The lake breeze prevails! Visible on radar, a strong lake breeze off Lake Superior has given some quick heat relief to our coastal regions. Areas in Superior and Park Point have dropped into the upper 50s up on the hill we have fallen into the mid 70s. #mnwx #wiwx #lakebreeze pic.twitter.com/3RwKYtsvAH

— NWS Duluth (@NWSduluth) June 5, 2021

GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) images (above) displayed the cooling effect of the lake breeze on land surfaces in Minnesota and Wisconsin on 05 June 2021.

A plot of surface data from Duluth Sky Harbor Airport (below) showed that the temperature dropped from 97ºF to 64ºF in 20 minutes as the lake breeze arrived. Large and rapid temperature drops were also seen at Superior, Wisconsin (plot | data) and Cloquet, Minnesota (plot | data).

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This past CIMSS Blog Post showed a region of very strong bowing winds diagnosed by Synthetic Aperture Radar (SAR) data and associated with a convective complex over Lake Superior before sunset on 25 May 2021.   On 3 June 2021, shortly after sunrise (SAR overpasses over the Great Lakes typically occur around 0000 and 1200 UTC), SAR winds from RCM3 (RADARSat Constellation Mission 3) (as shown at this website), showed isolated patches over northern Lake Superior of very strong winds — in excess of 25 m/s! (SAR wind imagery is from this website)

GOES-16 visible imagery (0.64 µm), below, from 1120 – 1200 UTC, visualized using CSPP Geosphere, shows the modest convection associated with these winds.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed an interesting contrast in the character of Above-Anvil Cirrus Plumes (reference | VISIT training) over central Texas just before sunset on 02 June 2021. The northernmost AACP was generated by a single brief overshooting top (during the 0031-0041 UTC time period), but produced the most robust “warm” (brighter shades of green) plume signature in the Infrared imagery. Other AACP signatures could be seen in the southern portion of that mesoscale convective system, but none of them exhibited such a notable warm infrared signature (in spite of prolonged periods of pulsing overshooting tops).

The coldest cloud-top infrared brightness temperature of the brief overshooting top was -71ºC at 0034 .UTC (above) — soon afterward, the infrared brightness temperatures within the “warm wake” immediately downwind of the overshooting top were generally in the -51ºC to -55ºC range, highlighted by the brighter green enhancement (below).

A plot of 00 UTC rawinsonde data from Midland, Texas (below) indicated that the -71ºC overshooting top brightness temperature corresponded to a Most Unstable air parcel ascent of about 1 km beyond its Equilibrium Level. The warming temperature within the lower stratosphere (just above the tropopause / equilibrium level) was also apparent.

It should be mentioned that not all Above-Anvil Cirrus Plumes exhibit a warmer signature on Infrared imagery — depending on the ambient temperature profile just above the tropopause / equilibrium level, some plumes can appear colder (for example: Nov 2018, Sep 2019 and May 2020)

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GOES-17 (GOES-West) “Red” Visible (0.64 um) images (above) showed the motion of ice within Norton Sound — inbound early in the day, transitioning to outbound later in the day — on 28 May 2021. This ice motion was likely driven primarily by tidal motions within the Sound; for example, a plot of tide height for Unalakeet (below) depicted rising tide (water moving into the Sound) from 04-20 UTC followed by falling tide (water moving out of the Sound) after 20 UTC.

Farther inland over the Alaska North Slope, comparisons of Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 1838 and 2015 UTC (below) revealed the formation and subsequent expansion of an “aircraft dissipation trail”. As an aircraft — likely headed to or from Prudhoe Bay — flew through a relatively thin cloud layer composed of supercooled water droplets, it caused glaciation of supercooled water droplets along its flight path (which then fell out of the cloud as snow).

1-minute GOES-17 Day Cloud Phase Distinction RGB images created using Geo2Grid (below) showed the formation and growth of the aircraft dissipation trail.

===== 29 May Update =====

On the following day, 1-minute GOES-17 Visible images (above) showed a similar inbound/outbound diurnal shift in the direction of ice flow within Norton Sound. Plots of NAM12 model surface winds and Metop-A ASCAT surface scatterometer winds indicated that the ice motion was generally orthogonal to surface wind direction — which reaffirmed that tides were the primary factor influencing ice motion during those 2 days.

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