Widespread showers and a few thunderstorms developed across upstate New York as a slow moving upper level low pressure system rotated across the area. These showers and thunderstorms produced heavy rainfall, and resulted in flash flooding for parts of the area.
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The episode as NWS BGM wrote it up.
Widespread showers and a few thunderstorms developed across upstate New York as a slow moving upper level low pressure system rotated across the area. These showers and thunderstorms produced heavy rainfall, and resulted in flash flooding for parts of the area.
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 Binghamton, NY wrote its last area forecast discussion before the first event at May 20, 3:34 AM EST, 1 hour 56 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 434 AM EDT FRI MAY 20 2011 .SYNOPSIS... LOW PRESSURE WILL MOVE SLOWLY OFF THE NEW JERSEY COAST THIS EVENING. OCCASIONAL SHOWERS WILL CONTINUE TODAY, MAINLY THIS AFTERNOON WITH HEAVY DOWNPOURS POSSIBLE. CONDITIONS WILL IMPROVE ON SATURDAY WITH SUNNY BREAKS AND JUST A CHANCE OF A BRIEF SHOWER. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AT 415 AM...WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS ROTATING AROUND THE BACK SIDE OF THE UPPER LEVEL LOW WHERE LOCATED OVER THE CENTRAL SOUTHERN TIER AND ACROSS THE SOUTHERN POCONOS. THIS ACTIVITY IS EXPECTED TO GRADUALLY WEAKEN DURING THE EARLY MORNING HOURS. EARLY THIS MORNING THE UPPER LEVEL LOW WAS LOCATED OVER EXTREME EASTERN PENNSYLVANIA WITH THIS FEATURE EXPECTED TO SLOWLY MOVE INTO NRN NEW JERSEY THEN TOWARD NYC BY LATE DAY. SHOWERS WILL BECOME MORE WIDESPREAD AGAIN LATER TODAY ONCE DAYTIME HEATING INCREASES THE INSTABILITY. MODEL SOUNDINGS INDICATE SLIGHTLY LESS CAPE THEN YESTERDAY, TALL/SKINNY 200-500 J/KG. PWATS CONTINUE AROUND ONE INCH, AGAIN IMPLYING THE POTENTIAL FOR HEAVY DOWNPOURS IN ANY SIGNIFICANT CONVECTION. ANOTHER CONCERN FOR LOCALIZED FLOODING IS WEAK WIND FIELDS ESPECIALLY OVER EASTERN PORTION OF CWA. ANY CONVECTION THAT DOES DEVELOP IN THIS AREA WILL BE SLOW MOVING. OUTSIDE OF THE AREAS MENTIONED ABOVE WILL INCREASE POPS TO LIKELY THIS AFTERNOON ALONG WITH THE CHC FOR THUNDERSTORMS. MAX TEMPS WILL ONCE AGAIN RANGE FROM THE UPPER 60S TO LOWER 70S. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... TONIGHT...SYSTEM THAT HAS DOMINATED OUR WEATHER ALL WEEK WILL FINALLY MOVE OFF THE COAST. AFTER SOME LINGERING EVENING SHOWERS ACTIVITY WILL END BUT DUE TO WEAK MIXING AND LOW LEVEL MOISTURE SKIES WILL BE SLOW TO IMPROVE. SATURDAY...UPPER LEVEL RIDGE STARTS BUILDING OVER THE REGION WITH LOW LEVEL DRYING RESULTING IN PARTLY SUNNY SKIES ESPECIALLY DURING THE AFTERNOON. A WEAK FRONTAL BOUNDARY WILL MOVE THROUGH THE REGION DURING THE AFTERNOON, THIS COMBINED WITH SOME INSTABILITY MAY TRIGGER A BRIEF SHOWER OR THUNDERSTORM. WILL CONTINUE WITH LOW CHC POPS. SATURDAY NIGHT...SFC HIGH PRES AND RIDGE AXIS IN VCNTY WILL MAKE FOR A MAINLY CLEAR TO PARTLY CLOUDY NIGHT. LOWS WILL RANGE FROM THE UPPER 40S TO MID 50S. SUNDAY/SUNDAY NIGHT... AS THE RDG BLDS...MODELS PUSH A WRM FNT TWRDS THE AREA ON SUN. BIG THREE MODELS DO INDEED SPIT OUT SOME LGT PCPN WITH THE FEATURE...BUT WITH RDGG ALOFT...BELIEVE PCPN SHD BE LIMITED. SO...HAVE CONTD WITH THE PRVS FCST IDEA OF CHANCE POPS...ALONG WITH SOME AFTN TRWS IN THE WRM AIR. SUN NGT...RDG FLATTENS SOMEWHAT AND DIRTY SW FLOW FILLED WITH SFC AND UPR WVS MAY CONT TO TRIGGER SCT CONV SHWRS. FOR TEMPS USED A COMPROMISE BETWEEN THE EURO BASED HPC GUID AND BLENDED MOS GUID. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 PM EDT... VRY FEW CHGS TO ONGOING LONG TERM FCST. UL RIDGING VRY EARLY ON IN THE PD WL FLATTEN AS A STRONG TROF ROTATES THRU THE NRN PLAINS AND CANADIAN PRAIRIE PROVINCES. FAIRLY FLAT RIDGING WL BE MAINTAINED ACRS THE REGION THRU TUESDAY WITH SW FLOW AHD OF SYSTEM APPCHG FM CANADA ALLOWING SOME RISING HEIGHTS. THIS WL SERVE TO KEEP TEMPS NR TO ABV NORMAL THRU EARLY IN THE WEEK. HWVR THIS WL ALSO KEEP CHC FOR SHOWERS AND TSTMS IN THRU THE PD. CONVECTION WL GRNLY BE DIURNALLY DRIVEN THRU THE LONG TERM WITH WX GRIDS INDICATING THUNDER FM 16Z-03Z EACH PD. HPC SIDING WITH BLEND OF EC/GFS AS THEY ARE BOTH SIMILAR IN SOLNS. CDFNT PROGGED TO CROSS THE CWA TUE/TUE NGT TIMEFRAME AND THEN STALL OUT ALONG ERN SEABOARD DUE TO STRENGTHENING HIGH OFF THE SOUTHEAST COAST. THIS FRONT WL LKLY COME NORTH AGAIN AS A WMFNT LATE IN THE PD AS STRONG STORM SYSTEM WINDS UP TO OUR SOUTHWEST. THUS CONTD CHCS FOR PCPN THRU THE END OF THE LONG TERM. MAX TEMPS EXPECTED TO GNRLY RANGE IN THE MID-UPR 70S WITH LOWS IN THE 50S. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... UPR LOW CONTS TO SPIN AND DRFT VERY SLOWLY TO THE EAST. THIS CONTS TO KEEP PLENTY OF LL MOISTURE AND SOME INSTABILITY TO THE REGION. GNRL WET CONDS AND LGT WINDS BRING VLIFR CONDS AT TIMES WITH FOG...RAISING AT TIMES TO MVFR WITH SHWRS AND MIXING AS BKN LINES OF PCPN MVE THRU. XPCT LTL CHG OVRNGT...WITH IMPRVMT AFT SUNRISE AS ADTNL MIXING HELPS IMPROVE CONDS. DAYLIGHT HRS WILL FEATURE DVLPG CONV RAINS...WITH OCNL LWRD CIGS AND VSBYS IN THE HEAVIER SHWRS. CONDS SHD GNRLY LWR AGAIN AFT 00Z AS WINDS BECOME LGTR AND FOG DVLPS. OUTLOOK... FRI NGT/SATURDAY...MVFR STILL POSSIBLE EARLY...IN LINGERING SHWRS. SAT NGT TO SUN MORNING...MAINLY VFR. SUN AFTN TO TUE...MVFR...IN SHOWERS AND POSSIBLE THUNDERSTORMS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && SYNOPSIS...RRM NEAR TERM...RRM SHORT TERM...DGM/RRM LONG TERM...PVN AVIATION...DGM
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BINGHAMTON NY 336 AM EDT FRI MAY 20 2011 NYZ009-015>018-022>025-036-037-044>046-055>057-062-PAZ038>040-043- 044-047-048-072-210745- NORTHERN ONEIDA-YATES-SENECA-SOUTHERN CAYUGA-ONONDAGA-STEUBEN- SCHUYLER-CHEMUNG-TOMPKINS-MADISON-SOUTHERN ONEIDA-CORTLAND-CHENANGO- OTSEGO-TIOGA-BROOME-DELAWARE-SULLIVAN-BRADFORD-SUSQUEHANNA- NORTHERN WAYNE-WYOMING-LACKAWANNA-LUZERNE-PIKE-SOUTHERN WAYNE- 336 AM EDT FRI MAY 20 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NEW YORK...SOUTHEASTERN NEW YORK AND NORTHEAST PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. OCCASIONAL SHOWERS WITH ISOLATED THUNDERSTORMS WILL CONTINUE TODAY...WITH LOCALLY HEAVY RAINFALL POSSIBLE. STAY TUNED FOR THE LATEST FORECASTS AND UPDATES FROM THE NATIONAL WEATHER SERVICE. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY. NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. RRM
The Binghamton radar (KBGM), 120 km away, was scanning. The volume nearest the first event began at 10:31 UTC.
6 flash flood. Local standard time, as filed.
Routes 471 was closed in both directions from Woodhull to Addison, and Route 15 was closed in both directions from the Steuben county line to the Pennsylvania state line.
Several roads were affected by flooding. Water covered the southbound lanes of Route 10 just south of Walton. In Sidney Center, Route 35 was closed, and route 27 between Trout Creek and Sidney Center was closed. Depot Street was completely underwater. In Youngs, people were evacuated near Carrs Creek.
Numerous roads were flooded and impassable due to flooding in the Rome area. On East Dominick Street, water was up to the bumpers of cars.
A stream went out of its banks and flooded parts of Butts Road.
Numerous roads were flooded in Binghamton, especially near underpasses, low spots and poor drainage areas. Route 11 was closed due to flooding in Kirkwood.
Heavy rain caused flooding in and around the Oneonta area. Main Street in Oneonta experienced flooding, from Main Street south on County Route 28 toward the Franklin Mountain area. Small streams and basements flooded, with water running down hillsides through some homes. An automated rain gauge east of Oneonta recorded 2.86 inches.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New York in 2011Every state in 2011This day in weather historyWarnings in New York, May 2011
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 2026-09-24. Each event’s entry at NCEI: 305950, 305961, 308915, 308942, 308916, 308941.