Flood Potential Outlook
Issued by NWS State College, PA

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Winter/Spring Flood Potential Outlook
National Weather Service State College PA
1115 AM EST Thu Mar 15 2018



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

This outlook is valid Thursday March 15th 2018 through Thursday March
29th, 2018.

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.

Two week river flood potential...The current potential for river
flooding is average.

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

Recent precipitation...Above average. The wet weather over the last
month has the entire region above average in precipitation
over the 30 days.

Snow conditions...Below average. Recent winter storms have largely
missed central Pennsylvania with only light snow accumulations over
the area.  The western and Laurel Mountains have increased their
snow pack in the last week. Upstream river basins in northeast
Pennsylvania and southern New York have a much more substantial
snow pack which will eventually flow into central Pennsylvania via
the Susquehanna River.

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 no river ice left in the region and the river ice season is

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

Stream flow conditions...average.
Streamflows have fallen in the last week with the colder weather.
Flows over the west are generally a bit below average while flows
over the east are near average.

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 levels are above average across the western half of
the area tapering to normal or even below normal levels over the
far southeast portions of our area.

The long term Palmer Drought Severity Index is used to infer deep
soil moisture conditions. The March 10th, 2018 chart found at
regional_monitoring/palmer.gif .

The most recent version (Mar 15, 2018) of the US Drought Monitor
chart does shows the entire region free of drought conditions.

GROUND WATER...Above.  Most monitoring wells are running well above
average for this time of year, due to the recent rainfall.

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...Temperatures are forecast to remain below
average for the next couple weeks.  Precipitation is forecast to
be close to or slightly above average.

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

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. It is quite common for water levels to be high this
time of year and excessive rainfall could lead to flooding. River
information can be found at water.weather.gov .

Summary of flood potential March 8 to March 22 2018: Given the high
stream flows and groundwater content, the regional flood potential
is above average for the next couple of weeks.

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

The next flood potential outlook will be issued on Thursday March

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



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