COLORADO/GILA BASINS SNOWPACK AND PRECIP THURSDAY: OCTOBER 17 , 2024 07:03 SCS SNOTEL Basin Reports (http://www.wcc.nrcs.usda.gov) Lake Elevations USBR, USGS, SRP These Reservoir Inflow Forecasts GRT (http://getmyrealtime.com) Official Flood Forecasts NWS (https://www.cbrfc.noaa.gov) ABOVE LAKE POWELL SWE% Median PRCIP% Avg UPPER GREEN RIVER BASIN 88* 10 DUCHESNE RIVER BASIN * 20 YAMPA/WHITE RIVER BASINS 94* 13 PRICE-SAN RAFAEL * 25 ESCALANTE RIVER BASINS * 9 DIRTY DEVIL RIVER BASIN * 23 UPPER COLORADO RIVER HEADWATERS 43* 21 ROARING FORK RIVER BASIN 225* 10 GUNNISON RIVER BASIN 475* 14 DOLORES/SAN MIGUEL RIVER BASINS * 13 SAN JUAN RIVER HEADWATERS 1850* 36 ANIMAS RIVER BASIN * 20 ================================================================== Flow Weighted Basin Wide: 185% 18% #By April 1: 101% 96% Green: 78% 13% Colorado: 167% 18% San Juan: 510% 30% ================================================================== ##Apr-Jul Forecast: 94% of normal runoff ( 103% on Snowpack ) (84% chance it's less than 117%, and a 98% chance it's less than 139%) Recurrrence 1/P: 1.78yr (100% (8740 kaf)=2.1yr flood & 1.9yr drought) Current forecast 1.78yr flood is a 2.3yr year drought. UPPER GILA BASIN (Verde+Salt+Gila) SWE% Median PRCIP% Avg VERDE RIVER BASIN * 17 SALT RIVER BASIN * 9 SAN FRANCISCO / UPPER GILA RIVER BAS * 12 ================================================================== Flow Weighted Basin Wide: 0% 12% #By April 1: 91% 96% Dec1 Jan1 Feb1 Mar1 Apr1 May1 Forecast Precip: 87% 91% 93% 95% 96% 96% Forecast Flow: 95% 109% 137% 107% 114% 117% !Monthly CFS: 640 1067 1674 2336 1390 697 $Recurrence Int: 2.10yr 2.18yr 2.20yr 2.06yr 2.16yr 2.39yr Drought R.I.: 1.9yr 1.8yr 1.8yr 1.9yr 1.9yr 1.7yr Observed Flow: 53% 46% 102% 86% 247% 148% 109% 66% Drought R.I.: 160yr 15yr 1.1yr 2.4yr 1.2yr 1.5yr 0.0yr 0.0yr ================================================================== Basin Contributing Flow Weighted Average Snowpack & Precip (% of normal for this date) COLORADO BASIN GILA BASIN WATER YEAR PRECIP TO DATE 18% (0.2") 12% (0.1") CURRENT BASIN SNOWPACK 185% (0.1") 0% (0.1") ================================================================== RESERVOIRS: Powell Power Pool % Full ([Elev - 3490]/ 210) = 41.19% Mead Power Pool % Full ([Elev-950]/269.6) = 42.10% Roosevelt Lake Level % Full ([Elev-1906]/ 275) = 80.98% San Carlos Lake Level % Full ([Elev-2390]/ 110) = 54.12% * Data may not provide a valid measure of conditions. # Assumes average precipitation over the forecast period. ## Precip forecast error=??, std error Upper runoff calc=23% ! Std error Gila runoff calcs=16%, 20%, 20%, 20%, 20%, 18% $ Cumulative probability of 2 sets for high skew (mean>>median). Gila flow sum of USGS gages VR_nrCampV+SR_Roosevelt+GR_Calva. Gila flow monthly normals are medians for 30 wy's 1991-2020. Gila flow calcs use 1st day of next month precip%. ie q3=f(p4). Forecasts are not updated with gaged history. Precip/Snow % of normals if ever approaching 150% combined with reservoir capacities are red flags for offical daily forecasts. Here's what an Upper Gila 150% precip forecast would look like: Dec1 Jan1 Feb1 Mar1 Apr1 May1 Forecast Precip: --- 150% 150% 150% 150% 150% Forecast Flow: 452% 499% 482% 408% 400% 364% Monthly CFS: 3057 4885 5874 8877 4872 2172 Recurrence Int: 10yr 6.17yr 5.87yr 11yr 10yr 10yr