Flood Potential Outlook
Issued by NWS Wakefield, VA

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE WAKEFIELD VA
135 PM EDT Tue Mar 21 2017

...Sixth winter/spring flood outlook for 2017...

...River Flood Potential is below normal through March 30th...

Each winter and early spring, The National Weather Service office
in Wakefield VA issues a series of flood potential outlooks.
These outlooks estimate the potential for river flooding across
the Wakefield forecast office`s Hydrologic service area (HSA).
The HSA includes Central and Eastern Virginia, the Lower Maryland
Eastern Shore, and portions of Northeast North Carolina. The
outlook is based on the current assessment of hydrometeorological
factors which contribute to river flooding. These factors include,
but are not limited too recent precipitation, soil moisture, snow
cover and snow water equivalent, stream flows, river ice and
expected future weather conditions.

In this part of the Mid-Atlantic Region, heavy rainfall is the
primary factor that leads to river flooding. Heavy rainfall can
rapidly cause river flooding at anytime of the year, even when
overall river flood potential is considered low.

The following is a summary of the current conditions as of Tuesday
March 21 2017:

Current Flooding - No rivers are currently in flood as of 12 PM
Tuesday March 21 2017.

Recent precipitation - For the first 20 days of March, rainfall
totals have generally been in the 2" - 4" range across much of the
HSA. These totals range from near normal to as much as 1" above
normal. However, the Central Piedmont counties continue to run at
a bit of a precipitation deficit as that area has received only 1"
- 2" of rain during this time period. These totals range from near
  normal to as much as 1.5" below normal.

Looking at precipitation totals from January 1st to March 20th
shows rainfall amounts of 5" - 10" across the HSA with the lower
amounts generally still across the Central Virginia Piedmont
counties. The amounts across the HSA range from near normal to as
much as 4" below normal.

Lastly, for the current water year from October 1 2016 to March
20 2017 the area is divided with portions of Southeast Virginia,
coastal parts of the Delmarva and Northeastern North Carolina
reporting 18 to 25 inches of rain while the remainder of the HSA
saw much less rain with only 11 - 18 inches. The totals in
Southern VA and Northeastern NC are as much as 4" above normal,
while the other area was on the negative side with totals ranging
from 2" - 6" below normal.

Snow Conditions - There is currently no snow on the ground across
the HSA as of 12 PM Tuesday March 21st.

River ice conditions - There is currently no ice on area rivers across
the HSA as of 12 PM Tuesday March 21st.

Stream flow conditions - The 14 day average stream flows, through
March 20th, were improved since the previous outlook was issued in
early March. The average streamflows in the Lower Maryland Eastern
Shore have rebounded and are now in the normal to above normal
range. Across Southeastern Virginia and Northeast North Carolina,
the average streamflows are now in the normal to below normal
range. In each of these two areas, the flows are higher thanks to
significant rain over the last 15 days. The last area across
Central Virginia, from the Virginia Piedmont into the Interstate
95 corridor, the stream flow continue to run at below normal to
much below normal levels.

When looking at the real time flows as of 10 AM March 21st, the
river levels are mainly in the normal to much below normal range
for this time of year. Here are some real time stream flows as of
10 AM March 21st:

Location Observed Level/Median Flow/Percentage of Median
Rivanna River
Palmyra VA  151 CFS/ 793 CFS/ 19.0
James River
Cartersville VA    3400 CFS/9430 CFS/ 36.1
Richmond VA    3140 CFS/9550 CFS/ 32.9
Appomattox River
    Farmville VA             134 CFS/    317 CFS/    42.3
Mattoax VA     275 CFS/ 847 CFS/ 32.5
    Matoaca VA     563 CFS/ 1660 CFS/ 33.9
Nottoway River
    Rawlings VA     170 CFS/    360 CFS/    47.2
    Stony Creek VA     365 CFS/    767 CFS/    47.6
    Sebrell VA    1160 CFS/   2220 CFS/    52.3
Meherrin River
    Lawrenceville VA      331 CFS/    548 CFS/    60.4
    Emporia VA      424 CFS/    842 CFS/    50.4
Blackwater River
    Franklin VA     930 CFS/   1000 CFS/    93.0
Mattaponi River
    Bowling Green VA     558 CFS/    338 CFS/   165.1
    Beulahville VA     767 CFS/    911 CFS/    84.2
Pocomoke River
    Willards MD     116 CFS/    108 CFS/   107.4
Potecasi Creek
    Union NC     325 CFS/    270 CFS/   120.4

Soil Moisture Conditions - Near normal to below normal.

Soil moisture indicators including the Palmer Drought Severity
Index, which is used to infer deep soil moisture, shows that, as
of March 18th, the entire hydrologic service area, HSA, is
depicted as being near normal for deep soil moisture.

The CPC Soil Moisture Monitor, which looks more at top soil
moisture, shows that Eastern North Carolina, Southeastern
Virginia and the Virginia portion of the Delmarva show normal
levels of top soil moisture. However, areas along and west of
Interstate 95 into the Central VA Piedmont, the Northern Neck of
VA and the Lower Maryland Eastern Shore are still showing top
soil moisture deficits of -20mm - -60 mm.

Ground Water - Normal to Below Normal Levels.

Ground water levels across the HSA are reporting water levels in
the normal to below normal range across the region. The ground
water stations in the coastal plain are showing near normal levels
for this time of year, while the ground water locations further
inland toward the Piedmont are showing lower levels which are in
the below normal range.

Reservoirs - Normal Pool Levels

Area reservoir pool levels are in the normal range for this time
of year.

Future Precipitation...There are a couple chances for light rain
showers across the region over the next 7 days. A cold front will
cross the region during the overnight hours of the 22nd, but rain
amounts are expected to be light, generally less than a tenth of
an inch. The next chance for rainfall will not come until early
next week from Sunday night into Tuesday as a storm systems lift
northeast out of the Southern Plains into the Great Lake states.
This will allow warmer and more humid air to move into the region
which could help produce some additional showers.

The latest CPC 8 to 14 day outlook for March 28 - April 3 2017 is
indicating above normal temperatures and precipitation for the 7
day time period.

Lastly for the 3 month outlook for April through June, the
precipitation forecast is for an equal chance of being below
normal, near normal, or above normal and the temperatures have a
higher chance of being above normal.

WWW.CPC.NCEP.NOAA.GOV

The river flood potential through March 30 2017 across the
Wakefield HSA is below normal for this time of year. Again
remember that heavy rainfall is the most common cause of river
flooding in the Mid-Atlantic States. However river flooding can be
exacerbated when heavy rain is combined with snow melt.

This product represents the final update of the winter/spring
flood outlook for the 2017 winter/spring season...unless
conditions warrant an additional update. Otherwise, the next
outlook will be issued in early January 2018.

For additional weather or hydrologic information, please visit our
website at WWW.WEATHER.GOV/AKQ.

$$

Seymour



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