Blowing snow in southern Manitoba and the Red River Valley

January 15th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and Near-Infrared “Snow/Ice (1.61 µm, right) images, with hourly plots of surface wind and weather type [click to play animation | MP4]

A comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed plumes of blowing snow originating over northern Lake Winnipeg and southern Lake Manitoba, lofted by strong northerly winds in the wake of a cold frontal passage. The blowing snow originating over the southern portion of Lake Manitoba was then then channeled southward into the Red River Valley (topography), with horizontal convective roll clouds eventually developing.

In a sequence of MODIS Visible (0.65 µm) and Snow/Ice (1.61 µm) images from Terra and Aqua in addition to VIIRS Visible (0.64 µm) and Snow/Ice (1.61 µm) from NOAA-20 and Suomi NPP (below), the plumes of blowing snow were also easier to detect in the Snow/Ice images (due to better contrast against the existing snow cover).

MODIS Visible (0.65 µm) and Snow/Ice (1.61 µm) images from Terra and Aqua plus VIIRS Visible (0.64 µm) and Snow/Ice (1.61 µm) from NOAA-20 and Suomi NPP [click to enlarge]

MODIS Visible (0.65 µm) and Snow/Ice (1.61 µm) images from Terra and Aqua plus VIIRS Visible (0.64 µm) and Snow/Ice (1.61 µm) from NOAA-20 and Suomi NPP [click to enlarge]

A closer view of the Lake Manitoba plume is shown below; surface observations indicated that visibility was reduced to 1/4 statute mile at locations such as Calilier ND (plot | text) and Hallock MN (plot | text).

NOAA-20 and Suomi NPP VIIRS Snow/Ice (1.61 µm) images, with plots of surface observations [click to enlarge]

NOAA-20 and Suomi NPP VIIRS Snow/Ice (1.61 µm) images, with plots of surface observations [click to enlarge]

An Aqua MODIS True Color Red-Green-Blue (RGB) image centered on Winnipeg, Manitoba (source)  is shown below.

Aqua MODIS True Color image [click to enlarge]

Aqua MODIS True Color image [click to enlarge]

Toggles between 250-meter resolution Terra/Aqua MODIS True Color and False Color RGB images (centered between Lake Manitoba and the North Dakota border) from the MODIS Today site (below) provided a more detailed view of the blowing snow streaming southeastward from Lake Manitoba into far northeastern North Dakota and far northwestern Minnesota.

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

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

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

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

Lake effect clouds downwind of Fort Peck Lake, Montana

January 11th, 2019 |
GOES-17 (left) and GOES-16 (right)

GOES-17 (left) and GOES-16 (right) “Red” Visible (0.64 µm, top) and Shortwave Infrared (3.9 µm, bottom) images [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

A comparison of GOES-17 (soon to become GOES-West) and GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) revealed a plume of lake effect clouds streaming south of Fort Peck Lake in northeastern Montana on 11 January 2019. As a cold front moved south-southwestward across the region (surface analyses), surface winds shifted to northerly at Glasgow KGGW which brought a flow of colder air across the still-unfrozen lake. Note that before sunrise the initial formation of the lake effect clouds could be seen on Shortwave Infrared imagery — and after sunrise, the feature appeared progressively warmer (shades of orange) on 3.9 µm images as the supercooled water droplets at the cloud top reflected increasing amounts of incoming solar radiation.

An Aqua MODIS Sea Surface Temperature product at 1942 UTC (below) showed that mid-lake water temperatures south of Glasgow were as warm as 36ºF (lighter shades of blue) — significantly warmer than Glasgow’s early morning surface air temperatures that were as cold as 17ºF at 14 UTC.

Aqua MODIS Sea Surface Temperature product [click to enlarge]

Aqua MODIS Sea Surface Temperature product [click to enlarge]

A comparison of the Sea Surface Temperature product with the corresponding Aqua MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.9 µm) and Infrared Window (11.0 µm) images at 1942 UTC (below) showed the lake effect cloud plume as well as a patch of snow cover northeast of the lake — snow absorbs radiation at the 1.61 µm wavelength, making it appear dark on the “Snow/Ice” image.

Aqua MODIS Visible (0.65 µm), Near-Infrared

Aqua MODIS Sea Surface Temperature, Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.9 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra and Aqua MODIS True Color and False Color Red-Green-Blue (RGB) images viewed using RealEarth (below) showed that parts of the Missouri River upstream (to the west of) of Fort Peck Lake — in the area of the UL Bend National Wildlife Refuge — were beginning to freeze (ice and snow appear as shades of cyan on the False Color RGB images).

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

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

Snowfall in Texas and Oklahoma

January 4th, 2019 |

GOES-16

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

A winter storm produced 6-8 inches of snowfall from the eastern Texas Panhandle to central Oklahoma on 03 January 2019 (NWS AmarilloNWS Norman). On the following day, GOES-16 “Red” Visible (0.64 µm) images (above) revealed the areal extent of the snow cover, with significant melting occurring by the late afternoon hours. The snow cover seen in the far northwestern portion of the images is from a winter storm that occurred 8 days earlier on 27 December 2018.

In a comparison between Terra and Aqua MODIS Visible (0.65 µm) images and the corresponding Land Surface Temperature product at 1757 and 1936 UTC (below), LST values in the 30s F (darker shades of blue) were 20ºF colder over the snow cover than over adjacent bare ground in Oklahoma, and 35-40ºF colder than the more sparsely-vegetated bare ground in Texas. By increasing the surface albedo, the snow cover acted to suppress daily maximum temperatures by several degrees.

Terra and Aqua MODIS Visible (0.65 µm) image and Land Surface Temperature product at 1757 an 1936 UTC [click to enlarge]

Terra and Aqua MODIS Visible (0.65 µm) image and Land Surface Temperature product at 1757 an 1936 UTC [click to enlarge]

===== 05 January Update =====

GOES-16 "Red" Visible (0.64 µm) images, 04 and 05 January [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images with hourly plots of surface reports, 04 and 05 January [click to play animation | MP4]

A sequence of GOES-16 “Red” Visible (0.64 µm) images on 04 and 05 January (above) showed the continued melting of residual snow cover.

A toggle between NOAA-20 VIIRS True Color Red-Green-Blue (RGB) images on 04 and 05 January as viewed using RealEarth (below) provided a higher-resolution view of the snow cover just after 1 PM local time on those two days.

NOAA-20 VIIRS True Color RGB images on 04 and 05 January [click to enlarge]

NOAA-20 VIIRS True Color RGB images on 04 and 05 January [click to enlarge]

Southern US storm, and a Tehuano wind event

December 15th, 2018 |

GOES-16 Low-level Water Vapor (7.3 µm) images, 13-15 December [click to play MP4 animation]

GOES-16 Low-level Water Vapor (7.3 µm) images, 13-15 December [click to play MP4 animation]

A large midlatitude cyclone moved from the southern High Plains to the Lower Mississippi Valley during the 13 December15 December 2018 period (surface analyses) — GOES-16 (GOES-East) Low-level Water Vapor (7.3 µm) images (above) showed the evolution of this system.

The corresponding GOES-16 Water Vapor images with plots of hourly surface wind gusts are shown below; peak wind gusts exceeding 50 knots occurred in parts of Colorado, New Mexico and Texas on 13 December.

GOES-16 Low-level Water Vapor (7.3 µm) images with hourly plots of surface wind gusts, 13-15 December [click to play MP4 animation]

GOES-16 Low-level Water Vapor (7.3 µm) images with hourly plots of surface wind gusts in knots, 13-15 December [click to play MP4 animation]

This event was unusually windy in South Texas and the Rio Grande Valley:

Another notable aspect of this storm was a very localized area of heavy snowfall just south of Sweetwater, Texas:


The remnant patch of snow cover was evident in VIIRS Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) imagery on 14 and 15 December (below). The heaviest snowfall occurred over an isolated ridge along the eastern edge of the Edwards Plateau, where elevations of 2500-2600 feet were about 500 feet higher than the adjacent rolling plains. Since snow is a very effective absorber of energy at the 1.61 µm wavelength, it appeared dark on the Snow/Ice imagery.

Topography, Suomi NPP VIIRS Visible (0.64 µm) and Near-Infrared "Snow/Ice" (1.61 µm) images on 14 December [click to enlarge]

Topography plus Suomi NPP VIIRS Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images on 14 December [click to enlarge]

Topography plus NOAA-20 VIIRS Visible (0.64 µm) and Near-Infrared "Snow/Ice" (1.61 µm) images on 15 December [click to enlarge]

Topography plus NOAA-20 VIIRS Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images on 15 December [click to enlarge]

The residual snow cover on 14 December was also seen in Terra/Aqua MODIS True Color and False Color Red-Green-Blue (RGB) images, viewed using RealEarth (below). The snow appeared as shades of cyan in the False Color images.

Terra/Aqua MODIS True Color and False Color images on 14 December [click to enlarge]

Terra/Aqua MODIS True Color and False Color images on 14 December [click to enlarge]

A toggle between Terra MODIS True Color RGB images on the late morning of 14 and 15 December (below) demonstrated the amount of snow melt in 24 hours.

Terra MODIS True Color RGB images on 14 and 15 December [click to enlarge]

Terra MODIS True Color RGB images on 14 and 15 December [click to enlarge]

The strong cold front associated with this storm moved rapidly southward across the western Gulf of Mexico on 14 December (surface analyses), crossing the terrain of the Isthmus of Tehuantepec in southern Mexico and emerging into the Gulf of Tehuantepec as a gap wind (known as a Tehuano wind). A curved rope cloud marking the leading edge of the Tehuano winds was evident on GOES-17 and GOES-16 “Red” Visible (0.64 µm) images (below).

* GOES-17 images shown here are preliminary and non-operational *

GOES-17 (left) and GOES-16 (right)

GOES-17 (left) and GOES-16 (right) “Red” Visible (0.64 µm) images [click to play animation | MP4]

A comparison of GOES-16 Visible imagery from 14 and 15 December (below) showed how far southwestward the gap winds spread out across the Pacific Ocean during those 2 days. Note that on 15 December there were ship reports with wind speeds of 50 knots, at 12 UTC and at 17 UTC.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images with surface and ship reports, 14-15 December [click to play animation | MP4]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images on 14 and 15 December (below) also showed the progression of the Tehuano wind rope cloud — the hazy signature of dust-laden air within the offshore flow was also apparent on the daytime True Color images.

NOAA-20 VIIRS True Color and Infrared Window (11.45 µm) images on 14 and 15 December [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images on 14 and 15 December [click to enlarge]

Metop-A and Metop-B ASCAT surface scatterometer winds across the western Gulf of Mexico [click to enlarge]

Metop-A and Metop-B ASCAT surface scatterometer winds across the western Gulf of Mexico [click to enlarge]

On 14 December, a sequence of EUMETSAT Metop-A and Metop-B ASCAT surface scatterometer winds (source) showed the cold front moving southward across the western Gulf of Mexico (above), and also showed the northerly gap wind flow just beginning to emerge into the Gulf of Tehuantepec around 1607 UTC (below).

Metop-A and Metop-B ASCAT surface scatterometer winds across the southern Gulf of Mexico and the Gulf of Tehuantepec [click to enlarge]

Metop-A and Metop-B ASCAT surface scatterometer winds across the far southern Gulf of Mexico and the Gulf of Tehuantepec [click to enlarge]

The plume of dry air being transported southwestward across the Pacific Ocean by the gap winds was apparent on MIMIC Total Precipitable Water images (below). The majority of this dry air was within the surface-850 hPa layer (21 UTC comparison).

MIMIC Total Precipitable Water product (Total column, and Surface-850 hPa layer) [click to play animation]

MIMIC Total Precipitable Water product (Total column, and Surface-850 hPa layer) [click to play animation]