Portland OR had a snowfall of 5.3″ on 22 February 2023, a record for the date. (Update! The snow on 22 February ended up being 10.8″, the second snowiest day of record!) The GOES-18 Clean Window Infrared (10.3) imagery animation, above, taken from the CSPP Geosphere site (direct link to animation) shows the system responsible for the precipitation. Colder higher clouds (lighter grey in the enhancement) over western Oregon are moving northward while low clouds (darker grey in the enhancement) over the Pacific are moving southeastward.

What satellite-based products could be used with this system to monitor the strength of the cold air? The 4-panel below shows gridded NUCAPS 850-mb temperature fields derived from NOAA-20 data from overpasses at 2100 UTC on 22 February and at 1051 UTC on 23 February. GOES-18 Band-13 imagery at the same time are shown. A large region of -10^oC air is off the coast of Oregon late on the 22nd, and it persists through the morning of the 23rd. Use of gridded NUCAPS fields can give information about the atmosphere out over oceans where land-based (“conventional”) observations are sparse.

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Gridded NUCAPS fields are available online. The toggle below shows the 1055 UTC 23 February 2023 gridded 850-mb Temperatures (along with NUCAPS quality flags), taken from this site. (You can also find gridded NUCAPS fields here). Here is a similar toggle from 2100 UTC on 22 February 2023.

The AWIPS display of NUCAPS Sounding Availability for the morning pass on 23 February is shown below. Note the ‘green’ sounding point just off the coast of Oregon, just west of the mouth of the Columbia River. The toggle below compares the sounding there with the 1200 UTC sounding at Salem (KSLE) (Here’s a toggle of a more complete NSharp sounding window for the two soundings). The overall aspects of the two soundings are very similar, but the NUCAPS profile is smoother.

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Some of the AWIPS imagery in this post was created using the TOWR-S AWIPS Cloud Instance. Thank you!

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GOES-18 “Clean” Infrared Window (10.3 µm) images (above) include plots of 15-minute surface observations — which showed that the surface visibility at both Portland International Airport (KPDX) and Vancouver Pearson Field (KVUO) was restricted to 1/4 mile at times. The highest snowfall totals included 12.0 inches in the Greater Portland area and 16.0 inches in the Greater Vancouver area.

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Added, 27 February 2023

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On 25/26 February 2023, another system moved through. This time, however, 850-mb Temperatures were a bit warmer, as shown in the two toggles below (of 850-mb temperature and NUCAPS Quality flags), one from 2138 UTC on 25 February, before the onset of precipitation, and one from 2119 UTC on 26 February, after the cold frontal passage. Note in particular the warmer temperatures on 25 February (green enhancements vs. cyan in the imagery above from early on 23 February!) Instead of snow, Portland had cold rain on the 26th. Here is the Meteorogram that includes 26 February (from this site).

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GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed strong southwesterly winds ahead of an approaching cold front, causing areas of blowing dust across parts of New Mexico, Texas and Oklahoma on 22 February 2023. Strongest wind gusts were in the 60-70 mph range, and blowing dust was reducing the surface visibility to 1.5 miles or less at some locations.

Max Wind Gusts – The axis of severe maximum gusts through 1:30pm CST have been from Hobbs and Tatum New Mexico into the southwestern South Plains to near Lubbock. Highest gusts have been 69mph at Plains and Denver City. #lubwx #txwx pic.twitter.com/3yD9gdXaXY

— NWS Lubbock (@NWSLubbock) February 22, 2023

A better signature of the blowing dust was seen in True Color RGB images — produced using Geo2Grid — from GOES-18 (GOES-West), GOES-17 and GOES-16 (below). GOES-17 (formerly GOES-West) was temporarily operating from its pre-storage checkout position over the Equator at 104.7 W longitude. Along the western edge of the widespread blowing dust, note the presence of a relatively narrow and brighter white plume (whose source region was White Sands National Park in New Mexico).

===== 23 February Update =====

On the following morning, the hazy signature of airborne dust was evident in GOES-16 True Color RGB images (from the GeoSphere site) over cloud-free areas of Illinois, Indiana, Ohio and Kentucky — and to a lesser extent, above the clouds in southern Lower Michigan (above).

Due to the more favorable forward scattering geometry associated with GOES-18 (below), the hazy blowing dust signature was apparent for a longer period of time — and farther to the east (eventually moving over West Virginia) — compared to what was seen in GOES-16 imagery.

HYSPLIT model forward trajectories — initialized at 3 points where the blowing dust appeared to be particularly dense at 0000 UTC on 23 February (below) — supported this pathway of long-range dust transport from New Mexico / Texas / Oklahoma to the lower Great Lakes and Ohio Valley 12-18 hours later.

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Indian Ocean Cyclone Freddy had an unusually long track and lifespan as it crossed the southern Indian Ocean. The animation above (created using geo2grid software) shows hourly Himawari-9 Clean Window infrared (10.4 µm) imagery from 5 February through 19 February, when Freddy could no longer be viewed by that geostationary satellite. Freddy appears over the eastern part of the domain on 6 February and shows a nice eye on the 11th of February, and again from 14-16 February, and at the end of the animation as well.

The MIMIC-TC animation, below, courtesy Derrick Herndon, CIMSS, shows how the microwave-sensed presentation of the storm evolved during its lifetime from 06 February through 22 February 2023. The maximum inferred windspeed, 135 knots, occurred twice, once on 16 February and once on 19 February. SATCON wind estimates, here, from this website, also showed the twin peaks in intensity.

MIMIC TPW fields, shown below as in an mp4 (Click here for an animated gif) also tracked Freddy across the Indian Ocean, from its formation near Australia on the 6th to its landfall in Madagascar on the 21st and Mozambique on the 24th.

NOAA/NESDIS has produced a story on Freddy, available here; the animation in that story is on YouTube.

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US Space Force EWS-G1 (formerly GOES-13) Infrared Window (10.7 µm) images (above) showed Category 3 Cyclone Freddy making landfall along the east coast of Madagascar on 21 February 2023.

According to products from the CIMSS Tropical Cyclones site, during the 12-15 hours leading up to landfall Freddy was traversing warm water with Sea Surface Temperature values of 28C, and moving through an environment characterized by low values of deep-layer wind shear (below).

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