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FGUS73 KFGF 242026
ESFFGF

NDC005-027-071-281200-

Probabilistic Hydrologic Outlook
National Weather Service Eastern North Dakota/Grand Forks ND
0303 PM CDT Thu May 24 2018

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

                          Devils and Stump Lakes
                    Long-Range Probabilistic Outlook

.DISCUSSION...

  After a spring snowmelt crest of roughly 1449.9 feet, any
additional lake level rises this summer will come from heavy rains.
Recent climate outlooks call for near normal precipitation throughout
the summer.

  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.

.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.

  Interpretation Aid: There is a 50 percent chance that Devils
   Lake will rise above 1450.1 feet during the valid period and
    only a 5 percent chance that it will rise above 1450.4 feet.

           Probabilities for Exceeding Listed Lake Levels

               FROM MAY 20, 2018 TO SEPTEMBER 30, 2018

LOCATION              95%    90%    75%    50%    25%    10%    05%
--------            ------ ------ ------ ------ ------ ------ ------
Devils Lake.....
  CREEL BAY         1450.0 1450.0 1450.0 1450.1 1450.2 1450.3 1450.4
Stump Lake.....
  EAST STUMP LAKE   1450.0 1450.0 1450.0 1450.1 1450.2 1450.3 1450.4

.Current and Previous Record High Lake Levels...

 *  The current height of Devils Lake at Creel Bay is 1449.76 feet
 *  The current height of  Stump Lake near Lakota  is 1449.77 feet

 *  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

.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 2012 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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      weather.gov/fgf
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