Flood Potential Outlook
Issued by NWS Buffalo, NY

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Winter/Spring Flood Potential Outlook
National Weather Service Buffalo NY
802 PM EST Fri Jan 6 2017

...NEAR NORMAL FLOOD RISK THROUGH JANUARY 19TH...

This is the first flood potential outlook of the 2017 season.
Flood outlooks will be issued every two weeks into early spring to
summarize basin conditions and to assess the potential for
flooding. The outlooks are based on current and forecast
hydrometeorological conditions. This includes snow cover and
water equivalent, creek and river levels and the amount of ice on
them, along with the expected conditions during the next two
weeks.

...CURRENT CONDITIONS SUMMARY...

Although the winter season got off to a late start, two weeks of
cold weather resulted in an active period for lake effect snow. A
warm up late in December melted much of this snow in all but the
Black River Basin. This also flushed out much of the river and
creek ice. Then recent cold temperatures has brought another round
of lake effect snow which has re-established a portion of the snow
pack.

Snow Water Equivalent (SWE) is below normal for the Buffalo Creeks
and Genesee River Basins. There is more snow pack across the
Western Southern Tier, which is about normal for this time of
year. Amounts vary considerably due to the localized nature of
lake effect snow.

The most significant snow pack is across the Black River Basin
where lake effect snows were more frequent and heavier. This area
was also spared a complete melt during the period of warmer
temperatures in December. As a result, SWE are about 140 percent
of normal, or roughly an inch more than normal. There is also more
ice on this basin, probably thick enough for ice jam development
in the event of a rapid warm up.

The following is a summary of the conditions by basin as of
Thursday morning, January 6th:

...BUFFALO AREA CREEKS / LAKE ERIE BASIN...
.SNOW COVER..........4 to 8 inches, less north of Buffalo.
.WATER EQUIVALENT....Up to 2 inches.
.CREEK FLOWS.........Above normal.
.CREEK ICE...........Patchy.
.GROUND FROST........Less than 2 inches.
.GROUND STATE........Partially frozen.

...GENESEE RIVER BASIN / FINGER LAKES / ROCHESTER AREA...
.SNOW COVER..........Less than an inch, 1 to 3 inches Upper Basin.
.WATER EQUIVALENT....Less than a half inch.
.RIVER/CREEK FLOWS...Above normal.
.RIVER/CREEK ICE.....Patchy.
.GROUND FROST........Less than 2 inches.
.GROUND STATE........Partially frozen.

...ALLEGHENY RIVER BASIN...
.SNOW COVER..........8 to 16 inches.
.WATER EQUIVALENT....1 to 3 inches.
.RIVER/CREEK FLOWS...Above normal.
.RIVER CREEK ICE.....Patchy.
.GROUND FROST........Less than 2 inches.
.GROUND STATE........Partially frozen.

...BLACK RIVER BASINS / TUG HILL...
.SNOW COVER..........4 to 12 inches, 1 to 2.5 feet on the Tug Hill.
.WATER EQUIVALENT....1 to 2 inches, 2 to 5 inches on the Tug Hill.
.RIVER/CREEK FLOWS...Near normal.
.RIVER/CREEK ICE.....Creeks mostly frozen, some ice on the Black
River.
.GROUND FROST........3 to 6 inches.
.GROUND STATE........Frozen.

...TEMPERATURE AND PRECIPITATION OUTLOOK...

Lake effect snows will continue through the weekend, which will
add to the snow pack across the typical snow belts east of the
lakes. It is likely that going into next week SWE will be above
normal in these areas. Cold temperatures will also allow some
creek ice to develop, however this is likely to be thin in all
basins except for the Black River Basin where ice is already in
place. Any precipitation through early next week should fall as
snow.

After this a progressively warmer pattern will develop. Low
pressure will track across the Central Great Lakes with a round of
rain and a brief warm up Tuesday and Tuesday night. Following a
brief period of colder temperatures a frontal boundary will
develop near our region late in the week, with frequent chances
for precipitation. This boundary will divide seasonably cold air
from a much above normal air mass. It is uncertain which side of
this boundary our region will be, but it appears increasingly
likely that much of Western New York will be on the warm side of
this boundary heading into next week. This pattern is also
favorable for low pressure to develop and bring widespread rain
somewhere in the general region, even though it is too far off to
tell when or where. In line with this, the 8 to 14 day outlook
calls for above normal temperatures and precipitation.

...FLOOD POTENTIAL OUTLOOK...

Flood risk during the next two weeks is near normal.

Through early next week flood risk is minimal. After this, the
pattern becomes more likely to produce flooding. Warmer
temperatures and possibly some rain are likely to melt much of
the snow pack in the Buffalo Creeks and Allegheny River Basins.
Whether or not this causes flooding depends on how quickly this
happens, and if rainfall occurs in addition to the warmer
temperatures.

There is more than ample snow pack in the Black River Basin for
flooding to occur, however it is less certain if temperatures will
warm enough to melt the snow in this basin. This uncertainty
somewhat offsets the greater snowpack.

As a result the flood risk is near normal for the region. The
potential for flooding will begin during the middle portion of
next week, and last through mid-January as the warm pattern
becomes established.

...ADDITIONAL INFORMATION...

Real time river information and probabilistic forecast for
specific locations along rivers across Western New York can be
found on the internet at www.weather.gov/buf. Since conditions can
change, please refer to the latest flood watches, warnings, and
statements for additional information.

Thank you to all the observers and agencies which have helped
gather data in support of this outlook. The next Winter/Spring
Flood Outlook will be issued on January 19th.

$$

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