TWDB Drought Update for the Week of March 11, 2014
Mixed results over the past week: a slight decrease (1.5 percentage points) of the state in
drought and a slight increase (10,000 acre-feet) in reservoir storage but also a slight
increase of the amount of the state in the Exceptional Drought category. The latest U.S.
Drought Outlook looks better than the last one, particularly in South and Far West Texas,
but still projects continuing and developing drought for much of the state.
The El Nino Watch has received a bit of press play over the past week. You can read a
summary report here:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.htm
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El Nino generally means wetter conditions in Texas in fall and winter but can also
suppress tropical storm development.
The key figure from the summary report is this one:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/figure6.gif
which shows a spaghetti plot of the various model projections of sea surface temps in the
eastern mid-Pacific. Take special note of the shaded lines which represent average of the
different models. We need temperatures to rise above 0.5 degrees Celcius to be called an
El Nino. The dynamical model average projection just hits that threshold in June through
November while the statistical model projection doesn't quite make it.
We shall see...
Some notes from Dr. Wentzel:
·
The US Drought Monitors' latest map shows mixed results across the state, a
welcome improvement from the last few weeks which showed steady worsening of
drought. In the last week, the area of the state with no drought impacts (Nothing) was up
more than 1½ percentage points. Severe (D2) and Extreme (D3) Drought areas were
each down more than 1 percentage point. Statewide, Exceptional (D4) Drought was up a
small amount. This included improvement from this drought category in several areas
across the state (near Amarillo and southeast of Uvalde), but a large expansion around
Wichita Falls. More than two thirds of the state remains in Moderate or more severe
drought.
·
In the last week, statewide conservation storage was up less than 10,000 acre-feet, a
change of less than 0.1 percentage points. We are currently more than 2 percentage
points lower than we were at this time last year and about 20 percentage points below
what is considered normal for this time of year. We continue to record the lowest
conservation storage values for this time of year for data going back to 1990.
·
Looking at things by climate region, as of Thursday, March 6th, conservation
storage was up in 1 of the 9 climate regions with reservoirs across the state, unchanged in
3 and down in 5. Changes were relatively small. The only increase was 0.4 percentage
points in the East Texas Region. The largest decrease was 0.3 percentage points, which
occurred in both the North Central and Upper Coast Regions.
·
Conservation storage decreased in 12 of the 20 municipal reservoir systems that we
track across the state, remained unchanged in 4, and increased in 4. Tyler had the largest
increase at 1.6 percentage points. Both Beaumont/Port Arthur and El Paso had increases
of 0.4 percentage points. All other changes were 0.2 percentage points or less.
·
The National Weather Service has released their Monthly Drought Outlook for
March 2014. Through the end of the month, it anticipates some improvement in Eastern
Texas but continued or worsening drought for most of the state. Drought is expected to
expand in west and south Texas.
Download the full report here.