Early-season winter storm in the Northern Plains

October 12th, 2019 |

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly surface weather type plotted in red [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly surface weather type plotted in red [click to play animation | MP4]

With the approach of an anomalously-deep 500 hPa low, an early-season winter storm produced very heavy snowfall and blizzard conditions across the Northern Plains — particularly in central/eastern North Dakota and southern Manitoba — during the 10 October12 October 2019 period. GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed the long duration of precipitation across that region. Text listings of snowfall totals and wind gusts are available from WPC, NWS Bismarck and NWS Grand Forks (more complete storm summaries: NWS Bismarck | NWS Grand Forks). The highest storm total snowfall amount in far southern Manitoba was 32 inches south of Morten (which reported a snow depth of 30 inches on the morning of 12 October), with 30 inches in central North Dakota at Harvey.

GOES-16 “Red” Visible (0.64 µm) images (below) displayed the storm during the daylight hours on 10/11/12 October.

GOES-16 "Red" Visible (0.64 µm) images on 10/11/12 October, with hourly precipitation type plotted in red [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images on 10/11/12 October, with hourly precipitation type plotted in red [click to play animation | MP4]

On 11 October, GOES-16 Visible images with an overlay of GLM Flash Extent Density (below) revealed intermittent clusters of lightning activity over northwestern Minnesota, northeastern North Dakota and southern Manitoba — while no surface stations explicitly reported a thunderstorm, NWS Grand Forks received calls from the public about thundersnow. The texture of cloud tops in the Visible imagery also supported the presence of embedded convective elements, which likely enhanced snowfall rates as they pivoted across that area. An animation of GOES-16 Visible imagery with plots of GLM Groups and surface weather type is available here.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with an overlay of GLM Flash Extent Density [click to play animation | MP4]

Note that this lightning-producing convection was occurring near the leading edge of the cyclone’s mid-tropospheric dry slot, as seen in GOES-16 Water Vapor imagery (below).

GOES-16 "Red" Visible (0.64 µm, left) and Mid-level Water Vapor (6.9 µm, right) images, with GLM Groups plotted in red [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, left) and Mid-level Water Vapor (6.9 µm, right) images, with GLM Groups plotted in red [click to play animation | MP4]

One important aspect of this storm was the formation of a trough of warm air aloft or trowal (SHyMet | Martin, 1998) as the surface low began to enter its occluded phase on 11 October — contours of Equivalent Potential Temperature along the 295 K isentropic surface (below) helped to diagnose the axis of the trowal as it curved cyclonically from southwestern Ontario to southern Manitoba and then southward over North Dakota.

GOES-16 Mid-level Water Vapor (6.9 µm) images, with 295 K equivalent potential temperature contours plotted in yellow and surface fronts plotted in red [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with 295 K Equivalent Potential Temperature contours plotted in yellow and surface fronts plotted in red [click to play animation | MP4]

A similar animation with contours of 295 K specific humidity (below) also displayed the orientation of a west-to-east cross section B-B’ (green) across northern Northern Minnesota and northern Minnesota.

GOES-16 Mid-level Water Vapor (6.9 µm) images, with 295 K Specific Humidity contours plotted in yellow and surface fronts plotted in red [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with 295 K Specific Humidity contours plotted in yellow and surface fronts plotted in red [click to play animation | MP4]

The Line B-B’ cross section at 16 UTC (with and without contours of Equivalent Potential Temperature) is shown below. Note the deep column of upward vertical velocity (highlighted by color shading of Omega) centered over Langdon, North Dakota — the moist trowal airstream can be seen sloping isentropically upward and westward behind the 3 g/kg Specific Humidity contour, as it approached the region of upward vertical motion. Langdon received 27 inches of snowfall; the prolonged southward passage of the trowal over North Dakota likely contributed to this accumulation.

Cross section of RAP40 model fields along Line B-B' at 16 UTC [click to enlarge]

Cross section of RAP40 model fields along Line B-B’ at 16 UTC [click to enlarge]

As the storm was gradually winding down on 12 October, its circulation exhibited a very broad middle-tropospheric signature on GOES-16 Water Vapor imagery (below).

GOES-16 Mid-level Water Vapor (6.9 µm) images, with surface frontal positions [click to play animation]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with surface frontal positions [click to play animation | MP4]

===== 17 October Update =====

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

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

After the area had already experienced its wettest Fall season on record, additional rainfall and snowmelt from this winter storm exacerbated ongoing flooding problems. A comparison of 250-meter resolution Aqua MODIS True Color and False Color Red-Green-Blue (RGB) images (source) centered over northeastern North Dakota (above) revealed flooding along the Red River (which flows northward along the North Dakota / Minnesota border) — water appears as darker shades of blue in the False Color image.

A Suomi NPP VIIRS Flood Product depicting floodwater fractions in the Red River Valley north of Grand Forks ND (as visualized using RealEarth) is shown below.

Suomi NPP VIIRS Flood Product, depicting floodwater fractions in the Red River Valley north of Grand Forks, ND [click to enlarge]

Suomi NPP VIIRS Flood Product, depicting floodwater fractions in the Red River Valley north of Grand Forks, ND [click to enlarge]

===== 18 October Update =====

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

On 18 October — 1 week after the height of the historic blizzard — GOES-16 Day Cloud Phase Distinction RGB images showed snow cover (brighter shades of green) remaining in areas that received the highest snowfall accumulations (such as Morden MB 32″; Vang ND 29″; Olga ND 28″; Langdon ND 27″).

Decker Fire in Colorado

October 2nd, 2019 |

GOES-16 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the afternoon/evening smoke plume and the persistent thermal anomaly (cluster of hot pixels) associated with the Decker Fire burning just southwest of Salida, Colorado on 02 October 2019.

A closer view of the fire was provided by a 4-panel comparison of GOES-16 Shortwave Infrared, Fire Power, Fire Temperature and Fire Area products (below). More information on these GOES Fire Detection and Characterization Algorithm (FDCA) products can be found here. Windy conditions on this day —  with sustained speeds of 20-30 mph and gusts to 46 mph — promoted rapid fire growth during the afternoon hours.

GOES-16 Shortwave Infrared (3.9 µm), Fire Power, Fire Temperature and Fire Area [click to play animation | MP4]

GOES-16 Shortwave Infrared (3.9 µm), Fire Power, Fire Temperature and Fire Area [click to play animation | MP4]

A sequence of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) showed the smoke plume and the fire’s thermal anomaly (cluster of dark black pixels).

VIIRS True Color RGB and Infrared Window (11.45 um) images from Suomi NPP and NOAA-20 [click to enlarge]

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

A time series of surface observation data from the Salida Airport (identifier KANK, located just northwest of the fire) revealed southwesterly winds gusting to 20-29 knots as the dew point dropped to the -1 to -11ºF range — creating Relative Humidity values as low as 4% — during the afternoon hours (below).

Time series of surface observation data from Salida, Colorado [click to enlarge]

Time series of surface observation data from Salida, Colorado [click to enlarge]

===== 03 October Update =====

GOES-17 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

The Decker Fire continued to burn on 03 October, as seen using 1-minute Mesoscale Domain Sector GOES-17 “Red” Visible and Shortwave Infrared images (above). Although surface winds were still gusting as high as 30 knots at Salida, additional boundary layer moisture (dew points were in the 20s F) helped to slow the rate of fire growth compared to the previous day. The southeasterly winds transported some low-altitude smoke toward Salida, reducing the visibility to 5-7 miles at times (below).

Time series of surface observation data from Salida, Colorado [click to enlarge]

Time series of surface observation data from Salida, Colorado [click to enlarge]

A comparison of GOES-16 (GOES-East) and GOES-17 (GOES-West) Shortwave Infrared images with topography (below) demonstrated the effect of large satellite viewing angles on apparent fire location in areas of rugged terrain — note the offset in the position of the Decker Fire thermal anomaly between the 2 satellites (the viewing angle of the fire from each satellite is about 53 degrees).

GOES-16 and GOES-17 Shortwave Infrared (3.9 µm) images, with topography [click to play animation | MP4]

GOES-16 and GOES-17 Shortwave Infrared (3.9 µm) images, with topography (highways are plotted in cyan) [click to play animation | MP4]

Hurricane Lorenzo in the Atlantic Ocean

September 26th, 2019 |

 

GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images (above) showed Hurricane Lorenzo as it rapidly intensified from a Category 2 storm at 00 UTC to a Category 4 storm by 15 UTC (ADT | SATCON) on 26 September 2019.

A toggle between VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) provided a detailed view of the eye and eyewall region of Lorenzo at 1542 UTC and 1632 UTC. On the Suomi NPP Infrared image, note the transverse banding northwest of the eye, and a small packet of gravity waves southwest of the eye.

VIIRS True Color RGB and Infrared Window<em> (11.45 µm)</em> images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP (at 1542 UTC) and NOAA-20 (at 1632 UTC) [click to enlarge]

A DMSP-18 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) revealed a well-defined eyewall wrapping around the southern, eastern and northern periphery of the eye.

DMSP-18 SSMIS Microwave (85 GHz) image at 1941 UTC [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image at 1941 UTC [click to enlarge]

Saharan Air Layer plume over the Atlantic Ocean

September 20th, 2019 |

Saharan Air Layer product [click to play animation | MP4]

GOES-16 “Split Window” Saharan Air Layer product [click to play animation | MP4]

GOES-16 (GOES-East) Split Window images (above) showed a large plume of the Saharan Air Layer (SAL) that moved westward off the coast of Africa then westward and northwestward across the eastern and central Atlantic Ocean during the 15-20 September 2019 period.

On 20 September, the hazy SAL plume could be easily seen in Full Disk GOES-16 True Color Red-Green-Blue (RGB) images from the AOS site (below).

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

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

The SAL plume was also apparent in True Color RGB images from Suomi NPP and NOAA-20 as viewed using RealEarth (below).

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

A comparison of GOES-16 CIMSS Natural Color RGB, Aerosol Optical Depth and Dust Detection product images from 1500-1900 UTC on 20 September (below) revealed AOD values as high as 0.5 within the hazy dust-laden SAL plume; the Dust Detection product indicated large areas of Low- to Medium-Confidence dust (with isolated pockets of High Confidence).

GOES-16 CIMSS Natural Color RGB, Aerosol Optical Depth, and Dust Detection product [click to play animation | MP4]

GOES-16 CIMSS Natural Color RGB, Aerosol Optical Depth, and Dust Detection product [click to play animation | MP4]


On a side note, the Full Disk True Color shown above images revealed 3 different types of solar backscatter: a small spot of very bright sun glint off the water of the Amazon River and its tributaries, which moved from east to west (below)

GOES-16

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

along with 2 separate (and larger) areas of more diffuse solar backscatter, which propagated from west to east: the first (possibly a 180º-42º=138º or “rainbow” backscatter) appeared about midway between the Equator and the southern tip of South America — and the second  (a 180º backscatter) appeared farther north, closer to the Equator, slightly later in time (this type of solar backscatter was previously discussed here). These 3 solar backscatter features can also be seen in a rocking animation below.

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

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

Thanks to Fred Wu (NOAA/NESDIS) and Steve Miller (CIRA) for providing further insight regarding the nature of the 2 larger types of solar backscatter.