Color-enhanced wind speeds observed from Synthetic Aperture Radar (SAR) data on the second RADARSAT Constellation Mission satellite (RCM-2), shown above in AWIPS (Click here for a similar image online at this website) show parallel lines of enhanced wind speeds, a wind structure suggestive of a bore (click here for many previous blog posts on this phenomena), over southern Lake Michigan. Peak wind values (in yellow over the water) are near 14 m/s, with minima in between the lines showing winds around 5-6 m/s. (Note that SAR wind information over land is invalid). When this kind of event happens under mostly clear skies, parallel lines of clouds (that are perpendicular to the observed wind) develop. In this case, widespread clouds prevented satellite detection of cloud bands. The toggles below show Visible (Band 2, 0.64 µm) and Infrared (Band 13, 10.3 µm) at the time of the SAR observations.

Modest convection (cloud tops are only around -48^oC) over central Lake Michigan likely generated the bore. For a bore to propagate, a strong inversion is required. Soundings at Green Bay WI and Gaylord MI likely are unrepresentative of the environment over southern Lake Michigan. The sounding at White Lake Michigan — near Detroit — (from this website) does show a surface inversion, as does the sounding at Davenport IA. The cool late-Spring waters of Lake Michigan will serve to anchor a similar low-level inversion over the Lake; bore features travel along those inversions.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) and “Red” Visible (0.64 µm) images (above) showed Tropical Storm Alex after it reached tropical storm intensity at 0900 UTC on 05 June 2022. Overshooting tops within the deep convection exhibited infrared brightness temperatures of -80ºC or colder (shades of violet).

GOES-16 Infrared Window (11.2 µm) images from the CIMSS Tropical Cyclones site (below) include contours of deep-layer wind shear at 17 UTC  — which displayed the high shear that was displacing the convection associated with Alex well northeast of the storm center.

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The MIMIC Total Precipitable Water (available at this website) animation below tracks Pacific Hurricane Agatha as it makes landfall, and then the accumulation of moisture that is incorporated into Alex.

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Some National Data Buoy Center buoys do include webcams that provide sky information (link). How well do those observations compare to IFR Probability fields, as shown above in an image from RealEarth? There are three BuoyCams along the Oregon coastline, as shown in the image below, and 3 more offshore that can be compared to the IFR Probability fields above. Consider Buoy 46029, 20 nm offshore of the mouth of the Columbia River, shown below. It shows what appear to be low overcast skies in a region where IFR Probabilities are large. Proceed counterclockwise around the 6 buoys near/offshore Oregon (the one just south of the Oregon/California border is not included here), and you’ll note low clouds are present in most of the BuoyCam observations: Buoy 46089; Buoy 46005; Buoy 46002; Buoy 46015. Only Buoy 46050, along the central Oregon coast, shows multiple breaks in the clouds. This is in a region where IFR Probabilities are smaller!

The animation below shows the 6 WebCam observations in sequence. Use these webcams to become more confident in using IFR Probability fields in the open ocean.

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The mp4 animation above (produced using CSPP Geosphere‘s latest beta version) shows strong convection over Oklahoma and the eastern Texas panhandle, with lower clouds (in a bluish hue) over the northwestern Texas panhandle. With time, the Night Microphysics RGB acquires a reddish hue (as cloud tops cool), and then convection develops. A nowcaster can use changes in the colors of this RGB to anticipate initiation. (A similar recent example is shown here).

The AWIPS imagery from 0701 UTC below shows the RGB with Level 2 Products: Cloud Top Phase — showing liquid water clouds over Texas where the RGB suggests low clouds, and Cloud Top Temperature — where values of 7-8^oC are common. The default color table Cloud Top Temperature has been changed. Recall also that the Level 2 Cloud Top Temperature product is not produced for the CONUS sector, so Full-Disk values are shown. Surface winds suggest low-level convergence: winds are northeasterly over the NW Texas panhandle, and southeasterly to easterly over the southern portions of the Texas panhandle. GOES-16 Cloud Top Heights (not shown) show cloud heights around 12000 feet over the NW Texas panhandle.

Fifty minutes later, at 0751, the band of low clouds over the northeastern Texas panhandle has reddened somewhat (click here for a toggle between 0701 and 0751). Cloud top temperatures in that cloud band have dropped to between 1^o and 4^oC, and cloud top heights have increased to 14000 feet. Cloud-top phase is still liquid however (except over northern New Mexico, as might be inferred by the yellower tinge to those low clouds in the RGB). There is also a red tint to the RGB just north of the obvious east-west band of clouds near the Hereford TX airport (where the temperature and dewpoint are 65 and 60, respectively, and no wind is reported). Convective initiation is likely occurring in these regions.

From 0801 to 0816 UTC, shown below, supercooled clouds are noted, as the Night Microphysics RGB continues to redden. By 0816 UTC, mixed phase clouds are noted in the line developing near Hereford. Cloud-top heights increase from 15000 to 21000 feet between 0811 and 0816 UTC.

By 0826 UTC, Cloud Tops are shown to include ice over the line developing over the east-central part of the Texas panhandle.

A rocking animation of the 4-panels above, from 0801 to 0901 (and back) is here. If convection is expected overnight, and low clouds are present, use the Night Time Microphysics RGB to monitor when convection might initiate. Color changes in the low clouds give important information.

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