Parts of northern Alaska were under a Winter Storm Warning for much of the weekend, as shown below by the red regions to the north of Fairbanks. (The red regions around the Seward Peninsula were regions where a High Wind Warning had been cancelled after strong winds weakened. This toggle of MetopB and MetopC ASCAT winds from 0530-0630 UTC on 13 October (source) shows the very strong winds offshore). The Airmass RGB animation (created using Geo2Grid software) above shows the abundant mid-level moisture streaming north and the development of a storm system by 1200 UTC on 13 October as evidence by the comma cloud.

What products can be used to highlight where snow might be falling over northern Alaska, where no radars are present, and where webcams are scarce. Microwave Integrated Retrieval System products include snowfall rate. This product is computed from Microwave sounders on board many Low-Earth-Orbit (LEO) satellites including Suomi-NPP, NOAA-20/NOAA-21, and MetopB/C. The animation below shows values (computed from data downloaded at the GINA Direct Broadcast antenna and processed using CSPP software; created imagery is here). The heaviest snowfall is diagnosed to the south of the Brooks Range through about 1400 UTC (as shown in this image from 0452 UTC, for example), at which point maximum snowfall shifts to the north.

Polar2Grid software can be used to create MIRS snowfall rate imagery with data downloaded from (for example) Amazon Webservice websites that hold Suomi NPP or NOAA-20 data. The toggles below compare the computed Snowfall rates and the airmass RGBs. As is often the case over Alaska, the GOES animations give the evolution of the atmosphere and LEO data gives important smaller-scale information, in this case snowfall rates. The heaviest snow is diagnosed to occur right in the comma head over the near the Brooks Range from 1130-1331 UTC. By 2300 UTC, the heaviest snowfall rates have diminished. MiRS snowfall rates are available in Alaska Region AWIPS machines for a simple comparison to other satellite imagery.

Microwave Snow Fall Rate imagery is also available at this website. The Snow Fall Rate Quick Guide is here.

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Another vivid auroral display occurred over the northern United States and southern Canada early on 11 October (and was also visible late on the 10th!). Day Night Band imagery from JPSS Satellites, above, show the patterns in the emitted energy.

RealEarth includes Day Night Band imagery, as at this link.

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Both mesosectors for GOES-16 and GOES-19 were placed over Hurricane Milton on 9 October. Consequently, 30-second imagery from both satellites was acquired. The animation above shows visible imagery from sunrise to 2159 UTC. To view a three-dimensional image, cross your eyes so that three images are present, and focus on the image in the middle. A similar animation showing the ‘snow-ice band‘, GOES-R Band 5 at 1.61 µm, is below.

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GOES-16 Infrared Imagery overnight on the 9th of October shows the evolution of Milton as it moves towards landfall over southwestern Florida. Of note is the disappearance of a pronounced eye. Lightning continues within the eye, however, as shown by the GLM overlay below, and deep convection (black/grey in the enhancement applied) continues to develop and wrap around the eye. Satellite estimates of strength (ADT, for example, from here) continue to show a very strong system.

Derived Motion Wind vectors from GOES-16, shown below on top of an Upper Level Water Vapor image at 1201 UTC, show the excellent outflow that is helping to ventilate Milton. There is very strong outflow above 350 mb to the northeast over Florida and the southeastern United States, and a second outflow channel above 250 mb to the west-southwest over the Yucatan and into the Pacific Ocean. The Water Vapor imagery also shows mid-level drying over the western Gulf of Mexico; perhaps some of that dry air is being entrained into the western edges of Milton, but at sunrise, any weakening due to dry air is subtle at best.

The very strong outflow — a positive for the strength of the storm — also means that Milton is now in an environment of significant vertical wind shear. That is shown in the shear analysis below from the CIMSS Tropical Website.

Both mesoscale sectors for GOES-16 are over Milton as of 1200 UTC on 9 October, meaning 30-second imagery is being produced. The 15-minute animation below was retrieved from the CSPP Geosphere site.

The National Hurricane Center has the latest information on this storm (link). Heavy Rain is overspreading southwest Florida on 9 October in advance of Milton. Conditions will continue to deteriorate during the day.

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