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FGUS71 KLWX 211525 RRA
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DCZ001-MDZ003>007-009>011-013-014-016>018-501-502-VAZ021-025>031-036>
042-050>057-WVZ050>055-501>504-220000-

HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE STERLING VA
1120 AM EST SAT MAR 21 2009

...WINTER/SPRING FLOOD OUTLOOK...NUMBER 3

...RIVER FLOOD POTENTIAL BELOW NORMAL...

THIS IS THE THIRD 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 AAPRIL 2 2009.

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 FLOOD POTENTIAL IS BELOW NORMAL FOR THIS 
TIME OF YEAR. 

CURRENT FLOODING - NONE.

RECENT PRECIPITATION... 
PRECIPITATION TOTALS...RAIN AND MELTED SNOW AND ICE...HAVE BEEN 
BELOW NORMAL SINCE JANUARY 1ST ACROSS MOST OF THE AREA. FEBRUARY 
2009 WAS THE DRIEST FEBRUARY ON RECORD AT WASHINGTON'S REAGAN 
NATIONAL AIRPORT...WITH ONLY 0.35 INCHES OF PRECIPITATION RECORDED 
FOR THE ENTIRE MONTH.  AS OF TODAY...THE TOTAL PRECIPITATION 
RECORDED AT WASHINGTON REAGAN NATIONAL AIRPORT SINCE JANUARY 1ST IS 
3.90 INCHES...WHICH IS A DEPARTURE FROM NORMAL OF -4.30 INCHES. 
PRECIPITATION DEPARTURE FROM NORMAL MAPS CAN BE FOUND AT 
HTTP://WWW.ERH.NOAA.GOV/ER/MARFC.

SNOW COVER - AS OF MARCH 21...THERE IS NO SNOW COVER ANYWHERE IN THE 
HYDROLOGIC SERVICE AREA.

RIVER ICE - NONE. 

STREAMFLOW - RIVER FLOW IS WELL BELOW NORMAL. RIVER FLOW TODAY ON 
THE POTOMAC RIVER AT LITTLE FALLS PUMPING STATION JUST ABOVE 
WASHINGTON WAS 3920 CUBIC FEET PER SECOND...THE MEDIAN FLOW AT 
LITTLE FALLS FOR MARCH IS 23400 CUBIC FEET PER SECOND. ON THE 
SHENANDOAH RIVER AT MILLVILLE WEST VIRGINIA...FLOW WAS MEASURED AT
1300 CUBIC FEET PER SECOND...THE MEDIAN FOR MARCH IS 4990 CUBIC 
FEET PER SECOND.  ON THE RAPPAHANNOCK RIVER JUST ABOVE 
FREDERICKSBURG VIRGINIA...FLOW WAS MEASURED TODAY AT 614 CUBIC FEET 
PER SECOND...THE MEAN FLOW AT FREDERICKSBURG FOR MARCH IS 3190 CUBIC 
FEET PER SECOND.

RESERVOIR CONDITIONS - RESERVOIR CONDITIONS ARE NORMAL TO BELOW 
NORMAL. 

SOIL MOISTURE - SOIL MOISTURE IS NEAR NORMAL.  

FUTURE WEATHER/WATER CONDITIONS - CURRENTLY...THE BEST CHANCE FOR 
SIGNIFICANT RAIN IN THE NEXT 10 DAYS APPEARS TO BE AROUND THURSDAY 
OF NEXT WEEK...THE 26TH. THE 8 TO 14 DAY OUTLOOK CALLS FOR BELOW 
NORMAL TEMPERATURES AND NO INDICATIONS OF ABOVE OR BELOW NORMAL 
PRECIPITATION TOTALS. MUCH OF THE AREA IS EITHER ABNORMALLY DRY OR 
IN A MODERATE DROUGHT...WITH THE DRIEST CONDITIONS BEING EXPERIENCED 
FROM THE WASHINGTON METRO AREA TO THE CENTRAL SHENANDOAH MOUNTAINS 
IN VIRGINIA. THE DROUGHT MONITORING CENTER CAN BE ACCESSED ON THE 
INTERNET AT HTTP://WWW.DROUGHT.GOV.

THE COMBINATION OF RIVER ICE...SOIL MOISTURE AND FORECAST 
PRECIPITATION OVER THE NEXT TWO WEEKS INDICATES THE POTENTIAL OF 
RIVER FLOODING IS BELOW NORMAL ACROSS THE AREA. 

THIS WILL BE THE LAST REGULARLY SCHEDULED SPRING FLOOD OUTLOOK FOR 
THIS SEASON.  

$$
RDH
SENIOR SERVICE HYDROLOGIST
NWS FORECAST OFFICE - STERLING VIRGINIA