Okreek Fire in south-central South Dakota

October 5th, 2011 |
GOES-11 + GOES-15 + GOES-13 visible channel images

GOES-11 + GOES-15 + GOES-13 visible channel images

Strong southerly winds (gusting as high as 50 mph) helped a large grassland fire (named the Okreek fire) spread rapidly northward across south-central South Dakota during the afternoon hours on 05 October 2011. The light gray smoke plume and the dark burn scar grew very quickly, which could be seen on GOES-11 (GOES-West),  GOES-15, and GOES-13 (GOES-East) visible channel images (above). Each of the 3 sets of images is displayed in the native projection of the respective satellite.

The corresponding 3.9 µm shortwave IR images from each satellite (below) showed the large and intense “hot spot” (dark black to yellow pixels) associated with the Okreek fire. Note there were also a few other smaller fires burning in other parts of central South Dakota during that time period, which also exhibited very intense hot spot signatures.

GOES-11 + GOES-15 + GOES-13 shortwave IR images

GOES-11 + GOES-15 + GOES-13 shortwave IR images

A comparison of 250-meter resolution false-color Red/Green/Blue (RGB) images from the SSEC MODIS Today site from before (04 October), during (05 October), and after (07 October) the Okreek fire revealed the development and growth of the 26 mile long burn scar (which appears as the light brown line). The bright pink feature on the 05 October image was the heat signature of the active front line of the fire, which was rapidly advancing northward on that day.

MODIS false-color RGB images from 04 October, 05 October, and 07 October 2011

MODIS false-color RGB images from 04 October, 05 October, and 07 October 2011

 

Fog and stratus in the Ohio River Valley and central Appalachians

October 5th, 2011 |
MODIS and GOES-13 fog/stratus product images

MODIS and GOES-13 fog/stratus product images

Strong nocturnal radiational cooling beneath a large area of high pressure centered over the Ohio River Valley led to the formation of widespread areas of fog and stratus on 05 October 2011. AWIPS image comparisons of the 1-km resolution MODIS and the 4-km resolution GOES-13 fog/stratus products at 03:30 UTC or 11:30 pm local time (above) and 07:45 UTC  or 3:45 am local time (below) demonstrated the clear advantage of having improved spatial resolution to detect the more subtle features such as river valley fog.

MODIS and GOES-13 fog/stratus product images

MODIS and GOES-13 fog/stratus product images

 

To compliment the improved fog/stratus detection capabilities offered by higher spatial resolution, other products are being developed (as part of the CIMSS participation in GOES-R Proving Ground activities) that provide more quantitative information about areas of fog and/or low cloud: for example, Fog Depth, Marginal Visual Flight Rules (MVFR) Probability, and Instrument Flight Rules (IFR) Probability (below). In this case, the 07:45 UTC products indicated that the Fog Depth values were as high as 1231 feet (cyan color enhancement) over parts of northern West Virginia, where there were also MVFR Probabilities greater than 90% and IFR Probabilities greater than 75% (brighter red color enhancement).

GOES-13 fog/stratus product, Fog Depth, MVFR Probability, and IFR Probability

GOES-13 fog/stratus product, Fog Depth, MVFR Probability, and IFR Probability