Signatures of fresh snowfall in the Dakotas

March 17th, 2019 |

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) Near-Infrared “Snow/Ice” (1.61 µm) images (above) depicted the signature of northwest-to-southeast oriented swaths of fresh snowfall (lighter gray shades) which had recently fallen on top of the aged snow pack across North Dakota on 17 March 2019. As discussed here, the surface of the preexisting snow cover had experienced rapid melting several days earlier, which increased its “water to ice crystal” ratio — making it appear darker, since water is a stronger absorber of radiation at the 1.61 µm wavelength.

A similar (albeit broader and more continuous) northwest-southeast swath of fresh snowfall was seen across South Dakota (below).

GOES-16 Near-Infrared "Snow/Ice" (1.61 µm) images [click to play animation | MP4]

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

The radar-derived 24 hour precipitation ending at 12 UTC on 17 March is shown below.

24-hour precipitation ending at 12 UTC on 17 March [click to enlarge]

24-hour precipitation ending at 12 UTC on 17 March [click to enlarge]

Intense central US midlatitude cyclone

March 13th, 2019 |

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

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

An unusually deep midlatitude cyclone — which easily met the criteria of a “bomb cyclone”, with its central pressure dropping 25 hPa in only 12 hours (surface analyses) — developed over the central US on 13 March 2019 (WPC storm summary). GOES-16 (GOES-East) Air Mass RGB images from the AOS site (above) showed the large size of the cloud shield — and the deeper red hues over the High Plains indicated the presence of ozone-rich air (from the stratosphere) within the atmospheric column as the tropopause descended. A preliminary new all-time low surface pressure of 975.1 hPa occurred at Pueblo, Colorado just after 13 UTC; to the east of Pueblo, a 970.4 hPa minimum pressure recorded at Lamar (plot) possibly set a new state record for Colorado.

On a map of NWS warnings/advisories valid at 14 UTC (below), Blizzard Warnings (red) extended from Colorado to the US/Canada border. South of the Blizzard Warnings, High Wind Warnings (brown) were in effect to the US/Mexico border.

Map of NWS warnings and advisories at 14 UTC [click to enlarge]

Map of NWS warnings and advisories at 14 UTC [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) displayed a hook-like signature resembling that of a sting jet, which developed over the Texas/Oklahoma Panhandle area after 11 UTC. At 14 UTC an interesting burst of surface wind gusts occurred at 3 sites — Burlington CO, Goodland KS and Colby KS — which may have been related to the downward transfer of momentum along the leading edge of the sting jet flow. The corresponding 7.3 µm Low-level Water Vapor animations are also available: GIF | MP4.

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

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

The MIMIC Total Precipitable Water product (below) showed the northward surge of moisture from the Gulf of Mexico.

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

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

During the afternoon hours, the strong surface winds began to create plumes of blowing dust across parts of southeastern New Mexico and western Texas — a blowing dust signature first became apparent on GOES-16 Split Window Difference imagery as plumes of yellow, but then became more obvious on “Red” Visible (0.64 µm) images as the afternoon forward scattering angle increased (below). Blowing dust reduced the surface visibility to 1-2 miles at Snyder (KSNK) and Lubbock (KLBB).

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

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

The blowing dust signature (lighter shades of brown) was also easily seen in late-afternoon GOES-16 True Color RGB images (below) — the dust plume reached southwestern Oklahoma by the end of the daytime hours, restricting the visibility to 5 miles at Frederick (KFDR). The blowing dust was also evident in True Color imagery from GOES-17, as seen here.

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

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

Not long after the cyclone reached its lowest analyzed surface pressure of 968 hPa at 18 UTC, an overpass of the Suomi NPP satellite around 19 UTC provided a swath of NUCAPS soundings covering much of the storm (below). The air was very dry and stable near the near the center of the surface low in eastern Colorado (TPW=0.29″, CAPE=0 J/kg), in western Texas (TPW=0.31″, CAPE=0 J/kg) and near the frontal triple point in southeastern Nebraska (TPW=0.30″, CAPE=0 Jkg) — and out ahead of the warm front, the air was moist but stable behind a line of thunderstorms in northeastern Arkansas (TPW=1.09″, CAPE=0 J/kg) but both moist and unstable in western Mississippi (TPW=1.36″, CAPE=3506 J/kg).

Suomi NPP VIIRS Visible (0.64 µm) image, with overlays of the surface analysis and available NUCAPS soundings [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image, with overlays of the surface analysis and available NUCAPS soundings [click to enlarge]

During the early stages of cyclone development, this system spawned severe thunderstorms that produced tornadoes, large hail and damaging winds across New Mexico and Texas (SPC storm reports) late in the day on 12 March. A GOES-17 (GOES-West) Mesoscale Domain Sector had been positioned over that region — which was helpful during a brief GOES-16 data outage — providing images at 1-minute intervals (below).

GOES-17

GOES-17 “Clean” Infrared Window (10.3 µm) images, with plots of SPC storm reports [click to play animation | MP4]

===== 14 March Update =====

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of surface winds and gusts in knots [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of surface winds and gusts in knots [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images (above) showed the storm moving slowly northeastward across Kansas, Nebraska and Iowa on 14 March — with strong winds continuing north and west of the surface low, blizzard conditions persisted across much of the Midwest.

Farther to the east, severe thunderstorms produced large hail, damaging winds and tornadoes as far north as northern Illinois/Indiana/Ohio and southern Lower Michigan (SPC storm reports | NWS Detroit) — as shown with 1-minute Mesoscale Domain Sector GOES-16 Visible images (below). The corresponding GOES-16 Infrared image animation is available here; the coldest cloud-top infrared brightness temperatures were only in the -30 to -40ºC range

GOES-16 "Red" Visible (0.64 µm) Visible images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm) Visible images, with SPC storm reports plotted in red [click to play MP4 animation]

Cold temperatures in Montana

March 3rd, 2019 |

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with observed minimum surface air temperatures [click to play animation | MP4]

GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) revealed unseasonably cold surface infrared brightness temperatures in the -30 to -40ºC range (dark blue to green color enhancement) across much of Montana on the morning of 03 March 2019. Overnight low temperatures at a number of first-order reporting sites were colder than -30ºF (-34ºC) — with the coldest location across the state (and the entire US, including Alaska) dropping to -44ºF (-42ºC). This was only 1ºF warmer than the all-time record low for Montana during the month of March (record low: -45ºF at Glasgow in 1897, and at Fort Logan in 1906). A few daily/monthly cold temperature records were set in the Great Falls and Billings areas.

A sequence of 3 consecutive VIIRS Infrared Window  (11.45 µm) images (from NOAA-20 and Suomi NPP) with a different color enhancement is shown below — the red shades indicate surface infrared brightness temperatures of -40ºC and colder.

Sequence of 3 consecutive VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

Sequence of 3 consecutive VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

===== 04 March Update =====

GOES-16 "Clean" Infrared Window (10.3 µm) images, with observed minimum aurface air temperatures [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with observed minimum surface air temperatures [click to play animation | MP4]

On the morning of 04 March, GOES-16 “Clean” Infrared Window images (above) showed a more localized pocket of very cold surface infrared brightness temperatures over the southwest part of Montana. The coldest measured surface air temperature was -46°F at Elk Park (at an elevation of 6292 feet) —  which, if certified, will establish a new all-time March low temperature record for the state of Montana.

A sequence of 3 consecutive VIIRS Infrared Window images from NOAA-20 and Suomi NPP (below) revealed surface infrared brightness temperatures as cold as -46ºC or -51ºF within the red-enhanced areas.

Sequence of 3 consecutive VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

Sequence of 3 consecutive VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

Lake effect snow in Nevada

February 21st, 2019 |


GOES-17

GOES-17 “Clean” Infrared Window (10.3 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Clean” Infrared Window (10.3 µm) images (above) showed an unusual lake effect snow feature downwind of Pyramid Lake in northwestern Nevada on 21 February 2019 — the surface visibility dropped to 0.5 mile with moderate snow as ihe lake effect cloud moved over Reno-Tahoe International Airport around 16 UTC. Prior to that, the lake effect snow also affected portions of Interstate 80 in the Patrick area.

A morning overpass of the NOAA-19 satellite provided a 1-km resolution Infrared Window (10.8 µm) image of the lake effect cloud at 1254 UTC (below). The coldest cloud-top infrared brightness temperature on that image was -46ºC.

NOAA-19 AVHRR Infrared Window (10.8 µm) image at 1254 UTC [click to enlarge]

NOAA-19 AVHRR Infrared Window (10.8 µm) image at 1254 UTC [click to enlarge]

GOES-17 cloud-top infrared brightness temperatures associated with this feature were as cold as -47ºC just after 15 UTC, which were very close to the tropopause temperature of -47.9ºC on 12 UTC rawinsonde data from Reno (below).

Plot of 12 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Plot of 12 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Although clouds often prevented a good view of Lake Pyramid, Terra MODIS Sea Surface Temperature values of 42º and 43ºF were sampled on 11 and 16 February (below). With a northerly flow of air having temperatures around 20ºF across such warm water, significant boundary layer instability was generated to aid the growth of the lake effect cloud feature.

Terra MODIS Sea Surface Temperature product on 11 and 16 February [click to enlarge]

Terra MODIS Sea Surface Temperature product on 11 and 16 February [click to enlarge]

Although the view angle from GOES-16 (GOES-East) was rather large, a Land Surface Temperature pixel mapped to the northern portion of the lake had a value of 39.3ºF at 1701 UTC (below).

GOES-16 Land Surface Temperature product at 1701 UTC [click to enlarge]

GOES-16 Land Surface Temperature product at 1701 UTC [click to enlarge]