Historic October Northeastern US Snowstorm

October 30th, 2011
GOES-13 6.5 µm water vapor channel images (click image to play animation)

GOES-13 6.5 µm water vapor channel images (click image to play animation)

A historic early season October winter storm produced snowfall amounts of 12 inches or more across 9 Northeastern US states during the 29 October30 October 2011 period, with a storm total snowfall as high as 32.0 inches reported at Peru, Massachusetts (HPC storm summary). McIDAS images of 4-km resolution GOES-13 6.5 µm water vapor channel data (above; click image to play animation) showed the evolution of the storm system during the period, which included rapid intensification following the approach of a jet streak and associated dry slot.

1-km resolution GOES-13 0.63 µm visible channel images (below; click image to play animation) showed a good portion of the resulting swath of snow cover on the morning of 30 October — areas of inland fog and stratus could be seen burning off across the southwestern portion of the satellite scene, and the center of the storm circulation was very evident over the adjacent offshore waters of the Atlantic Ocean.

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)

An AWIPS image of 1-km resolution MODIS 0.65 µm visible channel data with overlays of ocean buoy data and ASCAT scatterometer surface winds (below) showed that buoy winds were still gusting as high as 56 knots at that time, with a number of 50-knot ASCAT winds to the west and southwest of the center of the circulation.

MODIS 0.65 µm visible channel image + buoy reports + ASCAT surface winds

MODIS 0.65 µm visible channel image + buoy reports + ASCAT surface winds

A comparison of the 0.65 µm MODIS visible channel image with the corresponding false color Red/Green/Blue (RGB) image creted using the MODIS visible channel and the MODIS 2.1 µm “snow/ice” channel (below) was helpful for discriminating between liquid and supercooled water droplet cloud features (which appeared as lighter shades of white) and the swath of snow cover on the ground (or clouds composed of ice crystals, which appeared as shades of red).

MODIS 0.65 µm visible channel + MODIS false color Red/Green/Blue (RGB) image

MODIS 0.65 µm visible channel + MODIS false color Red/Green/Blue (RGB) image

The MIMIC Total Precipitable Water product (below; click image to play animation) indicated that the storm was able to tap into a long plume of tropical moisture (originating in the Caribbean Sea) that was feeding northeastward across the western Atlantic Ocean.

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

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

Snow cover across Colorado

October 27th, 2011
MODIS true color and false color Red/Green/Blue (RGB) images

MODIS true color and false color Red/Green/Blue (RGB) images

The first major winter storm of the season to affect the central Rocky Mountains region produced up to 19.9 inches of snowfall across parts of Colorado on 26 October 2011. On the following day, 250-meter resolution Terra MODIS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) showed a nice view of the resulting snow cover across northeastern Colorado (the snow cover was cyan-colored in the false color RGB image, with cloud features appearing as shades of white). The morning snow depths included 10 inches at Boulder and Greeley, with reports of 12 inches on the ground at a number of higher elevation stations.

A corresponding AWIPS image comparison of 1-km resolution MODIS 0.65 µm visible channel data and a false color RGB image created using the 2.1 µm “snow/ice channel” (below) further demonstrated the utility of using RGB imagery to discriminate between snow cover (which appeared red in this second RGB image) and cloud features (which again appeared as lighter shades of white).

MODIS visible and false color Red/Green/Blue (RGB) image

MODIS visible and false color Red/Green/Blue (RGB) image

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18:13 UTC and 19:53 UTC MODIS false color RGB images

18:13 UTC and 19:53 UTC MODIS false color RGB images

Some of the snow cover began to melt during the day across eastern Colorado, as could be seen in a comparison of the 18:13 UTC (12:13 PM local time) and 19:53 UTC (1:53 PM local time) MODIS false color RGB images (above). GOES-15 0.63 µm visible channel images at 15 minute intervals (below; click image to play animation) more clearly showed the temporal evolution of the melting snow cover.

GOES-15 0.63 µm visible channel images (click image to play animation)

GOES-15 0.63 µm visible channel images (click image to play animation)

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations. Currently there are 49 NWS offices receiving MODIS imagery and products from CIMSS.

Hurricane Rina

October 24th, 2011
GOES-13 0.63 µm visible channel images + ASCAT scatterometer surface winds

GOES-13 0.63 µm visible channel images + ASCAT scatterometer surface winds

Tropical Storm Rina rapidly intensified (CIMSS ADT plot) to hurricane intensity off the coast of Honduras on 24 October 2011 — GOES-13 0.63 µm visible channel images with an overlay of ASCAT scatterometer surface winds from the CIMSS Tropical Cyclones site (above) showed that Hurricane Rina exhibited a central dense overcast early in the day, with convective bursts near the center of the circulation.

A longer animation of GOES-15 10.7 µm IR channel images (below; click image to play animation) revealed a number of convective bursts, with large areas of the central dense overcast exhibiting cloud top IR brightness temperatures of -80ºC or colder (violet color enhancement).

GOES-15 10.7 µm IR channel images (click image to play animation)

GOES-15 10.7 µm IR channel images (click image to play animation)

AWIPS images of the MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) suggested that Hurricane Rina may have been tapping moisture from the Eastern Pacific Ocean Intertropical Convergence Zone / Monsoon Trough.

MIMIC Total Precipitable Water product + tropical surface analysis (click image to play animation)

MIMIC Total Precipitable Water product + tropical surface analysis (click image to play animation)

It is interesting to note that an increasing pressure gradient between high pressure located over the Gulf of Mexico and the deepening circulation of Hurricane Rina was beginning to enhance the intensity of dry Tehuano gap winds flowing southward into the Gulf of Tehuantepec (below).

MIMIC TPW + Tropical surface analysis + ASCAT scatterometer surface winds

MIMIC TPW + Tropical surface analysis + ASCAT scatterometer surface winds

===== 25 October Update =====

NOAA-16 false color Red/Green/Blue (RGB) image

NOAA-16 false color Red/Green/Blue (RGB) image

On 25 October 2011, widespread high altitude cirrus “transverse banding” was seen along the western periphery of Hurricane Rina on a 1-km resolution NOAA-16 false color Red/Green/Blue (RGB) image (above), created using AVHRR visible channels 1 (0.63 µm) and 2 (0.86 µm) along with IR channel 4 (10.8 µm).

4-km resolution GOES-13 6.5 µm “water vapor channel” images (below; click image to play animation) showed that Hurricane Rina was a prolific producer of transverse banding during much of the day. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as often as every 5-10 minutes.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

GOES-13 6.5 µm water vapor channel images (click image to play animation)

1-km resolution GOES-13 0.63 µm visible channel RSO images (below; click image to play animation) revealed the formation of a well-defined eyewall during the afternoon hours.

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)

Blowing dust event in Texas and New Mexico

October 18th, 2011
GOES-11, GOES-15, and GOES-13 visible channel images (click image to play animation)

GOES-11, GOES-15, and GOES-13 visible channel images (click image to play animation)

A major blowing dust event occurred in the wake of a strong cold frontal boundary that moved rapidly southward across western Texas and eastern New Mexico late in the day on 17 October 2011 — the blowing dust reduced surface visibilities to near zero in some locations as winds gusted as high as 75 mph (see NWS Lubbock story). McIDAS images of GOES-11 (GOES-West), GOES-15, and GOES-13 (GOES-East) visible channel data during the daylight hours and shortwave IR data after sunset (above; click image to play animation) showed the southward propagation of the well-defined arc of blowing dust (or “haboob”), along with the surge of cooler air behind the cold front. A few wildfire “hot spots” (darker black pixels) were also evident on the GOES shortwave IR images, a result of fires started by downed power lines.

Much of that region had been experiencing long-term extreme to exceptional drought conditions — and an AWIPS image of the MODIS Normalized Difference Vegetation Index (below) showed very low NDVI values across much of western Texas the day before the dust storm.

MODIS Normalized Difference Vegetation Index

MODIS Normalized Difference Vegetation Index