Extended Streamflow Guidance
Issued by NWS Middle Atlantic RFC

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FGUS61 KRHA 292021
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Winter/Spring River Flood Potential Outlook
NWS Middle Atlantic River Forecast Center (MARFC)
State College, PA
2:00 pm EST Thu, February 29, 2024

Outlook Number 24-05 - February 29, 2024

This Winter/Spring River Flood Potential Outlook is valid for the two-week period February 29 -
March 14, 2024.

This outlook estimates the potential for river flooding (not flash flooding) to develop during the
next two weeks across the Middle Atlantic River Forecast Center`s (MARFC) area of
responsibility (Mid- Atlantic Region) based on a current assessment of hydrometeorological
factors which can contribute to river flooding. Across the MARFC area, these factors include
future weather conditions, recent precipitation, soil moisture, snow cover and snow water
equivalent, river ice, streamflow and other factors. This outlook does not address the
severity/extent of any future river flooding.

Remember, in the Mid-Atlantic region, heavy rainfall is the primary factor which leads to river
flooding. Heavy rainfall can rapidly cause river flooding any time of the year, even when overall
river flood potential is considered to be low or below average.

TWO-WEEK RIVER FLOOD POTENTIAL - AVERAGE, EXCEPT BELOW AVERAGE SOUTH-
CENTRAL NY TO FAR NORTHERN PA

The river flood potential during the next two weeks (through March 14, 2024) is mostly average
for early to mid-March in the MARFC area of responsibility.  Below average river flood potential
exists across south-central NY to adjacent areas of far northern PA where snow cover is much
below normal for this time of year.  Factors which contribute to this assessment of river flood
potential are discussed in some detail below.

CURRENT RIVER FLOODING - NONE

No river flooding is currently occurring within the MARFC service area.

RECENT PRECIPITATION - NEAR TO SLIGHTLY BELOW AVERAGE

During the last 30 days (January 30, 2024 - February 28, 2024) observed precipitation across
the entire MARFC area of responsibility is running near to slightly below average.  Observed
precipitation is generally ranging within 0.5 inches of normal amounts to around 1.5 inches
below average across south-central NY, PA, NJ, DE, MD, the eastern panhandle of WV, and
VA.  Precipitation departure data can be seen at
www.weather.gov/marfc/Precipitation_Departures.

SNOW CONDITIONS - MUCH BELOW NORMAL NORTH TO NORMAL SOUTH

As of this morning (February 29, 2024), little or no snow covers the ground in the MARFC area
of responsibility.  Areal extent, depth, and snow water equivalents are much below normal for
northern areas including southern NY and northern PA, as well as down along the higher terrain
of the Allegheny and Appalachian Mountains from west-central PA into western MD and the
eastern panhandle of WV.  Below normal snow coverage also exists across the remainder of
southern to eastern PA, central MD to northern VA, and into northern to central NJ where some
snow coverage is normal for the end of February.  Farther south, no snow coverage across
southern NJ, the Delmarva peninsula, and central to southern VA represents normal conditions
for the end of February.  Snow information can be found at www.weather.gov/marfc/Snow and
www.nohrsc.noaa.gov.

RIVER ICE - NONE

Currently, no significant river ice exists on rivers within the MARFC service area.  A general
trend of above average temperatures is expected for early to mid-March based on the latest
NWS Climate Prediction Center’s 6-10 and 8-14 day outlooks.  Thus, significant river ice
formation is not expected during this period.

STREAMFLOW CONDITIONS - NEAR/SLIGHTLY ABOVE NORMAL NORTH TO SLIGHTLY
BELOW NORMAL SOUTH

The latest data from the United States Geological Survey (USGS) indicates current streamflow
conditions within the MARFC region are generally near normal across northern areas, including
south-central NY, central to southern NJ, much of PA, DE, MD, and the eastern panhandle of
WV.  An area of slightly above normal streamflows exists across northern NJ to northern PA.
Meanwhile, normal to slightly below normal streamflow conditions exist across most of VA.  For
current streamflow conditions, please visit waterdata.usgs.gov/nwis/rt.

SOIL MOISTURE CONDITIONS - NEAR TO ABOVE AVERAGE

Soil moisture is running near to above average across the entire Mid-Atlantic region.  Moist to
extremely moist soils still exist across NJ, much of PA, and into southern NY.  Meanwhile, soil
moisture conditions are running near to somewhat above average farther south across MD, DE,
the eastern panhandle of WV, and VA.  The long-term Palmer drought severity index is useful to
estimate deep soil moisture conditions.  The February 24, 2024 map (seen at
www.cpc.ncep.noaa.gov/products/analysis_monitoring/regional_ monitoring/palmer.gif)
suggests deep soils are moist to extremely moist across northern NJ, much of eastern PA, and
adjacent portions of southern NY, with near to somewhat above average conditions into central
PA southward into VA.  Additional soil moisture data shows that above average anomalies exist
across most of the MARFC service area.  For more information, visit
www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/ and then click on U.S. Monitoring.

GROUNDWATER - NEAR/ABOVE AVERAGE NORTH, NEAR/SLIGHTLY BELOW
AVERAGE SOUTH

Within the MARFC service area, real-time USGS groundwater monitoring wells indicate current
groundwater levels generally range from average to above average in southern NY, most of PA,
most of NJ, and DE.  Groundwater wells are normal to slightly below normal across most of MD,
VA, and the eastern panhandle of WV.  To see groundwater levels visit
waterdata.usgs.gov/nwis/gw.

RESERVOIR CONDITIONS - NEAR/ABOVE AVERAGE NORTH, NEAR/SLIGHTLY BELOW
AVERAGE SOUTH

Most major reservoirs within the MARFC region are holding storages that are running mostly
near average for this time of year, though some reservoirs in southern areas are slightly below
average while some reservoirs in northern areas are slightly above.  For example, reservoirs in
the Delaware River Basin that supply NYC with water are showing above average storage for
this time of year.

FUTURE WEATHER CONDITIONS - ABOVE AVERAGE TEMPERATURES FAVORED

During the next two weeks, a few passing weather systems are expected to bring mainly light to
perhaps moderate precipitation into the Mid-Atlantic region.  The latest (February 28, 2024) 6 -
10 and 8 - 14 day weather outlooks issued by the NWS Climate Prediction Center indicate that
above average temperatures are favored through the outlook period.  In addition, above normal
precipitation chances are favored over the nine-day period March 5 - March 13, 2024.  Visit
www.cpc.ncep.noaa.gov/ to view the outlooks.

ENSEMBLE RIVER FORECASTS - LIMITED/LOW THREAT OF RIVER FLOODING

The most recent runs (February 29, 2024) of the short-term (6-10 day) ensemble river forecasts,
which take into account anticipated future weather conditions including precipitation and
temperatures, show no strong signals for any river flooding developing during the next 6-10
days (through the morning of March 10, 2024).  Please visit www.weather.gov/erh/mmefs.
Longer-term forecasts suggest no apparent increased chance for river flooding compared to
normal for early to mid-March.  Any future river flooding will depend primarily on shorter-term
weather conditions, such as the occurrence of widespread heavy rainfall.

SUMMARY

Precipitation departures and streamflow conditions are generally running relatively close to
average or normal amounts for this time of year across the MARFC service area.  Meanwhile,
soil moisture continues to run above average across much of the region.  Below to much below
normal snow conditions exist across northern parts of the MARFC service area, while no snow
coverage across southern areas represents normal conditions.  No significant river ice exists in
the MARFC service area.  Ensemble river forecast runs don’t show any strong signals for river
flooding developing during the next 6-10 days.  With these factors in mind, generally average
river flood potential exists for most of the MARFC service area.  However, below average river
flood potential exists across south-central NY to adjacent areas of far northern PA due to the
lack of significant snow cover which plays a role in producing river flooding this time of year for
this region.

WATER SUPPLY OUTLOOK

According to the latest (February 27, 2024) U.S. Drought Monitor (droughtmonitor.unl.edu),
normal conditions exist across the MARFC service area.  Precipitation amounts over the last 30
days have been near to slightly below normal.  Assuming a continuation of near normal
precipitation over the next couple of months, few or no water supply shortages are anticipated
within the MARFC region through April, 2024.  Please visit www.drought.gov,
www.cpc.ncep.noaa.gov and www.weather.gov/marfc/WRO for additional drought and water
supply information.

Please visit the NWS MARFC homepage at www.weather.gov/marfc or find us on Facebook at
www.facebook.com/nwsmarfc/?REF=aymt_homepage_panel and on Twitter @nwsmarfc.

The next winter/spring river flood outlook product will be issued by this office March 14, 2024.


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