Clear skies over most of the five Great Lakes on 28-29 November allowed the VIIRS instrument on NOAA-20 to gather information for Advanced Clear-Sky Processing for Ocean (ACSPO) Sea Surface Temperatures.  The animation above shows two afternoon images (from 28 November 2020, at 1728 UTC and 1911 UTC) and one morning image (from 29 November 2020 at 0727 UTC).  The color enhancement shows values from 35ºF to 55ºF.

Lake Erie shows the warmest temperatures, just over 50ºF in the eastern part of the Lake. High Pressure over the Ohio River valley on 28 November (2100 UTC analysis) meant light winds over Lake Erie. The lack of wind-induced mixing allowed for warming (a few degrees F between 1728 and 1911 UTC) of the surface skin of the lake. Lake Superior shows temperatures around 40º F (albeit a bit warmer along just off the Upper Peninsula of Michigan); Lakes Michigan and Huron, western Lake Michigan and northwest Lake Ontario show temperatures in the mid-40s. Eastern Lake Ontario shows temperatures in the upper-40s.

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Note: You can compare these observations to previous years here, for Lake Michigan. (Links to comparisons at other lakes are at that link as well). Thanks to the Blog Reader for this link!

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1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Mid-level Water Vapor (6.9 µm) and Air Mass Red-Green-Blue (RGB) images (above) showed a Storm Force low (surface analyses) developing in the Gulf of Alaska on 26 November 2020. As the storm intensified, trends of warming//drying on the Water Vapor images and brighter orange/red hues on the Air Mass RGB images near the center of circulation indicated the development of a potential vorticity anomaly that lowered the dynamic tropopause (bringing dry, ozone-rich  air into the upper portion of the atmospheric column).

A toggle between Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images (below) showed the storm at 2228 UTC.

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An extratropical cyclone deposited a mesoscale snowband — a few counties wide — in south-central Kansas late in the day on 24 November 2020 (Click here to see the storm at 0300 UTC on 25 November). As is often the case, such bands have profound impacts on surface temperatures. It is therefore important to monitor their precise location. The animation above shows the Day Snow Cloud RGB; its use of the 1.61 µm band allows the RGB to distinguish easily between snow and clouds, both of which are bright in the visible, as shown in the image below, courtesy Mike Umscheid, NWS ICT, that shows the snow band and the similarly reflective clouds to the east. (Imagery created at this nifty website!)

GOES-16 Land Surface Temperatures (a baseline level 2 product) shows the effect of the snow on skin temperature, below. Shortly after sunrise, temperatures over the snowband are several degrees (Fahrenheit) cooler, as expected with clear skies and a fresh snowpack. (Warm lakes also shine through!)  Bare land in Kansas warms quickly, with Skin Temperatures reaching into the upper 60s and 70s by 1900 UTC, whereas the snow band remains in the 30s!

A comparison of GOES-R Land Surface Temperatures with METAR observations, below, underscores the notion that the skin temperature can be much warmer than the temperature 1.5 m above the ground, where METAR thermometers (or thermistors) measure the air temperature. The warmest METAR temperature at 2000 UTC is 57º F at Scott City, KS. Land Surface Temperatures there are in the mid-60s, with 70 just to the northeast.

Note that the default bounds of the colorbar range in Land Surface Temperature have been changed. Default values range from -10º to 110º F; values shown above range from 10º to 80º F. The toggle below compares the two, at 1501 UTC.

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Towards sunset, the Day Snow Fog RGB (or any RGB that relies on reflectances from visible, near-Infrared or infrared channels) can become dim. In that event, an AWIPS user can edit the Composite Options, reducing the upper bounds of all three RGB channels o that the image retains brightness and utility (in this case upper bounds were reduced for Red from 100 to 60; for Green from 70 to 40; for Blue from 30 to 19).

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US Space Force EWS-G1 Infrared (10.7 µm) images (above) showed Category 1 Cyclone Nivar making landfall along the southeastern coast of India on 25 November 2020.

EUMETSAT Meteosat-8 Infrared Window (10.8 µm) images with contours of deep-layer wind shear from the CIMSS Tropical Cyclones site (below) indicated that Nivar was moving through an environment of low shear (and over warm water) — factors favorable for the storm maintaining its intensity.

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