Flood Potential Outlook
Issued by NWS Grand Forks, ND
FGUS73 KFGF 021520
Probabilistic Hydrologic Outlook
National Weather Service Eastern North Dakota/Grand Forks ND
920 AM CST Thu Mar 2 2017
...18% RISK OF DEVILS LAKE RISING ABOVE RECORD LAKE LEVEL...
...DEVILS LAKE OUTLOOK FOR FLOOD POTENTIAL...
Devils and Stump Lakes
Long-Range Probabilistic Outlook
Valid from February 26th to September 30th 2017
* There is an 18% chance of Devils Lake rising above the current
record of 1454.3 feet and a 50% chance of the lake rising 3.4 feet
to 1453.6 feet sometime in late spring or early summer. Changes from
last outlook are minimal.
* Since the last outlook, there has been a period of above normal
temperatures resulting in a reduction in the areal coverage and
volume of the snow pack. Current Snow Water Equivalents (SWE) range
from about 3 to 4 inches with isolated pockets of 5 inches on the
western side of the basin and ranks in the top quartile of modeled
SWEs (1949-2011) used in this outlook. The highest modeled crest of
1455.5 feet is from the 2004 weather used during the valid period.
* This is the best estimate at this time applying 60 plus years of
past weather to current lake conditions. These estimates will be
recomputed on or around the March 24th outlook update and the numbers
will change as hydrologic conditions of the Devils Lake basin change.
The National Weather Service is providing long-range probabilistic
hydrologic outlooks for Devils and Stump lakes between January
and September. They will not be provided between October and
The AHPS graphics associated with this outlook will be on the web
no later than 10:30 AM this Friday under the experimental
long-range flood risk tab at...
Depending on the season, the high or low water probabilities may
be omitted due to their applicability to the hydrologic situation.
Refer to the scheduling section farther on in this message.
. 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
Interpretation Aid...There is a 50 percent chance that Devils
Lake will rise above 1453.6 feet during the valid period and
only a 5 percent chance that it will rise above 1455.2 feet.
Probabilities for exceeding listed lake levels
FROM FEBRUARY 26, 2017 TO SEPTEMBER 30, 2017
LOCATION 95% 90% 75% 50% 25% 10% 05%
-------- ------ ------ ------ ------ ------ ------ ------
CREEL BAY 1452.8 1452.8 1453.2 1453.6 1454.0 1454.6 1455.2
EAST STUMP LAKE 1452.8 1452.8 1453.2 1453.6 1454.0 1454.6 1455.2
. Current and previous record high lake levels...
* The current height of Devils Lake at Creel Bay is 1450.2 feet
* The current height of Stump Lake near Lakota is 1450.0 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
* For more high water marks...see the USGS flood tracking charts at:
. 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, two weeks later, in 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...
Wind and Wave forecasts for Devils and Stump lakes are available for
a seven day period when the lakes are sufficiently ice-free at:
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
A YouTube video on "How to Interpret River Outlook Products" is at:
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 Noah`s
National Weather Service`s Advanced Hydrologic Prediction
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 from...the NWS Grand Forks AHPS web page at:
When available (see schedule above) the AHPS graphics for monthly
outlooks should be available by mid-morning or early afternoon.
Monthly probabilistic outlooks are issued on the Friday of the week
following the first Thursday after the 15th of the month. Special
spring flood and water management outlooks are issued on Thursday
afternoons in late February and then again, two weeks later in
early March to coincide with the spring snow melt. Due to the lake
freeze-up will not be issued from October through December.
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.