Note that if drought conditions are not being experienced, or in the case of river flooding or heavy rain, this statement may be used to indicate river flows or flood potential.
000
FGUS71 KLWX 070242
ESFLWX
DCZ001-MDZ003>007-009>011-013-014-016>018-501-502-VAZ021-025>031-036>
042-050>057-WVZ050>055-501>504-192100-
WINTER/SPRING FLOOD OUTLOOK
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
930 PM EST SAT MAR 6 2010
...WINTER/SPRING FLOOD OUTLOOK...NUMBER 5
...RIVER FLOOD POTENTIAL OUTLOOK THROUGH MARCH 18...
THIS IS THE FIFTH IN A SERIES OF ANNUAL WINTER/SPRING FLOOD
POTENTIAL STATEMENTS INTENDED TO PROVIDE INSIGHT INTO THE POTENTIAL
OF RIVER FLOODING (NOT FLASH FLOODING) ACROSS THE STERLING
HYDROLOGIC SERVICE AREA (HSA). THIS INCLUDES THE
POTOMAC...SHENANDOAH...AND RAPPAHANNOCK RIVER BASINS.
THESE STATEMENTS WILL PROVIDE INFORMATION ON FLOOD THREAT CONDITIONS
SUCH AS RECENT PRECIPITATION...SOIL MOISTURE...SNOW COVER AND ITS
WATER EQUIVALENT...RIVER ICE CONDITIONS...STREAMFLOW...FUTURE
PRECIPITATION AND OTHER FACTORS. THIS OUTLOOK IS VALID FOR THE
PERIOD THROUGH MARCH 18.
IN THIS PART OF THE MID-ATLANTIC REGION...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.
IN THE STERLING HSA...THE RIVER FLOOD POTENTIAL IS EXPECTED TO BE
ABOVE NORMAL FOR THE POTOMAC RIVER BASIN AND NEAR TO SLIGHTLY ABOVE
NORMAL FOR THE SHENANDOAH AND RAPPAHANNOCK RIVER BASINS FOR THE TWO
WEEK PERIOD ENDING MARCH 18. WARMER TEMPERATURES WILL ALLOW FOR
SNOWPACK ACROSS THE POTOMAC HIGHLANDS AND ALLEGHENY MOUNTAINS TO
MELT. THIS COMBINED WITH EXPECTED RAINFALL DURING THE MID TO LATE
PORTION OF NEXT WEEK MAY ALLOW FOR SOME RIVERS TO RISE NEAR OR ABOVE
FLOOD STAGE LATE NEXT WEEK. REMAIN ALERT TO THE LATEST FORECASTS
FROM THE NATIONAL WEATHER SERVICE FOR TEMPERATURE AND PRECIPITATION
FORECASTS.
CURRENT FLOODING - NONE.
RECENT PRECIPITATION...
PRECIPITATION HAS BEEN ABOVE NORMAL FOR THE PAST FEW MONTHS. AT
BALTIMORE...14.55 INCHES OF RAIN AND MELTED SNOW HAVE FALLEN
DECEMBER 1 THROUGH MARCH 5. THE AVERAGE IS 10.60 INCHES. AT
WASHINGTON...11.13 INCHES OF RAIN AND MELTED SNOW HAVE FALLEN
DECEMBER 1 THROUGH MARCH 5. THE AVERAGE IS 9.57 INCHES.
SNOW COVER...
SNOW COVER IS VARIABLE ACROSS THE STERLING HSA. NO SNOW COVER EXISTS
FOR AREAS OF VIRGINIA EAST OF THE BLUE RIDGE...THE DISTRICT OF
COLUMBIA...AND CENTRAL AND SOUTHERN MARYLAND. ACROSS NORTHERN
MARYLAND...2 TO 5 INCHES OF SNOW EXISTS. FURTHER WEST TOWARD THE
POTOMAC HIGHLANDS...SNOW DEPTHS RANGE FROM 4 TO 12 INCHES...WITH AS MUCH
AS 2 TO 3 FEET OVER THE HIGHEST ELEVATIONS WEST OF THE ALLEGHENY
FRONT...WHERE SNOW WATER EQUIVALENT IS NEAR 6 INCHES.
RIVER ICE - NOT SIGNIFICANT.
STREAMFLOW - DISCHARGE ON THE POTOMAC JUST ABOVE WASHINGTON DC WAS
AROUND 23900 CUBIC FEET PER SECOND AT THIS TIME. THE MEDIAN FOR THE
DATE IS 14300 CFS. ON THE RAPPAHANNOCK JUST ABOVE
FREDERICKSBURG...FLOW WAS MEASURED AT 1950 CUBIC FEET PER SECOND.
THE MEDIAN FOR THE DATE IS 1860. LEVELS ARE EXPECTED TO INCREASE
SOME OVER THE NEXT TWO WEEKS.
RESERVOIR CONDITIONS - RESERVOIR CONDITIONS ARE ABOVE NORMAL. WATER
SUPPLIES ARE EXPECTED TO REMAIN PLENTIFUL FOR AT LEAST THE NEXT FEW
MONTHS.
SOIL MOISTURE - SOIL MOISTURE IS ABOVE AVERAGE.
FUTURE WEATHER/WATER CONDITIONS - TEMPERATURES ARE FORECAST TO BE AT
OR BELOW NORMAL THROUGH THE FORECAST PERIOD. BOTH THE 6 TO 10 DAY
AND THE 8 TO 14 DAY OUTLOOKS FROM THE CLIMATE PREDICTION CENTER
INDICATE BELOW AVERAGE TEMPERATURES. PRECIPITATION IS EXPECTED TO BE
NEAR NORMAL...WITH A STORM SYSTEM LIKELY BRINGING RAINFALL TO THE
AREA DURING THE MID TO LATE PORTION OF NEXT WEEK.
ANTECEDENT CONDITIONS ARE VERY MOIST AT THIS TIME.
REPEATING...THROUGH MARCH 18...THE POTENTIAL FOR RIVER FLOODING IS
ABOVE NORMAL ON THE POTOMAC BASIN...AND NEAR TO SLIGHTLY ABOVE
NORMAL ON THE SHENANDOAH AND RAPPAHANNOCK BASINS. THIS IS DUE TO
WARMER TEMPERATURES CAUSING SNOWMELT FROM THE POTOMAC HIGHLANDS AND
ALLEGHENY MOUNTAINS...AND RAINFALL FROM A STORM SYSTEM TOWARD THE
END OF NEXT WEEK.
THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED ON OR AROUND
MARCH 19.
IMPORTANT HYDROLOGIC LINKS...
HTTP://WWW.DROUGHT.GOV (US DROUGHT MONITOR)
HTTP://WATER.USGS.GOV (US GEOLOGICAL SURVEY)
HTTP://WWW.ERH.NOAA.GOV/ER/MARFC (NATIONAL WEATHER SERVICE MID
ATLANTIC RIVER FORECAST CENTER)
$$
LWX
