Flood Potential Outlook
Issued by NWS State College, PA
FGUS71 KCTP 171140
Winter/Spring Flood Potential Outlook
National Weather Service State College PA
740 AM EDT Fri Mar 17 2017
...WINTER/SPRING FLOOD POTENTIAL OUTLOOK ISSUED MARCH 17 2017...
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 16 through Thursday March 30,
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.
Two week river flood potential...The current potential for river
flooding is average.
No flooding is occurring in the region at this time.
Precipitation within the State College Forecast area during the last
30 days (March 14th - March 16th) is variable across the
region...with most of the region seeing slightly below average
values. Parts of far western and central areas are at or slightly
Snow conditions...Above Average.
The recent snow storm brought high snow amounts to eastern and
northern portions of the area. Snow depths range from just a few
inches up to two feet across the north, with higher amounts in the
Susquehanna Basin in New York State. Water equivalents of up to
three inches with a large area over one inch. With the warm
conditions over the winter almost all of the region has no snow on
the ground. There are trace amounts over far northern Pennsylvania.
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 may be some minor ice across smaller rivers and streams with
the recent cool weather. The ice is not thick and not expected to be
a factor in any flooding. Follow river ice conditions at
Stream flow conditions...Below Average.
Most rivers and streams are flowing a bit below normals for mid
Real time water data is available from the United State Geological
Survey by visiting http://water.usgs.gov .
Soil moisture conditions...Average.
The latest soil moisture reports show that most of the region is
reporting near average moisture conditions. The March 11, 2017 chart
(found at www.cpc.ncep.noaa.gov/products/analysis_monitoring/
regional_monitoring/palmer.gif) suggest deep soils across the area
contain moisture that is fairly close to normal for this time of
year. The most recent version (March 14, 2017) of the US Drought
Monitor chart does show eastern portions of the area experiencing
abnormally dry to moderately dry conditions
Moisture monitoring charts from NOAA`s Climate Prediction Centre can
be found at:
soilmst.shtml and www.drought.gov .
Monitoring wells are all at or above normal for western areas while
southern and eastern areas of the region are below or even much
below average...corresponding to where drought conditions are being
Current ground water conditions based on a 30 day moving average can
be found at http://pa.water.usgs.gov/monitor/gw/index.html .
Most water supply reservoirs within central Pennsylvania are holding
average storage for this time of year...as are most flood control
Future weather conditions...Temperatures are expected to remain a bit
below average for the next week. There will be several weak weather
systems that will bring mixed precipitation to the area over the
period but precipitation totals will be rather light. Longer range
weather outlooks can be viewed at www.cpc.ncep.noaa.gov .
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. River information
can be found at water.weather.gov .
Summary of flood potential March 2 to March 16, 2017: The regional
flood potential is average for the next couple of weeks. While no
flooding is expected next week...an active weather is expected for
the next couple of weeks. The lack of deep snow pack and lack of
river ice would work against the threat of flooding. Heavy rainfall
would be required to cause river flooding.
Overview: Current Flooding...None.
Snow Conditions...Above average.
Stream Flow Conditions...Average.
Soil Moisture Conditions...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 .