The storm system named ‘Mocha’ is brewing in the Bay of Bengal and was upgraded to tropical storm status earlier today. Mocha began as a deep depression in in the southeast Bay of Bengal. It is forecasted to continue moving north and gain strength, predicted to become a typhoon within 24 hours. Mocha’s current wind speeds are 50 mph.

Mocha will likely make landfall near the border between Myanmar and Bangladesh on Sunday, May 14. By that time, it will be upgraded to a ‘cyclonic storm’, or typhoon. It is predicted to cause winds up to 80 mph. Andaman and Nicobar Islands are already experiencing heavy rains from the system. Mocha will trigger heavy rains over north east India on Saturday and Sunday, as it approaches and makes landfall.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed thunderstorms that produced several tornadoes, hail up to 4.00 inches in diameter, wind gusts to 81 mph and heavy rainfall (SPC Storm Reports) across northeast Colorado, northwest Kansas and southwest Nebraska on 10 May 2023.

1-minute GOES-16 Infrared images (below) include an overlay of GLM Flash Extent Density — most of the storms exhibited only modest lightning activity, although a few brief lightning jumps were evident.

GOES-16 Visible/Infrared Sandwich RGB images at 2213 UTC and 2218 UTC (below) include a cursor sampling of the associated Rainfall Rate (red), Cloud Top Phase (yellow) and Cloud Top Height (green) Level 2 Derived Products over the location of Local Storm Reports of Heavy Rainfall and Flash Flooding in northwest Kansas. As discussed in this TOWR-S Satellite Book Club presentation, beginning with TOWR-S RPM 22 various types of “GOES RGBs w/Derived Product Readouts” are available in AWIPS under Satellite -> Local Menu Items, which includes these options.

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Cincinnati’s 25th running of the Flying Pig Marathon commenced on the morning of Sunday, May 7th, despite deteriorating weather conditions. After a round of storms at about 09:30 UTC, which subsequently passed through, race officials began the marathon as scheduled at 10:30 UTC. Figure 1 shows the composite reflectivity and LightningCast contours 0-30 minutes prior to the start time. The point marked “H” in the center of the animations below is the Cincinnati Municipal Airport — Lunken Field, which is about 3 miles east of downtown Cincinnati, where the marathon took place. In Figure 1, we see some storm cells intensifying and heading east toward downtown Cincinnati. The LightingCast probability of lighting in the next hour was > 50% at 10:30 UTC, when the race began.

ProbSevere LightningCast uses artificial intelligence and GOES-R ABI data to predict the probability of lightning in the next 60 minutes, as observed by the GOES-R Geostationary Lightning Mapper (GLM). Figures 2 and 3 show animations of LightningCast probabilities with GOES-16 10.3 µm brightness temperature and GLM flash-extent density (Figure 3). As the convection approaches downtown Cincinnati, we see cooling cloud tops and intensifying lightning flash rates. Furthermore, in Figure 3, we see a number of anvil flashes “overhead” of point H (i.e., within the GLM pixel containing point H) just prior to the start of the race. With thick ice from the anvil of the departing round of storms and the anvil of the approaching line of storms, LightningCast probabilities remained high despite no flash centroids within 10 miles of downtown Cincinnati during the inter-storm period (~10:15 to 11:00 UTC).

Using the LightningCast time series capability at Cincinnati Municipal Airport — Lunken Field (Figure 4), we see that the probability of lightning remained elevated (40-60%) in the inter-storm period, then jumped up to 71% by 10:36 UTC. The probability steadily increased to 96% at 10:51 UTC, 28 minutes before a shelter-in-place order was issued to runners. The “order” was more of a recommendation, according to race officials, as many runners were either confused by it or ignored it. The race began at 10:30 UTC, which was 15 minutes after the last flashes (within 10 miles) from the first round of storms.

Fortunately, there were no reported lightning-related injuries to racers or spectators, despite dozens of observed flashes every 5 minutes, within 5 miles of downtown Cincinnati. We aim to make LightningCast usable by forecasters and event managers to help make informed decisions such as postponements and sheltering at events with high vulnerability to lightning.

h/t to Kevin Thiel for providing information for this event.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed an isolated supercell thunderstorm that produced a few tornadoes and hail as large as 4.00″ in diameter (SPC Storm Reports) across northern Missouri late in the day on 06 May 2023. Pulses of overshooting tops exhibited infrared brightness temperatures of -70ºC or colder (brighter shades of white).

1-minute GOES-16 Infrared images (below) include an overlay of GLM Flash Extent Density — one feature of note was the anvil lightning that eventually extended about 100 miles northeast of the thunderstorm core (which was producing a tornado and 4.00-inch diameter hail at 0042 UTC), stretching into southern Iowa.

GOES-16 Visible images (below) include overlays of Total Precipitable Water, Lifted Index and Convective Available Potential Energy (CAPE) derived products — showing that the thunderstorm was moving into an environment of moisture and instability, helping to sustain its intensity.  

Farther to the west, thunderstorms produced hail and damaging winds across parts of north-central and southeast Nebraska, as seen in 1-minute GOES-16 Visible and Infrared images (below). One notable feature of interest was the cooler (lighter shades of gray) west-to-east oriented swath of hail on the ground in the wake of the southern Nebraska storm — even though that storm was initially producing primarily small-diameter hail (1.00 inch or less), that hail fell at a high enough rate to accumulate and remain on the ground for several hours. Another similar (but more subtle) southwest-to-northeast oriented swath of accumulating hail was evident in the wake of the storm over north-central Nebraska.

A closer view of the southern Nebraska storm is shown below, using 1-minute GOES-16 Infrared images with a color enhancement tailored to highlight the colder swath of hail accumulation (brighter shades of cyan to darker shades of blue). Surface 10.3 µm infrared brightness temperatures within the narrow hail swath were in the 5-8ºC range, in contrast to 10-13ºC over adjacent bare ground. A few Local Storm Reports (2328 UTC | 0004 UTC | 0102 UTC | 0157 UTC) mentioned hail accumulation or a long duration of hail.

1-minute GOES-16 True Color RGB and Nighttime Microphysics RGB images from the CSPP GeoSphere site (below) provided another close-up view of the southern Nebraska storm — its hail swath showed up as pale shades white in the Nighttime Microphysics RGB imagery.

In a toggle between the GOES-16 Land Surface Temperature (LST) derived product at 0000 and 0100 UTC (below), LST values within the narrow hail swath were in the low-middle 50s F (darker shades of blue), compared to the low-middle 60s F (shades of green) over adjacent bare ground. Another cold LST hail swath was apparent in the wake of the thunderstorm over north-central Nebraska.

Thanks to NWS Hastings for bringing this interesting feature to our attention!

Here's something we don't see every day:

Tonight's storm was such a prolific hail producer that the lingering hail on the ground can be seen on IR satellite! This is due to the temperature differences between the warm/dry ground and cooler hail-covered ground#scienceiscool ? pic.twitter.com/5WxQT4smzZ

— NWS Hastings (@NWSHastings) May 7, 2023

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