GOES-13 (GOES-East) 4-km resolution Infrared Window (10.7 µm) images (above) showed the development of a large Mesoscale Convective System (MCS) which produced tornadoes, large hail, and damaging winds (SPC storm reports | NWS La Crosse summary) as it propagated southeastward across the Upper Midwest during the evening and overnight hours of 05 July – 06 July 2016.

A sequence of 1-km resolution Terra/Aqua MODIS (11.0 µm), 1-km resolution POES AVHRR (12.0 µm) and 375-meter resolution Suomi NPP VIIRS (11.45 µm) Infrared images (below) showed better details of such features as overshooting tops, some of which exhibited IR brightness temperature values as cold as -78º C on MODIS, -81º C on AVHRR and -86º C on VIIRS.

A comparison of Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images at 0852 UTC or 3:52 am local time (below) showed the MCS as its core was centered over northern Illinois. Note how the tall, dense cloud mass blocked the view of nearly all city lights over a large area — including the normally very large and very bright lights of the Chicago metroplex. With almost no illumination from the Moon (which was in its Waxing Crescent phase, at 1% of Full), only the faint light of airglow helped to illuminate some cloud features over the northern portion of the satellite scene. In addition, numerous bright white streaks were seen in the Day/Night Band image along the leading (southern) edge of the MCS, due to cloud illumination from intense lightning activity; one lone lightning streak was evident in Wisconsin, whose intensity was bright enough to saturate the Day/Night Band detectors (hence the long “post-saturation recovery” streak as the sensor continued scanning toward the southeast).

A few hours earlier at 0339 UTC, the CLAVR-x POES AVHRR Cloud Top Height product (below) showed areas with height values of 16-17 km (lighter cyan color enhancement) — the large amount of water and ice particles contained within such tall clouds was therefore able to effectively block the view of city lights on the VIIRS Day/Night Band image. Note that a Cloud Top Height product will be available from the ABI instrument on GOES-R.

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Inspired by this as seen on Twitter:

Not a hurricane…sea ice caught in an eddy off of Newfoundland and Labrador, Canada. Via a pilot friend of mine. pic.twitter.com/bpAxLqMPSN

— Kyle Roberts (@KyleWeather) July 3, 2016

we decided to take a look at some satellite imagery. GOES-13 (GOES-East) Visible (0.63 µm) images (below) captured the fluid motion of ice floes off the coast of Labrador and Newfoundland on 02 July 2016.

A comparison of Terra MODIS true-color and false-color Red/Green/Blue (RGB) images viewed using RealEarth (below) aided in the discrimination of cloud vs ice/snow — in the false-color images, snow/ice appeared as shades of cyan, in contrast to supercooled water droplet clouds which appeared as shades of white.

An alternative RGB image for use in the discrimination of cloud vs snow/ice is shown below; in this particular false-color RGB image, snow/ice features appear as shades of red. Surface observations at the time of the Terra MODIS image are plotted in yellow.

2 days later, 04 July maps from the Canadian Ice Service (below) indicated that much of these larger ice floes consisted of thick first-year ice with concentrations in the range of 4-6/10ths to 8-10/10ths; the existence of such ice concentration at this particular location was 4-6/10ths to 9-10/10ths above normal.

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The MIMIC Total Precipitable Water product (above) showed the westward movement of a surge of dry trade winds toward Hawai’i during the 28 June – 01 July 2016 period. This push of dry air was being driven by a large area of high pressure centered about 1200 miles northeast of the island chain. A very sharp gradient in TPW existed along the leading edge of the dry surge, with values of 50-55 mm (2.0-2.2 inches) ahead of the boundary dropping to as low as 20-25 mm (0.8-1.0 inch) behind it.

GOES-15 (GOES-West) Visible (0.63 µm) images (below) revealed a sharp contrast in cloudiness east of Hawai’i on 29 June, with far fewer and much smaller marine boundary layer cloud elements seen in the dry air east of the leading edge of the trade wind surge.

On the following day (30 June), GOES-15 Visible (0.63 µm) images (below) showed a vast expanse of small closed-cell convective clouds in the marine boundary layer — a signature of a stable air mass; in this case, due to strong low-level subsidence — extending to distances as far as 1000 miles east and northeast of Hawai’i.

The progression of the leading edge of the dry trade wind surge could also be followed on daily composites of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from 26-30 June, as viewed using RealEarth (below).

Skew-T diagrams of rawinsonde data from the 2 upper air sites in Hawai’i (Hilo PHTO, and Lihue PHLI) are shown below. At Hilo on the Big Island of Hawai’i, the height of the trade wind temperature inversion descended from the typical height of 5500-6000 feet (near the 850 hPa pressure level) on 30 June to an unusually-low height of around 2500 feet (near the 930 hPa pressure level) at 12 UTC on 01 July. Farther to the west at Lihue on the island of Kaua’i, the dry trade wind surge was just beginning to arrive around the time of the 12 UTC sounding on 01 July — a sharpening of and a slight lowering of the trade wind inversion could be seen in comparison to the earlier 00 UTC sounding.

As the strong trade wind flow interacted with the terrain of the islands, areas of high wind gusts were observed — for example, 36 knots (41 mph) at Bradshaw Army Air Field on the Big Island of Hawai’i. In addition, the dew point temperature at that site was as low as 21º F within an hour after that peak wind gust on the afternoon of 01 July.

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Props to the Boston/Taunton National Weather Service forecast office for sending out the following on Twitter:

Late May ? late June, tree defoliation per caterpillars across SE New England is notable, esp W RI pic.twitter.com/AfRYKxdPEL

— NWS Boston (@NWSBoston) June 26, 2016

Taking a closer look at 250-meter resolution Terra MODIS true-color (Bands 1/4/3) Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above), the loss of “green-ness” due to defoliation of large areas of trees is quite evident — most notably in western Rhode Island, but also across the border into extreme southern Massachusetts and in parts of eastern Connecticut. This defoliation was caused by an infestation of gypsy moth caterpillars (media report 1 | media report 2).

The corresponding Terra MODIS false-color (Bands 7/2/1) RGB images (below) also help to highlight the areas of tree defoliation, as indicated by a decrease in bright green hues.

On 25 June, the highly-concentrated area of tree defoliation across northwestern Rhode Island exhibited a low Normalized Difference Vegetation Index (NDVI) of 0.4 to 0.6, compared to other areas in the southern and eastern part of the state where NDVI values were in the 0.7 to 0.8 range (below).

Much of the affected region was experiencing Abnormally Dry to Moderate Drought conditions, and had only received  between 25-75% of normal precipitation during the preceding 30/60/90-day periods — this created ideal conditions for the hatching of gypsy moth caterpillar eggs. If these dry conditions persist, it will limit the ability of the deciduous trees to recover and begin producing leaves again during the remainder of the summer season.

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