It has been an active period of impactful weather in and near Australia, and today is no exception. Severe Tropical Cyclone Alfred continues to spin northeast of Queensland. The latest update from the Australian Bureau of Meteorology indicates a central pressure of 956 mb. Over the last day, it was downgraded from a Catergory 4 to a Category 3, but sustained winds are still at 85 knots (155 km/h) and gusts are reaching 120 knots (220 km/h). Recent Band 14 (infrared window) and true color imagery from AHI aboard Himawari-9 as displayed on RealEarth confirms Alfred’s weakening, with a filled-in eye that is well over 100 km across.

The current forecasted track for Alfred is to continue along a largely southerly path, and it is  expected to pass between mainland Australia and the French island of New Caledonia with no landfall.  The most significant impacts expected to be storm surges and waves. However, outer rain bands may prove to be challenging to the Queensland coast, which has already been struggling with the aftermath of recent significant rainfall.

MetOp-C passed directly over the center of Alfred on 26 February enabling ASCAT analysis of the near-surface winds. While most meteorologists already know that the strongest hurricane winds are not directly in the center of the rotation but near the eyewall, this image helps to reinforce that idea. Due to the relatively narrow swath of ASCAT and the geometry of low earth orbits, it can be challenging to get more frequent wind updates.

Alfred was one of three named tropical cyclones that were concurrently active in the tropical western Pacific Ocean this week, alongside Seru and Rae. While these latter storms were not as intense as Alfred at its peak, the impacts were more significant due to passing much more closely to the Pacific island nations of Vanuatu and Fiji. This true color AHI loop shows the rare sight of three Category 1+ tropical storms in such close proximity. Since then, the later two storms have both weakened and moved away from the populated islands.

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High pressure and mild temperatures over the western Atlantic and adjacent Gulf waters early on 26 February 2025 (here is the 1200 UTC surface analysis) meant NOAA-20 VIIRS data could provide near-complete views of sea- (and lake-) surface temperatures. The above image was captured from the RealEarth website. The warm waters (mid-70s ^oF) of the Gulf Stream off the North Carolina coast are in very close proximity to cold (mid-40s ^oF). Direct Broadcast data processed into AWIPS-ready VIIRS tiles are available from CIMSS and an example swath is shown below.

A zoomed-in view over the Outer Banks of North Carolina, below, shows the strength of the SST gradient, from very warm to much colder in less than 40 miles.

The SSTs over the northern part of the South Atlantic bight, shown below, include filaments of colder water extending from the shelf waters out into the open ocean.

NOAA-20 True-Color imagery, below, from the VIIRS Today website, shows filaments of turbid water that suggest a link between the observed cold filaments above and cold fresher water from the Continent. (Note also the smoke plumes over the southeastern US!)

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5-minute CONUS Sector GOES-16 (GOES-East) Visible and Infrared images (above) displayed a thunderstorm that was moving southeast from Aberdeen (KABR) to Watertown (KATY) in northeastern South Dakota on 24 February 2025. While overall GLM-detected lightning activity was relatively modest, periodic increases in Flash Extent Density (orange to red pixels) were evident.

A Special Weather Statement was issued for this thunderstorm at 2058 UTC (below), advising on its potential to produce 50 mph winds and nickel-size hail. Note the slight northwest displacement of the Flash Extent Density pixels, compared to the thunderstorm overshooting top as seen in GOES-16 Visible and Infrared imagery — this is because the commonly-used Gridded GLM products (such as Flash Extent Density, Minimum Flash Area and Total Optical Energy) are not corrected for parallax. With this particular low-topped storm, the magnitude of GOES-16 parallax correction would be about 15 km (9 miles) to the southeast.

GOES-19 (Preliminary/Non-operational) Visible and Infrared images (below) included a red “T” denoting the location of a brief tornado that occurred at 2211 UTC, southeast of Watertown (NWS Aberdeen | SPC Storm Reports).

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LightningCast probabilities (source), below, from 2042 – 2232 UTC, showed high probabilities confined to the storm that produced the tornado; those probabilities diminished quickly after the tornado occurred.

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Hazardous weather conditions associated with winter storms and flooding can be seen throughout the northwestern continental United States due to the presence of an atmospheric river brining significant amounts of moisture from the eastern Pacific to the North American shore. Alerts include winter storm warnings in western Washington and flood warnings, watches, and advisories in northern Idaho and western Montana. Flood conditions are already primed by temperatures exceeding freezing in this part of the United States thus ensuring that meltwater is significant and surfaces are saturated.

Atmospheric rivers are long, narrow bands of enhanced moisture transport. Depending on their strength, they can provide positive impacts like bringing desperately needed rain to regions of drought or fire. However, they can also have negative impacts by creating flooding, mudslides, and other hazardous conditions. Satellites, of course, are an excellent tool for diagnosing the position and strength of atmospheric rivers. The water vapor imagery from geostationary satellites provides a simple way to identify where the rivers are and how quickly they are flowing. In this example from AWIPS, the 6.19 micron brightness temperature shows a band of enhanced water vapor content streaming in from the Pacific toward the west coast of the continental US. It’s even possible to see the river helping to feed the development of an offshore extratropical cyclone that is approaching the Oregon coast.

The river is even more easily seen in the Morphed Infrared Microwave Imagery at CIMSS (MIMIC) total precipitable water (TPW) product. Since microwave sounders are currently only present aboard polar-orbiting platforms, derived products often contain gaps between overpasses. MIMIC takes the snapshot view of a TPW swath and uses numerical weather prediction winds to move the observed field in space so that it can be matched to and blended with adjacent TPW swaths. This creates a near-seamless view of the global TPW field at an hourly temporal resolution. In this case, MIMIC clearly identifies the position of the river and its origin from the warm, moist air near Hawaii. Real time imagery from MIMIC is available here.

As noted above, the impact of all this moisture as it hits shore can be significant. One impact is local streamflow rates. The following image shows the past month of stream observations from the Palouse River near the Idaho/Washington border. The river swelled to nearly triple its depth in the last 48 hours, and has reached a level that is by far the greatest it has experienced in the last year. Numerous similar examples can be seen on the USGS streamflow gauge site.

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