AWIPS images of global water vapor composites (above) showed a large and powerful Pacific storm that was beginning to impact the US West Coast on 04 January 2008. This storm was tapping a very long plume of high total precipitable water (TPW) originating from the western Pacific Ocean, as seen in an animation of MIMIC TPW (below).

The dynamics associated with this storm were also impressive, with a very strong polar jet stream that stretched across the entire Pacific Ocean. AWIPS images of the GFS model Maximum Wind field (below) indicated jet stream wind speeds as high as 210 knots over the North Pacific (south of Alaska’s Aleutian Islands) and greater than 170 knots over Japan at 06:00 UTC on 04 January.

MADIS satellite-derived atmospheric motion vectors (AMVs) produced using hourly water vapor imagery (below) showed a large number of high-altitude wind targets having speeds of greater than 200 knots during the period between 03 January at 12:00 UTC and 04 January at 18:00 UTC. The highest satellite-derived water vapor wind speed seen was 252 knots at a pressure of 258 mb; satellite winds of greater that 100 knots had moved inland over California after 15:00 UTC on 04 January.

A beautiful view of the storm was captured on AWIPS images of the MODIS visible, IR window, and water vapor channels (below).

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A sequence of MODIS true color images (from the SSEC MODIS Direct Broadcast site) covering the period from 27 November 2007 to 02 January 2008 (above) shows the transition from predominantly bare ground (with only isolated patches of thin snow cover) at the end of November to widespread deep snow cover across all of southern Wisconsin during the month of December 2007. Madison, Wisconsin (located at the center of the images) experienced its second snowiest December on record, with 33.5 inches falling during the month. The maximum snow depth at the Madison airport was 12 inches (on both 12 and 16 December), but NWS Cooperative Observers in the Madison metro area reported snow depths as high as 16 inches; across southern Wisconsin, a maximum snow depth of 22 inches was reported at Germantown and Jackson.

While the official temperature at the Madison airport did get as low as -10ºF on 06 December, the month as a whole was only 1.8ºF below normal (average temperature: 21.2ºF); as a result, the lakes in the Madison area froze within about a week of their median freeze dates. The images above show that several of the more shallow lakes southeast of Madison were the first to freeze, with the largest of the Madison lakes (Lake Mendota) appearing totally frozen and white with deep snow cover on the final 02 January 2008 true color image. Contrast this to the previous winter season, when Lake Mendota did not freeze until 20 January 2007 (the second latest freeze date on record!).

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An animation of GOES-12 3.9 µm shortwave IR (nighttime) and visible channel (daytime) images (above) shows a well-defined meso-vortex and single lake-effect snow (LES) band moving southward across the southern portion of Lake Michigan on 02 January 2008. This narrow (but intense) LES band and meso-vortex contributed to impressive storm total snowfall amounts that included 26.0 inches at Hudson Lake, Indiana (located about 15 miles west of South Bend, Indiana — station identifier KSBN) and 18.5 inches at Buchanan, Michigan (located about 10 miles northwest of KSBN) — however, it appears that the majority of those storm total snowfall amounts were due to synoptic-scale snow and lake-enhanced snow processes during the preceding 24-48 hours.

Mid-lake convergence played a role in the formation and maintenance of the LES band, as seen in an AWIPS image of the MODIS visible channel with CIMSS GOES Mesoscale Winds overlaid (below).

An AWIPS 4-panel display of MODIS images (below) shows the visible channel (upper left panel), 2.1 µm near-IR “Snow/Ice” channel (upper right panel), Cloud Top Temperature product (lower left panel), and Cloud Phase product (lower right panel) at 16:45 UTC (10:45 am local time). The darker appearance of the thickest (eastern) portion of the LES band on the MODIS “snow/ice” image suggested that part of the cloud band had glaciated and was composted primarily of ice crystals at that time (snow and ice are strong absorbers at the 2.1 µm wavelength, and appear much darker than supercooled water droplet clouds on the MODIS Snow/Ice channel imagery); this idea was further supported by corresponding MODIS Cloud Top Temperatures in the -15ºC to -20ºC range (cyan to dark blue enhancement, lower left panel) and “mixed phase” pixels on the MODIS Cloud Phase product (dark gray enhancement, lower right panel).

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If you thought that Tropical Storm Olga was the last gasp of the 2007 North Atlantic basin’s Tropical Cyclone season, think again: GOES-12 10.7 µm IR channel imagery (above; closer view) and 6.5 µm water vapor channel imagery (below) revealed a circulation southwest of the Azores on 29 December 2007 (centered near 28º North latitude, 47º West longitude) that appeared to be acquiring subtropical characteristics as it began to produce gale-force winds and some convection (evident in this 500-m resolution MODIS visible image) within the northeastern quadrant of the disturbance.

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A Meteosat-8 visible channel image (above) showed the circulation well off the coast of Africa at 12:00 UTC on 29 December. In addition, note the “hazy” appearance of the cloud-free region over and just south of the Cap-Vert region of northwestern Africa (not the larger sun glint feature seen farther south over the subtropical South Atlantic — the Saharan Air Layer (SAL) tracking product (below) suggests that this could be an area of airborne dust (yellow to orange enhancement) moving westward from the Sahara desert across the far eastern Atlantic Ocean (a good deal of the yellow-to-orange signal across the rest of the North Atlantic is a “false positive” SAL/dust signal).

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