Flood Potential Outlook
Issued by NWS State College, PA

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Winter/Spring Flood Potential Outlook
National Weather Service State College PA
917 AM EDT Thu Apr 4 2019

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 April 4th 2019 through Thursday April
18th, 2019.

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...Below Average.
With the exception of Lancaster and York County, the region has been
below average for precipitation over the last 30 days.

Snow conditions...About average.
Very little snow remains over the area. This is to be expected for
early April.

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...Average.
The river ice season is over for the region.

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

Stream flow conditions...Average.
Rivers and streams are flowing close to average right now. Some
streams are running below average over the western portion of the
area.

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 well above average across the 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 (April 4, 2019) of the US Drought Monitor
chart shows the entire region free of drought conditions.
(http://droughtmonitor.unl.edu).

GROUND WATER...Above Average.
Most monitoring wells are running above average for this time of
year, due to the months of above average 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...
An active weather pattern is forecast with occasional periods of
storminess. Any flooding in the next couple weeks would be driven by
excessive rainfall.

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 April 4 to April 18 2019: The regional
flood potential about average for the next couple of weeks.

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

The next flood potential outlook will be issued on Thursday April
18th.

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


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