Flood Potential Outlook
Issued by NWS Binghamton, NY

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Winter/Spring Flood Potential Outlook
National Weather Service Binghamton NY
233 PM EST Thu Jan 18 2018

...AVERAGE RIVER FLOOD POTENTIAL THROUGH FEBRUARY 1ST...
...RISK OF ICE JAM FLOODING IS ABOVE NORMAL...

This is the second 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...January 18th
through February 1st.

...SUMMARY...

.The risk of widespread river flooding for the next two weeks is
average. The risk for ice jam flooding is currently above average
in some places, and may increase with time.

...CURRENT CONDITIONS...

.PRECIPITATION: Average to Above average. Precipitation since the
middle of December 2017 ranged from 75 to 100 percent of normal
in the Upper Delaware basin, to over 150 percent of normal from
the Finger Lakes region to the headwaters of the Mohawk River.

.SNOW COVER AND WATER EQUIVALENT: Variable. The current snow
depth, as of January 18, ranged from about 4 to 8 inches for much
of the Upper Susquehanna and Upper Delaware basins and 8 to 16
inches across the Finger Lakes/Oswego basin. These amounts varied
from a few inches above normal in the Finger Lakes region, to
slightly below normal in the Upper Delaware. Snow water equivalent
ranged from around 0.5 to 1.5 inches in the deepest snow cover,
with local amounts across the Eastern Finger Lakes as high as 2
inches of liquid. These amounts are generally below average. The
snow pack at this time was very cold with a low density and will
thus take time to melt.

.RIVER ICE COVER: Normal. River and stream channels have varying
amounts of ice, which is normal for January. Known ice jams are
occurring on the Susquehanna between Owego and Binghamton, and
also for several miles near, and upstream of Wilkes-Barre. An ice
jam may still be in place on Fishs Creek in Oneida county between
Taberg and Sylvan Beach. Elsewhere, ice cover may be quickly
reforming, since the January 11-13 thaw, as temperatures have been
well below freezing, and even sub-zero on some nights.

.STREAMFLOW: Normal to below normal. Monthly averaged streamflow,
at a majority of the recording stream gauges, was experiencing
generally normal flows when compared to the history of each
stream gauge.

.SOILS AND GROUNDWATER: Per the Palmer Drought and
the Crop Moisture index, the first several inches of topsoil was
considered wet and frozen across the Finger Lakes and Chemung
basins, while the remainder of the region was frozen, at about
average wetness. Most groundwater wells were average to slightly
below average.

.RESERVOIR AND LAKE LEVELS...Variable. NYC Reservoirs were below
the long term median pool heights, but still considered in a
normal range for the time of year. The Finger Lakes levels were
variable. Keuka Lake was experiencing a level well above the high
level guideline, but ice near the gauge could be a factor with
this reading. Lake Wallenpaupack in NEPA was above the January
average level.

...FORECAST OUTLOOK...

.FUTURE WEATHER CONDITIONS: The 6 to 14 day outlook calls for
milder than normal temperatures and above average precipitation.
Medium range models suggest a couple more January thaws are
possible during this outlook period, with the first being early
next week, and the second arriving toward the end of the month.
Precipitation during Week 1 looks to be about average, but trends
suggest Week 2 could be wetter. Milder temperatures will
contribute to snowmelt runoff, and may help to dislodge lingering
river ice downstream.

.LONG RANGE RIVER MODELING AND PROBABILITY FORECASTS: The
ensemble of river forecast systems indicates a near normal chance
for flooding during the next two weeks. A climatological analysis
of flooding, using current hydrologic conditions compared to
historical flows, also suggests the chance for river flooding
during the two week period is about average. Historically, the
average chance for minor flooding from rain and melting snow this
time of year is about once in 10 to 20 years.

...IN CONCLUSION...
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 February 1st, 2018. If conditions change in the
interim: Flood Watches, Warnings or Advisories will be issued as
necessary.

$$

JAB



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