Drought information, according to the Oklahoma Mesonet

A look at rainfall since May 1 of this year. This encapsulates both our primary rainy season (especially May through

mid-June) and then our secondary rainy season of September through early November. Since May 1, the statewide average rainfall total is 12.43″, nearly 13″ below normal (49% of normal) and the driest such period since 1921 and the second driest since 1895.

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Region Avg. Dep. Normal Pct. Normal Rank Since 1921

Panhandle 7.51″ -8.35″ 47% 2nd driest

N. Central 8.15″ -14.84″ 35% 1st driest

Northeast 14.66″ -14.59″ 50% 1st driest

W. Central 9.56″ -11.68″ 45% 2nd driest

Central 13.85″ -12.07″ 53% 2nd driest

E. Central 15.24″ -15.38″ 50% 2nd driest

Southwest 11.49″ -10.74″ 52% 3rd driest

S. Central 14.33″ -12.30″ 54% 5th driest

Southeast 16.89″ -15.76″ 52% 4th driest

Statewide 12.43″ -12.81″ 49% 1st driest

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A look to the future? We do have the arctic front coming through this weekend, but it is not expected to have much precipitation associated with it.

The longer-term wet signal we needed faded away with El Nino, which began to develop in the equatorial pacific ocean waters before mysteriously dissipating to neutral conditions (neither El Nino or La Nina, known otherwise as “ENSO- Neutral”).

 Drought is expected to persist or intensify through the end of February according to the newest U.S. Seasonal Drought Outlook from the NWS’ Climate Prediction Center (CPC).

The longer-term wet signal we needed faded away with El Nino, which began to develop in the equatorial pacific ocean waters before mysteriously dissipating to neutral conditions.

That leaves us with another oceanic player working against us … the Pacific Decadal Oscillation (PDO). This climate index tracks ocean temperature anomalies in the North Pacific. Unlike ENSO, this ocean phenomenon tends to last from two-to-three decades (ENSO from 6 months to a couple of years, usually). When the PDO is in its negative phase, the west pacific warms and the east Pacific cools. This is the pattern we are in now, and we should remain in the negative PDO phase and also ENSO-Neutral conditions through February.

After all of that confusion, here’s the result. When those two patterns combine (the negative PDO and ENSO-Neutral), this is the rainfall pattern that emerges for December-February. This map was made using all the instances of negative PDO and ENSO-Neutral since 1948.

http://ticker.mesonet.org/archive/20121206/PDO.Negative.ENSO.Neutral.jpg

As you can see, Oklahoma is painted with negative precipitation anomalies during this type of climate signal. It’s not necessarily strong across the entire state (i.e., in the Panhandle, north central and southeast areas), but it doesn’t have to be. Remember, we are in our climatological driest part of the year, facing long-term deficits of more than 12 inches! Any hint of dryness during these next three months will keep us in significant drought through that period.

In other words, drier than normal during the driest part of the year spells …dry.

Now keep in mind that this is really the only “known” climate driver over the next few months, so it’s the big player at the moment. However, it’s usually what we don’t know that makes fools of us later.

Here’s the takeaway message: it looks likely at this time that Oklahoma will remain in significant drought conditions through the winter as we begin to emerge into spring. The type of winter relief we had last year is just not showing up, and is frankly already a couple of months behind.

Finally, it is absolutely imperative that we have something close to a normal rainy spring season in Oklahoma or our chances of a full-fledged three-year drought cycle increase dramatically.

 

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