An upper level disturbance moving in from the northwest coupled with a very moist air mass over New Hampshire where dewpoint temperatures rose to around 70 degrees. This allowed for strong instability with strong thunderstorm development.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS GYX wrote it up.
An upper level disturbance moving in from the northwest coupled with a very moist air mass over New Hampshire where dewpoint temperatures rose to around 70 degrees. This allowed for strong instability with strong thunderstorm development. Excessive rainfall rates allowed for localized flash flooding in urban areas.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Gray, ME wrote its last area forecast discussion before the first event at Jul 8, 2:10 PM EST, 1 hour 59 minutes earlier.
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</html>The Boston radar (KBOX), 145 km away, was scanning. The volume nearest the first event began at 21:08 UTC.
1 flash flood. Local standard time, as filed.
Multiple thunderstorms dropped 3 to 5.5 inches of rain in about 3 hours causing flooding at the intersection of Park Avenue and Arch St. in Keene, New Hampshire. Up to 3 feet of standing water.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New Hampshire in 2020Every state in 2020This day in weather historyWarnings in New Hampshire, July 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-10-01. Each event’s entry at NCEI: 914005.