Drought Information Statement
Issued by NWS Tulsa, OK

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AXUS74 KTSA 181801

Drought Information Statement
National Weather Service TULSA OK
101 PM CDT Fri May 18 2018

...Moderate to Severe Drought remains over a small portion of
northeast Oklahoma...


Drought and abnormally dry conditions continue northwest of the
Interstate 44 corridor as below normal rainfall continues to
affect this area. Only minor changes in the drought conditions
have occurred over the past month. The data provided in this
statement will focus on the D0-D2 area. No drought or abnormally
dry conditions were present in northwest Arkansas.

According to the U.S. Drought Monitor (USDM) valid May 17, 2018,
Severe (D2) Drought conditions covered portions of Osage and
Pawnee Counties in northeast Oklahoma.

Moderate (D1) Drought conditions were present in portions of
Osage, Pawnee, Washington, and Nowata Counties in Eastern

Abnormally Dry (D0) but not in drought conditions remained over
parts of Creek, Pawnee, Osage, Tulsa, Washington, Rogers, Nowata,
and Craig Counties in northeast Oklahoma.

The USDM is a collaborative effort between several government and
academic partners. It is a weekly national product issued on
Thursday morning using data collected through the previous Tuesday
morning, so it does not consider precipitation which has fallen
after the data cut-off time.

There are five levels of intensity depicted on the USDM. The USDM
levels are the following: D0 - Abnormally Dry (not in drought but
showing dryness) D1 - Moderate Drought D2 - Severe Drought D3 -
Extreme Drought D4 - Exceptional Drought

The local Drought Information Statement is issued by the NWS
office in Tulsa when needed to supplement the national USDM
product. Local statements may be issued monthly during times when
the USDM indicates severe drought conditions or as local
conditions warrant.

Summary of Impacts...

State and Local Actions:
The Oklahoma State Climate Office (Oklahoma Climatological
Survey, OCS) hosts recorded briefings focused on the current
conditions, impacts, and outlooks for drought conditions across
the Southern Plains. Updated drought briefings are available at

Soil Moisture Impact:
The OCS daily averaged fractional water index for April 19, 2018
shows values of 0.1 to 0.4 (where 1.0 is saturated and 0.0 is
completely dry) at 2 inches below ground across Pawnee, southern
Osage, northern Creek and north/west Tulsa Counties, with values
of 0.5 to 1.0 elsewhere across the drought area. At 4 and 10
inches below ground low values of 0.0 to 0.5 were observed across
primarily Pawnee and southern Osage Counties, with 0.5 to 1.0
elsewhere in the drought area. Further down at 24 inches below
ground, the values were 0.9 to 1.0.

As of May 18, 2018, the Arkansas-Red Basin River Forecast Center
(ABRFC) gridded soil moisture indicates that the upper zone, which
responds to short term rainfall, is 5 percent to around 30
percent full across most of the drought area, except along the
OK/KS state line, where it is greater than 40 percent full. This
represents slight to severe agriculturally dry conditions for the
majority of the drought area. These values corresponds from around
70 to less than 30 percent of normal across most of the drought
area, except near the OK/KS state line. The lower zone was
primarily 10 to 40 percent full in the drought area, which
represents moderate hydrologically dry to neutral conditions.
These lower zone anomalies were 30 to 90 percent of normal.

The Climate Prediction Center (CPC) calculated soil moisture
anomaly analysis as of April 19, 2018 showed soil moisture was
40-100 mm (1.57-3.9 inches) below normal across the drought area
in northeast Oklahoma.

Agriculture Impacts:
According to a former Osage County Extension Agent, farm ponds in
Osage County were low at the beginning of May despite the light
rainfall they had received.

Fire Impacts:
No burn bans were in effect.

Climate Summary...

Over the past 7 days, zero to around 1 inch of rain fell across
the drought impacted area. However, a supercell brought 1.4 to 4
inches of rain to northern Osage County.

In the last 30 days, 2 to 4 inches of rain has fallen in the
D0-D2 area of northeast Oklahoma, with 2 to 7 inches across far
northwest Osage County.

According to OCS, for the last 30 days May 17, 2018, northeast
Oklahoma ranks as the 25th driest period since records began in
1921. North central Oklahoma ranks as the 23rd driest. Since the
beginning of the Water Year (October 1, 2017), northeast Oklahoma
ranks as the 39th driest and north central Oklahoma ranks as the
6th driest.

Precipitation/Temperature Outlook...

Above normal temperatures are expected for the next 7 days. Low
rain chances are forecasted for much of the upcoming week.

The CPC 8-14 Day Outlook calls for an increased chance for above
normal temperatures and below normal rainfall across northeast

Beyond this period, the CPC outlook for June 2018 (issued May 17,
2018) indicates a significantly enhanced chance for above normal
temperatures and an equal chance for above, near, and below median
rainfall across all of eastern Oklahoma and northwest Arkansas.

Hydrologic Summary And Outlook...

According to the U.S. Army Corps of Engineers (COE), most of the
reservoirs in the drought area of northeast Oklahoma were
operating at or slightly above the top of their normal
conservation pool levels as of May 18, 2018. Birch Lake was
operating at 94 percent of its conservation pool level.

According to the U.S. Geological Survey (USGS), the 7-day average
streamflow as of May 17, 2018 was below (10th-24th percentile)
normal across the drought area. The Black Bear Creek at Pawnee,
Bird Creek at Avant, and the Arkansas River at Tulsa were much
below (less than 10th percentile) normal. The Arkansas River at
Ralston was the lowest value ever measured for this day of the

Next Issuance Date...

This product will be updated on June 22, 2018 or sooner if
significant changes in drought conditions occur.

Related Websites...

U.S. Drought Portal

U.S. Drought Monitor

National Weather Service Tulsa

Arkansas-Red Basin River Forecast Center

Oklahoma Climatological Survey Drought Tools

Arkansas Forestry Commission

Oklahoma Forestry Commission

U.S. Army Corps of Engineers Tulsa District

U.S. Geological Survey Realtime Data

Climate Prediction Center


The U.S. Drought Monitor is a collaborative effort between
several government and academic partners including the NWS, the
National Climatic Data Center, the USDA, state and regional
climatologists, and the National Drought Mitigation Center.
Information for this statement has been gathered from NWS and FAA
observation sites, the Oklahoma Climatological Survey, the USACE
and the USGS.

Questions or Comments...

If you have any questions or comments about this drought
information statement, please contact,

National Weather Service Tulsa
10159 E. 11th St. Suite 300
Tulsa Oklahoma 74128
Phone:   918-838-7838
Email:   sr-tsa.webmaster@noaa.gov


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