000 FGUS71 KLWX 091649 ESFLWX DCZ001-MDZ003>007-009>011-013-014-016>018-501-502-VAZ021-025>031-036> 042-050>057-WVZ050>055-501>504-101200- WINTER/SPRING FLOOD OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1055 AM EST TUE FEB 9 2010 ...WINTER/SPRING FLOOD OUTLOOK...NUMBER 3 ...RIVER FLOOD POTENTIAL OUTLOOK THROUGH FEBRUARY 18... 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 FEBRUARY 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 NORMAL TO BELOW NORMAL FOR THIS PERIOD. ALTHOUGH A SIGNIFICANT SNOWPACK IS IN PLACE...A RAPID WARMUP IS NOT EXPECTED DURING THE PERIOD. CURRENT FLOODING - NONE. RECENT PRECIPITATION... PRECIPITATION HAS BEEN ABUNDANT FOR THE PAST FEW MONTHS. AT BALTIMORE...12.76 INCHES OF RAIN AND MELTED SNOW HAS FALLEN SINCE DECEMBER 1. THE NORMAL IS 7.65". SNOW COVER... SNOW DEPTHS FROM THE METROPOLITAN AREAS NORTH AND WEST GENERALLY RANGES FROM 15 TO 25 INCHES. RIVER ICE - NOT SIGNIFICANT. SOME LIGHT SLUSH AND CHUNKS ARE REPORTED IN THE UPPER POTOMAC. STREAMFLOW - DISCHARGE ON THE POTOMAC JUST ABOVE WASHINGTON DC WAS AROUND 12300 CUBIC FEET PER SECOND AT THIS TIME. THE MEDIAN FOR THE DATE IS 11100 CFS. ON THE RAPPAHANNOCK JUST ABOVE FREDERICKSBURG...FLOW WAS MEASURED AT 1830 CUBIC FEET PER SECOND. THE MEDIAN FOR THE DATE IS 1739. 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 WILL 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 COLDER THAN AVERAGE TEMPERATURES ARE EXPECTED WITH PRECIPITATION TOTALS AT OR BELOW NORMAL AFTER OUR NEXT STORM WHICH WILL AFFECT THE AREA TODAY INTO WEDNESDAY. ANTECEDENT CONDITIONS ARE VERY MOIST AT THIS TIME. REPEATING...THROUGH THE 18TH...THE POTENTIAL FOR RIVER FLOODING IS NORMAL TO BELOW NORMAL DUE TO COLD TEMPERATURES EXPECTED. BE ALERT THAT A RAPID WARMUP COMBINED WITH RAIN...SHOULD IT DEVELOP DURING THIS PERIOD OR THEREAFTER...COULD PRODUCE FLOODING OF AREA RIVERS. THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED AROUND FEBRUARY 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) $$ RDH SENIOR SERVICE HYDROLOGIST NWS FORECAST OFFICE - STERLING VIRGINIA