Eastern Kentucky Weather

Raindrops Were Falling On My Head... Not Now Though!

Once again our shot at seeing real rainfall has faded away! So that means that we are slipping into another dry period. Though I do see more activity coming down the road.

Some of my most favorite people in the world are having some serious water issues. That would be the folks in Magoffin County... (for those of you that don't know... I am from Magoffin County) Water officials over there are now saying that they are down to a 3 day supply of water. That is very concerning! While we did see rain across the region, it wasn't enough to help the situation out at all! I don't know the specifics on the issue, but from the news story I read I gathered that their main water supply is running over two feet low. In order to get there water supply back up and running at a normal level we'll need several inches. Just to lower concerns I'd say they need about 6 inches of rain.

I have done a little research here and found some great explanations on Drought.

The Palmer Index was developed by Wayne Palmer in the 1960s and uses temperature and rainfall information in a formula to determine dryness.

The Palmer Index is most effective in determining long term drought—a matter of several months—and is not as good with short-term forecasts (a matter of weeks). It uses a 0 as normal, and drought is shown in terms of minus numbers; for example, minus 2 is moderate drought, minus 3 is severe drought, and minus 4 is extreme drought.

The Palmer Index can also reflect excess rain using a corresponding level reflected by plus figures; i.e., 0 is normal, plus 2 is moderate rainfall, etc.

The advantage of the Palmer Index is that it is standardized to local climate, so it can be applied to any part of the country to demonstrate relative drought or rainfall conditions. The negative is that it is not as good for short term forecasts, and is not particularly useful in calculating supplies of water locked up in snow, so it works best east of the Continental Divide.

The Crop Moisture Index (CMI) is also a formula that was also developed by Wayne Palmer subsequent to his development of the Palmer Drought Index.

The CMI responds more rapidly than the Palmer Index and can change considerably from week to week, so it is more effective in calculating short-term abnormal dryness or wetness affecting agriculture.

CMI is designed to indicate normal conditions at the beginning and end of the growing season; it uses the same levels as the Palmer Drought Index.

It differs from the Palmer Index in that the formula places less weight on the data from previous weeks and more weight on the recent week.

Finally, tracking drought blends science and art. No single definition of drought works for all circumstances, so people rely on drought indices to detect and measure droughts. But no single index works under all circumstances, either. That's why we need the U.S. Drought Monitor, a synthesis of multiple indices and impacts, that represents a consensus of federal and academic scientists. The product will be refined over time as we find ways to make it better reflect the needs of decision-makers and others who use the information.

Why doesn't a drought go away when it rains?

Rainfall in any form will provide some drought relief. A good analogy might be how medicine and illness relate to each other. A single dose of medicine can alleviate symptoms of illness, but it usually takes a sustained program of medication to cure an illness. Likewise, a single rainstorm will not break the drought, but it may provide temporary relief.

A light to moderate shower will probably only provide cosmetic relief. It might make folks feel better for awhile, provide cooling, and make the vegetation perk up. During the growing season, most of the rain that falls will be quickly evaporated or used by plants. Its impact is short term.

A thunderstorm will provide some of the same benefits as the shower, but it also may cause loss of life and property if it is severe. Thunderstorms often produce large amounts of precipitation in a very short time, and most of the rain will run off into drainage channels and streams rather than soak into the ground. If the rain happens to fall upstream of a reservoir, much of the runoff will be captured by the reservoir and add to the available water supply. No matter where the rain falls, stream levels will rise quickly and flooding may result. Also, because the rainfall and runoff can be intense, the resulting runoff can carry significant loads of sediment and pollutants that are washed from the land surface.

Soaking rains are the best medicine to alleviate drought. Water that enters the soil recharges ground water, which in turn sustains vegetation and feeds streams during periods when it is not raining. A single soaking rain will provide lasting relief from drought conditions, but multiple such rains over several months may be required to break a drought and return conditions to within the normal range.

Tropical storm rains are usually of the soaking variety, although they may also be intense such as during a thunderstorm and lead to some of the same problems. Tropical storms often produce more total rainfall than a "regular" soaking rain and can provide longer relief than a single soaking rain. However, tropical rains may also be of such intensity that they exceed the capacity of soil to absorb water and often result in significant runoff and flooding. Tropical rains can help to fill water-supply reservoirs and provide long-term drought insurance. However, the path of a tropical storm is very important in determining its impacts. For example, tropical storms are for the most part a near-coast phenomena whereas water-supply reservoirs may be inland, such as is the case for the Washington, D.C, water supply. If significant rainfall does not occur upstream of reservoirs, the drought relief aspects of tropical storms may be of only little consequence. All things considered, a single tropical storm at the right place, at the right time, and with the right amount of rainfall can break a drought.

Considering all of the above, even when a drought has been broken it may not be truly over. The benefits of substantial rainfall such as from a tropical storm may last for months, but a return to normal rainfall patterns and amounts is necessary for conditions in streams, reservoirs, and ground water to also return to normal.

Unfortunately, our weather pattern will remain on the dry side over the coming days. These days will be comfortable and gorgeous, but that isn't what eastern Kentucky or the rest of the commonwealth needs!

Our next chance of rain will not arrive until next week. I am leaning more towards Tuesday-Wednesday timeframe. It actually looks a little active and this might bring us one step closer to where we need to be, but not out of the drought. Any chance for real relief from a drought would probably rest on the shoulders of a tropical system. We'd either need a couple or one slow mover and then you run into a whole different issue with the ground only being able to take in so much water at a time. That could result in a flood. So our best bet is consistent rain events. Again, this isn't the best time to go looking for that! The outlook appears to stay on the dry side these next few months. In the table below you can see what we should be seeing each month.

Location

October

Normal Amount

November

Normal Amount

December

Normal Amount

Jackson 3.18 4.20 4.27  

So to end the year we normally see 11.65 inches of rainfall. The odds of this happening do not look very well at all. The month of September itself only had 0.67" of rain. That's more than 3 inches below normal!

The U.S. Drought Monitor comes out on Thursday so I will include that in my discussion!

C-Ya Bye

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