The RCM-1 satellite carrying SAR instruments overflew Lakes Superior and Erie/Ontario at 2350 30 April 2023 and 1135 UTC 1 May 2023, respectively. What kind of wind structures were observed, and how easily can one explain them? The imagery above shows a GOES-16 Visible animation from 2301 UTC on 30 April through 0001 UTC on 1 May 2023. Higher-level clouds are overspreading central Lake Superior from the east (part of a large occluded system ove the Great Lakes), and northwesterly winds might be inferred over the lake — especially given the 0000 UTC surface analysis shown below. Note in particular the relative closeness of the two isobars extending northward from the western Upper Peninsula of Michigan!

SAR winds for just before 0000 UTC are shown below. Rather than one region of stronger winds associated with those more closely-packed isobars, 3 or 4 separate bands of slightly-stronger northwesterly winds (a still image is here; winds are upwards of 30 knots — yellow/green in the enhancement — vs. about 20 knots — cyan in the enhancement — in between the strongest winds) are apparent both upwind and downwind of Isle Royale! Isle Royale does have topographic features (here’s an image) — but it’s hard to relate those features to the downstream wind bands. AWIPS presentations of the wind speed does not include direction; those directions are available online however, at this website. This toggle shows both the derived wind speed and the Normalized Radar Cross Section field.

---

Twelve hours later, RCM-1 had a descending pass over the eastern Great Lakes between 1100 and 1200 UTC. GOES-16 Visible imagery from 1116 to 1136 UTC, bracketing the RCM-1 overpass, is shown below. The easterly flow on the Poleward side of the occluded low is readily apparent in the higher clouds over northern Lake Huron. Similarly, southwesterly winds are apparent over Lake Erie. Here is the 1200 UTC surface analysis.

Strong southwesterly winds (around 30 knots — yellow/green in the enhancement used) are apparent over northeast Lake Erie, except for the nearshore waters off Erie County (NY) at the extreme eastern edge of Lake Erie, where winds are closer to 15 knots (dark blue/purple in the enhancement used). There is a linear low cloud feature extending west-northwestward from Chautauqua County — the westernmost county in New York). It is close to the transition zone between lighter winds upstream and stronger winds downstream. The sector with the southernmost winds is here; here‘s the view with winds primarily over Lakes Ontario and Huron.

View only this post Read Less

5-minute CONUS sector GOES-16 (GOES-East) images from all 16 ABI spectral bands (above) displayed the northeast-moving warm thermal signature of a SpaceX Falcon Heavy rocket booster as the ViaSat-3 Americas Mission was launched from Cape Canaveral Space Force Station in Florida at 0025 UTC on 01 May (8:25 PM EST on 30 April 2023). The rocket launch condensation cloud was also evident in imagery from Infrared spectral bands (07-16), drifting slowly east-northward away from the launch site. One or both of these rocket launch signatures were detected by nearly all’ of the ABI spectral bands (except for Visible Band 1), as well as Plume RGB images.

A thermal signature of the rocket booster was also seen in 10-minue Full Disk sector GOES-18 (GOES-West) Nighttime Microphysics RGB images frm the CSPP GeoSphere site (below).

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) include an overlay of GLM Flash Extent Density — which showed the severe thunderstorm that produced an EF3-rated tornado in Virginia Beach, Virginia on 30 April 2023. With that particular storm a lightning jump began around 2135 UTC and peaked at 2142 UTC, and the coldest cloud-top infrared brightness temperature of -55.58ºC occurred at 2145 UTC — both during the minutes leading up to the tornado, which formed at 2148 UTC.The coldest Cloud Top Temperature derived product (which also occurred at 2145 UTC) was about 0.9ºC colder, at -56.49ºC.

A plot of rawinsonde data (source) from Wallops, Virginia at 0000 UTC on 01 May (below) indicated that the -56.49ºC Cloud Top Temperature value roughly corresponded to a Most Unstable air parcel Equilibrium Level (MU EL) overshoot of about 1 km.

A toggle between GOES-16 Visible, Infrared and GLM Flash Extent Density images at 2147 UTC (above) showed that the thunderstorm responsible for the 2148-2153 UTC tornado — whose SW-to-NE track was from Lynnhaven to Cape Henry — was apparently located just offshore (centered over the Chesapeake Bay Bridge Tunnel). However, one must take parallax into account — which in this case was a northward displacement of around 14 km or 8.7 miles (below).

A blog post discussing the use of Polar Hyperspectral Sounding data in a numerical model simulation for this storm is available here.

View only this post Read Less

Overlapping 1-minute Mesoscale Domain Sectors provided GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images at 30-second intervals (above), which included plots of time-matched (+/- 3 minutes) SPC Storm Reports — showing thunderstorms that produced a few tornadoes, hail as large as 1.75 inches in diameter and wind gusts to 76 mph across parts of the Florida Panhandle (and adjacent far southwestern Georgia) on 27 April 2023. Pulsing overshooting tops exhibited infrared brightness temperatures as cold as -82ºC (violet pixels).

The coldest overshooting tops were associated with experimental CLAVR-x Cloud Top Height of 16.64 km (54593 ft), vs. 47866 ft (14.59 km) with the Operational CONUS sector Cloud Top Height product (below). The CLAVR-x derived GOES cloud products produced at CIMSS are at full 2 km spatial resolution — in contrast to some of the Operational cloud products, including Cloud Top Height, which are still disseminated at reduced resolutions of 10 km over the CONUS sector (although the Cloud Top Height spatial resolution is 4 km for the Mesoscale Domain Sector).

View only this post Read Less