GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a cyclone (surface analyses) moving off the coast of Uruguay on 05 February 2021. What appeared to be an eye-like feature developed at the storm center toward the end of the day.

A toggle between VIIRS True Color RGB images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) provided a larger scale perspective of the cyclone.

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Suomi NPP VIIRS Infrared Window (11.45 µm) images (above) revealed a large area of cold surface infrared brightness temperatures across much of the North Slope of Alaska on 04 February 2021 — with the coldest IR temperature being -56ºC (darker shades of violet) about 30 miles south-southeast of Umiat (PAUM) on the 1221 UTC image. The surface air temperature at the nearby Umiat RAWS site around that time was -55ºF (-48.3ºC). Narrow fingers of cold air drainage into some of the river valleys along the northern slopes of the Brooks Range (topography) were also apparent.

The corresponding GOES-17 “Clean” Infrared Window (10.35 µm) images (below) also showed the large area of cold surface IR brightness temperatures, but the temperatures were not as cold (in the -40 to -50ºC range), and the small-scale signatures of various topographical features were not depicted.

A toggle between Infrared Window images from Suomi NPP VIIRS and GOES-17 (10.35 µm) at 1223 UTC is shown below.

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A rare, mostly clear day over the Great Lakes (and favorable orbital geometry) allowed NOAA-20, above, and Suomi-NPP, below, to image all 5 Great Lakes in one scene.  These images were produced from data that were downloaded at the Direct Broadcast site at CIMSS and processed with CSPP and Polar2Grid;  imagery is available at this link:  ftp://ftp.ssec.wisc.edu/pub/eosdb.  Although many bays appear ice covered (Green Bay in Lake Michigan, Saginaw Bay in Lake Huron, Chequamegon Bay in Lake Superior, there is otherwise a notable lack of ice in the lakes (the feature in central Lake Michigan is cloud).  Current forecasts of sub-zero weather over the western Great Lakes by this coming weekend suggest an increase in ice cover is likely.

The biggest difference between Lake Erie and the other lakes is color.  Why is Lake Erie not a dark blue?  Part of this is depth:  Lake Erie is the shallowest of the Great Lakes.  The browns and lighter blues are the result of sediment from both rivers and from white clay minerals along the northern shore of Lake Erie.  Phytoplankton is also affecting the water color;  not in the sense of an algal bloom, but a persistent algal presence  (Click here for an estimate of Chlorophyll from 21 January, from this website).  (Thanks to scientists at the Great Lakes node of NOAA’s Coast Watch — part of GLERL — for this explanation).

The (mostly) clear skies over the Lakes allowed for an estimate of Lake Surface Temperatures using VIIRS data and the ACSPO (Advanced Clear Sky Processor for Oceans) algorithm, shown below with colors representing temperatures from 32 to 41ºF (0 to 5º C).  Portions of Lakes Michigan, Huron and Ontario (red and white in the color enhancement) show surface temperatures near 41ºF.  Lakes Superior and Erie are relatively cooler.  Much of central Lake Erie is near 35ºF (cyan in the enhancement);  values in eastern Lake Erie are closer to 38ºF (yellow in the enhancement).  Eastern Lake Superior also shows values in the upper 30s.

GOES ABI

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GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images with plots of hourly surface weather type (above) showed the formation of a well-defined cold conveyor belt that moved westward across parts of the Northeast US during the 01 February – 02 February 2021 period. This moist airstream helped to enhance snowfall rates, with 2-4 inches per hour occurring at some locations. Storm total snowfall accumulations were as high as 36.1″ in Pennsylvania, 35.5″ in New Jersey, 25.6″ in New York, 24.0″ in Massachusetts, and 19.0″ in Connecticut.

Another feature that played an important role in enhancing/prolonging heavy snowfall rates was a TROWAL — appearing as a tongue of higher Equivalent Potential Temperature within the 850-700 hPa layer, just north of the surface occluded front — moving inland and feeding moisture into the southern edge of the cold conveyor belt seen on GOES-16 Water Vapor imagery (below).

 

Updated January 30-February 2 snowfall reports based on reports received as of 6 pm Tuesday. Here are the latest highest totals in each state (1 of 2).
PA – Nazareth 36.1″
NJ – Mount Arlington 35.5″
NY – Fishkill/Saugerties 25.6″
MA – Lowell 24″
WV – Terra Alta 22.1″ pic.twitter.com/unxodO5ccS

— NWS Eastern Region (@NWSEastern) February 2, 2021

1-minute Mesoscale Domain Sector GOES-16  “Red” Visible (0.64 µm) images with 5-minute plots of Derived Motion Winds (below) revealed a mesoscale circulation just south-southwest of the analyzed location of the surface low — the majority of these wind vectors had height assignments within the 900-990 hPa range, indicating that the circulation was located above the surface. The highest DMW speed was 36 knots.

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