1-minute Mesoscale Domain Sector GOES-18 (GOES-West) images from all 16 of the ABI spectral bands — in addition to a Rocket Plume RGB (above) displayed signatures of the SpaceX USSF-62 Mission (to deploy the new WSF-M satellite) Falcon 9 rocket that was launched from Vandenberg Space Force Base, California at 1425 UTC on 11 April 2024. A warm thermal signature of the Stage 1 rocket booster was evident in images from all of the Near-Infrared and Infrared spectral bands (Bands 03-16) and the RGB imagery as it quickly moved east-northward from the launch site — and either a somewhat-bright reflectance signature or a relatively cool thermal signature of the Stage 1 rocket booster’s condensation cloud was seen in most of the spectral bands as it drifted slowly eastward from the launch site (evaporating quickly in the dry atmosphere).

In addition, a warm thermal signature of the Stage 1 rocket re-entry burn was apparent at 1431 UTC (just northeast of Vandenberg KVBG) to begin slowing its descent in order to make a landing back at Vandenberg.

One interesting aspect seen in Upper-level Water Vapor (Band 08) and Rocket Plume RGB images after Stage 2 rocket booster ignition (which occurred around 1427 UTC — at that time, the peak 3.9 µm infrared brightness temperature reached 71.81ºC — was the rapid southward expansion of the water-vapor-rich rocket plume. A plot of rawinsonde data from Vandenberg, California (below) showed that the high-altitude transition to general northerly flow began at altitudes of 20-30 km (the 40 hPa pressure level and above).

With GOES-16 (GOES-East) images (below), although the satellite viewing angle was larger (62.34 degrees, vs 43.82 degrees for GOES-18), similar rocket signatures were observed in many of the ABI spectral bands and the RGB — albeit displaced to the west, due to parallax associated with the high-altitude features.

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30-second (ending at 1200 UTC) and 1-minute Mesoscale Domain Sector GOES-16 “Clean” Infrared Window (10.3 µm) images (above) included plots of time-matched (within +/- 3 minutes) plots of SPC Storm Reports (09 April | 10 April) across parts of Texas, Louisiana, Mississippi and Alabama on 10 April 2024. The corresponding 1-minute GOES-16 “Red” Visible (0.64 µm) images after sunrise are shown below.

One notable event that occurred during this period was heavy rainfall which produced flooding in the New Orleans, Louisiana area — 1-minute GOES-16 Infrared images (below) showed the clusters of thunderstorms responsible for precipitation accumulations that exceeded 1.0-2.0 inches per hour at times.

A cursor sample of the GOES-16 cloud-top 10.3 µm infrared brightness temperature at 1250 UTC (below) displayed a corresponding GOES-16 Rain Rate of 2.16 in/hr (below).

Just prior to sunrise in southwest Louisiana, another notable event was a convective line that produced EF1/EF2-rated tornadoes in the Lake Charles area — overlapping 1-minute Mesoscale Domain Sectors provided GOES-16 Infrared images at 30-second intervals (below), which showed the pulses of cold overshooting tops associated with these thunderstorms. This event is also discussed from a hyperspectral model perspective in this blog post.

A cursor sample of 1126 UTC GOES-16 cloud-top 10.3 µm infrared brightness temperature (below) displayed a corresponding GOES-16 Cloud Top Temperature of -76.11ºC and a Cloud Top Height of 42974.84 ft.

30-second GOES-16 Infrared images with an overlay of GLM Flash Extent Density (below) revealed a notable amount of lighting actvity associated with this tornado-producing line of thundertorms.

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GOES-16 Clean Window infrared imagery (Band 13, 10.3 µm), above, shows a convective line moving into Louisiana around sunrise on 10 April 2024. SPC Storm Reports (below, and here), show tornadoes over extreme southwest Louisiana at around 1130 UTC on 10 April 2024 (Note the peak wind of 55 knots at the Lake Charles LA airport at 1136 UTC, within minutes of the times of the reported tornadoes nearby).

Composite Reflectivity radar fields (clumsily saved as screen captures from this site), show the line of convection responsible for the tornadoes.

CIMSS and Hampton University Scientists run a 4-km resolution WRF simulation that includes as its input information from Polar Hyperspectral Soundings. The great spectral resolution of the Sounders (both infrared and microwave) on Polar Orbiting Satellites (that is, CrIS and ATMS on NOAA-20/NOAA-21 and IASI and MHS/AMSU on Metop-B/Metop-C) is blended with the great spatial and temporal resolution of the ABI (via a fusion process described here and here) to provide assimilation data to the WRF model. How did this model perform (compared to other high-resolution mesoscale models) during this small outbreak of tornadoes?

The surface fields below from the 4-km WRF model with PHS information and the 3-km HRRR model are shown below. The WRF simulation better represents the character and timing of the convection moving into southwestern Louisiana. It’s tempting to attribute this to a better representation of moisture that comes from the inclusion information from the Polar Hyperspectral Soundings.

The model output shown below is the 0-1000m bulk shear. Shear values are larger and show small peak concentrations at the time and in the region of the observed tornadoes in the WRF model influenced by PHS data (top) compared to the HRRR model (bottom). The Shear at 1100 UTC is shown here.

Significant Tornado Parameter (STP), below, also has smaller-scale features in the WRF model run influenced by PHS data compared to the HRRR model run. The model output at 1100 UTC is shown here (tornadoes occurred close to 1130 UTC; one was rated an EF-2).

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PHS model output (available here online) will be demonstrated this year at the Hazardous Weather Testbed at SPC in Norman OK. One of the metrics available at the PHS Model website shows how many profiles are (or are not) assimilated into the model. Here‘s the field for 0800 UTC on 10 April: Many profiles are assimilated!!

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The Samoan Islands are again within a moisture-rich airmass, as shown by the MIMIC estimates of Total Precipitable Water shown below. The MIMIC fields do not show obvious gradient that might be used to estimate when rains might be especially widespead. The airport at Pago Pago American Samoa has had a little under 2″ of rain the 24 hours ending at around 9 AM Samoa Standard Time on 9 April. Flood Warnings were posted overnight on the 8th (in part because of scenes like this image from the NWS Pago Pago Slack Channel!)

Infrared imagery, below (source), from 0250 UTC to 1840 UTC (that is, 350 PM to 750 AM American Samoa Time), shows extensive overnight convection that moves from south of American Samoa northward. By the end of the animation, the focus of convection is north of the Samoan Islands with a strengthening line of westward-moving convection is also moving along 5^oS latitude. Convection over the Samoan Islands weakens as the westward-propagating line strengthens.

Water Vapor imagery for the same interval, below, also shows a diminishing trend for convection over the Samoan Islands.

LightningCast probabilities over Amercan Samoa, below (from this site) show a big difference between 0630 and 1930 UTC on 9 April 2024. Lightning probabilities were high and lightning was active at 0630 UTC. By 1930 UTC, activity was much reduced, with elevated LightningCast probabilities confined to regions south of American Samoa. This might be a region to watch for development.

GFS estimates of the Galvez-Davison Index (GDI), below (source) from the 1200 UTC GFS run show large values (>45) of GDI persisting over and south of the Samoan Islands until about 0000 UTC on 11 April. The potential for heavy rain continues over American Samoa for another day despite the respite shown in the ABI data above. (Note from this blog author: I find forecasting for American Samoa very very difficult!) (Here is blog post comparing GDI to DSI estimates of K-Index). The 2100 UTC LightningCast probabilities (here), do show an increase in probabilities of a GLM observation (and actual GLM observations) just to the south of Tutuila, so perhaps convection is starting to become more widespread.

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