A stagnant, moist air mass just north of a stationary front allowed areas of dense fog to develop late on May 9th and early on May 10th. The fog dissipated shortly after dawn.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 PHI wrote it up.
A stagnant, moist air mass just north of a stationary front allowed areas of dense fog to develop late on May 9th and early on May 10th. The fog dissipated shortly after dawn.
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 Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at May 9, 7:00 PM EST, 1 hour earlier.
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</html>Hazardous Weather Outlook National Weather Service Mount Holly NJ 834 PM EDT Sat May 9 2026 MDZ012-015-019-020-110045- Kent MD-Queen Annes-Talbot-Caroline- 834 PM EDT Sat May 9 2026 This Hazardous Weather Outlook is for northeast Maryland. .DAY ONE...Tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. Staarmann
The national radar mosaic for the moment the first event began.
4 dense fog. Local standard time, as filed.
Several hours of dense fog was observed at Wings Field.
Several hours of dense fog was observed at Heritage Field.
Several hours of dense fog was observed at Doylestown Airport.
Several hours of dense fog was observed at Quakertown Airport and Pennridge Airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2026Every state in 2026This day in weather historyWarnings in Pennsylvania, May 2026
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: 1332957, 1332958, 1332959, 1332960.