A vertically stacked upper level low moved slowly over eastern Pennsylvania, New Jersey and southern New York on Friday, May 20th. The surface low moved to near Long Island by the early afternoon. Showers and thunderstorms developed in a moist and unstable airmass across the region. Wet antecedent conditions existed over the mid-Hudson Valley and Catskills from the flash flooding the day before, May 19th.
Storms once again trained (repeatedly moved over the same areas) across portions of Columbia and Dutchess counties resulting in more flash flooding.  It was reported that Amtrak encountered some train delays around 6 pm EDT Friday evening due to a mudslide which affected CSX track between Albany and Rhinecliff. Other slow moving storms formed in the western Mohawk Valley producing flash flooding across a portion of central Herkimer County.

Flash Flood in DUTCHESS, NEW YORK
From 20-MAY-11 14:17:00 to 20-MAY-11 19:00:00 (EST-5)
Location: MABBETTSVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Route 44 was reported flooded in several locations between Millbrook and Amenia.

Hail in WASHINGTON, NEW YORK
From 20-MAY-11 14:20:00 to 20-MAY-11 14:25:00 (EST-5)
Location: BELCHER
Magnitude: 0.75 
Crop damage: 0.00K
Reported by: Public

Penny and dime size hail was reported during a thunderstorm in Belcher. The hail covered the ground.

Hail in COLUMBIA, NEW YORK
From 20-MAY-11 14:38:00 to 20-MAY-11 14:43:00 (EST-5)
Location: VALATIE
Magnitude: 0.75 
Crop damage: 0.00K
Reported by: Public

Penny size hail was reported during a thunderstorm in Valatie.

Flash Flood in GREENE, NEW YORK
From 20-MAY-11 14:50:00 to 20-MAY-11 19:00:00 (EST-5)
Location: WEST COXSACKIE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Mansion Street was reported closed due to flooding between Bailey Street and Lawrence Avenue in West Coxsackie.

Flash Flood in COLUMBIA, NEW YORK
From 20-MAY-11 15:13:00 to 20-MAY-11 19:00:00 (EST-5)
Location: HILLSDALE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Route 23 in Hillsdale was reported flooded.

Flash Flood in COLUMBIA, NEW YORK
From 20-MAY-11 14:58:00 to 20-MAY-11 19:00:00 (EST-5)
Location: MELLENVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: State Official

Route 217 was reported flooded north of Route 23 in Claverack.

Flash Flood in COLUMBIA, NEW YORK
From 20-MAY-11 14:45:00 to 20-MAY-11 19:00:00 (EST-5)
Location: STUYVESANT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: State Official

One lane of Route 9J was reported closed due to flooding and debris in the road just south of Stuyvesant. The nearby railroad tracks were also reported flooded.

Flash Flood in HERKIMER, NEW YORK
From 20-MAY-11 15:15:00 to 20-MAY-11 20:30:00 (EST-5)
Location: RUSSIA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Damage was reported to the roadway at the intersection and Russia Road and Lanning Road in Poland due to flooding.

Flash Flood in HERKIMER, NEW YORK
From 20-MAY-11 14:53:00 to 20-MAY-11 20:30:00 (EST-5)
Location: GRAVESVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A small creek was reported overflowing its banks and running over Russia Road just west of Military Road in Poland.