Flood Potential Outlook
Issued by NWS State College, PA

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Winter/Spring Flood Potential Outlook
National Weather Service State College PA
1015 AM EST Thu Mar 29 2018

...WINTER/SPRING FLOOD POTENTIAL OUTLOOK ISSUED MARCH 29 2018...

INTRODUCTION.

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 March 29th 2018 through Thursday
April 12th, 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...Average.
The wet weather over the last month has the entire region above
average in precipitation over the 30 days.

Snow conditions...Below average.
Most of the snow has melted across the region. Upstream river basins
in northeast Pennsylvania and southern New York still have snow
to melt which is occurring right now.  This will result in increased
flows on the Susquehanna River in coming days.

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
over.

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

Stream flow conditions...Variable.
Streamflows are running below average across the northern half of
the state and near average across the southern half of the state.

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 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 latest chart can be found at
www.cpc.ncep.noaa.gov/products/analysis_monitoring/
regional_monitoring/palmer.gif .

The most recent version (Mar 29, 2018) 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 running near
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
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. 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 29 to April 12 2018: The regional
flood potential near average for the next couple of weeks.

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

The next flood potential outlook will be issued on Thursday April
12th.

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

$$

CR



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