000 FGUS75 KBOI 141730 CCA ESFBOI IDZALL-072300 HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE BOISE IDAHO 1130 AM MDT THU MAY 14 2009 ...UPDATED IDAHO SPRING FLOOD OUTLOOK AND WATER SUPPLY FORECAST... DISCUSSION... THE LATEST SPRING FLOOD OUTLOOKS AND WATER SUPPLY FORECASTS HAVE CHANGED LITTLE SINCE THIS TIME LAST MONTH. MOST IDAHO RIVERS WILL FLOW AT NEAR NORMAL LEVELS THOUGH LATE SPRING AND WILL PRODUCE ENOUGH WATER TO REFILL MOST RESERVOIRS. THE HIGHEST STREAM FLOWS RELATIVE TO NORMAL VALUES WILL OCCUR IN THE CLEARWATER AND UPPER SNAKE RIVER BASINS. THE LOWEST STREAM FLOWS RELATIVE TO NORMAL VALUES WILL OCCUR IN SOUTHWESTERN IDAHO INCLUDING THE WEISER AND OWYHEE RIVER BASINS. IN ADDITION...SLIGHTLY BELOW NORMAL SEASONAL STREAM FLOWS CAN BE EXPECTED IN THE BIGWOOD AND THE LOST RIVER BASINS. THE THREAT OF FLOODING REMAINS BELOW AVERAGE IN MOST PORTIONS OF THE STATE... ALTHOUGH MANY RIVERS WILL SEE SIGNIFICANT RISES DURING THE NEXT TWO WEEKS AS WARM WEATHER CAUSES SIGNIFICANT MELTING OF HIGH ELEVATION SNOW PACK. LONG RANGE TEMPERATURE AND PRECIPITATION FORECASTS... RECENT LONG RANGE SEASONAL TEMPERATURE AND PRECIPITATION OUTLOOKS COVERING LATE SPRING AND EARLY SUMMER HAVE BEEN ISSUED BY THE NATIONAL WEATHER SERVICE CLIMATE PREDICTION CENTER. THERE IS A SLIGHTLY HIGHER PROBABILITY THAT IDAHO WILL EXPERIENCE ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION WHEN AVERAGED OVER THE MONTHS MAY THROUGH JULY 2009. IDAHO SPRING FLOOD OUTLOOK... HOT WEATHER EXPECTED MAY 15TH THROUGH MAY 18TH WILL CAUSE SIGNIFICANT SNOW MELT IN THE HIGH MOUNTAINS AND WILL CAUSE RIVERS TO RISE. MANY IDAHO RIVERS WILL SEE THEIR NATURAL SEASONAL PEAKS SOMETIME BETWEEN MAY 18TH THROUGH MAY 22ND. UPDATED PEAK FLOW FORECASTS SHOW THAT THE MOST PROBABLE PEAK STREAM FLOW WILL BE BELOW FLOOD STAGE AT MOST LOCATIONS...ALTHOUGH SOME STREAMS IN THE UPPER SNAKE RIVER BASIN WILL REACH BANK FULL. FLOOD CONTROL EFFORTS MADE BY THE U.S. ARMY CORPS OF ENGINEERS AND THE U.S. BUREAU OF RECLAMATION HAVE MADE SOME ADDITIONAL SPACE IN RESERVOIRS ON THE SNAKE RIVER AND FLOODING ON THE MAIN STEM SNAKE RIVER IS NOT ANTICIPATED AT THIS TIME. HOWEVER... ADDITIONAL STATEMENTS INCLUDING WATCHES OR WARNINGS WILL BE ISSUED IF THE THE SITUATION CHANGES OR THE THREAT OF FLOODING AS A RESULT OF HEAVY RAINFALL BECOMES APPARENT. PEAK SPRING FLOWS RESULTING FROM A NORMAL MELTING OF CURRENT AND PROJECTED SEASONAL SNOWPACK ARE LISTED IN THE FOLLOWING TABLE. LONG RANGE FORECASTS HAVE SOME MARGIN OF ERROR AND A REASONABLE RANGE OF POSSIBLE VALUES ARE LISTED FOR PLANNING PURPOSES. FORECAST FLOWS DOWNSTREAM FROM RESERVOIRS REPRESENT NATURAL FLOW AND DO NOT ACCOUNT FOR FLOOD CONTROL OPERATIONS WHICH WOULD MITIGATE THE PEAK TO SOME DEGREE. STREAM AND LOCK. FLOOD STAGE FORECAST REASONABLE RANGE SNAKE RIVER HEISER ID 24500 CFS 22700 CFS 18500 - 26900 CFS SHELLEY ID 25600 CFS 22200 CFS 17700 - 26700 CFS TETON RIVER ST ANTHONY ID 4750 CFS 3800 CFS 2800 - 4800 CFS HENRYS FORK ST ANTHONY ID 9000 CFS 7300 CFS 6100 - 8400 CFS REXBURG ID 9.5 FEET 9.8 FEET 9.4 - 10.2 FEET PORTNEUF RIVER POCATELLO ID 1140 CFS 800 CFS 500 - 1100 CFS BIG WOOD RIVER HAILEY ID 4000 CFS 2200 CFS 1600 - 2800 CFS BOISE RIVER LUCKY PEAK INFLOW NONE 11200 CFS 9300 - 13100 CFS BRUNEAU RIVER HOT SPRINGS ID 3200 CFS 2300 CFS 1400 - 3300 CFS PAYETTE RIVER EMMETT ID 16000 CFS 9000 CFS 7500 - 10600 CFS WEISER RIVER WEISER ID 8900 CFS 4700 CFS 3000 - 6500 CFS SELWAY RIVER LOWELL ID 42300 CFS 28000 CFS 23300 - 32700 CFS CLEARWATER RIVER STITES ID 9600 CFS 6700 CFS 5000 - 8500 CFS ORIFINO ID 75000 CFS 62800 CFS 54500 - 71100 CFS MIDDLE FORK SALMON MIDDLE FORK LODGE NONE 6.5 FEET 5.9 - 7.1 FEET SALMON RIVER SALMON 14000 CFS 9200 CFS 7800 - 10600 CFS WHITE BIRD 99000 CFS 67900 CFS 57400 - 78400 CFS COEURD ALENE RIVER ENAVILLE 27000 CFS 12500 CFS 8900 - 16000 CFS CATALDO 21350 CFS 15800 CFS 13800 - 17800 CFS ST JOE RIVER CALDER 25600 CFS 14000 CFS 10600 - 17400 CFS ST MARIES 32.5 FEET 32.0 FEET 31.0 - 33.0 FEET MALHEUR RIVER VALE 9.5 FEET 7.2 FEET 4.8 - 9.5 FEET VOLUME FORECASTS... SEASONAL VOLUME FORECASTS COORDINATED BETWEEN THE NATIONAL WEATHER SERVICE AND THE NATURAL RESOURCES CONSERVATION SERVICE ARE BASED ON PRECIPITATION AND SNOWPACK OBSERVED UP UNTIL MAY 1ST AND ASSUME NORMAL PRECIPITATION WILL OCCUR THROUGH THE RUNOFF SEASON. THE VOLUME FORECASTS AND PERCENT OF AVERAGE FOR SELECTED STREAMS AND LOCATIONS ARE LISTED BELOW. NOTE THAT THE VOLUMES ARE EXPRESSED IN THOUSANDS OF ACRE FEET. STREAM AND LOCATION STATE PERIOD VOL %AVE SNAKE RIVER JACKSON LAKE INFLOW WY APR-JUL 885 109 PALISADES RES INFLOW WY APR-JUL 3600 108 HEISER ID APR-JUL 3860 108 SHELLY ID APR-JUL 4850 110 BLACKFOOT ID APR-JUL 4780 104 AMER. FALLS RES IN ID APR-JUL 3240 100 KING HILL ID APR-JUL 2620 90 MURPHY ID APR-JUL 2780 90 WEISER ID APR-JUL 4570 79 BROWNLEE RES INFLOW ID APR-JUL 5000 79 HELLS CANYON ID APR-JUL 5080 78 HENRYS FORK ASHTON ID APR-JUL 540 95 ST. ANTHONY ID APR-JUL 705 96 REXBURG ID APR-JUL 1440 92 TEUTON RIVER ST. ANTHONY ID APR-JUL 380 94 BIG LOST RIVER MACKAY RES INFLOW ID APR-JUL 114 80 WILLOW CREEK RIRIE RES INFLOW ID APR-JUL 89 103 PORTNEUF RIVER TOPAZ, ID ID APR-JUL 77 81 GOOSE CREEK OAKLEY RES INFLOW ID APR-JUL 26 90 BIG WOOD RIVER HAILEY ID APR-JUL 190 74 MAGIC RES INFLOW ID APR-JUL 184 63 LITTLE WOOD RIVER CAREY ID APR-JUL 62 71 BEAR RIVER MONTPELIER ID APR-JUL 183 78 BRUNEAU RIVER HOT SPRINGS ID APR-JUL 200 96 OWYHEE RIVER OWYHEE RES INFLOW OR MAR-JUL 385 63 BOISE RIVER TWIN SPRINGS ID APR-JUL 540 85 ANDERSON RNCH RES INF ID APR-JUL 415 77 BOISE ID APR-JUL 1140 81 MALHEUR RIVER DREWSEY OR MAR-JUL 56 51 BEULAH RES INFLOW OR MAR-JUL 50 62 PAYETTE RIVER HORSESHOE BEND ID APR-JUL 1300 80 EMMETT ID APR-JUL 1010 81 N.F. PAYETTE RIVER CASCADE RES INFLOW ID APR-JUL 395 80 DEADWOOD RIVER DEADWOOD RES INFLOW ID APR-JUL 106 79 WEISER RIVER WEISER ID APR-JUL 295 75 POWDER RIVER SUMPTER OR MAR-JUL 56 80 SALMON RIVER SALMON ID APR-JUL 885 100 WHITEBIRD ID APR-JUL 5860 100 CLEARWATER RIVER ORIFINO ID APR-JUL 4920 106 SPALDING ID APR-JUL 7810 105 N.F CLEARWATER RIVER DWORSHAK RES INFLOW ID APR-JUL 2610 99 PEND OREILLE RIVER PEND OREILLE LAKE IN ID APR-JUL 12100 95 COEUR D ALENE RIVER ENAVILLE ID APR-JUL 775 102 COEUR D ALENE LAKE IN ID APR-JUL 2440 96 ST JOE RIVER CALDER ID APR-JUL 1040 92 KOOTENAI RIVER BONNERS FERRY ID APR-JUL 6430 84 DROUGHT... THE DROUGHT SITUATION CONTINUES TO IMPROVE WITHIN THE STATE OF IDAHO. HOWEVER...PORTIONS OF SOUTHWESTERN IDAHO CONTINUE TO SEE SOME LINGERING EFFECTS FROM DRIER THAN NORMAL CONDITIONS EXPERIENCED DURING 7 OUT OF THE LAST 10 YEARS. THE U.S. DROUGHT MONITOR INDICATES MODERATE DROUGHT CONDITIONS CONTINUING IN SOUTHWESTERN IDAHO...INCLUDING THE OWYHEE RIVER BASIN AND IN EXTREME SOUTHEASTERN IDAHO IN THE BEAR RIVER BASIN. SOME CONTINUED IMPROVEMENT IN THE DROUGHT SITUATION IS LIKELY WITH ADDITIONAL PRECIPITATION EXPECTED THROUGH LATE MAY. $$ BREIDENBACH