PROJECT ALERT NOTICE (NY) Record Local Flooding in western New York

Date: Thu, 13 Jul 2017 19:27:34 EDT

Summary: Flooding in western and central New York

Minor to moderate flooding occurred in a few basins in central and
western New York Thursday afternoon (July 13) as a result of locally
heavy rainfall in a few hours. Runoff was magnified by the wet
antecedent conditions from previous rainfall the past several days.

Two USGS streamgages reached NWS moderate flood category: one gage in
the Cayuga Creek basin near Buffalo, NY and the other gage in the
Owasco Inlet basin near Ithaca, NY. Preliminary data indicate a record
peak discharge at the Cayuga Creek near Lancaster gage of about 10,000
cfs (77 yrs of record; previous peak was 9,440 cfs; historic peak of
18,000 cfs in 1937). The approximate annual exceedence probability is
0.04 to 0.02 (25-50 year recurrence interval). The stage-discharge
rating was exceeded at Cayuga Creek and one short-term streamgage.
Another streamgage in the Towanda Creek basin at Attica, NY reached
NWS minor flood category.

Streamflows at most USGS streamgages are forecast to recede below NWS
flood stage overnight, although a few streams will remain near flood
stage through Friday. A total of three USGS crews (6 staff members)
from the Ithaca, NY office are making discharge measurements today for
rating calibration. All equipment is operating, except the back-up stage
sensor is temporarily replacing the primary stage sensor at Buffalo
Creek at Gardenville. Rating extensions, inspections, and possible
follow-up discharge measurements are planned for Friday July 14.