FGUS76 KSEW DDHHMM ESFSEW WAC009-027>035-041-045-053>057-061-067-073-312300- WATER SUPPLY OUTLOOK NATIONAL WEATHER SERVICE SEATTLE WA 830 AM PDT FRI MAY 11 2012 ...WESTERN WASHINGTON WATER SUPPLY OUTLOOK... NOTICE: WATER SUPPLY FORECASTING PROCEDURES AND THIS WATER SUPPLY FORECAST TEXT PRODUCT HAVE BEEN CHANGED FOR 2012. WATER SUPPLY TEXT PRODUCTS FOR WASHINGTON RIVERS WILL COME FROM THE NATIONAL WEATHER SERVICE FORECAST OFFICE WHOSE SERVICE AREA COVERS THAT PORTION OF THE STATE AND WILL HAVE MORE DETAILED INFORMATION. THERE WILL NO LONGER BE A SINGLE STATE-WIDE PRODUCT WITH JUST GENERAL INFORMATION. IN ADDITION TO THE SEATTLE FORECAST OFFICE...PLEASE REFER TO WATER SUPPLY PRODUCTS FROM THE SPOKANE... PORTLAND...AND PENDLETON FORECAST OFFICES. IN ALL CASES...THERE IS MUCH MORE EMPHASIS BEING PLACED ON THE NWRFC WEBSITE AS THE SOURCE OF WATER SUPPLY INFORMATION BECAUSE OF THE WEALTH OF INFORMATION THAT THAT IS THERE. APPROPRIATE NWRFC WEBPAGE ARE LISTED BELOW. THE WATER SUPPLY FORECASTING PROCEDURES FROM THE NORTHWEST RIVER FORECAST CENTER (NWRFC) HAVE CHANGED FOR THE 2012 WATER SUPPLY SEASON. ENSEMBLE STREAMFLOW PREDICTION SYSTEM (ESP)-GENERATED FORECAST HAVE REPLACED REGRESSION-BASED FORECASTS AS THE OFFICIAL NWRFC WATER SUPPLY METHOD. RELEASE OF WATER SUPPLY FORECASTS WILL NO LONGER BE LIMITED TO THREE TIMES PER MONTH AT SET TIMES. NEW ESP FORECASTS WILL BE PUBLISHED ON THE NWRFC WEBSITE AT A MINIMUM OF ONCE PER WEEK...BUT MAY BE UPDATED ON ANY DAY AT THE DISCRETION OF THE NWRFC. THERE NO LONGER WILL BE A NWRFC FINAL FORECAST FOR THE MONTH. THE CURRENT PUBLISHED FORECAST CONTAINS THE MOST UP TO DATE INFORMATION AND IS DESIGNATED AS THE NWRFC OFFICIAL FORECAST. IT WILL BE VALID UNTIL IT IS REPLACED WITH AN UPDATED VERSION. SYNOPSIS: THE FORECASTS OF WATER SUPPLY FOR THE SUMMER IN WESTERN WASHINGTON WERE FOR NEAR NORMAL TO ABOVE NORMAL VOLUMES FOR MOST WASHINGTON RIVERS. THERE WERE A FEW EXCEPTIONS THAT WERE BELOW NORMAL. PRECIPITATION SUMMARY --------------------- THE PRECIPITATION FOR THE MONTH OF APRIL WAS ABOVE NORMAL FOR THE ENTIRE STATE. IN WESTERN WASHINGTON...THE MONTHLY PERCENTAGE OF NORMAL FOR PRECIPITATION RANGED FROM 102 FOR THE WEST SLOPES OF THE CASCADES TO 169 FOR THE NORTHWEST INTERIOR. THE GREATEST AMOUNT OF PRECIPITATION AT CLIMATE STATIONS FOR THE MOUNTAINS...COAST...AND INTERIOR LOWLANDS WAS 8.91 INCHES AT CEDAR LAKE IN THE CENTRAL CASCADES... 10.29 INCHES AT QUILLAYUTE (NEAR FORKS)...AND 9.86 INCHES AT PALMER. SNOWPACK SUMMARY ---------------- THE SNOWPACK IS ABOVE NORMAL FOR WESTERN WASHINGTON AS OF MAY 10. THE WATER CONTENT OF THE MOUNTAIN SNOWPACK IN THE BASINS THAT FEED THE MAJOR RIVERS WEST OF THE CASCADES RANGED FROM 131 TO 180 PERCENT OF NORMAL. DATA FROM THE NORTHWEST WEATHER AND AVALANCHE CENTER AS OF MAY 1 SHOWED THAT SNOW DEPTHS IN WESTERN WASHINGTON WERE 106 TO 232 PERCENT OF NORMAL. STREAMFLOWS SUMMARY ------------------- STREAMFLOWS FOR LAST MONTH WERE NEAR AND ABOVE NORMAL FOR MOST OF WESTERN WASHINGTON RIVERS. RESERVOIR STORAGE SUMMARY ------------------------- STORAGE FOR RESERVOIRS AROUND THE STATE WERE NEAR NORMAL AS OF THE FIRST OF MAY. NOTE THAT DURING THE WINTER MOST RESERVOIRS ARE KEPT RELATIVELY LOW UNTIL THE SPRING RUNOFF AND STORAGE LEVELS ARE NOT INDICATIVE OF FUTURE WATER AVAILABILITY. WEATHER OUTLOOK --------------- THE OUTLOOK FOR MAY AND BEYOND...FOR THE NEXT TWO WEEKS IS FOR BELOW NORMAL PRECIPITATION ACROSS THE STATE. THE PREDICTION FOR ALL OF MAY CALLS FOR EQUAL CHANCES OF ABOVE...BELOW...OR NEAR NORMAL PRECIPITATION. THE THREE MONTH OUTLOOK BEGINNING IN MAY AND ENDING IN JULY CALLS FOR BELOW NORMAL PRECIPITATION FOR THE ENTIRE STATE. WATER SUPPLY OUTLOOK -------------------- LONG RANGE HYDROLOGIC MODELS WERE FORECASTING NEAR NORMAL TO ABOVE NORMAL RIVER FLOWS AND WATER SUPPLY FOR MOST RIVERS THROUGH THIS SPRING AND SUMMER. WATER SUPPLY FORECASTS FOR WESTERN WASHINGTON RANGED FROM A LOW OF 86 FOR THE SULTAN RIVER TO 127 PERCENT OF NORMAL FOR THE COWLITZ RIVER. WATER SUPPLY FORECASTS THAT INCLUDE REGULATION ARE USED FOR LOCATIONS WHERE FORECASTS ARE LISTED BELOW AS REGULATED...FOR ALL OTHER LOCATIONS FORECASTS ARE FOR NATURAL VOLUMES. HERE ARE THE STREAM FLOW VOLUME FORECASTS FOR SPECIFIC RIVERS AND SITES AS OF MAY 8. WATER SUPPLY FORECASTS NATURAL FLOW UNLESS OTHERWISE SPECIFIED (IN THOUSANDS OF ACRE FEET) RIVER AND GAUGING SITE PERIOD FORECAST PERCENT SKAGIT RIVER NEAR CONCRETE (REGULATED) MAY 8-SEP 30 7877 124 BAKER RIVER UPPER BAKER RESERVOIR INFLOW MAY 8-SEP 30 823 115 SULTAN RIVER SPADA LAKE INFLOW MAY 8-SEP 30 145 86 TOLT RIVER TOLT RESERVOIR INFLOW MAY 8-SEP 30 46 113 CEDAR RIVER CHESTER MORSE LAKE INFLOW MAY 8-SEP 30 106 103 NISQUALLY RIVER ALDER RESERVOIR INFLOW MAY 8-SEP 30 273 94 COWLITZ RIVER MAYFIELD RESERVOIR (REGULATED) MAY 8-SEP 30 2436 127 ELWHA RIVER MCDONALD BRIDGE MAY 8-SEP 30 454 105 DUNGENESS RIVER NEAR SEQUIM MAY 8-SEP 30 180 118 WYNOOCHEE RIVER WYNOOCHEE DAM INFLOW MAY 8-SEP 30 49 97 SKOKOMISH RIVER CUSHMAN DAM INFLOW MAY 8-SEP 30 240 114 THESE FORECASTS ARE SELECTED FROM THOSE PREPARED BY THE NWRFC. FOR FURTHER DETAILS...GRAPHICS...AND STATISTICS REGARDING THE WATER SUPPLY FORECASTS VISIT: HTTP://WWW.NWRFC.NOAA.GOV/WS (LOWER CASE) HTTP://WWW.NWRFC.NOAA.GOV/OUTLOOK (LOWER CASE) THE NEXT WATER SUPPLY OUTLOOK FOR WASHINGTON WILL BE ISSUED AROUND THE END OF THE FIRST WEEK OF JUNE. $$ WEATHER.GOV/SEATTLE