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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United Airlines Flight 89 enroute from Newark, New Jersey to Beijing, China encountered severe turbulence at an altitude of 33,000 feet over Vermont (pilot report) around 18:31 UTC on 16 January 2014, which injured 5 flight attendants and forced the flight to return to Newark where the injured crew members were taken to local hospitals for evaluation. AWIPS images of 4-km resolution GOES-13 6.5 µm water vapor channel data (above; click image to play animation) showed that a large baroclinic leaf signature was rapidly developing over the northeastern US and southeastern Canada during the day.

17:12 UTC images of 1-km resolution Suomi NPP VIIRS 0.64 µm visible channel data (above) and 11.45 µm IR channel data (below) displayed evidence of “transverse banding” structures along portions of the cloud top of the baroclinic leaf feature — such transverse banding is often associated with turbulence. Pilot reports of turbulence for the hours ending at 17, 18, and 19 UTC are also plotted on the VIIRS images; over this region there were 5 reports of severe turbulence within this 3 hour period.

GOES-13 water vapor images with overlays of CRAS model 250 hPa wind speed isotachs (below) showed that there was a strong (150-160 knot) upper level jet streak along the back (western) edge of the baroclinic leaf during the 12 UTC to 21 UTC period. At 18 UTC, the 2 pilot reports of severe turbulence were located in the vicinity of the left entrance region of the jet streak — an area generally expected to have strong downward vertical velocities forced by ageostrophic circulations near the altitude of the jet streak.

GOES-13 water vapor images with overlays of CRAS model pressure of the PV1.5 surface (below) — generally thought of as representing the dynamic tropopause — indicated that the tropopause was as low as 500-600 hPa within the narrow warm/dry band just west of the back edge of the baroclinic leaf during the 12 UTC – 21 UTC time period.

An automated Turbulence Risk product (below) also indicated that tropopause folding (blue) was occurring along the western edge of the baroclinic leaf, bringing the tropopause as low as 22,500 feet. The yellow ‘+’ symbols represent a portion of the flight track of United Airlines Flight 89.

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An extended period of hot, dry weather led to the development of multiple large bushfires across parts of southeastern Australia, some of which began to produce pyrocumulonimbus (pyroCb) clouds during the 15-16 January 2014 period. McIDAS images of MTSAT-2 0.68 µm visible channel and 3.75 µm shortwave IR channel data (above; click image to play animation; also available as an MP4 animation) showed the development of a well-defined pyroCb associated with the Northern Grampions fire in the state of Victoria. After the visible images on the left panels faded to black during the night-time hours, the shortwave IR images on the right panels showed that many of the fire “hot spots” (denoted by the darker black pixels) continued to grow during the night.

MTSAT-2 10.8 µm longwave IR channel images (below; click image to play animation; also available as an MP4 animation) indicated that cloud-top IR brightness temperatures associated with the rapidly-growing pyroCb cloud became as cold as -38.7º C (lighter green color enhancement) at 07:32 UTC. Other areas of cold-topped thunderstorms developed near the coast, likely initiated by sea breeze and/or local terrain influences. Surface reports ploted on the IR images revealed very hot temperatures: for example, it was 109º F (42.8º C) at Melbourne Essondon (station identifier YMEN) at 04 UTC.

A larger-scale view of MTSAT-2 0.68 µm visible channel images (below, visualized using the SSEC RealEarth web map server) showed that there were some large bushfires to the northwest that were producing long, dense smoke plumes which were drifting southward off the coast.

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