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November 2011 & Autumn 2011
- After many months of moderate to exceptional drought across the region, November 2011 brought drought-busting rainfall.
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- Fayetteville: No daily temperature records were set this month.
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- Muskogee: The November 2011 rainfall total was 8.46", making this the wettest November on record (NWS COOP data was used from Jan. 1905-Jun. 2000 and NWS ASOS data was used from Jul. 2000-present). The previous record was 8.29" in 1946.
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- Rainfall totals for November 2011 ranged from around 2.5” in portions of Pawnee and Osage Counties in northeast Oklahoma to an area of 15”-20” in southern Le Flore County in southeast Oklahoma. A large portion of eastern Oklahoma and northwest Arkansas received between 4” and 8” of precipitation during the month. While these rainfall totals corresponded to near to above November rainfall normals across much of the region, a few areas of far northeast Oklahoma and southeast Oklahoma received 75%-90% of the normal November rain. Some areas of east central and southeast Oklahoma, however, received 200% to over 300% of the normal rain for November.
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- The November 6-8 rainfall event was significant, with rainfall totals as high as 6”-8”. Most of the area received at least 1.5” with widespread 3” totals. A large portion of Muskogee County was inundated with 5”-8” of rain by the time the storm system moved east. Roads were closed across much of Muskogee County due to high water, with minor flooding also affecting roadways in portions of Okmulgee and Benton Counties. It is likely that the flash flooding from this event would have been much worse if an extreme-exceptional drought had not been ongoing. The 4”-5” rainfall over much of the Illinois River Basin led to minor flooding along the Illinois River near Watts and near Tahlequah. Several other rivers and creeks across northeast and east central OK rose several feet; however, due to the drought and preceding low flows, no other rivers exceeded flood stage. Additionally, area reservoirs saw significant improvements in conservation storage due to this event, with many lakes reporting an increase in storage of 10% - 30% compared to end of October levels.
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- A second heavy rain event occurred November 20-21, 2011. Showers and thunderstorms brought heavy rain to southeast OK and west central AR. Over 4” of rain fell over Pushmataha and Le Flore Counties, and a portion of southern Le Flore County received 8”-10” of rain. This heavy rain led to severe flash flooding in southern Le Flore County. Several campers were rescued from a campground at Cedar Lake (~13 miles southwest of Heavener). Many swift water rescues were performed and the county had to close multiple roads. The Le Flore County Emergency Manager had reports that 8’-10’ of water was over some of the roads. The NWS cooperative observer in Tuskahoma, OK (near Clayton in northern Pushmataha Co.) measured a 2-day total to 7.30”. The rain gage along the Kiamichi River near Big Cedar (southern Le Flore County) measured a storm total of 7.37” of rain. The river at this point crested at 17.9’ at 05:30Z 11/22/11, which is one of the highest USGS annual crests on record. The rain gage along the Kiamichi River near Clayton measured 6.65” of rain for the 2 days, and the river crested at 18.1’ at 05Z 11/22/11. Storm total rainfall of 6.61” was measured in Honobia, OK. At the NWS river forecast point along the Kiamichi River near Antlers, 5.89” of rain was measured over the 2-day event. This led to minor flooding, with the river cresting at 28.42’ at 2am CST on 11/22/11. At Sardis Lake, a storm total of 5.36” was measured. Wister Lake rose significantly due to this storm system. Prior to the rain, lake levels were near 479.5’. The lake then rose over 12’ in a 2-day period.
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- According to the Drought Monitor from December 6, 2011, significant improvements in drought conditions were made during November 2011. Severe drought (D2) conditions stretched across most of Pawnee, Osage, Washington, and northwest Nowata Counties in eastern Oklahoma. Moderate drought (D1) conditions were found across portions of Craig, Nowata, Rogers, Washington, Tulsa, Creek, Okmulgee, Okfuskee, western McIntosh, Pittsburg, and Choctaw Counties in eastern Oklahoma. Abnormally Dry (D0) conditions affected portions of Ottawa, Craig, Mayes, Rogers, Wagoner, far western Muskogee, eastern McIntosh, far eastern Pittsburg, Latimer, and far western Pushmataha Counties in eastern Oklahoma. No drought conditions were occurring in northwest Arkansas.
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- According to the Oklahoma Climatological Survey (OCS) for November 2011, northeast OK ranked as the 12th wettest, east central OK ranked as the 9th wettest, and southeast OK ranked as the 8th wettest November since records began in 1921. For the year so far (Januray 1, 2011 - November 30, 2011), northeast OK ranked as the 22nd driest, east central OK ranked as the 31st driest, and southeast OK ranked as the 11th driest year on record.
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- Two strong earthquakes affected the region on November 5th. The first earthquake, which was a foreshock, was a magnitude 4.7 and occurred at 02:12:45 AM on the 5th (Nov. 5 07:12:45 UTC) near Prague, OK (20 miles northeast of Shawnee, OK or 41 miles west of Okmulgee, OK). The second earthquake was a magnitude 5.6 and occurred at 10:53:10 PM CDT on the 5th (Nov. 6 03:53:10 UTC). The epicenter was located 5 miles northwest of Prague, OK (21 miles north-northeast Shawnee, OK or about 75 miles southwest of Tulsa, OK) and occurred at a depth of 3.1 miles. This second earthquake was the largest recorded in Oklahoma (previous strongest OK earthquake was M5.5 April 9, 1952 near El Reno, OK) and was clearly felt from Dallas, TX to St. Louis, MO, which are about 300 miles from the epicenter. USGS reports indicated that this quake was felt as far away as Wisconsin and Indiana. The USACE inspected dams within 70 miles of the epicenter, including Keystone, Skiatook, Eufaula, and Heyburn, but no damage was discovered. A third strong aftershock earthquake of magnitude 4.7 occurred 6.4 miles NNW of Prague at 8:46:57 PM CST on the 7th (Nov. 8 2:46:57UTC).
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| Autumn 2011 (September-October-November) |
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- According to the Oklahoma Climatological Survey (OCS) for Autumn 2011, northeast OK ranked as the 43rd driest, east central OK ranked as the 39th wettest, and southeast OK ranked as the 44th driest Autumn since records began in 1921.
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| Outlook |
- The Climate Prediction Center CPC outlook for December 2011 (issued November 30, 2011) indicates a slightly enhanced chance for above normal temperatures across southeast Oklahoma and west central Arkansas, and equal chances for above, near, and below normal temperatures elsewhere. This outlook also indicates an enhanced chance for above median precipitation for all of eastern Oklahoma and northwest Arkansas. This outlook was based primarily on short-term dynamical computer models with La Niña and Madden-Julian Oscillation (MJO) impacts considered.
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- For the 3-month period December-January-February 2011-12, CPC is forecasting an enhanced chance for above average temperatures and below median precipitation across all of eastern Oklahoma and northwest Arkansas (outlook issued November 17, 2011). This is consistent with a La Niña pattern, as well as long-range computer model output and patterns associated with a second winter La Niña during multi-year La Niña events.
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- According to CPC, weak La Niña conditions remained in place at the end of November. La Niña conditions are forecast to strengthen and continue through Winter 2011-12, with impacts waning during Spring 2012.
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