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FGUS73 KFGF 221722
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NDC005-027-071-281200-

Probabilistic Hydrologic Outlook
National Weather Service Grand Forks ND
1222 PM CDT Thu Aug 22 2024

...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...

Note: This outlook incorporates a daily average of 350 cfs worth of
pumping operations on Devils Lake from May 15th through October 30th.

Since the last outlook issuance, precipitation has been running
slightly above normal. While the second half of summer has been a bit
drier than the first half, precipitation for the summer season
overall (June through August thus far) has been roughly 8 to 10
inches above normal across the basin. This has allowed non-exceedance
numbers to continue to increase with each outlook issuance (i.e.,
lake levels to remain higher than initially outlooked as we approach
freeze-up).

Climate outlooks continue to indicate a strong signal for above
normal
precipitation through the end of August along with a switch to below
normal temperatures by the end of the month.

Looking farther out, climate outlooks indicate no signal either way
for above, below, or near normal temperatures and precipitation
through the fall.


.Current and Previous Record High Lake Levels...

 *  The current height of Devils Lake is 1450.0 feet NGVD29.
 *  The current height of  Stump Lake is 1449.8 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 49.4 feet during the valid period and
    only a 5 percent chance that it will fall below 49.1 feet.

           Probabilities for Non-Exceeding Listed Lake Levels

             FROM SEPTEMBER 01, 2024 TO NOVEMBER 30, 2024

LOCATION              95%    90%    75%    50%    25%    10%    05%
--------            ------ ------ ------ ------ ------ ------ ------
Devils Lake.....
  CREEL BAY           49.8   49.6   49.5   49.4   49.2   49.1   49.1
Stump Lake.....
  EAST STUMP LAKE     49.8   49.6   49.5   49.4   49.2   49.1   49.1

  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 National Water Prediction Service
 (NWPS).

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 NWPS web page at:

              www.water.noaa.gov/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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      weather.gov/fgf
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