Strong storm in the Gulf of Alaska

November 2nd, 2012 |
POES AVHRR 0.86 µm visible channel and 12.0 µm IR channel images

POES AVHRR 0.86 µm visible channel and 12.0 µm IR channel images

A strong storm (with a central pressure near 950 hPa or 28.05″) had been intensifying over the Gulf of Alaska on 02 November 2012, and eventually began to enhibit a classic tightly-wrapped signature of a cyclone that had reached the occluded stage on POES AVHRR 0.86 µm visible channel and 12.0 µ IR images at 19:05 UTC (above) and also on MODIS 0.64 µm visible channel and 11.0 µm IR channel images at 21:00 UTC (below). This storm was producing widespread storm-force winds, with some gusts to hurricane force over the western Gulf of Alaska.

MODIS 0.64 µm visible channel and 11.0 µm IR channel images

MODIS 0.64 µm visible channel and 11.0 µm IR channel images

High-elevation snow cover remaining from “Superstorm Sandy”

November 2nd, 2012 |
MODIS 0.65 µm visible channel and false-color Red/Green/Blue (RGB) images

MODIS 0.65 µm visible channel and false-color Red/Green/Blue (RGB) images

Cold air and upslope flow on the western side of Hurricane Sandy contributed to some very impressive snowfall totals across parts of the central Appalachian Mountains in the eastern US (HPC storm summary)| HPC snowfall contour map). Once some of the cloud cover began to clear from the region on 02 November 2012, a comparison of AWIPS images of visible channel data and false-color Red/Green/Blue (RGB) composites from MODIS at 16:09 UTC or 12:09 PM local time (above) and again at 17:55 UTC or 1:55 PM local time (below) revealed the extent of the remaining high-elevation snow cover. On the false-color RGB images (created using the 2.1 µm “snow/ice channel” on MODIS, and the 1.61 µm “snow/ice channel” on VIIRS as the Green and Blue components of the image composites), snow cover appeared as the darker red features (which also appeared white on the corresponding visible images).

Data from the National Operational Hydrologic Information Center (observed snow depth | model-derived snow depth) indicated that some sites still had a snow depth in excess of 20 inches on on the morning of 02 November.

Suomi NPP VIIRS 0.64 µm visible channel and false-color Red/Green/Blue (RGB) images

Suomi NPP VIIRS 0.64 µm visible channel and false-color Red/Green/Blue (RGB) images