FGUS65 KSTR 072008
ESGUT 

NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY, UT
April 6, 2023
   
                       SPRING FLOOD POTENTIAL OUTLOOK
                                UTAH                    

Great Salt Lake, Sevier, Virgin, Price/San Rafael, Duchesne and Lower Green
River Basins.

The 2023 spring runoff flood potential due to snowmelt is high at 
this time for all major river basins in Utah due to near record
or record snowpack. These basins include the Bear, Weber, Provo,
Six Creeks,Duchesne,Sevier,Virgin,Price/San Rafael,and Green River
basins. It should be emphasized that snow typically accumulates into
April,therefore conditions may change before the runoff begins.

Currently, the following sites are forecast to have mean daily peak flows 
at or above the defined flood flow at the given exceedance level:

  Segment                     Threshold   Exceedance Value 
                                          (probability)
  -------                     --------    -------------
Blacks Fk-Robertson             Flood           10
Green-Jensen                    Flood           50
Green-Green River UT            Flood           25

Duchesne - Tabiona              Flood           25

Bear-Utah-Wyoming State Line   Bankfull         90
Bear-Evanston                   Flood           10
Bear-Border                     Flood           90
Logan-Logan                     Flood           25
Little Bear-Paradise            Flood           90
Blacksmith Fork-Hyrum           Flood           10

Weber-Oakley                    Flood           25
Chalk Ck-Coalville              Flood           25
Mcleod Ck-Park City             Flood           25

Provo-Woodland                  Flood           10

Little Cottonwood-SLC           Flood           50
Big Cottonwood-SLC              Flood           90
Mill Ck-SLC                     Flood           25
Emigration Ck-SLC               Flood           50
City CK-Salt Lake City          Flood           90

Sevier-Hatch                    Flood           50

Specific forecast procedures and flood flow levels do not exist for all streams.
Areas that typically experience high water in normal or above 
normal snow years will be susceptible during peak runoff this year. Instantaneous 
peaks can be higher than mean daily peaks, especially in headwater basins.

Precipitation for all major river basins in Utah was much above average for March
and is also much above average for the water year. April 1 snow water equivalent is 
much above median with many basins having record or near record snow conditions. 
Temperatures have remained below normal limiting any significant snowmelt which 
has resulted in much above normal snow conditions at all elevations.  

PRECIPITATION (% OF AVERAGE) AND SNOWPACK (% OF MEDIAN):

SUBBASIN                 MAR PRECIP     OCT-MAR PREC     APR 1 SNOWPACK
----------------------   ----------     ------------     -------------
BEAR                        205             135               175
WEBER                       230             150               220 
SIX CREEKS (SLC)            255             160               230 
PROVO                       245             160               250 
SEVIER                      195             150               225
VIRGIN                      210             170               400
DUCHESNE                    210             140               200
PRICE/SAN RAFAEL            220             150               245


Spring temperatures and rain events greatly affect the pattern of snowmelt 
runoff and consequently the magnitude of peak flows. It is important to keep in 
mind that an extended period of much above normal temperatures or heavy rainfall
during the melt period can cause or exacerbate flooding problems in any year.

A list of specific spring peak flow forecasts is available at:
https://www.cbrfc.noaa.gov/dbdata/station/peakgraph/list/peaklist.html?type=rank

A map of the current spring peak flow forecasts is available at:
https://www.cbrfc.noaa.gov/lmap/lmap.php?interface=peakfp

The spring runoff flood potential will be re-evaulated in mid April and 
an updated product will be issued at that time.


CBRFC/P.Kormos, B.Alcorn, T.Grout