Tropical Storm Imelda Flooding vs. Harvey, Others

Tropical Storm Imelda dumped massive rainfall, over 40 inches in some places, over the Texas Gulf Coast. This is a story I've reported before -- in 2017 during Hurricane Harvey, in 2001 with Tropical Storm Allison, and those aren't the only historical precedents.

Even before the last raindrop fell, meteorologists wondered how Imelda compared to Harvey, Allison and previous storms. The WPC had already drawn up comparisons from Harvey to Allison, and Harvey vs. Claudette in 1979, but they won't issue graphics that match those until next year. Using ESRI GIS, AccuWeather was able to take the NWS's 72-hour rainfall map (which at least approximates Imelda's rainfall) and plot it in the WPC historical map colors. Here are all four storms at once:

There is also a version in the viridis color table, which I understand is helpful for those who are colorblind.

It's easy to see from these images, that Harvey dropped larger rain totals over a larger area, but Imelda's amounts and coverage beat Allison and Claudette. While Harvey's extreme rainfall fell on parts of Houston, the city escaped Imelda's highest totals.

I have revised my list to match WPC's although I disagree with their amount for Roman, which got an additional 11.10 today, they had a duplicate (Hamshire/North Folk) and they were missing a CoCoRaHs (Beaumont 3.3). I have tweeted them about the corrections. (This does NOT change the top amount of 43.39).

Hamshire/Fannett/Winnie Area (all from Flood Dist. 66 with WPC #s):

• Taylor's Bayou (Hamshire/N. Fork): 43.39 inches

• Mayhaw Bayou: 42.76 inches

• Taylor's Bayou (Craigen): 41.57 inches

• Green Pond Gully: 40.98 inches

• Pevito Bayou: 39.41 inches

• Pine Tree Ditch: 39.25 inches

• 37 other gauges >20 inches

Outside of that area but still >20" (dupes from same creek removed; all from TX Mesonet unless otherwise mentioned):

• Roman Forest: 32.11 inches (CoCoRaHs)

• East Fork: 31.00 inches (HCFWS)

• Beaumont: 30.16 inches (CoCoRaHs)

• Freeport: 28.14 inches

• Peach Creek: 27.56 inches

• Pine Island (Sour Lake): 25.25 inches

• San Bernard: 24.76 inches

• Luce Bayou: 22.57 inches

• Liberty: 20.72 inches

• Cedar Bayou: 20.72 inches

• Caney Creek: 25.20 inches (HCFWS)

• Dayton: 19.99 inches

Major Cities:

• Beaumont Apt: 20.81 inches

• Galveston Apt: 16.03 inches

• Houston (HOU): 10.99 inches

• Houston (IAH): 11.68 inches

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