV) 1.5 surface (a general indicator of the height of the dynamic tropopause) suggested that a PV anomaly was associated with the high TCO values (below) — and this PV anomaly was likely helping to dynamically force some of the development of thunderstorms seen across the region.

GOES-13 sounder Total Column Ozone product with NAM40 PV 1.5 pressure and 500 hPa geopotential height

GOES-13 sounder Total Column Ozone product with NAM40 PV 1.5 pressure and 500 hPa geopotential height