MESONET TICKER ... MESONET TICKER ... MESONET TICKER ... MESONET TICKER ... August 21, 2012 August 21, 2012 August 21, 2012 August 21, 2012
Has drought turned the corner?
The early arrival of September-ish weather has improved, put a dent in, and diminished the progression of drought in many parts of Oklahoma. Now what category your area fits in depends on how much rainfall you received, but the cooler weather has helped all categories. Now that the rains have taken a hiatus for a few days, here's what the final tally looked like (Mesonet sites and radar estimates from the RFC in Tulsa) since last week.
http://ticker.mesonet.org/archive/20120821/rainrfc.168hr.png
The most widespread beneficial rains fell down in southeastern Oklahoma with a nice little area of 2-4 inches. A general area of 0.5-1.0 inches fell across much of central Oklahoma, with some places receiving more, some receiving less. I think it is safe to say that the southeast was one of the areas where drought improvement was realized. The southwest got into the act last night with generally light rain falling, but the extreme tip of that part of the state saw over an inch. The Mesonet site at Hollis received a whopping 1.24 inches.
So how did all of this affect the drought? It's obvious that it improved things in southeastern Oklahoma. A glance at the topsoil moisture data provides clues. http://ticker.mesonet.org/archive/20120821/2inch-soilmoisture.png
Go a bit farther down to the 10-inch and 24-inch soil moisture and the picture becomes a bit more clouded (and dry).
http://ticker.mesonet.org/archive/20120821/10inch-soilmoisture.png http://ticker.mesonet.org/archive/20120821/24inch-soilmoisture.png
A modicum of improvement was seen down in southeastern and south central parts at 10 inches, but very little of the recent moisture made it into the lower depths. As we have talked about many times, relieving drought is a process. The topsoils drank first and in some cases became saturated. Some percolated down to the 10-inch soils, but nothing really made it past that point. And that topsoil and 10-inch moisture is being worked on as we speak from above (by the atmosphere), below, and by plants suddenly thinking it's okay to grow again.
Here are the things we'll be looking for as we assess the drought: rainfall, obviously; soil moisture; lake levels; reports from the field; green-up.
Let's take a look at a test case in Norman, an area in exceptional drought that had gone 70 consecutive days without at least a tenth of an inch of rainfall in a single day. It received 1.4 inches of rain, which is more than they had received the previous 78 days (May 30). The trouble is that still only leaves them with 4.9 inches since May 1, and that's still a deficit of 6-8 inches. In fact, most of the state remains from 2-8+ inches down since May 1. So the 1.4 inches of rainfall is welcomed, but still a bit meager compared to the damage done by the previous months and the extreme heat.
http://ticker.mesonet.org/archive/20120821/may1-aug21-tots.png http://ticker.mesonet.org/archive/20120821/may1-aug21-dep.png
Soil moisture did improve at the 2-inch and 10-inch levels, but they are now on their way back down with too much built-up demands to satisfy. The moisture never reached the 24-inch level as evident by the flat green line. Reinforcing moisture is needed to avoid the type of drop-off shown in June. At least there will not be extreme heat (at least for awhile) to help facilitate that.
http://ticker.mesonet.org/archive/20120821/norman-soilmoisture.png
The reports from the field are not encouraging just yet, as evident from the latest USDA Crop Weather Report from our friends over at the National Agric. Statistics Service.
"Overall the rain was beneficial, but provided no significant improvements to conditions. In most areas there was no run-off to improve water availability for livestock, and hay supplies from the spring were already being used to supplement the lack of pasture. Producers continued culling herds and making difficult decisions in the face of the ongoing drought. Temperatures were significantly cooler than the previous week, with highs averaging from the upper 80s to the low 90s. Ninety-seven percent of topsoil was rated short to very short and subsoil moisture conditions worsened over the past week to 98 percent rated short to very short."
I'm not sure of the dynamics of "waking up" natural grasses, but I would think (DANGER!!) there is still plenty of time to see improvement of our pastures. Unlike last year when the rains returned too late in October.
Lake Thunderbird, Norman's main water supply, did recover a bit ... all the way back to the level it was at on, uhhh, August 16?? And on its way down it goes once again. So little recovery there, and it once again sits at 74% of normal still.
http://ticker.mesonet.org/archive/20120821/thunderbird.gif http://ticker.mesonet.org/archive/20120821/THUN.hp.png
The green-up will take a bit of time. I can see with my own eyes a few more shades of faint green amongst the yellows and browns. But given the right conditions, fire danger will still be a problem. Other than the green trees, which continue to drop leaves, we continue to look very January-ish around these parts.
So those are some of the things we will be looking at as we assess the drought conditions. The cool weather helps, but remember it's "relatively" cool weather. Evaporation is still advanced in the upper 80s and lower 90s. I don't think it's any secret that the Norman area will be remaining in the exceptional drought category with limited relief of most of the known impacts. Other areas received little-to-no rain and will be prospects for deterioration.
More rain is possibly on the way, which will help to reinforce what relief we have seen. Relieving drought is a process. Maybe we've turned the corner just a bit, at least for some.
Gary McManus Associate State Climatologist Oklahoma Climatological Survey (405) 325-2253 gmcmanus@mesonet.org
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