Snowpack
Snowpack over the State varied from above normal to well below normal.
The northwest portion of the State is generally slightly below normal
with some individual locations well above normal. The Wind River drainage
is near normal, while the remaining portions of the northwest part of Wyoming
are 10-15 percent below normal. SWE in the northeast part of
Wyoming is 5 percent below normal in the Powder River drainage and 50
percent below normal in the Belle Fourche and Cheyenne River drainages.
The southeast portion of the State is near normal to 85-90 percent of
normal at the end of April. Portions of the southeast are 60-70 percent
below normal. Generally, the southwest part of the State is average to slightly
below average; the Henrys Fork drainage is much above normal, and the
upper Green river basin is about 13 percent below
normal. The Bear River drainage appears to have just below normal SWE.
Precipitation
Most basins across Wyoming received below average precipitation this month. Ten of the 13 basins were below average
for the month of April. The following table displays the major river basins and their departure from normal.
Basin | Departure from normal | Basin | Departure from normal |
Snake River | -08% | Upper North Platte River | -30% |
Yellowstone & Madison | -18% | Lower North Platte River | -29% |
Wind River | +05% | Little Snake River | -28% |
Bighorn | +17% | Upper Green River | -10% |
Shoshone & Clarks Fork | -43% | Lower Green River | -21% |
Powder & Tongue River | +29% | Upper Bear River | -16% |
Belle Fourche & Cheyenne | -22% |
Streams
Runoff is expected to vary from average to just below average across the state.
The northwestern part of the state is expected to have yields varying from average
to about 12 percent below average. The northeast portion of Wyoming varies from
near average to about 15 percent below average (some areas will be nearly 24 percent
below normal). In most cases, the southeast portion of the state will be near
average to about 20 percent below normal (as much as 76 percent below normal
in the lower portion of the Platte River drainage). The southwest portion of
Wyoming varies from above average to 12 percent below average on the Green
River drainage, while the Bear River will produce 10-20 percent below average yields.
Reservoirs
Reservoir storage varies from well below to well above average, however, the
majority are average to above average for this time of the year. Even a
below average runoff should fill most reservoirs. See following table for
further information about reservoir storage.
Major Reservoirs in Wyoming
B A S I N W I D E R E S E R V O I R S U M M A R Y FOR THE END OF APRIL 1998 BASIN AREA CURRENT AS LAST YR AS AVERAGE AS CURRENT AS CURRENT AS RESERVIOR % CAPACITY % CAPACITY % CAPACITY % AVERAGE % LAST YR -------------------------------------------------------------------------------- ALCOVA 97 98 98 100 99 ANGOSTURA 99 99 93 106 100 BELLE FOURCHE 103 100 82 126 103 BIG SANDY 75 81 62 120 93 BIGHORN LAKE 61 52 58 105 119 BOYSEN 76 64 84 90 118 BUFFALO BILL 76 46 52 147 167 BULL LAKE 63 53 53 120 119 DEERFIELD 96 97 89 107 99 EDEN 44 61 50 88 72 ENNIS LAKE 80 80 86 93 100 FLAMING GORGE AVERAGE NOT ESTABLISHED FONTENELLE 38 39 47 81 98 GLENDO 94 96 90 104 97 GRASSY LAKE 49 90 77 64 55 GUERNSEY 70 68 72 97 102 HEBGEN LAKE 70 63 65 107 111 JACKSON LAKE 78 51 54 145 153 KEYHOLE 93 96 57 165 97 PACTOLA 98 101 87 112 97 PALISADES 65 19 68 96 350 PATHFINDER 97 91 60 161 107 PILOT BUTTE 78 75 95 82 103 SEMINOE 68 60 39 176 113 SHADEHILL 89 95 80 111 93 TONGUE RIVER 15 26 54 27 56 VIVA NAUGHTON RES 72 28 62 115 258 WHEATLAND #2 80 72 56 144 111 WOODRUFF NARROWS AVERAGE NOT ESTABLISHED GLENDO PROJECT USERS 91 91 70 130 100 KENDRICK PROJECT 80 68 67 119 117 NORTH PLATTE PROJ 104 99 74 140 105