First thunderstorms of the year around here. @DaveSnider @capture907 @AlaskaWx pic.twitter.com/xeMhNiLSiU

— Brian Brettschneider (@Climatologist49) May 5, 2022

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) showed these isolated thunderstorms as they moved north-northwestward up the Susitna Valley (northwest of Anchorage).

In the corresponding 1-minute GOES-17 “Clean” Infrared Window (10.35 µm) images (below), the coldest cloud-top infrared brightness temperatures of the thunderstorms were around -35ºC (darker blue enhancement).

A toggle between Suomi-NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images around 2201 UTC (below) included a plot of available NUCAPS sounding points from NOAA-20.

The NOAA-20 NUCAPS profile for the green (infrared + microwave) sounding point 25 miles WSW of Big Lake (below) diagnosed a surface parcel CAPE value of 616 J/kg, with a Lifted Index of -3.  

A later toggle between Suomi-NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images and 2345 UTC is shown below; the coldest cloud-top infrared brightness temperature of the thunderstorms was -38ºC (near Big Lake), which closely corresponded to the altitude of the Equilibrium Level on the NUCAPS profile.

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The Geostationary Lightning Mapper (GLM) on GOES-16 and the Lightning Imaging Sensor (LIS, additional information here) on the International Space Station (ISS) both observe lightning. The GLM has nadir resolution of approximately 8 km, and is in geostationary orbit, about 36000 km above the Earth’s surface. In contrast, the LIS has a resolution of approximately 4 km, and it’s on the ISS, only 400 km above the Earth’s surface. Both sensors detect the optical signal of the lightning. The animation above shows 2 minutes of LIS Flash Events plotted (in yellow) on top of 5-minute aggregates of GLM Flash Extent Density (updated at 1-minute time-steps). The animation below shows the same LIS observations, but plotted in black, on top of GOES-16 ABI Band 13 imagery. Many of the LIS flash events are colocated with cold cloud top as defined by the GOES-16 Band 13 (10.3 µm) brightness temperatures — meaning that the optical signal is strongest there. That’s not always the case though, as shown in this image with LIS data from 13:19:48.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed abroad arc of fog/stratus that persisted for much of the day across parts of eastern Virginia, Chesapeake Bay and the Delmarva Peninsula on 03 May 2022. Since this fog/stratus deck — which was on the cold side of a quasi-stationary frontal boundary — was slow to dissipate, it held daytime temperatures in the 50s and 60s F (in contrast to the 70s F in cloud-free areas east of the front, and 80s F west of the front). By the end of the day, some of the colder air and stratus had sagged southward across extreme northeastern North Carolina (including the northern end of the Outer Banks).

Afternoon thunderstorms reached strong to severe levels as they approached the frontal boundary, producing 1-inch diameter hail and damaging winds (SPC Storm Reports).

1-minute GOES-16 Visible images with overlays of the 5-minute GOES-16 Fog Depth product (below) provided an estimate of the fog/stratus deck thickness, helping to highlight which portions might be slower to dissipate.

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Flooding has been detected by satellite along the Red River of the North for more than a week (see this blog post from late April). The image above shows the Flood Estimates (from this website). The image below (courtesy William Straka, CIMSS) shows a high-resolution downscaled Flood-water depth map derived from VIIRS imagery only.

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An interesting aspect of this flooded land is that it affecting the boundary layer of the atmosphere, as shown below. Band 2 imagery (0.64 µm) shows lake breeze clouds developing around the lake; the Band 3 imagery (0.87 µm), farther below, better articulates the location of the land/water boundary. Dryer air moving in later in the day leads to dissipation of the clouds.

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NOAA-20 overflew this region at around 1800 UTC on 3 May 2022. The toggle below (using imagery taken from the CIMSS Direct Broadcast site for NOAA-20 located here), shows VIIRS Bands I01 through I04 (0.64 µm, 0.86 µm, 1.61 µm and 3.74 µm) at that time. The lake-breeze clouds are very apparent, and the cold waters of the lake are also obvious in the I04 imagery.

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Thanks to Carl Jones, WFO FGF, for drawing attention to the lake breezes!

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