GOES-16 Multispectral views of the eastern United States

March 14th, 2017 |

GOES-16 Snow/Ice (1.61 µm) animation, from 1100 UTC on 12 March through 1800 UTC on 14 March [click to play mp4 animation]

The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing.

The ABI on GOES-16 includes a Snow/Ice Channel at 1.61 µm and a Cirrus Channel at 1.38 µm. These bands offer different perspectives on the evolution of the atmosphere before and during the strong 13-14 March 2017 winter storm on the East Coast of the United States. The Snow/Ice channel, above, is dark in regions where ice clouds or snow on the ground are present because ice is a strong absorber of radiation with a wavelength of 1.61 µm. Water clouds, in contrast, readily reflect such radiation and appear brighter white. Consider the mp4 animation above (available here as a 150-megabyte animated gif). At the start of the animation, on 12 March, snow is indicated over Tennessee, a dark stripe that erodes on that day under the strong March sun. Cirrus retreating southward over the southeastern United States (cloud signals that are grey in the 1.61 µm imagery) reveal much brighter low-level stratus clouds (made of water droplets). Cirrus contrails are apparent above those low clouds. The Mesovortex over the Great Lakes is bright white — water clouds — and is gradually obscured by high-level cirrus clouds from the west and northwest. Terrain-induced wave clouds are also present over Pennsylvania. Their bright color suggests they are composed of water droplets.

On 13 March, low clouds are moving northward over the Piedmont of North Carolina and Virginia as Cirrus clouds spread northeastward from the Deep South. By 14 March, a well-developed wave cyclone is apparent with a large cirrus canopy outlining a warm conveyor belt.

What does the Cirrus Channel, below show? (Click here for a large animated gif.) Strong absorption by water vapor molecules occurs at 1.38 µm. Note, for example, that on 12 March the mesovortex is not apparent in the Cirrus Channel — but the wave clouds over Pennsylvania are. The conclusion is that the atmosphere over the northeast is much dryer than that over the western Great Lakes. On 13-14 March, lake-effect clouds are apparent downwind of Lake Superior in the Upper Peninsula of Michigan and over Wisconsin. The airmass has dried over the Upper Midwest in two days, allowing the Cirrus Channel to view features closer to the surface. In general, the cirrus channel provides outstanding delineation of cloud-top structures over the developing and mature extratropical cyclone.

GOES-16 Cirrus Channel (1.378 µm) animation, from 1100 UTC on 12 March through 1800 UTC on 14 March [click to play mp4 animation]

The Cirrus Channel and the Snow/Ice Channel rely on reflected Solar energy to provide a signal. As such they are useful primarily during the day.

Added: Animations showing the evolution of the three GOES-16 Water Vapor bands during part of the East Coast storm’s lifecycle are available here. A water vapor animation from a CONUS perspective is available here. A better-quality animation centered over the northeast US is available here. Here is an animated gif/mp4 with 6.9 µm brightness temperatures and surface observations. A blog post on this storm is here.

Mesovortex over Lake Michigan

March 12th, 2017 |

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2017/03/170312_0740utc_suomi_npp_viirs_DayNightBand_rtma_surface_winds_Lake_Michigan_mesovortex_anim.gif

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with RTMA surface winds [click to enlarge]

** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **

A Suomi NPP VIIRS Day/Night Band (0.7 µm) image (above) revealed the formative stage of a mesoscale vortex over Lake Michigan at 0740 UTC or 2:40 AM Central time on 12 March 2017.

During the subsequent daylight hours, GOES-16 Visible (0.64 µm) images (below) showed the continued development and motion of the mesovortex.

GOES-16 Visible (0.64 µm) images, with hourly surface reports [click to play animation]

GOES-16 Visible (0.64 µm) images, with hourly surface reports [click to play animation]

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As was shown in a Tweet from NWS Marquette (above), beginning at 1741 UTC one of the GOES-16 Mesoscale Sectors was moved far enough northward to provide 1-minute imagery of the mesovortex (below; also available as an MP4 animation).

GOES-16 Visible (0.64 µm) images, with hourly surface reports [click to play animation]

GOES-16 Visible (0.64 µm) images, with hourly surface reports [click to play animation]

At South Haven, Michigan (KLWA), the surface visibility was reduced to 5 miles with light snow at 2014 UTC (below) as one of the more well-defined cloud elements associated with the mesovorex moved inland over that location.

Time series plot of South Haven, Michigan surface observations [click to enlarge]

Time series plot of South Haven, Michigan surface observations [click to enlarge]

Nowcasting Snow Squalls with GOES-16 Mesoscale Sectors

March 3rd, 2017 |

GOES-16 Visible (0.64 µm) Imagery, every minute from 1427-2000 UTC on 3 March 2017 (Click to play mp4 animation)

Note: GOES-16 data shown on this page are preliminary, non-operational data and are undergoing on-orbit testing.

Heavy snow squalls led to multiple vehicle crashes that shut down both I-80 and I-99 in central Pennsylvania on Friday 3 March (link 1 | link 2). A Mesoscale sector over Pennsylvania today provided 1-minute imagery, enabling forecasters to view the event as it happened (Click image above for an mp4 animation, or here for a 300-megabyte animated gif). The excellent temporal sampling of the mesoscale sectors — which data typically shows up in AWIPS within two minutes — is key to monitoring the progression of the snow bands across Pennsylvania. ‘Clean Infrared Window’ (that is, 10.3 µm) animations for this event are available here (mp4, animated gif). These infrared animations end at 1845 UTC. Note that State College PA (KUNV) had 1/8th mile visibility in snow at 1835 UTC. DuBois (KDUJ) had 1/4-mile visibility at the start of both animations.

CIRA also has animations of this event: (mp4, animated gif).

Northeast US winter storm

February 9th, 2017 |

GOES-13 Water Vapor (6.5 µm) images, with surface fronts and MSLP pressure [click to play animation]

GOES-13 Water Vapor (6.5 µm) images, with surface fronts and MSLP pressure [click to play animation]

A strong winter storm impacted much of the Northeast US on 09 February 2017, dropping up to 24 inches of snow in Maine and producing wind gusts of 70 mph in Massachusetts (WPC storm summary). GOES-13 (GOES-East) Water Vapor (6.5 µm) images with surface fronts and Mean Sea Level Pressure (above) showed the rapid intensification of the mid-latitude cyclone.

GOES-13 Visible (0.63 µm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Visible (0.63 µm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Visible images (above) and Water Vapor images (below) with hourly surface weather symbols revealed the extent of thunderstorms in the south and heavy snow in the north. A number of sites in New England also reported thundersnow.

GOES-13 Water Vapor (6.5 Âm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Water Vapor (6.5 Âm) images, with hourly surface weather symbols [click to play animation]

Suomi NPP VIIRS Visible (0.64 µm) and infrared Window (11.45 µm) images (below) provided a high-resolution snapshot of the storm at 1708 UTC. Note the areas of banded convective elements both south of the storm center over the Atlantic, and also inland over parts of New England.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with surface fronts and MSLP [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with surface fronts and MSLP [click to enlarge]

===== 10 February Update =====

Terra and Aqua MODIS false-color RGB images [click to enlarge]

Terra and Aqua MODIS false-color RGB images [click to enlarge]

As the storm moved northward over Newfoundland and Labrador in eastern Canada on 10 February, a toggle between Terra (1601 UTC) and Aqua (1743 UTC) MODIS false-color “snow/cloud discrimination” Red/Green/Blue (RGB) images (above) showed the extent of the snow cover (darker shades of red), although supercooled water droplet clouds (shades of white) persisted over many areas at the times of the 2 images. Glaciated ice crystal clouds also appeared as shades of red.

Snowfall totals in the Canadian Maritimes were as high as 38 cm (15 inches).