Flash Flood and Hail in New York, May 13, 2004

Name: Flash Flood and Hail in New York, May 13, 2004
Start: 2004-05-13T11:38
End: 2004-05-13T13:45
Location: New York

May 13, 2004 · NWS BUF · 4 events in 2 counties and zones

Afternoon thunderstorms developed in a moist, unstable atmosphere. In Canandaigua, the thunderstorms produced very heavy rainfall that resulted in road flooding and closures.

Where it happened

Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $33,000
Crop damage: None recorded
Events: 4

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.

What happened

The episode as NWS BUF wrote it up.

Afternoon thunderstorms developed in a moist, unstable atmosphere. In Canandaigua, the thunderstorms produced very heavy rainfall that resulted in road flooding and closures. Thunderstorm winds downed trees in Canandaigua and New Bremen.

What forecasters said that day

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 Buffalo, NY wrote its last area forecast discussion before the first event at May 13, 8:48 AM EST, 2 hours 50 minutes earlier.

Area forecast discussion, May 13, 8:48 AM EST, 2 hours 50 minutes before

AREA FORECAST DISCUSSION UPDATED
NATIONAL WEATHER SERVICE BUFFALO NY
945 AM THU MAY 13 2004

...MENTIONED RECORD WARMTH FOR THE NIAGARA FRONTIER...
BUF RECORD OF 83 SET IN 1991 IN JEOPARDY. GOING FOR HIGHS IN THE MID
80S. ROC RECORD IS 89 IN 1879 GOING FOR HIGHS OF 84 TO 88 ROC AREA.

MODELS SHOW WEAK SHORT WAVE MOVING ACROSS WESTERN NY THIS AFTN.
MESOETA SHOWS 850-700 OMEGA FIELD DEVELOPING LTR THIS AFTN OVER THE
GENESEE VALLEY AND FINGER LKS REGION IN AREA OF SFC CONVERGENCE
BETWEEN LAKE BREEZE BNDRY OF LAKE ONTARIO WITH LIGHT SW SFC FLOW
SOUTH OF THE THRUWAY. WILL BUMP UP CHC POPS A BIT IN THE FINGER LKS
REGION...AS FAR EAST AS OSWEGO COUNTY AND AREAS TO THE SOUTH AND
EAST OF BUFFALO. CAPES UP ARND 1000-1500 THIS AFTN WITH LIS OF -3
TO -4. AIR QUITE MOIST WITH DEW PTS IN THE LOW TO MID 60S AND WITH
K INDEX VALUES OF 32-35 AND PW VALUES OF 1.2 TO 1.5 ALNG WITH LGT
WINDS ALFT COULD GET SOME LOCAL DOWNPOURS AGAIN THIS AFTN.

WILL ALSO BUMP UP TEMPS A BIT WITH TEMPS GETTING TO UPPER 80S TWD
THE GENESEE VALLEY.

NO CHANGES TO LTR PERIODS OF THE FCST.

EARLIER AFD FOLLOWS...

JJP

RIDGE OF HIGH PRESSURE ACROSS THE EASTERN U.S. WILL SLOWLY DRIFT
EAST OVER THE NEXT 48 HOURS. THIS WILL ALLOW A SOUTHERLY FLOW OF
INCREASINGLY MOIST, WARM AIR PREVAIL THROUGH FRIDAY NIGHT. 850 TEMPS
REMAIN WITHIN A FEW DEGREES OF +14C THROUGH SATURDAY MORNING SO
EXPECT TEMPS TO REACH BACK INTO THE 80S TODAY AND FRIDAY. DEWPOINTS
WILL REMAIN IN THE LOW TO MID 60S YIELDING WARM HUMID NIGHTS BOTH
TONIGHT AND FRIDAY NIGHT. PRECIP WISE FOR TODAY AND FRIDAY...EXPECT
SOME DIURNAL THUNDERSTORMS TO FORM BUT WITH NO REAL FORCING
MECHANISM OTHER THAN LAKE BREEZES OR LEFTOVER BOUNDARIES FROM
PREVIOUS CONVECTION.

COLD FRONT APPROACHES LATE FRIDAY NIGHT AND CROSSES THE REGION ON
SATURDAY. THIS WILL BE THE FORCING WEVE BEEN WAITING FOR AND HAVE
INCREASED POPS TO LIKELY ACROSS THE AREA (MAINLY IN THE MORNING WEST
AND AFTERNOON EAST). GFS PRETTY CONSISTENT WITH TIMING OF FROPA
WHILE THE ETA HAS SLOWED IT DOWN A BIT WITH FRONT NOW CROSSING KBUF
AROUND 14Z AND KART AROUND 20Z.

HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FROM WEST TO EAST
SATURDAY AFTERNOON AND NIGHT...CLEARING SKIES BUT DROPPING TEMPS TO
A BIT BELOW NORMAL FOR SUNDAY.

AVIATION DISCUSSION...

MVFR VSBYS IN FOG WILL DEVELOP ACROSS THE AREA THIS MORNING AS
TEMPERATURES COOL TOWARD THE DEWPOINTS WHICH ARE RUNNING IN THE
LOWER 60S. IFR CIGS AND VSBYS WILL DEVELOP VCNTY KJHW BEFORE
DAYBREAK. AFTER THE FOG BURNS OFF AROUND 14Z...MAINLY VFR CONDITIONS
WILL PREVAIL ACROSS THE AREA FOR THE REMAINDER OF THE DAY. A COUPLE
OF WEAK UPPER LEVEL DISTURBANCES MAY SET OFF A FEW THUNDERSTORMS
DURING THE AFTERNOON...MAINLY ACROSS THE SOUTHERN TIER AND ALONG THE
WEAK LAKE ONTARIO LAKE BREEZE. CIGS AND VSBYS MAY LOWER TO MVFR
LEVELS IN THE VCNTY OF ANY CONVECTION THAT FIRES UP.

.BUF...NONE.

PUBLIC...JJP/JML
AVIATION...TJP

Hazardous weather outlook, May 13, 3:50 AM EST, 7 hours 48 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BUFFALO NY
450 AM EDT THU MAY 13 2004

NYZ001>008-010>014-019>021-085-131050-
ALLEGANY-CATTARAUGUS-CHAUTAUQUA-GENESEE-JEFFERSON-LEWIS-LIVINGSTON-
MONROE-NIAGARA-NORTHERN CAYUGA-NORTHERN ERIE-ONTARIO-ORLEANS-OSWEGO-
SOUTHERN ERIE-WAYNE-WYOMING-
450 AM EDT THU MAY 13 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND NORTH CENTRAL NEW
YORK.

.DAY ONE...

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

THIS PRODUCT...ALONG WITH OTHER WATCHES...WARNINGS...ADVISORIES...AND
STATEMENTS ISSUED BY THE NATIONAL WEATHER SERVICE OFFICE IN BUFFALO
CAN BE FOUND ON THE INTERNET AT THE FOLLOWING (LOWER CASE):
HTTP://WWW.ERH.NOAA.GOV/BUF/

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

2 thunderstorm wind, 1 hail, 1 flash flood. Local standard time, as filed.

Thunderstorm Wind, Lewis

When: May 13, 11:38 AM EST
Where: Lewis County, New Bremen
Measured: 50 kt (58 mph) estimated gust
Property damage: $10,000
Reported by: FIRE DEPT/RESCUE SQUAD
Coordinates: 43.833, -75.433

Thunderstorm Wind, Ontario

When: May 13, 12:06 PM EST
Where: Ontario County, Canandaigua
Measured: 50 kt (58 mph) estimated gust
Property damage: $8,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.883, -77.283

Hail, Ontario

When: May 13, 12:20 PM EST
Where: Ontario County, Canandaigua
Measured: 0.75 in hail
Property damage: $5,000
Reported by: GENERAL PUBLIC
Coordinates: 42.883, -77.283

Flash Flood, Ontario

When: May 13, 12:30 PM EST to 1:45 PM EST
Where: Ontario County, Canandaigua
Property damage: $10,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.853, -77.300 (the zone’s center; the record gives no point)

What these are

Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in New York in 2004 Every state in 2004 This day in weather history Warnings in New York, May 2004

Sources

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: 5401299, 5401300, 5401301, 5401298.