Flood Potential Outlook
Issued by NWS Buffalo, NY

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FGUS71 KBUF 181953
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121-211415-

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

...NEAR NORMAL FLOOD RISK THROUGH FEBRUARY 1ST...

This is the second flood potential outlook of the 2018 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...

Across western and northern New York, the current potential for
river flooding is near normal. The arctic airmass at the start of
the month was broken up by a significant warmup last weekend. Area
snowpack was significantly reduced during this event, resulting in
minor flooding as well as ice jams along area rivers and creeks.
Additionally, in that event, area rivers and creeks saw a
significant break up of ice cover, resulting in ice jam flooding.
Since that time, a storm system brought widespread snowfall,
followed by lake effect snow to the area. The current snowpack
remains highest in the snowbelt, with reports of a foot or more in
higher elevations south and east of Buffalo to around two feet on
the Tug Hill Region/Black River Basin. Elsewhere snow depths were
around a half a foot with snow water equivalent values of around 1
inch. On the Tug Hill, snow water equivalent values range
dramatically from a few inches up to ten inches. Temperatures have
been colder than normal for most of the week resulting in some
regrowth of river ice. Ground conditions are frozen with above
normal water content, based on the Palmer Drought Severity Index.

The following is a summary of the conditions by basin as of early
Thursday morning, January 18th:

...BUFFALO AREA CREEKS / LAKE ERIE BASIN...
.SNOW COVER..........6 to 14 inches.
.WATER EQUIVALENT....Around an inch, with some approaching 3 inches.
.CREEK FLOWS.........Near normal.
.CREEK ICE...........About 75% open, significantly more ice coverage
                     near Buffalo.
.GROUND FROST........5 to 8 inches.
.GROUND STATE........Frozen.

...GENESEE RIVER BASIN / FINGER LAKES / ROCHESTER AREA...
.SNOW COVER..........5 to 10 inches.
.WATER EQUIVALENT....0.7 to 1.2 inches.
.RIVER/CREEK FLOWS...Near normal.
.RIVER/CREEK ICE.....Shore ice, some flowing.
.GROUND FROST........5 to 10 inches.
.GROUND STATE........Frozen.

...ALLEGHENY RIVER BASIN...
.SNOW COVER..........5 to 10 inches.
.WATER EQUIVALENT....1 to 2 inches.
.RIVER/CREEK FLOWS...Near normal.
.RIVER CREEK ICE.....Shore ice.
.GROUND FROST........6 to 12 inches.
.GROUND STATE........Frozen.

...BLACK RIVER BASINS / TUG HILL...
.SNOW COVER..........0.5 to 2 feet, 1 to 3 feet on the Tug Hill.
.WATER EQUIVALENT....1 to 3 inches, 4 to 10 inches on the Tug Hill.
.RIVER/CREEK FLOWS...Near normal.
.RIVER/CREEK ICE.....Partly Frozen.
.GROUND FROST........4 to 10 inches.
.GROUND STATE........Frozen.

...TEMPERATURE AND PRECIPITATION OUTLOOK...

The forecast for the upcoming weekend favors a warmer than normal
period, along with rain. Heavy rain is not expected with this system
at this time, but the combination of rain and snowmelt could
increase the risk for minor flooding. Ice on area rivers remains
thin enough with little additional growth expected. Some lingering
ice remains in the lower Buffalo Creeks watershed and on the Black
River, therefore the threat of ice jams is near normal.

Temperatures fall to below normal for the period Tuesday through
Friday, with lake effect snows across the Chautauqua Ridge and the
Tug Hill regions. Another warmup is expected for the following
weekend. Some rain may accompany the warmup next weekend.

...FLOOD POTENTIAL OUTLOOK...

The flood risk for the next two weeks is near normal. Based on the
above information, the flood potential for open water flooding is
near normal across the region at this time. The snowpack is most
notable in the Black River Basin, however the forecast doesn`t
indicate any warm up or rain events sufficient enough to melt off
this stored water. The area could see river and creek rises on
Monday, as a result of the warm weekend, and the rain that falls on
the frozen ground resulting in runoff. Flooding threat looks limited
to only of minor severity if at all. The threat for ice jam flooding
is near normal. It is important to remember that a heavy rainfall
event along with mild temperatures can lead to an increased
potential for flooding with snowmelt and runoff. Ice breaking up and
jamming can elevate the threat for flooding in a short period of
time.

...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 18th.

$$

SJ/DPK



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