GOES-16 Mid-level (6.9 µm) Water Vapor images (above) showed the development of a Nor’easter off the east coast of the US during the 12 March – 13 March 2018 period (surface analyses). The storm produced blizzard conditions with snowfall amounts as high as 28.3 inches and wind gusts as high as 81 mph in Massachusetts (WPC storm summary | Boston MA summary | Gray ME summary | Caribou ME summary).

GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed the cloud shied associated with the rapidly-intensifying Nor’easter on 13 March.

A closer view using 1-minute interval Mesoscale Sector “Red” Visible (0.64 µm) images on 13 March (below) included plots of hourly surface wind gusts.

View only this post Read Less

The CIMSS Natural True Color RGB, above, from 13 March 2018, shows the motion of alluvial sediment in the Gulf of Mexico in the outflow from various rivers. Muddy plumes from the Atchafalaya River in central Louisiana, the Mississippi River, and the Mobile River in Alabama are apparent. In particular, there is distinct northward motion during the 3 hours shown in this animation along the northern edge of the Mississippi River Delta.

A similar animation for 9 March 2018 is available here (courtesy Tim Schmit, NOAA and Mat Gunshor, CIMSS). Close monitoring of where the outflow from rivers is mixing with the Gulf of Mexico waters is a capability of GOES-16 Imagery when skies are clear.

Natural True Color is computed from GOES-16 Reflectance imagery using the “Blue” band (0.47 µm), the “Red” band (0.64 µm) and the “Veggie” band (0.86 µm), that latter being used to give information that in True Color Imagery from MODIS or Suomi NPP (for example) is supplied by a true “Green” band (0.55 µm).

The animation below shows True-Color imagery from MODIS for clear days between 30 January and 13 March 2018. The superior resolution of MODIS (on the Terra and Aqua spacecraft) and the presence of a 0.55 µm channel (in addition to 0.47 µm and 0.64 µm) allows for crisper imagery than from GOES-16; however, the ability to animate at small time scales over the Gulf of Mexico is a capability reserved for GOES-16 (and GOES-17, when it becomes operational). Terra and Aqua imagery are not useful if the overpass of the Polar Orbiters coincide with clouds; on days with variable cloud cover, GOES Imagery is more likely to provide useful information.

View only this post Read Less

A large Maersk container vessel caught fire in the Indian Ocean on 6 March 2018 (news report 1, news report 2), killing 4 sailors and necessitating the evacuation of the ship (the MAERSK HONAM).

Suomi NPP and NOAA-20 (which trails Suomi NPP by half an orbit) both passed over the ship fire on 6 March. As a singular light source in the middle of the Indian Ocean, the ship fire was evident in the Day Night Band imagery, as shown above, at 10.5º N and 65.8º E). The ship drifted southward in the 50 minutes between VIIRS scans from the two satellites. (Similar signatures were apparent in the 1.61 µm, 2.25 µm and 4.05 µm imagery from VIIRS on the two satellites).

One day later, on 7 March, above, Suomi NPP and then NOAA-20 (50 minutes later) again passed over the still-burning ship, then at 10.1º N and 65.6º E. A faint smoke plume is visible in the imagery from NOAA-20.

The zoomed-out image, below, might give you a better idea of how far away from the India and Africa this ship sits.

(Hat tip to William Straka, CIMSS, for the imagery and also to Steve Miller, CIRA, for alerting us to this event)

View only this post Read Less

Strong northwesterly winds over the Great Plains to the west of a storm system over the mid-Mississippi River Valley have resulted in Red Flag Warnings over Oklahoma, and High Wind Warning and Dust Storm Warnings — including the closing of I-70 over Kansas. Visible Imagery in the “Blue Band”, above, shows little indication of the blowing dust (Click here for an animation without surface observations); dust is difficult to observe when sun angle are high. The higher-(spatial) resolution “Red Visible” animation, shown below, similarly struggles to identify with clarity where the dust is occurring.

The ‘Blue Band’ does detect plumes of smoke that develop over southern Kansas during this animation, plumes that originate over ‘hot spots’ in the 3.9 µm shortwave infrared imagery (not shown).

Infrared Imagery can be used to detect dust, both during the day and at night. This is because dust selectively absorbs energy. For example, energy at 10.3 µm that is emitted by the surface, and destined to be observed by the satellite, will be absorbed (and re-emitted from a higher, cooler level in the atmosphere) as it passes through the dust layer. Energy with a longer wavelength (12.3 µm), passes through dust mostly unaffected. Thus, a difference field between the two — the so-called Split Window Difference — will show negative values in regions where lofted dust is present in the atmosphere. An animation is shown below. As with imagery in this blog post, the colormap in the AWIPS display was changed to “Grid/Lowrange Enhanced”; dust regions are highlighted in yellow.  Dust is first detected in central Nebraska before it shows up in central and western Kansas. A closer view of the area where Interstate 70 was closed (between Goodland and Colby in northwestern Kansas) can be seen here.

The Cloud Phase Channel Difference field in AWIPS (Currently 10.3 µm – 8.5 µm, shortly to transition in AWIPS to 11.2 µm – 8.5 µm) can also detect dust (as was shown in this blog post), and that animation is shown below. Blowing Dust in this field is a bright green — and this Difference field (compared to the Split Window Difference) better identifies sources of plumes over western Kansas.

The Dust RGB, below, combines both the Split Window Differerence (the ‘Red Gun’) and the Cloud Phase Brightness Temperature Difference (the ‘Green Gun’), as well as the Clean Window (10.3 µm, ‘Blue Gun’, not shown). Dust in this RGB is typically bright pink, and its presence is notable over western Kansas.

Closer to sunset, at 2252 UTC on 6 March, the Dust Plume is readily apparent in the Band 1 and Band 2 imagery, shown below in a toggle with infrared channel differences and the Dust RGB.

Hat tip to Jeremy Martin, the SOO in the Goodland KS National Weather Service Office, for alerting us to this case!

View only this post Read Less