Due to illumination by moonlight — the Moon was in the waning crescent phase, at 40% of full — a broad area of snow cover could be seen over parts of the High Plains and Foothills regions of the US on an AWIPS image of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) data at 08:15 UTC or 1:15 AM local time on 24 January 2014 (above). This was what remained of the general 1-4 inches of new snow that fell over that area, aided by upslope flow in the wake of a southward-moving cold frontal passage on 23 January.

A comparison of this Day/Night Band image with the corresponding VIIRS 11.45-3.74 µm IR brightness temperature difference (BTD) “Fog/stratus product” and 11.45 µm IR channel images (below) confirmed that this feature seen on the DNB image was not an area of fog or low-level clouds (although some patches of cold high-altitude clouds were seen from far northern Colorado into Wyoming and Nebraska). On the 11.45 µm IR image, some areas in eastern Colorado exhibited IR brightness temperature values of -30º C or colder (yellow color enhancement) — these were likely locations where the snow cover was the deepest, allowing faster radiational cooling of the surface air layer.

A Suomi NPP VIIRS 0.64 µm visible channel image at 19:42 UTC or 12:42 PM on the following afternoon (below) showed that while the areal coverage of the snow cover had decreased with daytime heating, what snow cover did remain was acting to hold surface air temperatures down at least 10-15º F compared to adjacent bare-ground locations.

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McIDAS images of 4-km resolution GOES-15 6.5 µm water vapor channel data (above; click images to play animation) showed the dramatic signature of rapid intensification of a very large mid-latitude cyclone over the eastern Pacific Ocean during the 20 January – 23 January 2014 time period.

A comparison of AWIPS images of 1-km resolution Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel data (below) revealed the tightly-wrapped center of circulation at 13:01 UTC on 20 January. Intricate mesoscale banding structures could also be seen within portions of the warm conveyor belt southeast and east of the storm center (which was analyzed to have a central pressure of 956 hPa).

A Suomi NPP VIIRS 0.64 µm visible channel image (below) showed a small but well-defined comma-shaped cloud feature marking the center of the storm at 00:13 UTC on 21 January (which was analyzed to have a central pressure of 952 hPa).

A Suomi NPP VIIRS 0.64 µm visible channel image at 23:54 UTC on 21 January (below) depicted the band of clouds associated with the 950 hPa cyclone’s cold front as it approached the northwestern portion of the Hawaiian Island chain. A narrow “rope cloud” marked the leading edge of the cold frontal boundary.

In a closer view centered over the Hawaiian Islands at 23:54 UTC on 21 January (below), a hazy “vog” plume (from the active Kilauea volcano on the Big Island) could be seen blowing northeastward ahead of the approaching cold front. Note how the areal coverage of the vog plume shows up better in the broadband 0.7 µm Day/Night Band image compared to the 0.64 µm visible channel image with its more narrow spectral width.

Finally, a Suomi NPP VIIRS 0.64 µm visible channel image at 23:35 UTC on 22 January (below) showed the cold frontal band as the leading edge was about to move southeast of the Big Island of Hawaii. Note that Honolulu (PHNL) had a temperature/dewpoint of 78ºF/45ºF, with northwesterly winds gusting to 34 knots at 00 UTC. Wind speeds on the summits of the Big Island of Hawaii were sustained hurricane force, with gusts to near 100 mph. The strong winds also caused a giant northwesterly ocean swell, with significant wave heights as high as 31 feet at Buoy 51101 (located 91 miles northwest of Kauai). There was also a notable air temperature drop at Buoy 51101 as the cold front passed, with a peak wind gust of 39 knots.

GOES-15 0.63 µm visible channel images (below; click image to play animation) showed the cold front as it was passing through the Hawaiian Island chain on 22 January. A few areas of orographic wave clouds could be seen as the strong northwesterly winds in the wake of the cold front interacted with the topography of the islands.

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McIDAS images of MTSAT-2 daytime 0.675 µm visible channel data and night-time 10.8 µm IR channel data (above; click image to play animation; also available as an MP4 animation) showed a monsoon low which exhibited a well-defined circulation for several days as it slowly tracked southwestward across the northwestern portion of Australia during the 15-21 January 2014 time period.

The mean seal level pressure analyses from the Australian Bureau of Meteorology (below; click image to play animation) indicated that the monsoon low deepened to a pressure of 988 hPa at 12 UTC on 19 January.

MTSAT-2 visible images and surface observations during the 17-18 January period are shown below (click image to play animation), visualized using the SSEC RealEarth web map server.

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A comparison of AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel data with the corresponding false-color “snow-vs-cloud discrimination” Red/Green/Blue (RGB) product (above) revealed numerous northwest-to-southeast oriented mesoscale bands of snow on the ground (varying shades of red on the RGB image) across much of Iowa extending into northern Missouri at 18:30 UTC or 12:30 PM local time on 17 January 2014. Some of these bands of snow cover appeared to be only about 10 miles wide!

The disturbance that created these snow bands moved across the region on the previous day (16 January) — GOES-13 0.63 µm visible channel images (below; click image to play animation) showed the development of a feature that resembled a “mesoscale squall line” which propagated southeastward across Iowa during the daylight hours. Surface METAR observations showed the strong winds (gusting to over 50 mph at a few sites) which created blizzard conditions as the fresh snowfall was easily lofted from the ground. Note that there was even one negative cloud-to-ground lightning strike noted just west of Des Moines (station identifier KDSM) at 21:45 UTC or 3:45 PM local time, indicating the presence of convective elements within the squall line which led to enhanced snowfall rates — in fact, the maximum snowfall reported from this fast-moving system was 3.1 inches at Des Moines (where surface visibility was reduced to 1/16 mile with thundersnow).

For a radar animation of the feature, see this NWS Des Moines event summary.

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