Erosion of supercooled cloud layers downwind of industrial sites

February 16th, 2019 |

GOES-16 "Red" Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images (above) revealed a cloud-free notch over northeastern Indiana during the early morning hours on 16 February 2019. The corresponding GOES-16 Cloud Top Phase product (below) indicated that the cloud layer across that region was composed of supercooled water cloud droplets. The point source of this cloud notch feature was the Steel Dynamics industrial site southeast of Columbia City — emissions from this location contained particles that acted as efficient ice condensation nuclei, causing the supercooled droplets to glaciate and fall from the cloud as snow. The cloud notch initially passed over Huntington (located about 15 miles to the south), and the Northern Indiana NWS office received a report of ice crystals or fine snow and hazy sunshine when the clearing moved over that location. The automated ASOS sensor at the Huntington airport did not report any snow, but the visibility briefly dropped to 7 miles with a lowering of cloud height just after 14 UTC.

GOES-16 Cloud Top Phase product [click to play animation | MP4]

GOES-16 Cloud Top Phase product [click to play animation | MP4]

Farther to the east, GOES-16 Visible images (below) showed prominent industrial plumes coming from the Detroit, Michigan and Cleveland, Ohio areas — with smaller plumes originating from points southeast of Lorain and southwest of Canton in Ohio. Light snow was intermittently reported at 2 sites south of Detroit as the industrial plume passed overhead. As with the previous case over Indiana, these industrial plumes were occurring within a supercooled water droplet cloud layer.

GOES-16 "Red" Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

250-meter resolution Terra MODIS True Color and False Color Red-Green-Blue (RGB) images from the MODIS Today site (below) provided a more detailed view of the industrial plumes coming from the Detroit and Cleveland areas. The darker cyan color appearing within the cloud gaps was a signature of glaciated cloud material that was descending from the supercooled cloud layer, falling as snow. Since there was no snow on the ground reported that morning at Detroit in Michigan or at Cleveland and Akron in Ohio, we can be confident that the dark cyan was not a signature of surface snow cover being viewed through gaps in the cloud deck.

Terra MODIS True Color and False Color RGB images [click to enlarge]

Terra MODIS True Color and False Color RGB images at 1610 UTC [click to enlarge]

In a larger-scale view of Terra MODIS True Color and False Color RGB images from RealEarth (below), note the presence of another industrial plume with its point source south of Sarnia, Ontario — in contrast to the other industrial plumes, the emissions from that source contained particles which acted as cloud condensation nucle — causing the supercooled cloud water droplets to become smaller, which made them more reflective and exhibit a brighter white appearance in the RGB images.

Terra MODIS True Color and False Color RGB images [click to enlarge]

Terra MODIS True Color and False Color RGB images [click to enlarge]

Looking at the Ontario plume using GOES-16 Visible, Near-Infrared “Snow/Ice” (1.61 µm) and Near-Infrared “Cloud Particle Size” (2.24 µm) imagery (below), higher reflectivity of the smaller supercooled water droplets within the industrial plume is most apparent in the Near-Infrared images. This plume passed over Chatham, Ontario (CYCK), where light snow was report — though it’s unclear whether this snow was simply ongoing synoptic system and/or lake effect snow, or if there was some minor plume enhancement aiding the snowfall.

GOES-16 "Red" Visible (0.64 µm, left), Near-Infrared "Snow/Ice" (1.61 µm, center) and Near-Infrared "Cloud Particle Size" (2.24 µm, right) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, left), Near-Infrared “Snow/Ice” (1.61 µm, center) and Near-Infrared “Cloud Particle Size” (2.24 µm, right) images [click to play animation | MP4]

The Ontario industrial plume also exhibited a warmer signature on GOES-16 Shortwave Infrared (3.9 µm) images (below), since smaller supercooled water droplets are more efficient reflectors of incoming solar radiation.

GOES-16 Near-Infrared "Snow/Ice" (1.61 µm, left) and Near-Infrared "Cloud Particle Size" (2.24 µm, center) and Shortwave Infrared (3.9 µm, right) images [click to play animation | MP4]

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm, left), and Near-Infrared “Cloud Particle Size” (2.24 µm, center) and Shortwave Infrared (3.9 µm, right) images [click to play animation | MP4]

Cyclogenesis along the US East Coast

February 4th, 2019 |


The approach of an upper-tropospheric Potential Vorticity (PV) anomaly induced rapid cyclogenesis just off the US East Coast on 04 February 2019, with the surface low rapidly occluding (surface analyses). The eastward-propagating PV Anomaly was apparent on GOES-16 (GOES-East) Air Mass RGB images from the AOS site (below) as darker shades of orange — transitioning to shades of red as the tropopause descended to lower altitudes bringing more ozone-rich air from the stratosphere into the atmospheric column.

GOES-16 Air Mass RGB images [click to play MP4 animation]

GOES-16 Air Mass RGB images [click to play MP4 animation]

A sequence of Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm) (below) showed the cyclone at various stages of development. The surface low passed over  the Cape Lookout, North Carolina buoy as it was intensifying, with winds gusting to 44 knots around 12 UTC (winds/pressure | peak wind gusts).

Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm), with plot of fixed buoy reports [click to enlarge]

Infrared Window images from Terra MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm), with plots of fixed buoy reports [click to enlarge]

A similar sequence of Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm) (below) showed the cyclone during daylight hours.

Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm), with plots of fixed buoy reports [click to enlarge]

Visible images from Terra MODIS (0.65 µm) and NOAA-20/Suomi NPP VIIRS (0.64 µm), with plots of fixed buoy reports [click to enlarge]

===== 05 February Update =====

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

After the primary center of circulation began to weaken, a pair of residual lower-tropospheric vortices (surface analyses) was seen to persist on GOES-16 “Clean” Infrared Window (10.3 µm) images (above), rotating around each other in a binary interaction known as the Fujiwhara effect. The two vortices were also evident in NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC (below) — in spite of the lack of illumination from a New Moon, airglow alone was sufficient to provide an impressive “visible image at night” with the Day/Night Band. (note: the NOAA-20 VIIRS images are incorrectly labeled as Suomi NPP)

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0620 UTC [click to enlarge]

During the early morning hours, an undular bore was evident on GOES-16 “Red” Visible (0.64 µm) images (below), moving toward the westernmost vortex. As the bore began to move over warmer waters of the Gulf Stream, it slowly dissipated.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Although not particularly intense, this slow-moving midlatitude cyclone was able to draw an appreciable amount of moisture northward from the tropics/subtropics as shown by the MIMIC Total Precipitable Water product (below).

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

Cold weather outbreak across the Upper Midwest and Great Lakes

January 30th, 2019 |

GOES-16 Air Mass RGB images, 28-30 January [click to play MP4 animation]

GOES-16 Air Mass RGB images, 28-30 January [click to play MP4 animation]

A highly-amplified upper air and jet stream pattern allowed a lobe of the polar vortex to migrate southward across southern Canada and the north-central US — leading to an outbreak of arctic air throughout the Upper Midwest and Great Lakes during the 29 January – 30 January 2019 period. The path and expansion of the cold arctic air was apparent in GOES-16 (GOES-East) Air Mass RGB images from the AOS site (above) — which first became evident over the Canadian arctic beginning on 28 January. The coldest air exhibited pale shades of yellow to beige in the Air Mass RGB images.

GOES-16 “Clean” Infrared Window (10.3 µm) images (below) also showed the southward expansion of arctic air into the north-central US — surface infrared brightness temperatures of -30 to -40ºC (darker blue to green enhancement) covered a large area. Such cold infrared brightness temperatures are normally associated with clouds in the middle to upper troposphere. Surface air temperatures of -20 to -40ºF were widespread, along with wind chill values of -40 to -70ºF, leading to numerous school and business closures. Two of the coldest official temperatures in the US on the morning of 30 January were -48ºF at Norris Camp, Minnesota and -44ºF at Bottineau, North Dakota (the high temperature in Bottineau on the previous day, 29 January, was only -26ºF); however, there were a few North Dakota Department of Transportation roadside sensors that reported low temperatures of -49ºF.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, 28-30 January [click to play MP4 animation]

GOES-16 True Color RGB images (below) revealed a variety of multiple-band and single-band lake effect snow features as the arctic air moved across the Great Lakes. In addition, elongated and long-lived cloud bands created snow squall conditions across parts of Ohio and Pennsylvania.

GOES-16 True Color images [click to play MP4 animation]

GOES-16 True Color images [click to play MP4 animation]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 (at 1802 UTC) and Suomi NPP (at 1852 UTC) viewed using RealEarth (below) provided a closer look at the cloud bands across Ohio and Pennsylvania.

True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 (at 1802 UTC) and Suomi NPP (at 1852 UTC) [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 (at 1802 UTC) and Suomi NPP (at 1852 UTC) [click to enlarge]


=======================================================

GOES-16 Clear-sky Total Precipitable Water, 1202 UTC on 30 January 2019 (Click to enlarge)

In addition to being extremely cold, the airmass over the Upper Midwest was extremely dry. The image above shows the Baseline GOES-R Total Precipitable Water product. The default AWIPS color enhancement has been modified to better capture the extreme dryness. Regions in light blue over western Minnesota and the eastern Dakotas curving through Iowa into northern Illinois show TPW values around 0.01″ ; green shadings over Wisconsin and eastern Minnesota correspond to values closer to 0.03″. In such dry airmasses, it is possible to see surface features in the infrared 7.3 low-level ABI Water Vapor Channel, Band 10, and the morning of 30 January was no exception, below. Surface features like rivers are notable in Illinois, for example. Even the heat island of the Minneapolis/St. Paul is apparent (albeit barely).  Surface features over northern Minnesota and Wisconsin aren’t quite so apparent, perhaps because of the increased amounts of moisture there.  There is likely less surface temperature contrast there, also, as rivers/lakes are more likely frozen.  It is the temperature contrast — as best exemplified by the Great Lakes shorelines — that allows features to appear in the Water Vapor imagery.

GOES-16 Low-Level Water Vapor Infrared (7.3 µm) Imagery, 1202 UTC on 30 January 2019 (Click to enlarge)

Weighting Functions (in real time, from this site) allow for an estimate of where information in different water vapor channels will be detected by the satellite. In the 0000 UTC 30 January 2019 example, below, from Chanhassen, MN (when total precipitable water there was 0.01″), a large signal is apparent from the low-level water vapor channel (7.3 µm); in fact, most of the information detected by the satellite was coming from the surface!  Even the mid-level water vapor (6.9 µm) had a component from the surface.  Weighting Functions for Davenport Iowa (The axis of the driest air shifted from near Chanhassen at 0000 UTC to near Davenport at 1200 UTC) at 0000 UTC and 1200 UTC are shown here; Note in the toggle that the level from which information is received by the satellite drops from 0000 to 1200 UTC as dry air moves in.

Clear-sky Weighting Function from Chanhassen MN, 0000 UTC on 30 January 2019 (Click to enlarge)

The GOES-16 Baseline Land Surface Temperature product, below, from 1200 UTC, shows many values at/below -45 F (purple shading) over Minnesota.  Dark blue values are around -25 F.  Note the relatively warm region over western Iowa, in cyan.  That part of Iowa lacks snowcover and exceptional cold rarely happens over bare ground.

GOES-16 Baseline Land Surface Temperature, 1202 UTC on 30 January 2019 (Click to enlarge)

===== 31 January Update =====

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with and without plots of hourly surface observations [click to play animation | MP4]

Across much of the Upper Midwest, the coldest temperatures occurred on the morning of 31 January. GOES-16 Infrared images (above) showed much of northeastern Minnesota and far northwestern Wisconsin — the low temperature of -56ºF at Cotton was only 4 degrees warmer than the all-time record low for Minnesota, and the low temperature of -47ºF at Butternut was 8 degrees warmer than the all-time record  low for Wisconsin (both of those records were set in early February 1996). The -56ºF in Cotton was not only the coldest temperature in the Lower 48 states on 31 January, but was also significantly colder than any official reporting station in Alaska that day. Also of interest in northeastern Minnesota, note the warmer plumes (darker blue enhancement; brighter greens are coldest) coming from power plants and industrial sites in the Iron Range area.

Farther to the south, GOES-16 Infrared images covering the Minnesota/Wisconsin/Iowa/Illinois region (below) also showed widespread cold surface brightness temperatures (shades of green). All-time record low temperatures were set at Cedar Rapids in Iowa (-30ºF) and at Moline (-33ºF) and Rockford (-31ºF) in Illinois. The cooperative observer at Mt. Carroll in northwestern Illinois reported a low of -38ºF — which, if verified, will establish a new all-time record minimum temperature for the state of Illinois.

GOES-16 "Clean" Infrared Window (10.3 µm) images, with plots of hourly surface observations [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with plots of hourly surface observations [click to play animation | MP4]

The recent stretch of days with cold air in place had helped the ice coverage to increase significantly in western Lake Superior — and the transition from northerly/northwesterly cold air advection to southwesterly warm air advection at the surface began to fracture a lot of this newly-formed lake ice (below).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with plots of hourly surface reports [click to play animation | MP4]

Ice coverage had also increased across much of western/central Lake Erie, although areas of open water continued to supply latent heat to help generate lake effect snow bands (below).

GOES-16 "Red" Visible (0.64 µm) images, with plots of hourly surface reports [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with plots of hourly surface reports [click to play animation | MP4]

A sequence of Terra MODIS True Color RGB images (below) showed substantial growth of nearshore ice in the southern end of Lake Michigan from 29 to 31 January.

Terra MODIS True Color RGB images [click to enlarge]

Terra MODIS True Color RGB images [click to enlarge]

.A summary of this cold outbreak was compiled by NWS Duluth, NWS La Crosse, NWS Twin Cities and NWS Grand Forks.

Dry air aloft over the western Atlantic Ocean

January 23rd, 2019 |

GOES-16 Mid-level Water Vapor (6.9 µm) images, with plots of rawinsonde sites in yellow [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with rawinsonde sites plotted in yellow [click to play animation | MP4]

With a ridge of high pressure in place over the western Atlantic Ocean, GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) indicated the presence of dry air within the middle troposphere off the Southeast US coast on 23 January 2019.

GOES-16 “Red” Visible (0.64 µm) images showed that marine boundary layer stratocumulus clouds covered much of this region of the Atlantic — and due to minimal absorption by mid-tropospheric water vapor, these stratocumulus clouds were also very apparent in the corresponding GOES-16 Near-Infrared “Cirrus” (1.38 µm) images (below).

GOES-16 "Red" Visible (0.64 µm) and Near-Infrared "Cirrus" (1.37 µm) images, with plots of rawinsonde sites in yellow [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.38 µm) images, with rawinsonde sites plotted in yellow [click to play animation | MP4]

Terra MODIS Visible (0.65 µm) and Near-Infrared “Cirrus” (1.38 µm) images at 1513 UTC (below) also showed a clear signature of the stratocumulus clouds at 1.38 µm.

Terra MODIS Visible <em>(0.65 µm)</em> and Near-Infrared "Cirrus" <em>(1.38 µm)</em> images at 1513 UTC, with plots of rawinsonde sites in yellow [click to enlarge]

Terra MODIS Visible (0.65 µm) and Near-Infrared “Cirrus” (1.38 µm) images at 1513 UTC, with rawinsonde sites plotted in yellow [click to enlarge]

Cross sections of GFS90 model fields along Line I-I’ — oriented from Charleston, South Carolina to Bermuda — are shown below. Note the very dry air within the middle troposphere, with Specific Humidity values of less than 0.2 g/kg and Relative Humidity values less than 10% centered around the 500 hPa pressure level. In addition, the depth of the moist marine boundary layer was higher to the west at Charleston (2.6 km, at 746 hPa) than to the east at Bermuda (1.9 km, at 822 hPa).

Cross sections of GFS90 model fields along Line I-I', from Charleston, South Carolina to Bermuda [click to enlarge]

Cross sections of GFS90 model fields along Line I-I’, from Charleston, South Carolina to Bermuda [click to enlarge]