Flood Potential Outlook
Issued by NWS State College, PA

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Winter/Spring Flood Potential Outlook
National Weather Service State College PA
1159 AM EST Thu Feb 20 2020

During the winter and spring...the National Weather Service issues a
series of winter and spring Flood Potential Outlooks. These outlooks
estimate the potential for river flooding (not flash flooding)
across central Pennsylvania based on a current assessment of
hydrometeorological factors which contribute to river flooding.
Across central Pennsylvania these factors include recent
precipitation...soil moisture...snow cover and snow water
equivalent...river ice...streamflows...future weather conditions and
other. This outlook does not address the severity or extent of any
future river flooding.

This outlook covers the Susquehanna River Basin including the West
Branch...Juniata...and much of the Middle and Lower Susquehanna
Valley. Also covered are portions of the Upper and Lower Allegheny
Basins...including areas from Warren and McKean Counties in the
south.

This outlook is valid Thursday February 20th, 2020 through Thursday
March 5th.

In central Pennsylvania...Heavy rainfall is the primary factor which
leads to river flooding. It is important to note that heavy rainfall
can rapidly cause river flooding any time of the year...even when
overall river flood potential is considered low or below average.

Detailed Discussion.

One week river flood potential...The current potential for river
flooding is near average.

Current flooding...None.
No flooding is occurring in the region at this time.

Recent precipitation...Average.
Most areas have received near average precipitation over the last 30
days.

Snow conditions...Below Average.
Only the northern most area of the region has a snow pack right now.
In Pennsylvania, including the West Branch of the Susquehanna River
the water content of any snow is below average. In New York where the
headwaters of the Susquehanna River is located, the water content of
the snow pack is closer to average.

Snow data and information sources include the NOAA/NWS
Operational Hydrologic Remote Sensing Center
(www.nohrsc.noaa.gov)...the US Army Corps of Engineers...NWS
Cooperative Observers...the Community Rain, Hail and Snow Network
(COCORAHS) and others. Snow depth and basin average water
equivalent estimates can be seen at www.erh.noaa.gov/er/marfc and
www.nohrsc.noaa.gov .

RIVER ICE...Below Average.
There is little to no river ice across the region. It is unlikely
that river ice will be a factor in any flooding this winter.

Follow river ice conditions at
http://erh.noaa.gov/ctp/hydro/riverice/index.php .

Stream flow conditions...Average.
Rivers are flowing close to or slight above average for the middle
of February.

Real time water data is available from the United State Geological
Survey by visiting http://water.usgs.gov .

Soil moisture conditions...Above Average.
Soil moisture conditions show above average moisture content across
a large portion of the region.

The long term Palmer Drought Severity Index is used to infer deep
soil moisture conditions. The latest chart can be found at
www.cpc.ncep.noaa.gov/products/analysis_monitoring/
regional_monitoring/palmer.gif .

The most recent version (February 20th, 2020) of the US Drought
Monitor chart shows the entire region free of drought conditions.
(http://droughtmonitor.unl.edu).

GROUND WATER...Average.
Most monitoring wells are reporting close to average water levels.
There are still areas with above average readings as well. Current
ground water conditions based on a 30 day moving average can be
found at http://pa.water.usgs.gov/monitor/gw/index.html .

Reservoir conditions...Average.
Most water supply reservoirs within central Pennsylvania are holding
near average storage for this time of year...as are most flood
control reservoirs.

Future weather conditions...
The weather will remain fairly quiet for the next five days. A return
to a more active pattern is expected after that.

Please visit http://www.cpc/ncep.noaa.gov for longer range weather
outlooks.

Advanced Hydrologic Prediction Service (AHPS)...Normal.
Another tool used to assess the potential for river flooding is the
Advanced Hydrologic Prediction Service...AHPS. AHPS generates
probabilistic river forecasts based on current basin conditions...
including river levels...soil moisture...extent and condition of any
snow pack...along with 50 years of history temperatures and
precipitation data. For this outlook period...AHPS indicates that the
likelihood of river flooding is near average compared to what has
been observed during this same time period across small river basins
in central Pennsylvania. With the high soil moisture contents, it
will not take as much rainfall to produce flooding across the region.
This is likely continue until green-up occurs this spring.

Summary of flood potential February 20th to March 5th 2020:

The regional flood potential about average for the next couple of
weeks.

Overview: Current Flooding...None.
Recent Precipitation...Average.
Snow Conditions...Below Average.
River Ice...Below Average.
Stream Flow Conditions...Above Average.
Soil Moisture Conditions...Above Average.
Ground Water...Average.
Reservoir Conditions...Average.
AHPS...Average. Overall Flood Potential...Average.

The next flood potential outlook will be issued on Thursday March 5th.

Other hydrometeorological information can be found by visiting the
State College Internet Homepage at http://weather.gov/ctp .

$$

CR


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