Flood watch covers northern and central Arizona as Alaska panhandle braces for atmospheric river

A car drives through a flooded road in a 2007 file photo from Melbourne, Australia, shown for illustration only — Shootthedevgru, Wikimedia Commons, CC BY-SA 3.0 / GFDL

Summary

NWS Flagstaff issued a flood watch for all of northern and central Arizona at 12:37 a.m. MST on Oct. 20, with storms expected Wednesday and Thursday.
NWS Juneau has a flood watch for the Alaska Gulf Coast from 10 p.m. AKDT Oct. 19 into late Tuesday, with 3 to 4 inches of rain possible in places.
Searches did not find a flood watch for South Florida on Oct. 19-20; the Florida flash flood warning headline in circulation is dated Oct. 17.
Rainfall totals for Arizona, expiry times and any damage reports are not yet confirmed.

Arizona: watch issued ahead of midweek storms

The National Weather Service office in Flagstaff issued a flood watch at 12:37 a.m. MST on Tuesday, Oct. 20, covering all of northern and central Arizona, according to the alert text. Listed zones include the Kaibab Plateau, Grand Canyon Country, the Coconino Plateau, the Mogollon Rim, the White Mountains and the Little Colorado River Valley, across Apache, Coconino, Gila, Navajo and Yavapai counties.^[2]

Showers and thunderstorms are expected to begin early Wednesday morning and continue through Thursday evening. The Flagstaff office's website, updated at 12:52 a.m. MST Tuesday, lists a flood watch and describes a strong system with a risk of flooding on Wednesday and Thursday, with both flash flooding and longer-duration flooding possible.^{[2] [1]}

Cause and expected impacts

The alert text attributes the threat to an upper-level trough drawing a deep surge of subtropical and tropical moisture into Arizona. Stronger thunderstorms could bring flash flooding, and prolonged rain could raise flows in streams, rivers and washes.^[2]

The weather service lists creeks, normally dry washes, swimming holes and recently burned areas as the most exposed spots, and warns that low-water crossings may flood. It advises people to have a way to receive flash flood warnings. FOX 10 Phoenix reported on Monday, Oct. 19, that showers and storms could reach about 60 percent in Phoenix on Wednesday and Thursday, with flash flooding, gusty winds and small hail possible, and the highest flood risk north and east of the city.^{[2] [3]}

Southeast Alaska: atmospheric river through Tuesday

Separately, NWS Juneau has a flood watch for the eastern and northeastern Gulf Coast, from Cape Fairweather to Lisianski Strait, including Yakutat, Elfin Cove, Pelican, Gustavus and Juneau. The alert text says it took effect at 10 p.m. AKDT on Oct. 19 and runs through late Tuesday night, as an atmospheric river over the Yakutat area continues through Tuesday.^[4]

Elfin Cove and Pelican could receive 3 to 4 inches of rain through Tuesday evening, and more than 6 inches is possible above 1,000 feet, the alert says. Juneau and Gustavus may see at least minor river flooding, and isolated landslides are possible on steep terrain.^[4]

South Florida: no matching watch found

The Florida headline appearing in news feeds, a flash flood warning for parts of South Florida, comes from a Local 10 video page dated Oct. 17. That page carries no text on the counties affected, timing or rainfall.^[6]

CBS Miami's forecast for Monday, Oct. 19 describes a frontal boundary stalling over the Florida Straits and drier air moving in, with low rain chances, spotty showers Tuesday morning and northeast winds of 20 to 25 mph gusting to 30 mph. It reports a high risk of rip currents on Atlantic beaches through Thursday, Oct. 22, and small craft advisories, and does not mention flooding.^[5]

What is not known

The Arizona alert text gives no rainfall totals, and its end time is inconsistent: the headline cites 11 p.m. MST on Oct. 22, while the expiration field says 6 a.m. MST on Oct. 21. The official Flagstaff product should be treated as the authority on timing. The Alaska alert's times are also listed inconsistently in the copy reviewed. No damage or injury reports tied to either watch were found as of early Tuesday.^{[2] [4]}

The sources reviewed do not show which watch drove the nationwide rise in searches for "flood watch", and other watches may be in effect elsewhere in the country that this report does not cover.^[1]

Reporting sources

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