GOES-13 10.7 µm IR channel images (click image to play animation)

From the Area Forecast Discussion issued by the National Weather Service forecast office in St. Louis, Missouri:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
340 AM CST SUN FEB 3 2013

.SHORT TERM…
ISSUED AT 330 AM CST SUN FEB 3 2013
(TODAY THROUGH TUESDAY)

THANKS TO A COMPACT AND POTENT NW FLOW VORT MAX…SOME RATHER IMPRESSIVE LOW LEVEL FORCING AND A POCKET OF STEEP MID LEVEL LAPSE RATES…A NICE BAND OF 2-4 INCHES OF SNOW FELL LAST NIGHT WITH THE HIGHEST AMOUNTS CENTERED RIGHT THROUGH THE ST LOUIS METRO. KUDOS TO THE SAT AFTERNOON RUNS OF THE HRRR WHICH WAS THE SOLE MODEL THAT COMPLETELY NAILED THE SNOWFALL FORECAST.

A sequence of 4-km resolution GOES-13 10.7 µm IR channel images (above; click image to play animation) showed the disturbance as it was moving southeastward through the region during the night-time (pre-dawn) hours on 03 February 2013. Some of the cloud elements appeared to be convective in nature, with cloud top IR brightness temperatures as cold as -40 C (yellow color enhancement).

A comparison of a 4-km resolution GOES-13 10.7 µm IR image with a 1-km resolution MODIS 11.0 µm IR image (below) demonstrated the advantage of improved spatial resolution for depicting the location and edges of the individual cloud elements with polar-orbiting satellite imagery. Despite the times shown on the image labels, the actual times that the 2 satellites were scanning this area were fairly close — the northwestward displacement of the cloud features on the GOES-13  IR image is due to parallax.

MODIS 11.0 µm IR channel and GOES-13 10.7 µm IR channel images

On the following afternoon, a comparison of a 1-km resolution Suomi NPP VIIRS 0.64 µm visible channel image with the corresponding False-color Red/Green/Blue (RGB) image at 18:51 UTC or 12:51 PM local time (below) showed the northwest-to-southeast oriented swath of snowfall — snow on the ground appeared as the darker shades of red in the RGB image. The highest snowfall amount reported was 5.0 inches (NWS St. Louis event summary).

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

A closer view using 250-meter resolution MODIS true-color and false-color RGB images from the SSEC MODIS Today site (below) showed the snow cover at 19:03 UTC or 1:03 PM local time. In this particular false-color RGB, snow cover appears as shades of cyan.

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

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Suomi NPP VIIRS 0.7 µm Day/Night Band, 11.45 µm IR channel, and IR brightness temperature difference “fog/stratus product” images

On a comparison of AWIPS images of Suomi NPP VIIRS 0.7 µm Day/Night Band, 11.45 µm IR channel, and IR brightness temperature difference “fog/stratus product” data at 08:09 UTC or 2:09 AM local time on 01 February 2013 (above), one prominent feature that stood out across the middle of the Day/Night Band image was the broad swath of fresh snow cover that extended northeastward from Kansas to Wisconsin. This band of snow cover resulted from a winter storm that produced snowfall amounts as high as 4.0 inches in Kansas, 6.0 inches in Nebraska, 7.8 inches in Iowa, and 12.0 inches in Wisconsin on 29-30 January (snowfall map). The IR and “fog/stratus product” images indicated that some layers of stratus clouds were moving over the southwestern portion of the snow swath (over Kansas and Nebraska), but the edge of the snow swath could still be seen throgh these thin cloud features.

Cold air in the wake of the storm then caused laked-effect snows in excess of 12 inches across parts of the Upper Peninsula of Michigan. A close-up view of Lake Superior using the VIIRS Day/Night Band and IR channel images (below) showed the widespread lake-effect snow bands, which showed up nicely due to the “visible image at night” utility of the Day/Night Band (provided that there is adequate illumination by moonlight).

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

Also of interest were a series of long, very narrow streaks of snow cover across parts of Illinois — in particular, the one than ran just southwest of Springfiled KSPI — which could be seen on the Day/Night Band image at 08:09 UTC or 2:09 AM local time, and again during the daytime at 17:50 UTC or 11:50 AM local time (below).

Suomi NPP VIIRS 0.7 µm Day/Night Band and 0.64 µm visible channel images

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MODIS 0.65 µm visible channel and 11.0 µm IR channel images, with METAR surface reports and SPC storm reports

AWIPS images of 1-km resolution MODIS 0.65 µm visible channel and 11.0 µm InfraRed (IR) channel images with an overlay of METAR surface reports and SPC storm reports (above) displayed a number of distinct banded convective features across parts of the Southeast US at 16:04 UTC or 11:04 AM local time on 30 January 2013. This banded structure could also be seen on a sequence of 1-km resolution POES AVHRR visible and IR images. In northwestern Georgia, note the isolated convective feature that produced a cluster of tornado and damaging wind reports — one of these tornadoes (rated EF-3) was responsible for a fatality in Adairsville, Georgia (NWS Peachtree City GA event summary), which ended a record 220-day streak with no tornado fatalities in the US.

GOES-13 10.7 µm IR channel images (click image to play animation)

On 4-km resolution GOES-13 10.7 µm IR channel images (above; click image to play animation) and 6.5 µm water vapor channel images (below; click image to play animation) this banded structure was quite evient throughout the morning and afternoon hours within the warm conveyor belt of moisture that was helping to fuel the pre-frontal squall line that was producing widespred severe weather across the region.

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

Blended Total Precipitable Water and Surface frontal analysis

Large amounts of moisture were being transported northward from the Gulf of Mexico ahead of the advancing cold frontal boundary — Blended Total Precipitable Water (TPW) values were in the 30-40 mm or 1.2-1.6 inch range (above; animation), and these TPW values were in excess of 200% of normal for this region and this time of the year (below; animation).

Percent of Normal TPW and Surface frontal analysis

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MODIS 11.0-3.7 µm IR brightness temperature difference “fog/stratus product”

An AWIPS image of the MODIS 11.0-3.7 µm IR brightness temperature difference “fog/stratus product” (above) indicated that fog/stratus features were in place across parts of the Southeast US, as well as along and just off the coast of Georgia, South Carolina, and North Carolina at 07:33 UTC or 2:33 AM local time on 29 January 2013.

The GOES-13 Instrument Flight Rules (IFR) Probability product (below; click image to play animation) showed very high probabilities of IFR conditions at many inland locations, but also suggested that the fog/stratus features were extending much farther off the coast.

GOES-13 IFR Probability product (click image to play animation)

During the daylight hours, McIDAS images of GOES-13 0.63 µm visible channel data (below; click image to play animation) showed that the near-shore sea fog did indeed persist for much of the day, especially off much of the Georgia and South Carolina coastlines.

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

A comparison of the MODIS 0.65 µm visible channel image and the corresponding MODIS Sea Surface Temperature (SST) product at 18:40 UTC or 1:40 PM local time (below) showed the reason for the persistent sea fog: there was an onshore flow of air with dew points in the lower to middle 60s F, moving over the cooler near-shore waters with SST values in the lower to middle 50s F.

MODIS 0.65 µm visible channel image + MODIS Sea Surface Temperature product

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