Winter/Spring River Flood Potential Outlook
NWS Middle Atlantic River Forecast Center (MARFC)
State College, PA
2:05 pm EDT Thu, February 3, 2022
Outlook Number 22-03 - February 3, 2022
This Winter/Spring River Flood Potential Outlook is valid for the two-week period February 3 - February 17, 2022.
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 - ABOVE AVERAGE SOUTHERN PA AND NJ EARLY, OTHERWISE AVERAGE
The river flood potential during the next two weeks (through February 17, 2022) is average for early February in the MARFC area of responsibility. However, early in the outlook period, the potential is above average for areas of PA, especially southern PA, and in NJ. 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 - BELOW OR MUCH BELOW AVERAGE
During the last 30 days (January 4, 2022 - February 2, 2022) observed precipitation across the entire MARFC region has been below or much below average, running 0.5 to 2 inches below average. Precipitation departure data can be seen at www.weather.gov/marfc/Precipitation_Departures.
SNOW CONDITIONS - MOSTLY NEAR NORMAL
As of this morning (February 3, 2022), snow covers about 60 percent of the ground in the Mid-Atlantic. The snow/no snow line runs north and west along the Blue Ridge Mountains from southwest VA northward into south-central and then east-central PA. From east-central PA the snow/no snow line then extends southward to the Chesapeake Bay where snow is on the ground east of this line and east of the Bay. Snow extent is fairly typical for early February except for the southern half of NJ and the Delmarva Peninsula where snow cover is above normal. Snow covers the ground in southern NY, in PA except for the lower Susquehanna Valley and southeastern sections, NJ, DE except the north, in western MD as well as in MD east of the Chesapeake Bay, western and northwestern VA, and the eastern panhandle of WV. In the region from southern NY, NJ, the northern half of PA, the higher mountains of central PA, and far western MD, snow depths range from 4 to 10 inches. Snow water equivalents in this area range from 1" to 2" except in NJ where water equivalents are under an inch. Elsewhere where snow exists, depths range from 1" to 2" and water equivalents are under 0.5". Snow conditions are relatively normal for this time of year plus or minus a fairly small amount. The exception is NJ and the Delmarva Peninsula where snow conditions are above normal. Snow information can be found at www.weather.gov/marfc/Snow and www.nohrsc.noaa.gov.
RIVER ICE - AVERAGE
Currently, most streams and rivers in NY, much of PA, northern NJ, western MD, eastern WV and northwestern VA have at least some ice in them with complete ice cover on some river locations. This is a fairly typical area for river ice to be observed in early February. The most river ice is found in streams and rivers throughout the Susquehanna and Delaware River Basins, which is also typical for early February. The river ice is not unusually thick or extensive for this time of year, but has increased a fair amount from just two weeks ago. In areas not specifically mentioned, little or no river ice exists, which is also normal for those areas. River ice conditions are expected to be variable during the next two weeks as periods of both above and below average temperatures appear likely. In the near term, a brief warm up and cool down is expected while today`s NWS Climate Prediction Center`s 6-10 and 8-14 day (through February 16) temperature outlooks both suggest that while short term temperatures are expected to be cold, moderating temperatures and then a cool down is likely later in these outlook periods.
STREAMFLOW CONDITIONS - BELOW NORMAL
The latest data from the United States Geological Survey (USGS) indicates current streamflow conditions within the entire MARFC region are below normal for the date. There are scattered exceptions where flows are near normal but also scattered areas of much below normal flow. For current streamflow conditions please visit waterdata.usgs.gov/nwis/rt.
SOIL MOISTURE CONDITIONS - AVERAGE FAR NORTH, OTHERWISE DRY/VERY DRY
Soil moisture is about average across southern NY and northern PA portions of the MARFC service area but are dry or very dry in the rest of PA, NJ, MD, DE, WV and VA. The long-term Palmer drought severity index is useful to estimate deep soil moisture conditions. The January 29, 2022 map (seen at www.cpc.ncep.noaa.gov/products/analysis_monitoring/regional_ monitoring/palmer.gif) suggests deep soils are moist in the north to dry in the south. Additional soil moisture data confirms the very dry soils across southern portions of the region. Visit www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/ and then click on U.S. Monitoring.
GROUNDWATER - AVERAGE TO BELOW AVERAGE
Within the MARFC service area, real-time USGS groundwater monitoring wells indicate current groundwater levels generally range from average to below average for this time of year region-wide. While some locations indicate above average levels, these areas are too few to pinpoint any particular part of the MARFC service area. To see groundwater levels visit groundwaterwatch.usgs.gov/usgsgwnetworks.asp.
RESERVOIR CONDITIONS - MOSTLY BELOW AVERAGE
Most major reservoirs within the MARFC region are holding storages that are running mostly below average for this time of year. For example, reservoirs in the Delaware River Basin that supply NYC with water are showing below average storage for this time of year.
FUTURE WEATHER CONDITIONS - VARIABLE
A major, on-going storm is expected to bring moderate to heavy amounts of precipitation to the MARFC service area. The heaviest precipitation is expected north of the Potomac River. And, the northern edge is expected to be frozen/freezing with this line slowly dropping south. Runoff will become decreasingly concerning the further north one is in the MARFC service area. Dry/mostly dry conditions are expected for the remainder of the next 7 days after this storm passes. When considering the entire 6 to 14 day period, an average temperature and precipitation outlook looks likely in the longer range. The latest (February 2, 2022) weather outlooks issued by the NWS Climate Prediction Center suggest that temperatures are likely to vary with periods of above as well as below normal temperatures. Meanwhile, precipitation is likely to be somewhat below normal much of the time but precipitation amounts are likely to increase late in the period. So to summarize, temperatures are likely to average out to normal while precipitation is likely to be average or below average over the entire nine-day period February 8 - 16, 2022. Visit www.cpc.ncep.noaa.gov/ to view the outlooks.
ENSEMBLE RIVER FORECASTS - VERY LIMITED THREAT OF RIVER FLOODING
The most recent runs (February 3, 2022) 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 February 13, 2022) within the MARFC region. Widespread river flooding in February is uncommon within the MARFC region, but is still possible. Please visit www.weather.gov/erh/mmefs. Longer-term forecasts suggest no apparent increased chance for river flooding compared to normal for February. Any future river flooding will depend primarily on shorter-term weather conditions, such as the occurrence of widespread heavy rainfall.
Long term dryness has led to overall drier than usual conditions for soils, streamflow, and groundwater. Cold weather has led to ice formation on rivers, especially in the north. Additional ice will likely form in the next two weeks though mainly in the north, as cold February temperatures persist. However, warm and cold periods are expected which may melt and/or move some ice during warmer periods but may also allow for more formation during colder stretches. Snow has increased over the past couple of weeks, mainly in areas affected by a storm this past weekend. Snow is on the ground for about 60 percent of the MARFC region. Above average temperatures are expected to begin the outlook period, then turn colder, and then moderate over the next week or two. With an on-going heavy precipitation event, then dry weather, then back to near normal, it appears that weather conditions are likely to be quite variable over the next two weeks. Affects will be felt on streams and rivers with both ice and river level fluctuations, but with the exception of the current storm, there are no strong signals that indicate more than average chances for flooding. Snow and ice are likely to increase in the north but decrease in the south. There are currently no strong indicators for heavy rainfall that could result in river flooding during the next 7 days after the current storm passes. And, there are no indications of any fast snowmelt events for this region at the present time, as temperatures are likely to fluctuate around normal for the next couple of weeks.
WATER SUPPLY OUTLOOK
According to the latest (February 2, 2022) U.S. Drought Monitor (droughtmonitor.unl.edu), abnormally dry conditions are scattered but present in the Catskill Region of NY; south-central, east-central and southeast PA; northwest and southern NJ; and west-central and southwestern VA. A pocket of moderate drought is present in western VA. Assuming near-normal precipitation over the next few months, few or no water supply shortages are anticipated within the MARFC region through April, 2022.
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 https://www.facebook.com/NWSMARFC and on Twitter @nwsmarfc.
The next winter/spring river flood outlook product will be issued by this office February 16-17, 2022.