May/Spring 2012 Climate and Hydrology Summary

May & Spring 2012

Tulsa: May 2012 was the 2nd warmest (74.3°F; since 1905) and the 4th driest (1.18"; since 1888) May on record.

Tulsa: Daily records set or tied this month include a record warm maximum temperature on May 28, record warm minimum temperatures on May 2, 3, 4, 26, and record warm mean temperatures on May 3, 4, 26, 28.

Fort Smith: May 2012 was the Record warmest (75.8°F, tied with 1962; since 1883) and the 3rd driest (1.15"; since 1883) May on record.

Fort Smith: Daily records set or tied this month include record max temperatures on May 6, 26, 27, 28 and record warm mean temperatures on May 3, 5, 25, 26, 27, 28.

McAlester: Daily records set or tied this month include record max temperatures on May 3, 28, 29, record warm min temperatures on May 3, 4, 25, and record warm mean temperatures on May 3, 4, 6, 28.

Fayetteville: Daily records set or tied this month include record max temperatures on May 26, 27, 28, 29, record warm min temperatures on May 2, 27, and record warm mean temperatures on May 2, 26, 27, 28.

May, normally the wettest month of the year, was very dry across the region, with Tulsa, Fort Smith, and Fayetteville ending May 2012 in the top 4 driest May’s on record.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for May 2012 ranged from a meager 0.25” in isolated areas to around 5” in a few spots. Most of the HSA received 0.5”-2”. These rainfall totals were woefully below normal, with almost all of the area receiving less than half of the normal May rainfall. A large portion of northeast OK and northwest and west central AR had less than 25% of the normal May rain, with a large portion of Franklin County, AR receiving less than 5%!

A heavy rain, flood, and severe weather event affected northeast OK April 29-May 1. After 3 days of thunderstorms, most locations northwest of I-44 received a total of 2” to 10” of rain. All of this rain led to widespread damage, especially to many roads and several homes, across northeast OK. Thankfully, no fatalities were reported, thanks in part to the efforts of swift water rescue teams. In addition to the flooding, 4 confirmed tornadoes (and 4 possible tornadoes pending at the time of this writing) also occurred.

Two river forecast points exceeded moderate flood stage this month, and one other river forecast point reached minor flood stage. See the detailed report for more information.

According to the Drought Monitor from May 29, 2012, moderate (D1) drought conditions had returned to northwest AR and portions of east central OK. Abnormally dry (D0) conditions existed across all of eastern OK except near the OK/KS state line.

According to the Oklahoma Climatological Survey (OCS) for May 2012, northeast OK ranked as the 3rd driest, east central OK ranked as the 4th driest, and southeast OK ranked as the 7th driest May since records began in 1921.

Spring (March-April-May) 2012

Tulsa: Spring 2012 was the Record warmest (67.2°F; since 1905) and the 52nd driest (11.04"; since 1888) Spring on record. Spring 2012 smashed the previous record Spring temperature of 64.9°F in 1936! Read more about the record hot Spring.

Fort Smith: Spring 2012 was the Record warmest (69.0°F; since 1883) and the 57th wettest (12.20", tied with 1961; since 1883) Spring on record. Spring 2012 smashed the previous record Spring temperature of 64.7°F in 2006! Read more about the record hot Spring.

According to the Oklahoma Climatological Survey (OCS) for Spring 2012, northeast OK ranked as the 23rd wettest, east central OK ranked as the 20th driest, and southeast OK ranked as the 25th driest Spring since records began in 1921.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for Spring 2012 were 10”-15” across much of eastern OK and northwest AR, which corresponds to 50%-100% of normal) for Spring time. However, some locations only received 6”-10” this Spring, which is around 50% of normal. Locations along the OK/KS state line, along with a small portion of southern Haskell County, ended this Spring with rainfall totals of 12”-22” or 110% to near 200% of the normal Spring rainfall.

Outlook

The Climate Prediction Center CPC outlook for June 2012 (issued May 31, 2012) indicates an enhanced chance for above normal temperatures and equal chances for above, near, and below median precipitation for the entire area. This outlook was based primarily on short-term dynamic computer models, which are indicating a persistent ridge pattern over the central U.S.

For the 3-month period June-July-August 2012, CPC is forecasting an enhanced chance for above average temperatures and equal chances for above, near, and below median precipitation across the region (outlook issued May 17, 2012). This outlook is based on dynamic computer model output and statistical forecast tools.

According to CPC, ENSO neutral conditions are ongoing and there is an equal chance for either neutral conditions or El Niño conditions by late this summer and this autumn (a return to La Niña is highly unlikely). CPC has issued an El Niño watch.