VIIRS data from NOAA-20 at the CIMSS Direct Broadcast download site, above, at 1734 UTC on 2 September were used to create True Color imagery, and SST fields over the largely-clear Great Lakes. Light winds associated with persistent high pressure over the Great Lakes (below) meant suppressed vertical mixing, leading to warm water temperatures on the lake surface. Most of Lake Superior’s surface is warmer than 60^oF, with portions of Lake Erie, Saginaw Bay, and Green Bay near 77^oF. This is also shown in the AWIPS Screen-capture with the same data, below.

Early on 1 September, skies were also mostly clear, and the VIIRS ACSPO SSTs are shown below in concert with Day Night Band visible imagery. The warmest temperatures in the color enhancement (white) are 77^oF (that is, 25^oC).

Clear skies continued overnight on 2-3 September, and another beautiful scene was produced. Lake Surface Temperatures and the Day Night Band at 0740 UTC on 3 September are shown below.

True-Color imagery from VIIRS and Lake Surface Temperatures are shown below from 1834 UTC on 3 September. Note the complete coverage over western Lake Superior. The anomaly in the analysis above has been rectified. Smoke is also apparent in this image over northern WI and central MN.

The smoke shows up well in the VIIRS AOD field, below (and in the GOES-16 fields as well here)

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Nighttime Microphysics RGB Imagery (Quick Guide) from the CSPP Geosphere site, above (direct link to image), from early on 1 September, shows a distinct color change from the southern US to the northern US, stretching east-northeast from Oklahoma to Pennsylvania. This abrupt change from deep purple to light purple heralds a change in moisture — as one might expect in early September as cooler, dryer air starts its inexorable move south as Summer wanes. The cyan color of low clouds is also present along this boundary (and in central Iowa). Part of the color change will be controlled by temperature as well: Blue in the RGB is a function of the Band 13 brightness temperature.

MIMIC Total Precipitable Water fields, above, from 0700 UTC, also show the sharp gradient in total precipitable water along this boundary as values drop from near 2″ over Arkansas to closer to 1/2″ over central Missouri. Blended TPW fields, below, taken from the CIRA SLIDER, show a similar sharp boundary.

How did Precipitable Water (PWAT) change across this boundary in the 0000 UTC Soundings on 1 September? Skew-Ts, below (from the Wyoming Sounding site), from Lincoln IL (left, in the dry air), Springfield MO (center) and Little Rock AR (right), show PWAT values of 15, 49 and 51 mm, respectively!

Hat tip to Jochen Kerkmann, EUMETSAT, for noting this event today and sending out an email.

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True-color imagery, above, shows the evolution of the Remington Fire in extreme northern Wyoming on 22 August 2024. (Geography note: The Wyoming/Montana border in the image is at 45^oN Latitude). The initial report for this fire occurred at 8:07 AM (MDT)/1407 UTC on 22 August 2024 (note that the time at the Watch Duty website (2:33 PM, link), below, refers to the report time at that site). This was after the NGFS detection. Fire initiation occurred in a sparsely populated region of northeast Wyoming, so it should not be a surprise that the initial report was after the fire was underway.

In contrast, the weather satellite-based Next Generation Fire System detected fire at this location nearly a day earlier, starting at 2143 UTC (3:43 PM Mountain Time) on 21 August (!) as shown below. This is an excellent example showing NGFS’s importance for wildfire detection in remote regions where human eyes (or webcams) aren’t available to monitor things. The animations below show the GOES-based Fire Temperature RGB and the NGFS Microphysics RGB. The complex nature of the RGBs is in part due to cloudiness occurring over the region. (Here’s the visible imagery at 21:47:54) An NGFS detection is shown by the orange polygons at 21:47:54 UTC on 21 August. Northern Wyoming was in a region of elevated fire risk as shown in this graphic from SPC.

An important feature of the NGFS RealEarth instance is that imagery can be probed. By clicking on the NGFS pixels (that is, the orange polygons), users can view information about the surface properties in the region of the developing fire. The Probe for this NGFS polygon is shown below, including the latitude/longitude (just south of the Wyoming/Montana border), and the physical description of the land — mostly vegetation — grass and chapparal — and very little urban areas. This information can help a forecaster determine the likelihood of fire and risk to populations. It might also influence a decision to commit fire-fighting resources.

NGFS output is available at this website. Previous blog posts on NGFS capabilities are here.

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VIIRS Day Night Band imagery from the Direct Broadcast site in Honolulu, above, shows Hurricane Hone as it passes south of South Point on the Big Island of Hawai’i on 25 August 2024. NOAA-21, Suomoi-NPP and NOAA-20 viewed the storm at 1130, 1154 and 1218 UTC, respectively. Data were processed at the antenna with CSPP Software.

More information on Hone is available at the Central Pacific Hurricane Center and from the National Weather Service forecast office in Honolulu.

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