This year is threatening to be Oklahoma’s all-time driest, from Gary McManus, Oklahoma Climatological Survey

Posted by
on October 20, 2011M at 10:08 am
Drought intensifies in eastern Oklahoma, CPC releases bleak winter outlook
 
By Gary McManus, Oklahoma Climatological Survey:

There is a lot of information contained in this Ticker, and little of it good.

As has been the case throughout 2011, one part of the state receives a decent rainfall but other areas of Oklahoma spend weeks with little relief. That pattern continued as northeastern Oklahoma missed out on the beneficial rains of two weeks ago. The newest U.S. Drought Monitor map reflects growing concerns over reservoir levels in eastern Oklahoma with an increase in coverage of D3 or “extreme” drought. The coverage of D3-D4 drought increased from 80 percent last week to 87 percent across the state. All of the state is covered by severe-to-exceptional (D2-D4) drought.

 

 

The little bit of rain that fell with the cold front earlier this week was not enough to generate improvement in the drought picture in southeastern Oklahoma where deficits are on the order of 20-25 inches since last October. The rainfall pattern for the month thus far is opposite of what we’ve seen for much of 2011

- above normal moisture in the western half of the state and below normal in the eastern half. Overall, the statewide average rainfall total through October 19 is 1.81 inches, about a quarter of an inch below normal. Deficits are between 1.5-2.5 inches in eastern Oklahoma, however.

 
2011 is shaping up to be one of the state’s driest on record, and is actually threatening the all-time driest year of 19.04″ in 1910. The statewide average total stands at 17.71 inches through the 19th, 12.72 inches below normal.

The Oklahoma Mesonet site at Hooker has only recorded 3.7 inches of precipitation this year, threatening the all-time lowest annual total for a single location of 6.53 inches recorded at the Cimarron County town of Regnier in 1956. Plenty of time remains to avoid those records during 2011, although the state’s driest time of the year is quickly approaching. Normal rainfall for the remainder of the year is approximately 5 inches.
 

The latest U.S. Seasonal Drought Outlook from the NWS’ Climate Prediction Center (CPC) gives little hope for improvement in the Southern Plains drought conditions at least through January 31st. Oklahoma remains firmly ensconced in the “drought to persist or intensify” area thanks to the strengthening La Nina in the equatorial pacific waters.

 Quoting the CPC directly (“HIGH CONFIDENCE FORECAST”):

“Across the southern tier of states and in the central Plains, drought
is expected to persist and expand into adjacent areas. Except for

wetness being favored in Colorado and northern New Mexico for the

6-10 day period, all tools are in remarkable concert, pointing toward

drier than normal conditions. Thus, this is a high confidence forecast.”

The outlooks for November/November-January/December-February are all dominated by the classic La Nina signal, and hold little good news for Oklahoma and the Southern Plains.

 
Winter Outlooks (December-February)

 

The three-month outlooks that blend into spring have similar patterns for both temperature and precipitation. The sea surface temperature models used by the CPC indicate this La Nina could become as strong or even exceed the strength of last winter’s event with three-month anomalies approaching -2 degrees Celsius.

 The resultant precipitation forecasts from those same models tell the story in pictures with precipitation deficits continuing through next spring for the western half of the state.

 
 

 

As I said at the top, there is little good news in this information, especially for Oklahoma agriculture. However, all hope is not lost. Here are some important caveats.
1) We should not necessarily expect the extreme deficits of the last year.

Those were “extreme” extremes, and don’t come around very often (and they were certainly not forecast).

2) Outlooks are not infallible, nor do La Nina impacts always follow the script.

3) A few well-placed precipitation events can keep the current wheat crop going through the worst of what Mother Nature has to offer. If there is one thing Oklahoma agricultural producers know, it’s not always the amount of precipitation that is most important. Timing is everything.

4) No information is contained within these outlooks or forecasts about extreme snow or ice events, although the dry signal would indicate less precipitation of any form. Remember, Oklahoma set its all-time 24-hour snowfall record last February with 27 inches at Spavinaw and the first half of that month was basically one big blizzard. The state’s all-time record low temperature of -31 degrees was reached at Nowata last February 10.

5) Many reservoir levels are very low going into our driest time of the year.

That will become a greater concern should the precipitation deficits continue into the warm months. Water usage bottoms out during the winter months so any precipitation that does fall is very important for recharge. The same goes for soil moisture.

We will continue to monitor the latest from the CPC and other governmental agencies to keep you informed as best as possible. Hopefully there will be better news as we go through the next several months.

 

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Comments
Comment by Jean Mcmahon on October 20, 2011 @ 10:42 pm

Global warming is a factor here and Mr McManus does humanity and Oklahomans a great disservice by not discussing this…He always blows smoke by mentioning La Nina,which is a factor.The oil/gas /companies love him for prolonginmg their power and profit

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