Consolidation of ice within Green Bay

March 4th, 2021 |

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 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the wind-driven consolidation of ice within Green Bay during the 03 March04 March 2021 period. Northerly winds in the wake of a cold frontal passage on 03 March led to the fracturing of land-fast ice in the far northern portion of Green Bay — this ice then began drifting south-southwestward.

By sunrise on 04 March, GOES-16 Visible images indicated that the fractured ice had continued to drift farther southward overnight, eventually merging with the land-fast ice that had been covering the southern half of Green Bay; overnight low temperatures in the upper teens to low 20s F likely aided this merger process. Note that some filaments of ice had also migrated through gaps between islands, drifting southward across far western Lake Michigan (just off the coast of Wisconsin).

A toggle between 250-meter resolution Aqua MODIS True Color RGB images (source) on the 2 days is shown below.

Aqua MODIS True Color RGB images [click to enlarge]

Aqua MODIS True Color RGB images [click to enlarge]

As an aside, farther inland the tornado damage path from an EF3 tornado in northeastern Wisconsin was still evident, 13.5 years later (below).

Aqua MODIS True Color RGB images [click to enlarge]

Aqua MODIS True Color RGB images [click to enlarge]

Blowing snow across the Upper Midwest

February 6th, 2021 |

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 (GOES-East) Day Snow-Fog RGB images (above) showed widespread horizontal convective rolls (HCRs) which highlighted areas where blowing snow was more concentrated across parts of southern Manitoba and the Upper Midwest on 06 February 2021. Snow cover (and glaciated clouds) appeared as shades of red, with bare ground exhibiting lighter shades of green and low-level water droplet clouds appearing as brighter shades of white.

Closer views of the northern, central and southern portions of the region where blowing snow was most prevalent are shown below. The HCRs were evident during the early to late morning hours across southern Manitoba, far eastern North Dakota and northwestern Minnesota — and then became more apparent across western/southern Minnesota extending into far northern Iowa as the day progressed. Surface reports showed that the visibility fluctuated dramatically at some sites as HCRs moved through.

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Snow-Fog RGB images [click to play animation | MP4]

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

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

In comparisons of MODIS True Color and False Color RGB images from Terra (above) and Aqua (below), the areal coverage of HCRs could be seen in the False Color imagery.

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

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

Farthest to the north, one cluster of HCRs appeared to originate over Lake Manitoba — as seen in 30-meter resolution Landsat-8 False Color imagery from RealEarth (below).

Landsat-8 False Color RGB image [click to enlarge]

Lansdsat-8 False Color RGB image [click to enlarge]

Two notable pilot reports across southern Minnesota (below) showed that flight visibility was restricted to 4 miles at an elevation of 3000 feet, and the tops of HCRs extended to 5000 feet.

GOES-16 Day Snow-Fog RGB images, with plots of Pilot Reports [click to enlarge]

GOES-16 Day Snow-Fog RGB images, with plots of Pilot Reports [click to enlarge]

GOES-16 Day Snow-Fog RGB images, with plots of Pilot Reports [click to enlarge]

GOES-16 Day Snow-Fog RGB images, with plots of Pilot Reports [click to enlarge]

Additional material on satellite identification of blowing snow is available here and here.

NOAA/CIMSS ProbSevere with a tornado in Tallahassee, FL

January 27th, 2021 |

NOAA/CIMSS ProbSevere display, 1545 – 1700 UTC on 27 January 2021 (Click to animate)

A tornado struck the Tallahassee, FL, airport at 1643 UTC on 27 January 2021 (SPC Storm Report).  The animation above shows ProbSevere (version 2) fields (from this site) in the hour leading up to tornadogenesis.  The animation demonstrates how ProbTor values can be used to identify for closer scrutiny a particular radar object:  the radar object that ultimately caused a tornado showed greater ProbTor values (than surrounding identified radar objects) in the hour leading up to tornadogenesis. In addition, ProbTor values ramped up quickly just prior to tornadogenesis as low-level azimuthal shear jumped.

One time series below compares ProbWind, ProbHail and ProbTor for the radar object (#15080) that produced the tornado; for this event, ProbWind and ProbTor values were comparable until a ramp-up in ProbTor values before the tornado occurred. The second time series shows the various components of ProbTor for radar object 15080 (both time series courtesy John Cintineo, SSEC/CIMSS).  Note in particular that this storm was not a lightning-producer.  Much of ProbTor’s variability was determined by changes in low-level azimuthal shear.

NOAA/CIMSS ProbSevere values (ProbWind, ProbHail, ProbTor) for radar object #15080, 1530 – 1658 UTC on 27 January 2021 (Click to enlarge)

NOAA/CIMSS ProbTor and component values for Radar object #15080, 1530 – 1658 UTC on 27 January 2021, associated with the Tallahassee FL tornado (Click to enlarge)

Lead time with ProbTor in this example was not exceptional.  However, its elevated values in the hour leading up to the tornado could have provided better situational awareness, and perhaps enhanced confidence in warning issuance for this well-warned event.

_________________________________________________________________________________________________________

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.35 µm, right) images, with plots of SPC Storm Reports [click to play animation | MP4]

Unfortunately, the default Mesoscale Domain Sectors were positioned too far north to cover the Florida Panhandle — but 5-minute CONUS Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) depicted a west-to-east oriented line of thunderstorms across the northern portion of the Panhandle; a trend of cooling cloud-top infrared brightness temperatures was seen as the convection began to produce the tornado.

There was an overpass of the Terra satellite about 19 minutes before the start of the tornado event, at 1618 UTC — 1-km resolution MODIS Visible (0.64 µm) and Infrared Window (11.0 µm) images are shown below.

Terra MODIS Visible (0.64 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.64 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Hurricane Zeta over the Gulf of Mexico

October 27th, 2020 |

GOES-16 “Clean” Infrared Window (10.35 µm) images, with an overlay of GLM Flash Extent Density [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with an overlay of GLM Flash Extent Density [click to play animation | MP4]

After making landfall as a Category 1 Hurricane along Mexico’s Yucatan Peninsula a day earlier, a weakened Tropical Storm Zeta (NHC advisories) began to slowly re-intensify as it moved northward across the Gulf of Mexico after sunset on 27 October 2020 — 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images with an overlay of GLM Flash Extent Density (above) displayed increasing organization, with the gradual emergence of a ragged eye. Zeta once again reached hurricane intensity at 0600 UTC on 28 October.

===== 28 October Update =====

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0739 UTC (credit: William Straka, CIMSS) [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0739 UTC (credit: William Straka, CIMSS) [click to enlarge]

In a toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0739 UTC (above), the coldest cloud-top infrared brightness temperature just east-northeast of the eye was -96ºC. Ample illumination from the Moon (in the Waxing Gibbous phase, at 91% of Full) helped to highlight the “visible image at night” utility of the Day/Night Band.

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) and “Red” Visible (0.64 µm) images [click to play animation | MP4]

Zeta experienced a period of rapid intensification during the day on 28 October (ADT | SATCON) — 1-minute GOES-16 Infrared images (with and without an overlay of GLM Flash Extent Density) and Visible images (above) showed a trend of increasing organization and the emergence of a fairly well-defined eye. Periodic lightning activity within the inner eyewall region began after 1800 UTC (when Zeta was upgraded to a Category 2 hurricane), along with overshooting tops exhibiting cloud-top infrared brightness temperatures as cold as -90ºC. The hurricane made landfall along the coast of Louisiana around 2100 UTC.

GOES-16 Longwave Infrared (11.2 µm) images, with contours of 20 UTC deep-layer wind shear [click to enlarge]

GOES-16 Longwave Infrared (11.2 µm) images, with contours of 20 UTC deep-layer wind shear [click to enlarge]

Zeta was intensifying in spite of the fact that it was moving across progressively colder water, and approaching an atmospheric environment that was more hostile in terms of increasing deep-layer wind shear (above) — however, these factors were likely offset by a broad and well-defined upper level outflow channel north of the hurricane, shown by 6.2 µm Derived Motion Winds with velocities around 100 knots over Arkansas (below).

GOES-16 Upper-level Water Vapor (6.2 µm) images, with plots of Derived Motion Winds [click to play animation | MP4]

GOES-16 Upper-level Water Vapor (6.2 µm) images, with plots of Derived Motion Winds [click to play animation | MP4]

===== 29 October Update =====

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

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

On the day after Zeta’s landfall, GOES-16 True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) showed an increase in turbidity within the shallow shelf waters off the Texas and Louisiana coasts. Also of note were the patches of fresh snow cover across portions of New Mexico, Texas and Oklahoma — areas having less snow depth experienced melting during the day.

A higher-resolution view of the nearshore turbidity was provided by 250-meter resolution Terra MODIS True Color RGB imagery from the MODIS Today site (below). Vigorous mixing of the water by the strong winds of Zeta stirred up a great deal of sediment.

Terra MODIS True Color RGB image [click to enlarge]

Terra MODIS True Color RGB image [click to enlarge]