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FGUS73 KFGF 282303
ESFFGF
NDC005-027-071-281200-

Probabilistic Hydrologic Outlook
National Weather Service Grand Forks ND
602 PM CDT Thu Jul 28 2022

...DEVILS LAKE OUTLOOK FOR FLOOD POTENTIAL...

                          Devils and Stump Lakes
                    Long-Range Probabilistic Outlook

  The National Weather Service provides long-range probabilistic
   hydrologic outlooks for Devils and Stump lakes between January
    and September. They will not be provided between October and
     December. Depending on the season, the high or low water
      probabilities may be omitted due to their applicability to
       the hydrologic situation.

.OUTLOOK SUMMARY...

The lake has fallen around two tenths after peaking in late June and
early July around 1450.8 feet. A dry July has aided the recession
with more evaporation than inflow into the lake system. Precip
amounts in July were 25 to 75% below normal with a basin wide 1 to 3
inches observed where 3 to 4 inches is normal.

Climate outlooks indicate equal chances for any outcome for
temperatures and precipitation for August through October with no
strong signal for warm or cold and wet or dry.

A normal fall would allow the lake to fall 10 to 14 inches, the 25 to
75% chance levels of 1449.4 to 1449.8 ft. A dry fall would allow the
lake to fall to around 1449.3 feet, a 5 to 10% chance.

Note: This outlook incorporates a daily average of 350 cfs worth of
pumping operations on Devils Lake from June 1st through November
10th.

.Chances of Devils and Stump Lakes Rising Above Given Lake Levels...

  The probability of exceeding a given lake level is the percentage
   of maximum lake level rises that are above that level for all the
    years that were run through the model using the precipitation
     and temperatures for those years during the valid period of the
      outlook.

  Note: The current gage zero datum of the Devils Lake at Creel Bay
gage is 1401.33 feet NAVD88 or 1400.00 feet NGVD29. The gage zero
datum of the Stump Lake at East Stump Lake gage is 1401.15 feet
NAVD88 or 1400.00 feet NGVD29.

           Probabilities for Exceeding Listed Lake Levels

               FROM JULY 25, 2022 TO SEPTEMBER 30, 2022

LOCATION              95%    90%    75%    50%    25%    10%    05%
--------            ------ ------ ------ ------ ------ ------ ------
Devils Lake.....
  CREEL BAY           50.6   50.6   50.6   50.6   50.6   50.6   50.6
Stump Lake.....
  EAST STUMP LAKE     50.6   50.6   50.6   50.6   50.6   50.6   50.6

.Current and Previous Record High Lake Levels...

 *  The current height of Devils Lake is 1450.56 feet NGVD29.
 *  The current height of  Stump Lake is 1450.60 feet NGVD29.

 *  The most recent USGS provisional record daily average height
    for Devils Lake at the Creel Bay gage:
                ...1454.30 feet on   June 27 of 2011
 *  Previous records:
                ...1452.05 feet on   June 27 of 2010
                ...1450.93 feet on   June 27 of 2009
                ...1449.20 feet on    May  9 of 2006
                ...1449.18 feet on   June 17 of 2004
                ...1449.17 feet on August  2 of 2005
    Note: All previous records are recorded in NGVD29.

.Chances of Devils and Stump Lakes Falling Below Given Lake Levels...

  The probability of not exceeding a given lake level is the
   percentage of lake level falls that are below that level for
    all the years that were run through the model using the
     precipitation and temperatures for those years during the
      valid period of the outlook.

  Interpretation Aid: There is a 50 percent chance that Devils
   Lake will fall below 1549.4 feet during the valid period and
    only a 5 percent chance that it will fall below 1549.3 feet.

           Probabilities for Non-Exceeding Listed Lake Levels

             FROM SEPTEMBER 01, 2022 TO NOVEMBER 30, 2022

LOCATION              95%    90%    75%    50%    25%    10%    05%
--------            ------ ------ ------ ------ ------ ------ ------
Devils Lake.....
  CREEL BAY           50.1   50.0   49.8   49.6   49.4   49.3   49.3
Stump Lake.....
  EAST STUMP LAKE     50.1   50.0   49.8   49.6   49.4   49.3   49.3

  The non-exceedance value for a listed percentage is the value
    where that percentage of all model cases run were below that
      lake level for the specified valid period of the outlook.

.OUTLOOK SCHEDULE...

 - Between January and May, only the high water exceedances will be
    provided with valid periods ending at the end of September.

 - Special Spring Flood and Water Management Outlooks will be issued
    in late February and early March.

 - For June and July, both high-water and low-water exceedances
    will be provided.

 - For August and September, only the low-water exceedances will be
    provided with valid periods ending at the end of November.

 - No probability of exceedance/non-exceedance information will be
    given from October through December, since lake freeze-up
     levels will be given in the fall outlooks previously issued.

.ADDITIONAL INFORMATION...

The long-range probabilistic outlook is based on high and low lake
  levels that were calculated for the valid period using multiple
  scenarios of temperature and precipitation from 1949 to 2018 and
  current conditions of the lake, snowcover (in winter), and soil
  moisture.

By providing the complete range of lake level probabilities, the
  amount of risk associated with long-range planning decisions can
  be determined. These probabilistic outlooks are part of NOAA`s
  National Weather Service`s Advanced Hydrologic Prediction
  Services (AHPS).

A YouTube video on "How to Interpret River Outlook Products" is at:

         www.youtube.com/watch?v=pSoEgvsnpv4

This outlook is also presented as probability graphs of lake height
  for the full period as well as weekly probabilities. The outlook
  graphics and explanations that help in interpreting these outlooks
  are available on the NWS Grand Forks AHPS web page at:

             water.weather.gov/ahps2/index.php?wfo=FGF

Wind and wave forecasts for Devils and Stump lakes are available for
a 7-day period when the lakes are sufficiently ice-free at:

           www.weather.gov/fgf/lake_info

If you have any questions, contact the NWS at 701-772-0720.

You can follow us on Facebook at www.facebook.com/NWSGrandForks
 and on Twitter at @NWSGrandForks.

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