Geosphere true-color imagery over the Atlantic Ocean to the east of Florida and Georgia, above, shows a low-level cyclonic circulation with strong convection to its south. The appearance of the system suggests strong shear; an analysis of shear from the SSEC Tropical Weather website, below, shows the northerly shear over the storm that displaces the convection.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a closer view of the exposed low level circulation center (LLCC) of Invest 92L. A slight amount of trochoidal motion (wobble) was seen as the LLCC moved toward the coast.

1-minute GOES-16 Visible images with plots of 5-minute Derived Motion Winds (below) depicted slightly higher wind speeds (30-35 knots, yellow wind barbs) within the northeast quadrant of 92L — but satellite-derived wind speeds with the circulation of 92L were generally in the 10-25 knot range. Invest 92L passed between Buoy 41008 to the north and Buoy SAUF1 to the south; on 21 June the highest wind speeds/gusts at those two buoys were in the 22-29 knot range. 92L eventually moved inland several hours after sunset, near the Georgia/Florida border — between Brunswick GA (KSSI) and Jacksonville FL (KCRG). Wind speeds/gusts remained below 30 knots at those two sites as well.

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GOES-16 Geocolor imagery, overlain with GLM Flash Extent Density fields, below, (from this source), show meager lightning within the convection to the south of the low-level cyclonic circulation.

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More information on this system is available at the National Hurricane Center, and from the NWS Forecast Offices in Jacksonville FL and in Charleston SC.

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Polar Hyperspectral Data (PHS) can be married to ABI data via Data Fusion, and that data that exploits the high spectral resolution of Polar Hyperspectral Data (from IASI and CrIS data on Metop and JPSS satellites, respectively) and the high spatial/temporal resolution of ABI data can be assimilated into a numerical model. The toggle above compares MUCAPE fields at 0000 UTC from an 1800 UTC 23 May 2024 initialization (more output from this day is shown in this blog post) created with and without PHS data. A similar toggle that compares 0-1 km Bulk Shear (with and without PHS data) is below. In both fields, the PHS data has introduced low-level variability that should better reflect the actual distribution of thermodynamics as measured by the sounders on the LEO satellites.

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Does the better representation of thermodynamic variability (and variability in dynamics) translate in this case to a better forecast. In the previous blog post, the WRF simulation with PHS data starting at 1600 UTC and 1700 UTC did show better convective initiation times than the HRRR simulation that did not benefit from the inclusion of PHS data (i.e, this figure, and this one, respectively). The 4-h forecast valid at 2200 UTC (that compares 4-km WRF with PHS data and 3-km HRRR data, here, shows better initialization in the WRF with PHS data). The toggle below compares 4-h forecasts from a 4-km WRF model initialized at 1800 UTC, and valid at 2200 UTC; one simulation includes assimilated PHS data, and one does not. The initiation of convection is not substantially different in the model runs initialized at 1800 UTC. The higher spatial variability for this case at this time does not lead to a better forecast of initiation as was apparent in the earlier model runs described in this blog post.

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1-minute Mesoscale Domain Sector GOES-18 (GOES-West) Day Cloud Phase Distinction RGB images (above) showed clusters of slow-moving thunderstorms across Torrance County in central New Mexico on 19 June 2024. In addition to generating strong winds and heavy rainfall, these storms were also prolific hail-producers — most notably, there was one Local Storm Report of 2.00-inch diameter hail that lasted for 1.5 hours and accumulated to a depth of 6 inches (9 miles southeast of Willard).

Parts of the northwest-to-southeast oriented swath of hail accumulation near Willard were evident through occasional breaks in the clouds — exhibiting varying shades of green, such as was seen at 2005 UTC, 2250 UTC, 2305 UTC and 0006 UTC. The hail swath appeared to have crossed State Highway 60, which jogs west-to-east across Torrance County (passing through Willard).

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MIMIC Total Precipitable Water fields from 15 June through 19 June 2024, above, show a broad cyclonic circulation over Central America and adjacent waters (the Central American Gyre). On 18 June, shown below in an animation from the CSPP Geosphere site, the convection in this gyre was diffuse and unorganized (although the National Hurricane Center initiated Potential Tropical Cyclone advisories on the system at 2100 UTC on the 17th.

By 1500 UTC on 19 June, the system had acquired sufficient convection near its center, and had become organized enough to achieve Tropical Storm status, and the first named storm of the 2024 Atlantic Season, Alberto, was named. The Geosphere animation below, from 1300-1700 UTC on 19 June (that is, 24 hours after the animation above), shows the increase in convection over the southern Gulf of Mexico.

The shear over the western Gulf of Mexico became much more favorable for tropical storm development between 1800 UTC on 18 June and 1800 UTC on 19 June 2024, that is, it has decreased, as shown below (imagery taken from here).

The projected path of Alberto is westward into Mexico, as shown in the image below showing the favorable shear values and warm Sea-surface Temperatures. Slow strengthening is forecast.

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Although the storm center is forecast to move into Mexico, the very moist airmass surrounding the system is affecting (and will continue to affect) much of coastal and southern Texas. Tropical Storm warnings are in place from Galveston southward to Mexico, and Flash Flood Warnings have also been raised. A Flood Watch is in effect for Texas south of San Antonio. For more information on Alberto, refer to the National Hurricane Center website.

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