Flood Potential Outlook
Issued by NWS Albany, NY

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE ALBANY NY
141 PM EDT THU MAR 19 2015

...Winter Spring Flood Potential Outlook 6 for Eastern New York
and Western New England...

This is the sixth of a series of Hydrologic Outlooks issued by
the National Weather Service every two weeks...which refers to
the potential for flooding across eastern New York State...southern
Vermont...Berkshire County Massachusetts...and Litchfield County
Connecticut. The major river basins in this area are the
Hudson...the Mohawk...and the Housatonic.

This outlook is valid for the two-week period March 19 to April 2.

...Overview...

The potential for snowmelt flooding for the winter and spring of
2015 is generally near normal, since snowpack is now near to above
normal. The potential for ice jam flooding is near normal for the
next week.

...Observed Snow Depths and Water Equivalents...

Snow depths between one half and two feet were the norm across
elevated terrain in the southern two thirds of the outlook
area, including the Catskills, the Berkshires, and the Litchfield
Hills. These locations are carrying between one and five, with up to
locally seven and a half, inches of liquid equivalent.

Elsewhere, snow totals in the Adirondacks measured between a foot
and two feet, containing 3 to 7 inches of liquid equivalent.

The big winner in terms of snow amounts at this point in the season
appears to be southern Vermont, where snow depths from a foot to as
much as 29.8 inches were measured. Snow water equivalents ranged
from 6 to 9.8 inches.

While snow depths have decreased, snow water equivalents have not
come down as much, as snow pack is increasing in density or
ripening.

...River Flows and Ice Conditions...

Flows in area rivers are below normal in the northern portion of
the outlook area with minimal runoff due to below normal
temperatures. Southern portions of the outlook areas that saw some
snow melt are rebounding to near normal river flow conditions.

River ice cover and thickness is above normal and with below normal
temperatures forecast for at least the first week of the
outlook period...minimal ice movement is forecast. The March sun
angle should continue to work to thin the ice on larger rivers and
open up ice free areas in creeks and streams.

...Soil Moisture Conditions and Water Supply...

Soil moisture is on the rise as, despite below normal temperatures,
some snow ripening and melt is occurring. Precipitation totals for
the last 30 days are about an inch and a half to three inches below
normal for the majority of the outlook area.

New York City water supply reservoirs are at about 73 percent of
capacity as of March 18th. This is about 20 percent below normal
for this time of year. Hudson River-Black River Regulating District
reservoirs range from mostly near target elevations to over 7 feet
below target at Stillwater Reservoir.

...Temperature and Precipitation Outlook...

The forecast for the next week calls for below normal temperatures
and some precipitation, mainly in the form of snow. A quick warmup
on the 21st will be quickly followed by below normal temperatures.
The official National Weather Service 8-14 day outlook for March
26th through April 1st calls for near below temperatures and above
normal precipitation.

...Summary...

While the potential for snowmelt flooding is near normal for this
time of year, the overall weather pattern favors colder than normal
temperatures for at least the first week of the outlook period. A
warmer day on Saturday the 21st could cause some limited snow melt
and river ice movement. However, it is unlikely that we will have
enough runoff to cause any significant rises on area rivers and
streams within the first week of the outlook period. Some warming
is possible by midweek next week, however there is still low
confidence in how long this warmup might last. Another quick warmup
bookended by cold periods would keep the melt at a slower pace,
while a longer warm period coupled with precipitation could cause
snowmelt and ice jam flood concerns. At this point it is too early
to determine which of these scenarios will materialize so interested
parties are urged to monitor forecasts at weather.gov/albany for
the most up to date information.

The seventh Winter Spring Flood Outlook is scheduled for Thursday...
April 2. Extended hydrologic information will be included
in the Hazardous Weather Outlook when necessary.

It is important to remember that heavy rainfall can produce flooding
at any time of year even in areas that have a below normal potential
for flooding.

Observed and forecast river information can be found on our web
page at www.weather.gov/albany.

$$




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