Satellite winds « CIMSS Satellite Blog

The Great Lakes, viewed using GOES-16 and NOAA-20 imagery

January 21st, 2022 | Scott Bachmeier

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) displayed mesovortices over southern Lake Michigan on 21 January 2022. The formation of these mesovortex features was aided by a mid-lake convergence of surface winds, which was suggested by RAP40 surface wind fields and shown n more detail by Metop-C ASCAT winds from this site (below).

Metop-C ASCAT surface scatterometer winds [click to enlarge]

Farther to the north, in spite of a cold night across northeast Wisconsin and Upper Michigan — with morning low temperatures of -30ºF at Laona, Wisconsin and -39ºF at Amasa, Michigan — GOES-16 Visible images (below) showed that southerly winds helped to open an ice lead near the center of Green Bay, with a slow northward drift of pack ice in the northern half of the bay. A lone ice floe was also seen moving northward near the western edge of the clouds in Lake Michigan.

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

A toggle between NOAA-20 VIIRS True Color and False Color RGB images (below) revealed a more detailed view of the ice structure — and also showed the narrow southwest-to-northeast oriented damage path that remained from a June 2007 EF-3 tornado that went through a portion of Menominee, Langlade and Oconto counties. The higher spatial resolution of the VIIRS imagery helped to highlight the aforementioned isolated ice floe in Lake Michigan (which appeared as cyan in the False Color RGB image).

NOAA-20 VIIRS True Color and False Color RGB images [click to enlarge]

To the east, mesovortices were also observed in Lake Huron – long with ice floes drifting away from the coast of Lower Michigan (below).

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

A was the case in Lake Michigan, these Lake Huron mesovortices were forming along an axis of surface wind convergence, seen in Metop-B ASCAT data (below).

Metop-B ASCAT surface scatterometer winds [click to enlarge]

A larger-scale toggle between NOAA-20 VIIRS True Color and False Color RGB images — created using data received from the SSEC/CIMSS Direct Broadcast ground station — provided a view of the entire Great Lakes region (below).

NOAA-20 VIIRS True Color RGB and False Color RGB images (credit: Margaret Mooney, CIMSS) [click to play animation]

Posted in GOES-16, Metop, NOAA-20, Red-Green-Blue (RGB) images, Satellite winds, VIIRS | Comments Off on The Great Lakes, viewed using GOES-16 and NOAA-20 imagery

SAR data for winds and ice over the Great Lakes

January 10th, 2022 | Scott Lindstrom

Radarsat Constellation Mission (RCM) observations over Lake Superior, 11:59 UTC on 10 January 2022 (Click to enlarge)

Data from this site shows SAR observations over the Great Lakes daily around 0000 and 1200 UTC. The image above shows SAR data over Lake Superior just before 1200 UTC on 10 January. The background flow used in processing shows strong northwesterly winds. Note the relative calm in the lee of the Keewenah peninsula, and an interesting boundary in the winds near Michipicoten Island. As noted in this blog post from December, the strongest winds are likely associated with enhanced Lake-Effect bands, as enhanced vertical mixing in those bands will allow stronger upper level winds to mix down to the lake surface.

Does ABI imagery show enhancements in the regions where the SAR data indicates enhanced mixing with convective bands? Consider the 3.9 µm image below (from this NOAA/STAR website) from 1201 UTC. Cold cloud tops northeast of Marquette MI do correlate well with the strong winds in that regions.

GOES-16 Band 7 (3.9 µm) at 1201 UTC on 10 January 2022 (click to enlarge)

Scatterometry can also be used to measure winds on the lake surface. The imagery below (from this website) shows vectors from the Chinese HY-2B scatterometer at 1330 UTC. Spatial resolution for this imagery is much coarser, and observations closer to shore do not occur. Northwest winds of at least 30 knots are indicated however.

HY-2B scatterometry at 1310 UTC, 10 January 2022 (Click to enlarge)

A careful observer of the SAR winds above might notice very strong winds in/around Little Bay de Noc, the northeastern part of Green Bay. Care must be taken to differentiate between ice and winds in regions where ice is present, as SAR data can be also used to identify regions of ice. The toggle below of NOAA-20 True and False color imagery over the western Great Lakes (from the VIIRS today website) does show cyan regions — typical of ice — over northeastern Green Bay. (Click here for highest resolution False Color imagery from NOAA-20 on 9 January)

NOAA-20 True and False color over the Great Lakes, 9 January 2022 (Click to enlarge)

What kind of wave heights are these strong northwesterly winds generating over Lake Superior? Altimetric data from SMAP, below, (source) shows 6-8 foot waves over western Lake Superior. The longer fetch for the region northeast of Marquette probably means much higher waves there.

Wave Heights (feet) at ~0315 UTC on 10 January 2022 (click to enlarge)

Posted in Arctic, GOES-16, NOAA-20, Other Satellites, Satellite winds, Winter weather | Comments Off on SAR data for winds and ice over the Great Lakes

Tropical disturbance near Fiji

January 7th, 2022 | Scott Lindstrom

GOES-17 Geocolor imagery and Flash Extent Density, 1506-1911 UTC on 7 January 2022 (Click to enlarge)

GOES-17 ABI and GLM imagery (from this NOAA STAR website), above, over the southern Pacific Ocean show a region of potential tropical cyclogenesis to the west of Fiji, near the western boundary of this mapping. This Invest Area has been percolating for much of the week. Despite low values of shear (shown below, from this website) and warm sea-surface temperatures, intensification to a tropical depression has not yet occurred (see this discussion from the Joint Typhoon Warning Center). However, GLM observations of Flash Extent Density (FED) do show occasional lightning events within the developing system.

Diagnosed wind shear, 1800 UTC on 07 January 2022 (Click to enlarge)

Upper-level water vapor imagery (GOES-17 Band 8, at 6.19 µm), below, from 1940 UTC, shows a distinct cirrus overcast at about 17 S, 172 E. Substantial dry air is not indicated in the water vapor imagery, nor in a MIMIC TPW mapping from 1200 UTC (downloaded from here), shown below.

Upper-level water vapor imagery (GOES-17 Band 8, 6.19 µm), 1930 UTC on 7 January 2022 (Click to enlarge)

MIMIC Total Precipitable Water fields, 1200 UTC on 7 January 2022 (Click to enlarge)

Scatterometry over this system on 7 January (downloaded from this website), show an increase in symmetry to the storm between the HY-2B overpass at 0630 UTC and the HY-2C overpass at 1330 UTC. For more information on this system over the weekend, refer to the SSEC/CIMSS Tropical Website, the Joint Typhoon Warning Center, and the Fiji Meteorological Service.

Scatterometery over the south Pacific, 0630 and 1330 UTC on 7 January 2022 (Click to enlarge)

Posted in GOES-17, Other Satellites, Satellite winds | Comments Off on Tropical disturbance near Fiji

Strong jet streak over the Upper Midwest

December 28th, 2021 | Scott Bachmeier

GOES-16 Upper-level Water Vapor images, with plots of Derived Motion Winds [click to play animated GIF | MP4]

An anomalously-strong 250 hPa jet streak (analysis) was moving across the Upper Midwest late in the day on 27 December 2021. The 205 knots at Chanhassen Minnesota was a 250 hPa record maximum speed for all 00 UTC rawinsondes on 28 December at that site, as was the 207 knots at Green Bay, Wisconsin. GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm) images with plots of Derived Motion Winds (DMW) (above) showed this jet streak as it moved over the Chanhassen (KMPX) and Green Bay (KGRB) areas.

GOES-16 Upper-level Water Vapor images, with plots of Derived Motion Winds and contours of RAP model Maximum Wind Speed isotachs [click to play animated GIF | MP4]

12 hours later, the tail end of the still anomalously-strong 250 hPa jet streak (analysis) was moving across Wisconsin and Michigan on the morning of 28 December. The 187 knots at Green Bay, Wisconsin was a 250 hPa record for 12 UTC rawinsondes on 28 December at that site, as was the 181 knots at Gaylord, Michigan. GOES-16 Upper-level Water Vapor images with plots of Derived Motion Winds and contours of RUC40 model maximum wind speeds (above) showed this jet streak as it moved over the Green Bay (KGRB) and Gaylord (KAPX) areas.

Examples of 3 DMWs over Wisconsin and Michigan having speeds in excess of 180 knots are shown below. The DMW speed values were generally in good agreement with the hourly RAP40 isotachs at the Level of Maximum Winds, demonstrating that DMWs can be useful for model verification.