Wednesday, February 6, 2013

The Southeast Drought Continues

Droughts can be insidious.  Just when you think they’re gone, they’re back.  Actually it never went away in the Southeast, it just moved around.  The center of the drought began in northeast Florida in 2011 and moved to southern Georgia a year later.  Now the center of the drought is central Georgia and it is beginning to expand thanks to a dry January.

The Drought Monitor for the end of January 2011-13.  Click on the image for a larger view.  Image Credit: USDA.

The current drought began in the Southeast with the end of El Nino in 2010.  That was followed by two years of La Nina which brought drier than normal conditions particularly in the winter and spring.  The worst of the drought has been centered in central Georgia where extreme to exceptional drought conditions have persisted for two years.

However, drought conditions for southeast Georgia and northeast Florida actually disappeared this past summer thanks to two tropical weather systems (Beryl & Debby) which inundated the region with rain in late May and June.  Drought is creeping back into those areas.

The picture of drought hasn’t change much year-over-year in South Carolina when you look at instantaneous pictures for the end of January.  However, that does not do justice to the drought situation.

The Drought Monitor for South Carolina.  The top image compares January 2012 & 2013.  The bottom image compares the end of the water year in 2012 with the end of January 2013.  Click on either image for a larger view.  Image Credit: USDA.

Last winter and spring were quite warm and dry.  The drought worsened into May.  However, rain began to increase during the month which lasted into the typical summer rainy season.  It was topped off by a surplus of about 4.5 inches in August.  Thus, by the end of the water season (late September), much of the state was out of drought.  The drought has intensified since that time as this winter has been quite dry.

There has been less than an inch and a half of rainfall since the beginning of the year (January 1 – February 5) bringing the deficit to about three inches.  The drought situation has worsened over all of the state with the exception of the mountains.

Prospects for rain are good in both the short-range and medium-range forecasts.  First, there is a very good chance for a system moving along the Gulf region to move rain into the Midlands on Thursday.  The map below is a first look at rainfall from our RPM model.  Amounts of .5 to 1 inch are forecast by the model which is in the mid-range of computer models from the National Weather Service.  Future runs of the computer models will vary depending on how much moisture is drawn into the system.

RPM forecast for rainfall ending 10 a.m. EST on Friday, February 8, 2013, based on data from the 4 p.m. run on February 5th.  Click on the image for a larger view.  Image Credit: WLTX-TV.

Then there will be a pattern change for much of the eastern half of the country going into next week.  Temperatures will be warmer than normal and rainfall will be greater than normal.  It is hard to know how much rain may fall early next week, but the pattern suggests that it could be in the one to two inch range.  There is still considerable uncertainty in that part of the forecast, but it certainly looks like beneficial rains are on the way.  This might be the best rainfall seen since August.

The 6 to 10 day outlook for the period February 11-15, 2013.  The top image is for temperature and the bottom image is for precipitation.  The percentages are for above and below normal values.  Click on the image for a larger view.  Image Credit: NOAA/CPC.

This would be a start to easing the drought, but there is much work to be done by Mother Nature.  The outlook for the spring is for drier than normal conditions.  If this is the case, then the drought will likely get worse before reaching the summer rains.