Flood Potential Outlook
Issued by NWS Binghamton, NY

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FGUS71 KBGM 151717

Winter/Spring Flood Potential Outlook
National Weather Service Binghamton NY
117 PM EDT Thu Mar 15 2018


This is the sixth in a series of regularly scheduled hydrologic
outlooks issued during the Winter and Spring season. This outlook
is designed to provide a generalized assessment of river flood
potential (not flash flooding) across Central New York and
Northeast Pennsylvania for the next two weeks...March 15th to
March 29th.


.Antecedent conditions in the majority of our basins would
suggest a higher than average risk of river flooding for the next
two weeks. However, medium and long range weather forecasts
suggest gradual warming trends and a limited chance for heavy
precipitation. The flood favorable conditions in place would thus
be mitigated by a gradual melting of the snow pack and no heavy
rainfall. The overall flood potential is therefore considered
about average for late March.


.PRECIPITATION: Above average. The first two weeks of March have
seen 1 to 3 inches of precipitation across the basins. Over the
past 30 days, precipitation departures ranged from 125 to 200% of

.SNOW COVER AND WATER EQUIVALENT: Above Average. Several coastal
storms, and lake effect events, have re-established a deep snow
cover across many of the basins. The deepest snow cover existed
across the headwaters of the Susquehanna and Upper Delaware basins
where snow depths ranged from 8 to 18 inches. Up to 2 feet of
snow was in place over the highest peaks in the Catskills, the
Tully-Heighburgs and the southern Tug Hill. Elsewhere, snow cover
ranged from 2 to 12 inches with the lowest totals in the Chemung
and Finger Lakes area. The liquid equivalent of the snowpack was
about 1 to 3 inches with locally higher amounts approaching 6
inches in the deep snow areas.

.RIVER ICE COVER: Normal. The river ice season has passed. All
main river channels were clear of any significant ice cover.

.STREAMFLOW: Above normal. Streamflow, averaged over the past 28
days, was above normal at a majority of the stream gauge locations
when compared to the long term history of each gauge. Some
streams from the northern Chemung across the Finger Lakes were
running at normal levels.

.SOILS AND GROUNDWATER: Above normal. The Palmer Drought Severity
Index, along with other multi-model soil moisture indicators,
showed wetter than average deep soil conditions throughout the
basins. Groundwater levels were generally normal to above normal.

.RESERVOIR AND LAKE LEVELS...Variable. NYC Reservoirs were
slightly above the long term median pool height. The Finger Lakes
levels were generally normal, while Lake Wallenpaupack in NEPA
was above its March target pool height.


.FUTURE WEATHER CONDITIONS: The 6 to 14 day outlook calls for
colder than normal temperatures and slightly above average
precipitation. Several other computer forecast simulations
suggested generally normal precipitation, and little to no
significant storms in the period. The exception being another
possible coastal storm during the March 20-21 time frame, which
right now is looking to be a cold-side event with mainly snow, or
mixed precipitation.

ensemble of river forecast systems indicated a lower than average
risk of flooding during the next 1-2 weeks. An analysis of
flooding, using current hydrologic conditions compared to
historical flows, suggested the majority of basins have a lower
than average chance of flooding, although basins in the Upper
Susquehanna and Delaware headwaters were exhibiting a higher than
historical average chance of minor to moderate flooding through
early April.


This outlook estimates the potential for river and lake flooding
based on a current overview of hydro-meteorological factors which
contribute to flooding.

It is important to note that significant flooding does not occur
from snow melt alone. Rainfall, how much and in how short a period
of time, is the most important factor in determining the severity
of flooding. Specific forecasts of heavy rainfall and flash
flooding are not included in this outlook.

The next Winter/Spring Flood Outlook will be issued by this
office in two weeks, on March 29th 2018. If conditions change in
the interim: Flood Watches, Warnings or Advisories will be issued
as necessary.



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